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Preprint Proposalsfor the 2012 Editionof the National Electrical Safety Code

Published by IEEE1 September 2009

The Institute of Electrical and Electronics Engineers, Inc.3 Park Avenue, New York, NY 10016-5997, USA

Copyright © 2009 by the Institute of Electrical and Electronics Engineers, Inc.All rights reserved. Published 1 September 2009. Printed in the United States of America.

IEEE is a registered trademark in the U.S. Patent & Trademark Office, owned by the Institute of Electrical and ElectronicsEngineers, Incorporated.

National Electrical Safety Code and NESC are both registered trademarks and service marks of the Institute of Electricaland Electronics Engineers, Incorporated.

National Electrical Code and NEC are both registered trademarks of the National Fire Protection Association, Inc.

PDF: ISBN 978-0-7381-5958-4 STD95934CD-ROM: ISBN 978-0-7381-5959-1 STDCD95934

No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the priorwritten permission of the publisher.

Foreword

This publication has been prepared to provide all interested persons an opportunity to study and comment onthe Proposed Revisions to be incorporated into the 2012 Edition of the National Electrical Safety Code(NESC®).

This Preprint provides the full text of each proposal to revise the 2007 Edition of the NESC together with therecommendation of the subcommittee that has cognizance of the rule addressed by the change proposal (CP).

The deadline for receipt of comments on the Proposal Revision contained herein is 1 May 2010. Allcomments shall be submitted through the Web site shown below. Only comments that are submittedelectronically through the Web site will be accepted.

http://standards.ieee.org/nesc/rp/welcome.html

Comments for each separate topic are to be uploaded separately using the template at the following URL:

http://standards.ieee.org/nesc/rp/Comment.doc.

In those cases where a single CP or a group of related CPs affects rules within the scopes of two or moresubcommittees, the recommendation of all subcommittees affected are included. Where the recommendationof two or more subcommittees are not compatible with each other, a recommendation by Subcommittee 1,which is responsible for coordination, is also included.

Please note that the subcommittee recommendations herein are subject to further review and revision by thecognizant subcommittee following study and evaluation of all comments received. The subcommittee finalrecommendation will be prepared for a January 2011 letter ballot of the National Electrical Safety CodeCommittee. It is anticipated that the approved text will be submitted for American National StandardsInstitute approval in May 2011, with publication of the NESC 2012 Edition on 1 August 2011.

Copyright © 2009 IEEE. All rights reserved. iii


Procedure for Revising the National Electrical Safety Code

1. Preparation of Proposals for Amendment

NOTE: The procedures for the collection of change proposals are subject to change as the revision ofthe 2012 Edition of the NESC approaches. Logon to the NESC Zone at http://standards.ieee.org/nesc/for updates.

1.1 A proposal may be prepared by any

(a) Substantially interested person(b) Interested organization(c) NESC Subcommittee(d) Member of the NESC Committee or its subcommittees

1.2 Change proposals shall be submitted to Secretary of the National Electrical Safety CodeCommittee via the following URL: http://standards.ieee.org/nesc/rp/welcome.html, using thechange proposal form on the Web site.

1.3 Each separate topic shall begin on a separate form and shall only address one rule, unless a changein a rule directly affects another rule. If a proposal references documents not readily available to allsubcommittee members, sufficient copies of the referenced documents to supply the subcommitteemust be furnished.

1.4 The proposal shall consist of

(a) A statement, in NESC rule form, of the exact change, rewording, or new material proposed(b) Words to be deleted shall be indicated via strike-throughs, and words to be added shall be

underlined. (c) The name of the submitter (organization or individual as applicable)(d) Supporting comments, giving the reasons why the NESC should be revised

(NOTE: A change proposal will not be accepted if these steps are not followed.)

2. The NESC Secretary will

(a) Acknowledge receipt of proposals for revision(b) Distribute to each member of the appropriate NESC Subcommittee all of the proposals

received, arranged in a coordinated sequence

3. Subcommittee recommendation

The NESC Subcommittee responsible will consider each proposal and take one or more of thefollowing steps:

(a) Endorse the proposal as received.(b) Prepare a proposed revision or addition for the NESC (this may be a coordination of several

comments, or a committee consensus on a modification of a proposal).(c) Refer the proposal to a technical working group for detailed consideration.(d) Request coordination with other NESC Subcommittees.(e) Recommend rejection of the proposal, for stated reasons.

For each item, the responsible subcommittee shall prepare a voting statement, accompanied by allmembers’ statements concerning their votes (cogent reasons are required for negative votes). Steps (c)and (d) are intended to result, eventually, in a proposal of category (b).

iv Copyright © 2009 IEEE. All rights reserved.



Action under steps (c) or (d) shall be completed and reported to the subcommittee before the end of thepublic review period if the item is to be included in the upcoming revision.

4. Preprint of proposals

The NESC Secretary shall organize and publish a Preprint of the proposed revisions including:

(a) The original proposal as received from the submitter.

(b) The recommendation of the subcommittee with respect to the proposal (including a votingstatement and subcommittee members’ statements).

(c) Copies of submittal form for comments.

The Preprint shall be distributed to all members of NESC Subcommittees and representatives oforganizations comprising the NESC Committee. Copies shall be available for sale to otherinterested parties. Notice of availability of the Preprint shall be submitted to ANSI for publicationin ANSI Standards Action. The Preprint shall carry information on how to submit comments on theproposals and the final date for such submissions.

5. Final processing of proposed revisions and comments

5.1 Following the public review period, the Secretary shall organize and distribute for subcommitteeconsideration all comments received electronically via the following URL: http://standards.ieee.org/nesc/rp/welcome.html.

5.2 The Preprint and the comments received shall be reconsidered by the subcommittees. No newchange proposals may be considered.

(a) The subcommittee may recommend adoption or rejection of the proposal by majority vote.

(b) When extended technical consideration or resolution of differing or conflicting points of viewis necessary, the subcommittee shall refer the problem to a working group of the subcommitteefor proposed resolution. If expeditious resolution is not possible, the subject shall be held onthe docket.

Each working group shall provide, to its parent subcommittee, recommendations on mattersconsidered as a result of subcommittee referrals under items 3(c) and 5.2(b).

Each subcommittee shall prepare a report showing its proposed revisions and all items held on thedocket together with a plan for their disposition.

5.3 The Secretary shall provide commenters with copies of actions taken on the rules affected by theircomments, and shall make all such reports available for examination upon request.

6. Final approval

6.1 Based upon the subcommittee reports, the Secretary shall prepare a draft of the revision of theNESC and distribute copies to

(a) The NESC Committee for approval by a six-week letter ballot

(b) The American National Standards Institute Board of Standards Review for concurrent 60-daypublic review

6.2 Comments received in response to the letter ballot and public review shall be referred to theExecutive Subcommittee for resolution or referral to the appropriate subcommittee. Those items onwhich consensus cannot be reached shall be referred to the appropriate subcommittee forconsideration during the next revision cycle. Unless a consensus for revision is established, therequirements of the current edition shall carry over to the proposed edition.

Copyright © 2009 IEEE. All rights reserved. v

Committee Membership

Michael J. Hyland, Chair James R. Tomaseski, Vice Chair

O. C. Amrhyn, Past Chair William A. Ash, SecretaryOrganization represented Voting position Name Employed by

Chair (Principal) Michael J. Hyland American Public Power Association

Past Chair (Principal) O. C. Amrhyn OPEC

AEIC (Principal) Swapan Dey NSTAR Electric & Gas Corp.

(Alternate) Billy Raley Progress Energy

APPA (Principal) Nathan Mitchell American Public Power Association

APTA (Principal) George S. Pristach Parsons Brinckerhoff

ATIS (Principal) Lawrence M. Slavin Outside Plant Consulting Services, Inc.

BPA (Principal) Maggie Emery Bonneville Power Administration

EEI (Principal) Ewell T. Robeson Progress Energy

(Alternate) Edward Harrel Oncor Electric Delivery

EIA (Principal) Percy E. Pool Verizon Network Services

(Alternate) Marie Shaw Verizon Network Services

IBEW (Principal) James R. Tomaseski IBEW

IEC (Principal) James C. Tuggle Malpaso Group Inc.

(Alternate) Robert W. Baird Independent Electrical Contractors

(Alternate) John Masarick Independent Electrical Contractors

IEEE (Principal) Frank A. Denbrock D&A Consulting Engineers

(Alternate) Vernon R. Lawson Allgeier, Martin & Associates

Intl Munic Sign Assn (Principal) Warren S. Farrell International Municipal Signal Association

NARUC (Principal) Paul Emerson NY State Dept. of Public Service

NCTA (Principal) Rex Bullinger National Cable Television Association

(Alternate) Christopher Austin Time Warner Cable, NYC-Liberty Division

NECA (Principal) O. L. Davis Manzano-Western Incorporated

NEMA (Principal) Vincent Baclawski National Electrical Manufacturers Assoc.

(Alternate) Scott Choinski National Electrical Manufacturers Assoc.

NRECA (Principal) Robert D. Saint National Rural Electric Cooperative Assoc.

(Alternate) Michael C. Pehosh National Rural Electric Cooperative Assoc.

NSC (Principal) Kenneth Schriner Western Area Power Admininstration

NSPE (Principal) Robert S. Fuller Texas-New Mexico Power Co.

RUS (Principal) Georg A. Shultz Rural Utilities Service

SCTE (Principal) Timothy Cooke Times Fiber Communications, Inc.

TVA (Principal) Clayton L. Clem TVA Power System Operations

(Alternate) Stephen Cantrell TVA Power System Operations

WAPA (Principal) Jeffrey Wild WAPA

Canadian Stds Assoc. Liaison David Singleton Cogeco Cable Canada Inc.

vi Copyright © 2009 IEEE. All rights reserved.

Subcommittee 1Purpose, Scope, Application, Definitions, and References

(Sections 1, 2, and 3)

Allen L. Clapp, Chair Charles C. Bleakley, Secretary

Subcommittee 2Grounding Methods

(Section 9)John B. Dagenhart, Chair Ewell T. Robeson, Secretary

Name Voting position Employed by Organization represented

Donald Hooper (Principal) ES&C, Inc. Int. SC

Michael J. Hyland (Principal) American Public Power Association Main

Allen L. Clapp (Principal) Clapp Research Associates, P.C. SC1

John B. Dagenhart (Principal) Clapp Research Associates, P.C. SC2

Ewell T. Robeson (Alternate) Progress Energy SC2

D. J. Christofersen (Principal) CeCe SC3

Gary R. Engmann (Alternate) IEEE PES/Sub SC3

David G. Komassa (Principal) We Energies SC4

Eric K. Engdahl (Alternate) American Electric Power SC4

Frank A. Denbrock (Principal) D&A Consulting Engineers SC5

Charles C. Bleakley (Principal) Retired SC7

John C. Spence (Alternate) Baltimore Gas & Electric Co. SC7

James R. Tomaseski (Principal) IBEW SC8

Samuel Stonerock (Alternate) Southern California Edison Co. SC8


Trevor Bowmer (Principal) Telcordia ATIS

Michael M. Dixon (Principal) Ameren EEI

Robert Molde (Principal) Xcel Energy EEI

Gregory Obenchain (Alternate) Edison Electric Institute EEI

Justin Rush (Alternate) Westar Energy EEI

Lauren E. Gaunt (Alternate) Northeast Utilities EEI

Marcus Schlegel (Alternate) American Electric Power EEI

Ron Wellman (Alternate) American Electric Power EEI

Timothy P. Hayden (Alternate) National Grid EEI

Ewell T. Robeson (Principal) Progress Energy EEI

Percy E. Pool (Principal) Verizon Network Services EIA

John Korman (Alternate) National Grid EIA

James R. Tomaseski (Principal) IBEW IBEW

Copyright © 2009 IEEE. All rights reserved. vii

Subcommittee 3Electric Supply Stations

(Sections 10–19)D. J. Christofersen, Chair Gary R. Engmann, Secretary

Donald W. Zipse (Principal) Zipse Electrical Engineering Inc. IEEE/IAS

John B. Dagenhart (Principal) Clapp Research Associates, P.C. IEEE/PES/T&D

Ned Maxwell (Principal) Public Utililties Commission of OH NARUC

Roger J. Montambo (Principal) Galvan Industries NEMA

Robert D. Saint (Principal) National Rural Electric Cooperative Assoc.

NRECA

Michael C. Pehosh (Alternate) National Rural Electric Cooperative Assoc.

NRECA

Harvey L. Bowles (Principal) Rural Utilities Service RUS

Timothy Cooke (Principal) Times Fiber Communications, Inc. SCTE

Keith Reese (Principal) Georgia Power Company SEEX

John Bruce (Alternate) Dominion Virginia Power SEEX


Alton L. Comans (Principal) Alabama Power Company AEIC

James Houston (Alternate) Alabama Power Company AEIC

George Zaczek (Principal) Eugene Electric & Water Board APPA

Brian Winoski (Principal) Niagara Mohawk Power Corp. EEI

Kenneth Posey (Alternate) American Electric Power EEI

Kevin Robinson (Alternate) American Electric Power EEI

Timothy Jyrkas (Alternate) Xcel Energy EEI


D. J. Christofersen (Principal) CeCe IEEE/PES/SUB

Gary R. Engmann (Principal) Burns and McDonnell Engineering IEEE/PES/SUB

W. Bruce Dietzman (Principal) Oncor Electric Delivery Company IEEE/PES/SUB

Kenneth D. White (Alternate) Georgia Transmission Corporation IEEE/PES/SUB

Keith Harrison (Principal) KAMO Power Cooperative NRECA

Robert D. Saint (Alternate) National Rural Electric Cooperative Assoc.

NRECA

Mark A. Konz (Principal) Gulf Power Company SEEX

Christopher A. Carson (Alternate) Georgia Power Company SEEX


viii Copyright © 2009 IEEE. All rights reserved.

Subcommittee 4Overhead Lines—Clearances(Sections 20, 21, 22, and 23)

David G. Komassa, Chair Eric K. Engdahl, Secretary


Charles C. Bleakley (Principal) Retired AEIC

Keith Reese (Alternate) Georgia Power Company AEIC

Jan Howard (Principal) Owensboro Municipal Utilities APPA

Lawrence M. Slavin (Principal) Outside Plant Consulting Services, Inc. ATIS


Dennis Henry (Alternate) Telcordia ATIS

Maggie Emery (Principal) Bonneville Power Administration BPA

Allen L. Clapp (Principal) Clapp Research Associates, P.C. Consultant

Donald E. Hooper (Principal) ES&C, Inc. Consultant

O. C. Amrhyn (Principal) OPEC Consultant

Rudolph J. Bednarz (Principal) JayCo Engineering, Inc. Consultant

David G. Komassa (Principal) We Energies EEI

Eric K. Engdahl (Principal) American Electric Power EEI

Kevin Drzewiecki (Principal) National Grid EEI

Mickey B. Gunter (Principal) Engineering Consultant EEI

Thomas R. Crowell (Principal) OH Distribution Design Engineer AIP Public Service Co. of Oklahoma

EEI

Tracy Dencker (Alternate) Ameren EEI

Barrett Thomas (Alternate) American Electric Power EEI

Frank Tucker (Alternate) American Electric Power EEI

Alan Kuipers (Alternate) Consumer Energy EEI

Chris Ann Shellberg (Alternate) Consumer Energy EEI


Jeffrey Steiner (Alternate) National Grid EEI

Jeffery Hall (Alternate) Florida Power and Light EEI

Alan T. Young (Principal) Verizon Network Services EIA

Mark Berlinger (Alternate) Verizon Network Services EIA

Joseph Renowden Emeritus


Marc Candels (Principal) Candels Consulting IEC

Robert G. Oswald (Principal) Power Engineers, Inc. IEE/PES/T&D

Mathew C. Schwarz (Principal) HDR Engineering, Inc. IEEE/IAS

Darren Gill (Principal) Pennsylvania Public Utility Commission

NARUC

Christopher Austin (Principal) Time Warner Cable NCTA

Rex Bullinger (Alternate) National Cable Television Association NCTA

Copyright © 2009 IEEE. All rights reserved. ix

Subcommittee 5Overhead Lines—Strength and Loading

(Sections 24, 25, and 27)

Frank A. Denbrock, Chair Allen L. Clapp, Secretary

Steve Mace (Alternate) National Cable & Telecommunication Assoc.

NCTA

Ernest H. Neubauer (Principal) Southern Rivers Energy NRECA


NRECA

Charles Crawford (Principal) Oncor Electric Delivery NSPE

David J. Marne (Principal) Marne and Associates, Inc. NSPE

Donald Junta (Principal) Rural Utilities Service RUS

Joseph J. White (Principal) KCI Technologies SEEX

Donnie Trivitt (Alternate) OG&E Electric Services SEEX

Branch Davis (Alternate) Entergy Corporation SEEX


John Busel (Principal) ACMA ACMA

Brian Lacoursiere (Alternate) RS Technogies ACMA

Dustin Troutman (Alternate) Creative Pultrusions Inc. ACMA

Helen Chen (Principal) American Iron and Steel Institute AISI

Richard Aichinger (Alternate) Valmont-Newmark AISI

Christopher Jones (Principal) Springfield City Utilities APPA

Joseph Rempe (Principal) Tacoma Power APPA


Nelson G. Bingel (Principal) Osmose Utilities Services, Inc. AWPA

Leon Kempner (Principal) Bonneville Power Administration BPA

Allen L. Clapp (Principal) Clapp Research Associates, P.C. Consultant

Bruce Freimark (Principal) American Electric Power EEI

C. Jerry Wong (Principal) Florida Power & Light EEI

Edward Harrel (Principal) Western Area Power Administration EEI

Jeffrey Erdle (Principal) Duke Energy EEI

Richard J. Standford (Principal) National Grid EEI

Robert O. Kluge (Principal) American Transmission Company EEI

Ronald Cotant (Principal) American Electric Power EEI

John-Chung Ng (Alternate) American Electric Power EEI

David West (Alternate) Duke Power Company EEI

G. Paul Anundson (Alternate) National Grid EEI

Bryan L. Williams (Alternate) Oncor EEI


x Copyright © 2009 IEEE. All rights reserved.

Mark Berlinger (Prinicipal) Verizon Network Services EIA

Alan T. Young (Alternate) Verizon Network Services EIA

Frank A. Denbrock (Principal) D&A Consulting Engineers IEE/PES/T&D

Andrew Schwalm (Principal) Victor Insulators, Inc. IEEE

Donald Soderberg, Jr. (Principal) Consumers Energy IEEE

Robert C. Peters (Principal) RCP Engineering IEEE

Richard W. Hensel (Alternate) CMS Energy IEEE

Walter D. Jones (Principal) Stanley Consultants, Inc. IEEE/IAS

Grant Glaus (Principal) Marne and Associates, Inc. Marne and Assoc.

Jacob Joplin (Principal) Carteret-Craven Electric Cooperative NCEMC

Rex Bullinger (Principal) National Cable Television Association NCTA

Steve Mace (Alternate) National Cable & Telecommunication Assoc.

NCTA

Christopher Austin (Alternate) Time Warner Cable, NYC-Liberty Division

NCTA

Jim Byrne (Principal) Poudre Valley Rural Electric Association, Inc.

NRECA


NRECA

Robert S. Fuller (Principal) Texas-New Mexico Power Co. NSPE

Otto J. Lynch (Principal) Power Line Systems, Inc. Power Line Systems

Thomas Haire (Principal) Rutherford EMC REMC

Donald G. Heald (Principal) RUS-U.S. Dept. of Agriculture RUS

Robert Lash (Alternate) Rural Utilities Services RUS


Ron Corzine (Principal) Georgia Power SEEX

Wade Shultz (Principal) Alabama Power Company SEEX

Frank Agnew (Alternate) Alabama Power Company SEEX

Russell Guerry (Alternate) Edgecombe-Martin County EMC SEEX

Clayton L. Clem (Principal) TVA Power System Operations TVA

Douglas Hanson (Principal) Western Area Power Administration WAPA

Terry Burley (Alternate) Western Area Power Administration WAPA


Copyright © 2009 IEEE. All rights reserved. xi

Subcommittee 7Underground Lines

(Sections 30–39)Charles C. Bleakley, Chair John C. Spence, Secretary


Michael Dyer (Principal) Salt River Project APPA

George S. Pristach (Principal) Parsons Brinckerhoff APTA




James D. Mars (Principal) Genesis Engineering, Inc. Consultant

O. C. Amrhyn (Principal) OPEC Consultant

Dennis B. Miller (Principal) Exelon Energy Delivery EEI

John C. Spence (Principal) Baltimore Gas & Electric Co. EEI

Lauren E. Gaunt (Principal) Northeast Utilities EEI

Donald Guinn (Alternate) Progress Energy EEI


Jonathan Gonynor (Alternate) National Grid EEI

Katie Croteau (Alternate) National Grid EEI

Raymond Pregler (Alternate) American Electric Power EEI

John Korman (Principal) Verizon Network Services EIA

Percy E. Pool (Alternate) Verizon Network Services EIA


James Cowan (Principal) Wakker Engineering IEC

Ewell T. Robeson (Principal) Progress Energy IEEE

Richard S. Vencus (Principal) Northeast Utilities IEEE

Christopher Austin (Principal) Time Warner Cable, NYC-Liberty NCTA

Rex Bulinger (Alternate) National Cable Television Association NCTA

Steve Mace (Alternate) National Cable & Telecommunication NCTA

Monte Szendre (Principal) Wilson Construction Company Inc. NECA

Michael C. Pehosh (Principal) National Rural Electric Cooperative Assoc.

NRECA

Robert D. Saint (Alternate) National Rural Electric Cooperative Assoc.

NRECA

Trung Hiu (Principal) Rural Development-Electric Program RUS


Charles C. Bleakley (Principal) Retired SEEX

Mickey B. Gunter (Principal) Engineering Consultant SEEX

Michael Kosinski (Alternate) Appalachian Power Company SEEX

xii Copyright © 2009 IEEE. All rights reserved.

Subcommittee 8Work Rules

(Sections 40–44)

James R. Tomaseski, Chair Samuel Stonerock, Secretary


Greg Herbinger (Principal) Alabama Power Company AEIC

William C. Weintritt (Alternate) Gulf Power Company AEIC

Brent McKinney (Principal) City Utilities of Springfield APPA

Kevin Dody (Alternate) City Utilities of Springfield APPA

Wayne Blackley (Principal) Associated Training Corporation ATC


Trevor Bowmer (Alternate) Telcordia ATIS

Charles W. Grose (Principal) Consultant Consultant

J. Frederick Doering (Principal) J. F. Doering Associates Consultant

Tommy Russell (Principal) American Electric Power EEI

Michael Granata (Principal) AEP EEI

Samuel Stonerock (Principal) Southern California Edison Co. EEI

Alan Kuipers (Alternate) Consumer Energy EEI

Thuy Nguyen (Alternate) American Electric Power EEI

Patrick Geoffrey (Alternate) PG&E EEI

Larry Nash (Alternate) Dominion Virginia Power EEI

George Kerstetter (Principal) Verizon EIA

John Korman (Alternate) Verizon EIA

James R Tomaseski (Principal) IBEW IBEW

Charles Woodings (Principal) Anderson & Wood Constructions Co. Inc.

IEC

James C. Tuggle (Alternate) Malpaso Group Inc. IEC

Robert W. Baird (Alternate) IEC IEC

Lawrence Schweitzer (Principal) InfraSource Power IEEE/PES/T&D

Thomas Verdecchio (Principal) PSE&G IEEE/PES/T&D

Stephen Poholski (Principal) Newkirk Electric NECA

Kenneth Brubaker (Principal) National Rural Electric Cooperative Assoc.

NRECA

Mark Zavislan (Alternate) Ohio Rural Electric Cooperatives, Inc. NRECA

Albert Smoak (Principal) Southwestern Electric Power Company NSPE

F. M. Brooks (Principal) Brooks & Jackson, Inc. NSPE

Steven Theis (Principal) MYR Group, Inc. NUCA

Brian Erga (Principal) ESCI Inc. NWPPA

David M. Wallis (Principal) OSHA Office of Engineering Safey OSHA

Charles Shaw (Principal) Alabama Power Company SEEX

Copyright © 2009 IEEE. All rights reserved. xiii

Executive Subcommittee

Michael J. Hyland, Chair James R. Tomaseki, Vice Chair

Interpretations Subcommittee

Donald E. Hooper, Chair

Bruce Gurley (Principal) Duke Energy SEEX

Edward Hunt (Principal) WAPA WAPA

Jeffrey Wild (Alternate) WAPA WAPA

Name Employed by Organizationrepresented

Ewell T. Robeson Outside Plant Consulting Services, Inc. EEI

Frank A. Denbrock D&A Consulting Engineers IEEE

James R. Tomaseski IBEW IBEW

Leon Kempner Progress Energy BPA

Lawrence M. Slavin Outside Plant Consulting Services, Inc. ATIS

Michael J. Hyland American Public Power Assoc. APPA

O. C. Amrhyn OPEC Consultant

Name Employed by Part Section

O. C. Amrhym OPEC A

Rudolph J. Bednarz JayCo Engineering, Inc. A

Charles C. Bleakley Retired A

D. J. Christofersen CeCe 1

Allen L. Clapp Clapp Research Associates, P.C. A

Alton L. Comans Alabama Power Company 1 9

John B. Dagenhart Clapp Research Associates, P.C. 2 9

O. L. Davis Manzano-Western Incorporated 3

Frank A. Denbrock D&A Consulting Engineers A

Eric K. Engdahl American Electric Power A

Gary R. Engmann Burns and McDonnell Engineering 1

Bruce Freimark American Electric Power 2

Charles W. Grose Consultant 4

Mickey B. Gunter Retired A

Donald E. Hooper ES&C, Inc. A

Herman N. Johnson, Jr. Shaw Energy Delivery Services, Inc. A

Robert G. Oswald Power Engineers, Inc. 2

Percy E. Pool Verizon Network Services 3 9


xiv Copyright © 2009 IEEE. All rights reserved.

Lisa PerryCoordinating Program Manager

IEEE Standards

Ewell T. Robeson Progress Energy 3 9

Wayne B. Roelle Consultant 2

Lanny L. Smith Consultant A

James R. Tomaseski IBEW A

A = All areas, P1 = Part 1, P2 = Part 2, P3 = Part 3, P4 = Part 4, S9 = Section 9 GroundingWhen a member has S9 and a Part number, they cover grounding and grounding for that part.

Name Employed by Part Section

AAR—Association of American RailroadsACMA—American Composites Manufacturers AssociationAEIC—Association of Edison Illuminating CompaniesAISI—American Iron and Steel InstituteAPPA—American Public Power AssociationAPTA—American Public Transit AssociationATIS—Alliance for Telephone Industry SolutionsAWPA—American Wood Preserves AssocationBPA—Bonneville Power Admin., U.S. Dept. of EnergyEEI—Edison Electric InstituteEIA—Electronic Industries AssociationIBEW—International Brotherhood of Electrical WorkersIEC—Independent Electrical ContractorsIEEE—Institute of Electrical and Electronics Engineers, Inc.IMSA—International Municipal Signal AssociationNARUC—National Association of Regulatory Utility

Commissioners

NCEMC—North Carolina Electric Membership CooperativeNCTA—National Cable Television AssociationNECA—National Electrical Contractors AssociationNEMA—National Electrical Manufacturers AssociationNRECA—National Rural Electric Cooperative AssociationNSC—National Safety CouncilNSPE—National Society of Professional EngineersOHSA—Occupational Safety and Health AdministrationREMC—Rutherford Electric Membership CorporationRUS—Rural Utilities Services, U.S. Dept. of AgricultureSCTE—Society of Telecommunication EngineersSEEX—Southeastern Electric ExchangeTVA—Tennessee Valley AuthorityWAPA—Western Area Power Administration, U.S. Dept. of

Energy

Copyright © 2009 IEEE. All rights reserved. xv

xvi Copyright © 2009 IEEE. All rights reserved.

Contents

Foreword ................................................................................................................................................ iii

Procedure for Revising the National Electrical Safety Code ................................................................. iv

Committee Membership ......................................................................................................................... vi

NESC Rules

Group 1. General ...................................................................................................................................... 1

Index ............................................................................................................................................... 35

Section 1. Introduction to the National Electrical Safety Code ...................................................... 36

Section 2. Definitions of special terms ........................................................................................... 64

Section 3. References ...................................................................................................................... 96

Section 9. Grounding methods for electric supply and communications facilities ........................ 97

Part 1. Rules for the Installation and Maintenance of Electric Supply Stations and Equipment ......... 124

Part 2. Safety Rules for the Installation and Maintenance of Overhead Electric Supply and Communication Lines, Sections 20–27 .................................................................................. 149

Part 3. Safety Rules for the Installation and Maintenance of Underground Electric Supply and Communication Lines ............................................................................................................ 505

Part 4. Rules for the Operation of Electric Supply and Communication Lines and Equipment .......... 546

Appendices

Appendix A .................................................................................................................................. 675

Appendix C ................................................................................................................................... 680

Appendix E ................................................................................................................................... 696

Time schedule for the next revision of the National Electrical Safety Code .............................................. 699

Copyright © 2009 IEEE. All rights reserved. xvii

Group 1. General

Revised Text

CP3442

Section: 3 Z535 references

Also Part: 1 Section: 11 110 A1 SC3

Part: 1 Section: 12 124 C1 SC3

Part: 1 Section: 14 146 B SC3

Part: 2 Section: 21 217 A1c SC4

Part: 2 Section: 21 217 A2a SC4


Part: 3 Section: 38 381 G2 SC7

Part: 4 Section: 41 411 D SC8

Submitter

Allen Clapp

Proposed Change

Revise Section 3 to show the appropriate Z535 standards information.

Revise the NOTES in Rules 110A1, 217A1c, 323C4, and 381G2 to refer to the correct applicable portions ofthe ANSI Z535 standards family and change the status from NOTE to Rule. In addition, revise Rule 411D torefer to applicable standards in the Z535 family.

Section 3. References

ANSI Z535.1-2006, American National Standard for Safety Colors Code. [Rules 110A1 NOTE, 124C1,146B, 217A1c NOTE, 217A2a, 323C4 NOTE, 381G2 NOTE, and 411D]

ANSI Z535.2-20062007, American National Standard for Environmental and Facility Safety Signs. [Rules110A1 NOTE, 124C1, 146B, 217A1c NOTE, 217A2a, 323C4 NOTE, 381G2 NOTE, and 411D]

ANSI Z535.3-20062007, American National Standard for Criteria for Safety Symbols. [Rules 110A1NOTE, 124C1, 146B, 217A1c NOTE, 217A2a, 323C4 NOTE, 381G2 NOTE, and 411D]

ANSI Z535.4-20062007, American National Standard for Product Safety Signs and Labels. [Rules 110A1NOTE, 124C1, 146B, 217A1c NOTE, 323C4 NOTE, 381G2 NOTE, and 411D]

ANSI Z535.5-20062007, American National Standard for Accident PreventionSafety Tags and BarricadeTapes (for Temporary Hazards). [Rules 110A1 NOTE, 217A1c NOTE, 323C4 NOTE, 381G2 NOTE, and411D]

ANSI Z535.6-2006, American National Standard for Product Safety Information in Product Manuals,Instructions, and Other Collateral Materials [411D]

Copyright © 2009 IEEE. All rights reserved. 1

PREPRINT PROPOSALS FOR THE 2012 EDITION

Rule 110A1

NOTE: ANSI Z535.1-2006, ANSI Z535.2-2006, ANSI Z535.3-2006, ANSI Z535.4-2006, and ANSIZ535.5-2006 contain information regarding safety signs.

Permanent safety signs in or on electrical supply station facilities shall meet the requirements of ANSIZ535.1-2006—Safety Colors and either ANSI Z535.2-2007—Environmental and Facility Safety Signs orANSIZ535.4-2007—Product Safety Signs and Labels, as applicable. Where symbols are used to replacewords in a safety message, such symbols shall be verified for comprehension to meet the requirements ofANSI Z535.3—Criteria for Safety Symbols.

Rule 124C1



Rule 146B



Rule 217A1c



Rule 217A2a



2 Copyright © 2009 IEEE. All rights reserved.

OF THE NATIONAL ELECTRICAL SAFETY CODE

Rule 323C4



Rule 381G2


Permanent safety signs in or on underground utility facilities (including aboveground apparatus) shall meetthe requirements of ANSI Z535.1-2006—Safety Colors and either ANSI Z535.2-2007—Environmental andFacility Safety Signs or ANSIZ535.4-2007—Product Safety Signs and Labels, as applicable. Wheresymbols are used to replace words in a safety message, such symbols shall be verified for comprehension tomeet the requirements of ANSI Z535.3—Criteria for Safety Symbols.

Rule 411D

D. Signs, and tags, and barricade tapes for employee safety

Safety signs, and tags, and barricade tapes required by Part 4 shall comply with the provisionsmeetthe requirements of ANSI Z535.1-2006—Safety Colors, ANSI Z535.2-2007—Environmental andFacility Safety Signs, ANSI Z535.4-2007—Product Safety Signs and Labels, or ANSI Z535.5-2007—Safety Tags and Barricade Tapes, as applicable. through ANSI Z535.5-2006, inclusive.Where symbols are used to replace words in a safety message, such symbols shall be verified forcomprehension to meet the requirements of ANSI Z535.3—Criteria for Safety Symbols.

Safety information included in training manuals should meet the requirements of ANSI Z535.6-2006—Product Safety Information in Product Manuals, Instructions, and Other CollateralMaterials.

Supporting Comment

The various standards in the Z535 safety sign and label family were revised in 2006 and 2007. Some of thenames changed. As a result, references to the standards need to be updated.

The modern safety sign and label standards of the ANSI Z535 series were first promulgated from the old Z53safety color code and Z35 safety sign standards and published in 1992. Representatives of the NESC havebeen active on this standards body since 1992 to assure that changes reflected good practice for electric supplyand communication utilities (Allen Clapp—Chair SC1, member C4, Secretary SC5, member Interpretations,and member of C2 Main Committee until 2008, and Chair ANSI Z535.2, and John Dagenhart—Chair SC2,member SC1, and member Interpretations representing IEEE on Z535; and David Young—member SC4representing EEI on Z535).

These Z535 standards have reached mature status and should be adopted as requirements (instead of beingreferenced in NOTES) for environmental and facility safety signs in Parts 1, 2, and 3. Z535 standards arealready required for worker safety signs in Part 4.



Previous references to the Z535 standards in the NESC included all of the standards, which is not appropriatefor all Parts of the NESC. This proposal correctly references the applicable Z535 standards in each Part of theNESC.

Subcommittee 1 Recommendation

Accept in part.

Subcommittee 1 Comment

Revised references in Section 3.

Vote on Subcommittee Recommendation

Affirmative: (9) Bleakley, Christofersen, Clapp, Dagenhart, Denbrock, Hooper, Hyland, Komassa,Tomaseski

Negative: (0)

Abstention: (0)


Accept in part.


Revised references in Section 3.


Affirmative: (8) Christofersen, Comans, Dietzman, Konz, Saint, Tomaseski, Winoski, Zaczek

Negative: (0)

Abstention: (1) Engmann

Explanation of Vote

Engmann: (Abstention) The intent of the CP is a mandatory requirement to conform to the industry consensusstandards for signage. The CP fell short of the intent in that it only included the ANSI standards in theReferences without an explicit mandatory conformance requirement. However, elevation beyond a NOTE isprogress.


Accept as modified.

Proposed Change

Revise Section 3 to show the appropriate Z535 standards information.



Revise the NOTES in Rules 110A1, 217A1c, 323C4, and 381G2 to refer to the correct applicable portions ofthe ANSI Z535 standards family and change the status from NOTE to Rule. In addition, revise Rule 411D torefer to applicable standards in the Z535 family.


ANSI Z535.1-2006, American National Standard for Safety Colors Code. [Rules 110A1 NOTE, 124C1,146B, 217A1c NOTE, 217A2a, 323C4 NOTE, 381G2 NOTE, and 411D]

ANSI Z535.2-20062007, American National Standard for Environmental and Facility Safety Signs. [Rules110A1 NOTE, 124C1, 146B, 217A1c NOTE, 217A2a, 323C4 NOTE, 381G2 NOTE, and 411D]

ANSI Z535.3-20062007, American National Standard for Criteria for Safety Symbols. [Rules 110A1NOTE, 124C1, 146B, 217A1c NOTE, 217A2a, 323C4 NOTE, 381G2 NOTE, and 411D]

ANSI Z535.4-20062007, American National Standard for Product Safety Signs and Labels. [Rules 110A1NOTE, 124C1, 146B, 217A1c NOTE, 323C4 NOTE, 381G2 NOTE, and 411D]

ANSI Z535.5-20062007, American National Standard for Accident PreventionSafety Tags and BarricadeTapes (for Temporary Hazards). [Rules 110A1 NOTE, 217A1c NOTE, 323C4 NOTE, 381G2 NOTE, and411D]

ANSI Z535.6-2006, American National Standard for Product Safety Information in Product Manuals,Instructions, and Other Collateral Materials, [411D]

Rule 110A1



Rule 124C1


Permanent safety signs in or on electrical supply station facilities shall meet the requirements of ANSIZ535.1-2006—Safety Colors and either ANSI Z535.2-2007—Environmental and Facility Safety Signs orANSIZ535.4-2007—Product Safety Signs and Labels, as applicable. Where symbols are used to replacewords in a safety message, such symbols shall be verified for comprehension to meet the requirements ofANSI Z535.3—Criteria for Safety Symbols

Rule 146B


Permanent safety signs in or on electrical supply station facilities shall meet the requirements of ANSIZ535.1-2006—Safety Colors and either ANSI Z535.2-2007—Environmental and Facility Safety Signs or



ANSIZ535.4-2007—Product Safety Signs and Labels, as applicable. Where symbols are used to replacewords in a safety message, such symbols shall be verified for comprehension to meet the requirements ofANSI Z535.3—Criteria for Safety Symbols.

Rule 217A1c

NOTE: ANSI Z535.1-2006, ANSI Z535.2-20072006, ANSI Z535.3-2006, and ANSI Z535.4-2007 2006,and ANSI Z535.5-2006 contain information regarding safety signs. ANSI Z535.3-2007 contains informationregarding safety symbols to be used in place of a safety word message.

Rule 217A2a

NOTE: ANSI Z535.1-2006, ANSI Z535.2-20072006, ANSI Z535.3-2006, and ANSI Z535.4-2007 2006,and ANSI Z535.5-2006 contain information regarding safety signs. ANSI Z535.3-2007 contains informationregarding safety symbols to be used in place of a safety word message.

Rule 323C4



Rule 381G2


Permanent safety signs in or on underground utility facilities (including aboveground apparatus) shall meetthe requirements of ANSI Z535.1-2006—Safety Colors and either ANSI Z535.2-2007—Environmental andFacility Safety Signs or ANSIZ535.4-2007—Product Safety Signs and Labels, as applicable. Wheresymbols are used to replace words in a safety message, such symbols shall be verified for comprehension tomeet the requirements of ANSI Z535.3—Criteria for Safety Symbols.

Rule 411D

D. Signs, and tags, and barricade tapes for employee safety

Safety signs, and tags, and barricade tapes required by Part 4 shall comply with the provisionsmeetthe requirements of ANSI Z535.1-2006—Safety Colors, ANSI Z535.2-2007—Environmental andFacility Safety Signs, ANSI Z535.4-2007—Product Safety Signs and Labels, or ANSI Z535.5-2007—Safety Tags and Barricade Tapes, as applicable. through ANSI Z535.5-2006, inclusive.Where symbols are used to replace words in a safety message, such symbols shall be verified forcomprehension to meet the requirements of ANSI Z535.3—Criteria for Safety Symbols

Safety information included in training manuals should meet the requirements of ANSI Z535.6-2006—Product Safety Information in Product Manuals, Instructions, and Other CollateralMaterials.




Affirmative: (19) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Drzewiecki, Engdahl, Gill, Gunter, Henry,Hooper, Komassa, Marne, Neubauer, Reding, Slavin, Steiner, White, Young

Negative: (0)

Abstention: (0)


Accept in part.


Revised references in the NOTES in for Rules 323C4, 323E3, and 381G2.

Leave the NOTES as NOTES, and not make them part of the rule. The ANSI dates will be updated.

Rule 323C4—Keep ANSI Z535.1-2006, ANSI Z535.2-2007, ANSI Z535.3-2007, ANSI Z535.4-2007.Delete the reference to ANSI Z535.5-2006.

Also revise Rule 323E3—Keep ANSI Z535.1-2006, ANSI Z535.2-2007, ANSI Z535.3-2007, ANSI Z535.4-2007. Delete the reference to ANSI Z535.5-2006.

Rule 381G2—Keep ANSI Z535.1-2006, ANSI Z535.2-2007, ANSI Z535.3-2007, ANSI Z535.4-2007.Delete the reference to ANSI Z535.5-2006.


Affirmative: (20) Amrhyn, Austin, Bleakley, Bowmer, Cooke, Dyer, Gaunt, Guinn, Gunter, Hiu, Miller,Pehosh, Pool, Pregler, Pristach, Robeson, Slavin, Spence, Szendre, Vencus

Negative: (0)

Abstention: (0)


Reject.


SC8 has not reviewed these newer referenced standards.


Affirmative: (21) Blackley, Bowmer, Brooks, Brubaker, Doering, Erga, Granata, Grose, Herbinger, Hunt,McKinney, Poholski, Russell, Schweitzer, Shaw, Smoak, Stonerock, Theis, Tomaseski, Tootle, Verdecchio

Negative: (0)



Abstention: (1) Wallis

Explanation of Vote

Doering: (Affirmative) Would accept original proposal if requirements were a NOTE.

Revised Text

CP3454

Part: 2 Section: 23 Rule: 230 B

Also Part: 2 Section: 25 251 B SC5

Submitter

SC5 Task Force 5.1.11

Proposed Change

Revise method of determining sags and clearances by elimination of additive constant and increasing windpressures accordingly. For consistency, this should be done in Section 23 and Section 25, as follows:

Section 23

230. General

A. Application

B. Ice and wind loading for clearances

1. ...

2. ...

3. ...

4. Table 230-2 shows the radial thickness of ice, wind pressures, and temperatures, and additiveconstants to be used in calculating inelastic deformation.

The load components shall be determined as follows:

a. Vertical load component

b. Horizontal load component

c. Total load

The total load on each wire, conductor, or messenger shall be the resultant of componentsin a) and b) above, calculated at the applicable temperature in Table 230-2, plus thecorresponding additive constant in Table 230-2.



Section 25

NOTE: The ice and wind pressures shown are used for determining the transverse loads from conductors andmessengers and wind loads on structures of Rule 252B1 and 252B2, respectively.

Table 230-2—Ice, wind pressures, and temperatures, and additive constants for purposes of calculating final inelastic deformation

Clearance zone (for use with Rule 230B)

Zone 1 Zone 2 Zone 3

Radial thickness of ice

(mm) 12.5 6.5 0

(in) 0.50 0.25 0

Horizontal wind pressure

(Pa) 190 380 190 380 430 480

(lb/ft2) 4 8 4 8 9 10

Temperature

(°C) –20 –10 –1

(°F) 0 +15 +30

Constant to be added to the resultant

(N/m) 4.40 2.90 0.73

(lb/ft) 0.30 0.20 0.05

Table 250-1—Ice, and wind, and temperature for purposes of calculating loads on line supports

Loading districts (for use with Rule 250B) Extreme wind

loading (for use with Rule 250C)

Extreme ice loading with concurrent

wind (for use with Rule 250D)Heavy Medium Light

Radial thickness of ice (mm)

12.5 6.5 0 0 See Figure 250-3

(in) 0.50 0.25 0 0 See Figure 250-3

Horizontal wind pres-sure (Pa)

190 190 430 See Figure 250-2 See Figure 250-3

(lbft2) 4 4 9 See Figure 250-2 See Figure 250-3

Temperature (ºC) –20 –10 –1 +15 –10

(ºF) 0 +15 +30 +60 +15



251. Conductor loading

A. General

B. Load components

The load components shall be determined as follows:

1. Vertical load component

The vertical load on a wire, conductor, or messenger shall be its own weight plus the weight ofconductors, spacers, or equipment that it supports, ice covered where required by Rule 250,with ice thickness indicated in Table 250-1 or Table 251-1.

2. Horizontal load component

For the purposes of determining the transverse loads from conductors and messengers andwind loads on structures of Rule 252B1 and 252B2, respectively, Tthe horizontal load shall bethe horizontal wind pressure of Table 250-1 determined under Rule 250 applied at right anglesto the direction of the line using the projected area of the conductor or messenger andconductors spacers, or equipment that it supports, ice covered where required by Rule 250,with ice thickness indicated in Table 250-1.

3. Total load

For the purposes of tension calculation only, tThe total load on each wire, conductor, ormessenger shall be the resultant of vertical load components 1 and 2 above and a horizontalload component determined by the applicable wind pressure of Table 251-1 applied at rightangles to the direction of the line using the projected area of the conductor or messenger andconductors, spacers, or equipment that it supports, ice covered where required by Rule 250,with ice thickness indicated in Table 251-1, calculated at the applicable temperature inTable 251-1, plus the corresponding additive constant in Table 251-1. In all cases theconductor or messenger tension shall be computed from this total load.

Table 251-1—Ice, wind, and tTemperatures and constants for purposes of calculating tension



Extreme ice loading with concurrent wind

(for use with Rule 250D)Heavy Medium Light

Radial thickness of ice (mm)

12.5 6.5 0 0 See Figure 250-3

(in) 0.50 0.25 0 0 See Figure 250-3

Horizontal wind pressure (Pa)

380 380 480

(lb/ft2) 8 8 10 See Figure 250-2 See Figure 250-3



NOTE: In all cases the ice, wind pressures, and temperatures shown are used for determining the wiretension loads. The indicated wind pressures are different than that of Table 250-1 because of the manner inwhich the wind loads are applied.

252. Loads on line supports

A. Assumed vertical loads

B. Assumed transverse loads

The total transverse loads on poles, towers, foundations, crossarms, pins, insulators, and conductorfastenings shall include the following:

1. Transverse loads from conductors and messengers

The transverse loads from conductors and messengers shall be the horizontal load determinedby Rule 251B2.

Supporting Comment

During the past (2007) Code cycle, as part of the effort to introduce the loading district map (Figure 250-1)of Section 25 into Section 23 (clearance zone map, Figure 230-1), including the associated conductor loadingcalculations of Rule 251, WG 4.10 had originally proposed that the “constant to be added to the resultant” ofRule 251B3, and Table 251-1 be eliminated in Section 23 in favor of a simpler procedure in which somewhatgreater wind pressures are applied to arrive at an equivalent loading (and tension) result for the purposes ofsag and clearance calculations. The corresponding wind pressures are included in above proposed Table 251-1. However, in order to facilitate the transition to the new format for clearance calculations, it was decided toretain the precise method of calculation, including use of the additive constant, for the 2007 Edition. At thattime, it was agreed that a joint task force, representing Subcommittees 4 and 5, would develop a changeproposal that would eliminate the use of the additive constant in a consistent manner. Thus, Task Force 5.1.11recommends that the use of the constant be added to the resultant of vertical and horizontal loads onconductors, as presently specified in Rule 230B4c and Table 230-2 as well as Rule 251B3, and Table 251-1be eliminated. This change is accomplished with minimal effect on previous sag and tension results byimposition of the higher wind pressures for this purpose only. Wind loadings for this purpose essentiallyrevert to 4th Edition values. Wind pressure imposed on conductors for the purposes of structural loadingremain unchanged.

Temperature (ºC) –20 –10 –1 +15 –10

(ºF) 0 +15 +30 +60 +15

Constant to be added to the resultant(all conductors) (N/m) 4.4 2.9 0.73 0.0 0.0

(lb/ft) 0.30 0.20 0.05 0.0 0.0

Table 251-1—Ice, wind, and tTemperatures and constants for purposes of calculating tension (continued)



Extreme ice loading with concurrent wind

(for use with Rule 250D)Heavy Medium Light



As a historical note, a review of earlier Code editions as far back as the 4th Edition revealed that the additiveconstants had been introduced into Table 251-1 of the 5th Edition. For reasons not explicitly documented, thewind loading was reduced from 8 lb/ft2 in the Heavy and Medium categories to 4 lb/ ft2 in the 5th Edition.The reduction in wind load apparently was not intended to substantially reduce the wind effect on either sagor load because additive constants were introduced in the 5th Edition. These additive constants approximatelyequate the calculated conductor loads, and corresponding tensions and sags, when using either the 4th or 5thEditions. In fact volume 10 of the Archives states:

While the method of specifying conductor loading in the 5th Edition differs from that in the 4th Edition,substantially the same conductor loading assumptions have been retained by the addition of the constantsgiven in Rule 251.


No action needed.


Affirmative: (0)

Negative: (0)

Abstention: (0)


Accept.


Affirmative: (16) Amrhyn, Bednarz, Bleakley, Bowmer, Clapp, Crawford, Emery, Gunter, Hooper,Komassa, Marne, Neubauer, Reding, Slavin, Steiner, White

Negative: (3) Engdahl, Drzewiecki, Hall

Abstention: (0)

Explanation of Vote

Drzewiecki: (Negative) I felt there was insufficient substantiation for the change. Our old philosophy wasused for a long time relative to constants, and I felt there was really no good reason for confusing the issueany further by increasing the wind pressures to just keep a status quo.

Engdahl and Hall: (Negative) Elimination of the “k” factor is simply change for the purpose of change, addsnothing to the safety aspect of the Code, and could add a new degree of confusion for line designers. While Iagree that the “k” factor may not be the best approach, the “k” factor has been a part of the Code for so longthat its correct application is understood by line designers and has been integrated into company standards.The wording and application of Rules 250, 251, and 252 have become so complicated, though correct if onestudies them long enough, that I feel the correct application of the Code may actually be hindered by thisunnecessary change. The net result of this CP is that conductor loading for tension calculation requires an8 lb wind, while conductor loading for transverse loading requires a 4 lb wind and some conductor clearancesare specified under a 6 lb wind; not exactly a consistent approach to wind loading. I agree a consistent



conductor wind loading approach would benefit the Code but this CP does not achieve this objective.


Accept.


Affirmative: (28) Berlinger, Bingel, Bullinger, Burley, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Fuller, Glaus, Haire, Heald, Jones, Joplin, Kempner, Lacoursiere, Lynch, Ng, Peters,Schwalm, Shultz, Slavin, Soderberg, Jr., Wong

Negative: (2) Kluge, Freimark

Abstention: (0)

Explanation of Vote

Freimark: (Negative) I applaud Task Force 5.1.11 for their attempt but feel that the submitted changesubstitutes what has been one alleged point of confusion, the need and application of the “k” constant, whichhas been in the NESC since the 1940s, with a new source of confusion. Apparently not everyone understandsthe purpose (and logic) of the “k” constant and this causes confusion. Life is not always logical; remember,the Rule 250B criteria dates back to the days of “working loads” and “overload factors,” which are no longerthe norm.

Regarding the proposed modifications in Rule 230, clearances, the changes are relatively simple andstraightforward. However in Section 25 we get a complexity with one loading case (Table 251-1) being usedto determine wire tensions and a second loading case (Table 250-1) being used to calculate the non-tensionrelated wind and ice loads on the structure.

If the “k” constant factor has been an issue for more than 60 years, will having two different loading cases forcalculating the NESC District structure strength (Rule 250B) simplify anything? This is substituting one“problem” for another set of potential problem; i.e., using the lower Table 250-1 loads for calculating thetension or the higher Table 251-1 loads for calculating the structure loads (where the structure becomesstronger than intended—which is not really a problem regarding public safety).

I prefer to maintain the status quo regarding the NESC loading cases, at least as far as NESC Section 25 isconcerned, an keep the “k” constant and other criteria in Rule 250B.

Kluge: (Negative) Negative as proposed, but supportable with modification. As long as the District Loadsremain in NESC, this should not be changed. When or if the NESC makes a complete transition to the ASCEload maps, then the “k” factor will automatically disappear.

The supporting reasons are weak. The “k” factor is obsolete but so is the method this proposal intends tochange. The district map with which the “k” factor is associated is flawed as was illustrated by the NESC SC5task force comparison to ASCE 7 concurrent wind and ice maps in the 2007 NESC Preprint.

This change will confuse people who are familiar with the present district load method and contains nosignificant change to a more technically sound loading methodology.



Revised Text

CP3437

Part: 2 Section: 23 Rule: 230 B1

Also Part: 2 Section: 23 230 Figure 230-1 SC4

Part: 2 Section: 23 230 Table 230-1 SC4


Part: 2 Section: 25 250B SC5

Part: 2 Section: 25 250D SC5

Part: 2 Section: 25 250 Figure 250-1 SC5



Submitter

Allen L. Clapp

Proposed Change

Revise Rules 230B1, 250B, and 250D; Figures 230-1 and 250-1; and Tables 230-1, 230-2, and 251-1 asfollows to reflect actual experience in Hawaii and other islands that have weather factors that differsignificantly from those of Clearance Zone 3 of Rule 230B and the Light Loading District of Rule 250B.

Rule 230B1

Revise to add a fourth loading zone for temperate island use.


1. Three Four general degrees of loading due to weather conditions are recognized and are designatedas clearance zones 1, 2, and 3, and 4. Figure 230-1 shows the zones where these loadings apply.

NOTE: The localities are classified in the different zones according to the relative simultaneousprevalence of the wind velocity and thickness of ice that accumulates on wires. Zone 3 is for placeswhere little, if any, ice accumulates on wires. Zone 4 applies to latitudes below 25 degrees wheremild temperatures exist at sea level, but icing may occur at altitudes above 1800 m (6000 ft) abovesea level. See Appendix B.

Figure 230-1

Change the designation for Hawaii on the map from Zone 3 to Zone 4. Add references for American Samoa,Guam, Puerto Rico, and Virgin Islands to Zone 4, to be consistent with Figure 250-2(b).



Table 230-1

Revise Table 230-1 to include a new Zone 4 to apply to Hawaii and islands in similar warm locales.

Table 230-2


Table 230-1—Ice thickness for purposes of calculating clearances

Clearance zone (for use with Rules 232, 233, 234, and 235)

Zone 1 see Figure

230-1

Zone 1see Figure

230-1

Zone 1see Figure

230-1

Zone 4: Hawaii and other islands below latitude

25 degrees north1

1Islands located at 0 to 25 degrees latitude include American Samoa (14°S), Guam (13°N), Hawaii (22°N), Puerto Rico(18°N), and Virgin Islands (18°N).

Altitudes sea level to

6250 ft

Altitudes above 6250 ft


(mm) 12.5 6.5 0 0 12.5

(in) 0.50 0.25 0 0 0.50

Figure 230-1—Clearance zone map of the United States



Rule 250B

B. Combined ice and wind district loading

Three Four general degrees of district loading due to weather conditions are recognized and aredesignated as heavy, medium, and light, and warm island loading. Figure 250-1 shows the districtswhere these loadings apply. Warm island loading applies to Hawaii and other island systemslocated in the range of 0 to 25 degrees latitude, north or south.

NOTE: The localities are classified in the different loading districts according to the relativesimultaneous prevalence of the wind velocity and thickness of ice that accumulates on wires. Lightloading is for places where little, if any, ice accumulates on wires. In the island loading zone, coldtemperatures and ice accumulation on wires only occurs at high altitudes.

Table 250-1 shows the radial thickness of ice and the wind pressures to be used in calculatingloads. Ice is assumed to weigh 913 kg/m3 (57 lb/ft3).

Table 230-2—Ice, wind pressures, temperatures, and additive constants for purposes of calculating final inelastic deformation


Zone 1Heavy ice:

see Figure 230-1

Zone 2Moderate

ice: see Figure

230-1

Zone 3Little or no ice:

see Figure 230-1

Zone 4: Warm islands located at 0 to 25 degrees latitude1



6250 ft



(mm) 12.5 6.5 0 0 12.5

(in) 0.50 0.25 0 0 0.50


(Pa) 190 190 430 430 190

(lb/ft2) 4 4 9 9 4

Temperature

(°C) –20 –10 –1 +10 –20

(°F) 0 +15 +30 50 0


(N/m) 4.40 2.90 0.73 0.73 4.40

(lb/ft) 0.30 0.20 0.05 0.05 0.30



Figure 250-1

Revise the map in Figure 250-1 in the following manner.

a. Add the words “Loading District” after “Heavy,” “Medium,” and “Light.”

b. Delete the reference of Hawaii to the Light district and move the Alaska reference to the top of thefigure.

c. Add the following sentence across the bottom of the figure.

The Warm Loading District includes American Samoa, Guam, Hawaii, Puerto Rico, Virgin Islands, andother islands located from 0 to 25 degrees latitude, north or south.

Rule 250D

Revise Rule 250D as shown.

D. Extreme ice with concurrent wind loading

If no portion of a structure or its supported facilities exceeds 18 m (60 ft) aboveground or waterlevel, the provisions of this rule are not required. Where a structure or its supported facilitiesexceeds 18 m (60 ft) aboveground or water level, the structure and its supported facilities shall bedesigned to withstand the ice and wind load associated with the Uniform Ice Thickness andConcurrent Wind Speed, as specified by Figure 250-3. The wind pressures for the concurrent windspeed shall be as indicated in Table 250-4. The wind pressures calculated shall be applied to theentire structure and supported facilities without ice and to the iced wire diameter determined inaccordance with Rule 251. No loading is specified in this rule for extreme ice with concurrent windloading for warm islands located from 0 to 25 degrees latitude, north or south.

Ice is assumed to weigh 913 kg/m3 (57 lb/ft3).



1. For Grade B, the radial thickness of ice from Figure 250-3 shall be multiplied by a factor of1.00.

2. For Grade C, the radial thickness of ice from Figure 250-3 shall be multiplied by a factor of0.80.

3. The concurrent wind shall be applied to the projected area resulting from Rules 250D1 and250D2 multiplied by a factor of 1.00.

Table 250-1

Revise the title of Table 250-1 for consistency and revise the first portion of Table 250-1 addressing theloading districts of Rule 250B as follows. Retain the additional columns for loadings of Rules 250C and 250Dwithout change.

Table 251-1

Revise the left half of Table 251-1 applying to loading districts of Rule 250B as follows. Retain the existingcolumns for loadings of Rules 250C and 250D—they are not shown below, due to room constraints.

Table 250-1—Ice, wind pressures, and temperatures

Loading districts (for use with Rule 250B)

Heavysee Figure

230-1

Mediumsee Figure

230-1

Lightsee Figure

230-1

Warm islands located at 0 to 25 degrees latitude1



6250 ft



(mm) 12.5 6.5 0 0 12.5

(in) 0.50 0.25 0 0 0.50


(Pa) 190 190 430 430 190

(lb/ft2) 4 4 9 9 4

Temperature

(°C) –20 –10 –1 +10 –20

(°F) 0 +15 +30 50 0



Supporting Comment

Islands such as Hawaii have weather factors that differ from those normally found in Clearance Zone 3 ofRule 230B and the Light Loading Zone of Rule 250B. Hawaiian islands are near the 22 degrees north latitude.Near ocean level, the temperature rarely drops below 55 °F, but ice can be formed on the tallest mountainpeaks. The General Orders of the Hawaii Public Utility Commission have traditionally recognizedappropriate icing and conductor temperature conditions based upon altitude above sea level. These changesto the NESC to add a new Clearance Zone 4 with appropriate conditions will bring the NESC requirementsin line with actual experience in Hawaii. These changes will also be useful be useful for other island systems,such as those in the U.S. Virgin Islands (18 degrees north latitude) and other islands that use the NESC.


No action needed.


Affirmative: (0)

Negative: (0)

Abstention: (0)


Accept as modified.


Loading districts (for use with 250B)

Heavy(heavy ice: see Figure

230-1)

Medium(moderate

ice: see Figure 230-1)

Light(little or no

ice: see Figure 230-1)




6250 ft


Temperature

(°C) –20 –10 –1 +10 –20

(°F) 0 +15 +30 50 0

Constant to be added to the resultant (all conductors)

(N/m) 4.40 2.90 0.73 0.73 4.40

(lb/ft) 0.30 0.20 0.05 0.05 0.30




Rule 230B1

Revise to add a fourth loading zone for tropical island use.


1. Three Four general degrees of loading due to weather conditions are recognized and aredesignated as clearance zones 1, 2, and 3, and 4. Figure 230-1 shows the zones where theseloadings apply.

NOTE: The localities are classified in the different zones according to the relativesimultaneous prevalence of the wind velocity and thickness of ice that accumulates on wires.Zone 3 is for places where little, if any, ice accumulates on wires. Zone 4 applies to latitudesbelow 25 degrees where mild temperatures exist at sea level, but icing may occur at altitudesabove 2743 m (9000 ft) above sea level. See Appendix B.

Figure 230-1

Change the designation of Hawaii on the map from Zone 3 to Warm Islands Zone 4. Add references forAmerican Samoa, Guam, Puerto Rico, and Virgin Islands to Zone 4, to be consistent with Figure 250-2(b).Add the following under Figure 230-1.

Clearance Zone 4 includes American Samoa, Guam, Hawaii, Puerto Rico, Virgin Islands, and other warmislands located from 0 to 25 degrees latitude, north or south.

Table 230-1





Table 230-2




Zone 1see Figure

230-1

Zone 2Zone 2

see Figure 230-1

Zone3Zone 3

see Figure 230-1

Zone 4: Warm islands below latitude 25 degrees north1



9000 ft



(mm) 12.5 6.5 0 0 6.5

(in) 0.50 0.25 0 0 0.25



Zone 1Heavy ice: see Figure

230-1

Zone 2Moderate

ice: see Figure

230-1


see Figure 230-1




9000 ft



(mm) 12.5 6.5 0 0 6.5

(in) 0.50 0.25 0 0 0.25


(Pa) 190 190 430 430 190

(lb/ft2) 4 4 9 9 4

Temperature

(°C) –20 –10 –1 +10 –10

(°F) 0 +15 +30 +50 +15


(N/m) 4.40 2.90 0.73 0.73 2.90

(lb/ft) 0.30 0.20 0.05 0.05 0.20



Rule 250B


Three Four general degrees of district loading due to weather conditions are recognized and aredesignated as heavy, medium, and light, and warm island loading. Figure 250-1 shows the districtswhere these loadings apply. Warm island loading applies to Hawaii and other island systemslocated in the range of 0 to 25 degrees latitude, north or south.

NOTE: The localities are classified in the different loading districts according to the relativesimultaneous prevalence of the wind velocity and thickness of ice that accumulates on wires. Lightloading is for places where little, if any, ice accumulates on wires. In the warm island loading zone,cold temperatures and ice accumulation on wires only occurs at high altitudes.


Figure 250-1

Revise the map in Figure 250-1 in the following manner:


b. Delete the reference of Hawaii to the Light district and move the Alaska reference to the top of the figure.


The Warm Island Loading District includes American Samoa, Guam, Hawaii, Puerto Rico, Virgin Islands,and other islands located from 0 to 25 degrees latitude, north or south.

Make Hawaii Zone Warm Island in the figure.



Rule 250D








Table 250-1

Revise the title of Table 250-1 for consistency and revise the first portion of Table 250-1 addressing theloading districts of Rule 250B as follows. Retain the additional columns for loadings of Rule 250C and Rule250D without change.


Loading Districts (for use with Rule 250B)

Heavysee Figure

250-1

Mediumsee Figure

250-1

Lightsee Figure

250-1



9000 ft



(mm) 12.5 6.5 0 0 6.5

(in) 0.50 0.25 0 0 0.25


(Pa) 190 190 430 430 190

(lb/ft2) 4 4 9 9 4



Table 251-1


Supporting Comment

Islands such as Hawaii have weather factors that differ from those normally found in Clearance Zone 3 ofRule 230B and the Light Loading Zone of Rule 250B. Hawaiian islands are near the 22 degrees north latitude.Near ocean level, the temperature rarely drops below 55 °F, but ice can be formed on the tallest mountain

Temperature

(°C) –20 –10 –1 +10 –10

(°F) 0 +15 +30 +50 +151 Islands located at 0 to 25 degrees latitude include American Samoa (14°S), Guam (13°N), Hawaii (22°N), Puerto

Rico (18°N), and Virgin Islands (18°N).

Table 251-1—Temperatures and constants


Heavy(see

Figure 250-1)

Medium(see

Figure 250-1)

Light(see

Figure 250-1)


1 Islands located at 0 to 25 degrees latitude include American Samoa (14°S), Guam (13°N), Hawaii (22°N), PuertoRico (18°N), and Virgin Islands (18°N).


9000 ft


Temperature

(°C) –20 –10 –1 +10 –10

(°F) 0 +15 +30 +50 +15


(N/m) 4.40 2.90 0.73 0.73 2.90

(lb/ft) 0.30 0.20 0.05 0.05 0.20

Table 250-1—Ice, wind pressures, and temperatures (continued)


Heavysee Figure

250-1

Mediumsee Figure

250-1

Lightsee Figure

250-1



9000 ft




peaks. The General Orders of the Hawaii Public Utility Commission have traditionally recognizedappropriate icing and conductor temperature conditions based upon altitude above sea level.

Furthermore, the Atlas of Hawaii Third Edition (1998) states, “The rate of temperature decrease withelevation, called the lapse rate, is fairly constant at about 3.6 °F per 1,000 ft (6.5 °C per 1,000 m) below4,100 ft (1,250 m) and 2.2 °F per 1,000 ft (4 °C per 1,000 m) at higher elevations.” The following is agraphical representation of the lapse rate with actual recorded National Oceanic and AtmosphericAdministration (NOAA) climatological data points.

These changes to the NESC to add a new Clearance Zone 4 with appropriate conditions will bring the NESCrequirements in line with actual experience in Hawaii. These changes will also be useful be useful for otherisland systems, such as those in the U.S. Virgin Islands (18 degrees north latitude) and other islands that usethe NESC.

Local temperature data obtained from NOAA Climatological Data Annual Summary Hawaii and Pacific2006, Volume 102 Number 13.


Affirmative: (19) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Drzewiecki, Emery, Engdahl, Gill, Gunter,Henry, Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White, Young

Negative: (0)

Abstention: (0)




Accept as modified.


Rule 230B1

Revise to add a fourth loading zone for tropical island use.


1. Three Four general degrees of loading due to weather conditions are recognized and aredesignated as clearance zones 1, 2, and 3, and 4. Figure 230-1 shows the zones where theseloadings apply.

NOTE: The localities are classified in the different zones according to the relativesimultaneous prevalence of the wind velocity and thickness of ice that accumulates on wires.Zone 3 is for places where little, if any, ice accumulates on wires. Zone 4 applies to latitudesbelow 25 degrees where mild temperatures exist at sea level, but icing may occur at altitudesabove 2743 m (9000 ft) above sea level. See Appendix B.

Figure 230-1

Change the designation for Hawaii on the map from Zone 3 to Zone 4. Add references for American Samoa,Guam, Puerto Rico, and Virgin Islands to Zone 4, to be consistent with Figure 250-2(b).

Table 230-1





Table 230-2




Zone 1see Figure

230-1

Zone 2Zone 2

see Figure 230-1

Zone 3Zone 3

see Figure 230-1

Zone 4: Warm islands below latitude

25 degrees north1



9000 ft



(mm) 12.5 6.5 0 0 6.5

(in) 0.50 0.25 0 0 0.25



Zone 1Heavy ice:

see Figure 230-1

Zone 2Moderate ice:

see Figure 230-1


see Figure 230-1



9000 ft



(mm) 12.5 6.5 0 0 6.5

(in) 0.50 0.25 0 0 0.25


(Pa) 190 190 430 430 190

(lb/ft2) 4 4 9 9 4

Temperature

(°C) –20 –10 –1 +10 –10

(°F) 0 +15 +30 +50 +15



Rule 250B


Three Four general degrees of district loading due to weather conditions are recognized and aredesignated as heavy, medium, and light, and warm island loading. Figure 250-1 shows the districtswhere these loadings apply.Warm island loading applies to Hawaii and other island systems locatedin the range of 0 to 25 degrees latitude, north or south.

NOTE: The localities are classified in the different loading districts according to the relativesimultaneous prevalence of the wind velocity and thickness of ice that accumulates on wires. Lightloading is for places where little, if any, ice accumulates on wires. In the warm island loading zone,cold temperatures and ice accumulation on wires only occurs at high altitudes.


Figure 250-1

Revise the map in Figure 250-1 in the following manner.


b. Delete the reference of Hawaii to the Light district and move the Alaska reference to the top of the figure.


The Warm Island Loading District includes American Samoa, Guam, Hawaii, Puerto Rico, Virgin Islands,and other islands located from 0 to 25 degrees latitude, north or south.


(N/m) 4.40 2.90 0.73 0.73 2.90

(lb/ft) 0.30 0.20 0.05 0.05 0.201 Islands located at 0 to 25 degrees latitude include American Samoa (14°S), Guam (13°N), Hawaii (22°N), Puerto


Table 230-2—Ice, wind pressures, temperatures, and additive constants for purposes of calculating final inelastic deformation (continued)


Zone 1Heavy ice:

see Figure 230-1

Zone 2Moderate ice:

see Figure 230-1


see Figure 230-1



9000 ft




Make Hawaii Zone Warm Island in the figure.

Rule 250D








Table 250-1

Revise the title of Table 250-1 for consistency and revise the first portion of Table 250-1 addressing theloading districts of Rule 250B as follows. Retain the additional columns for loadings of Rule 250C and Rule250D without change.



Table 251-1




Heavysee Figure

250-1

Mediumsee Figure

250-1

Lightsee Figure

250-1

Warm islands located at 0 to 25 degrees latitude 1


9000 ft



(mm) 12.5 6.5 0 0 6.5

(in) 0.50 0.25 0 0 0.25


(Pa) 190 190 430 430 190

(lb/ft2) 4 4 9 9 4

Temperature

(°C) –20 –10 –1 +10 –10

(°F) 0 +15 +30 +50 +151 Islands located at 0 to 25 degrees latitude include American Samoa (14°S), Guam (13°N), Hawaii (22°N), Puerto




Heavy(see

Figure 250-1)

Medium(see

Figure 250-1)

Light(see

Figure 250-1)

Warm islands located at 0 to 25 degrees latitude 1


9000 ft


Temperature

(°C) –20 –10 –1 +10 –10

(°F) 0 +15 +30 +50 +15


(N/m) 4.40 2.90 0.73 0.73 2.90

(lb/ft) 0.30 0.20 0.05 0.05 0.20



Supporting Comment

Islands such as Hawaii have weather factors that differ from those normally found in Clearance Zone 3 ofRule 230B and the Light Loading Zone of Rule 250B. Hawaiian islands are near the 22 degrees north latitude.Near ocean level, the temperature rarely drops below 55 °F, but ice can be formed on the tallest mountainpeaks. The General Orders of the Hawaii Public Utility Commission have traditionally recognizedappropriate icing and conductor temperature conditions based upon altitude above sea level.

Furthermore, the Atlas of Hawaii Third Edition (1998) states, “The rate of temperature decrease withelevation, called the lapse rate, is fairly constant at about 3.6 °F per 1,000 ft (6.5 °C per 1,000 m) below4,100 ft (1,250 m) and 2.2 °F per 1,000 ft (4 °C per 1,000 m) at higher elevations.” The following is agraphical representation of the lapse rate with actual recorded National Oceanic and AtmosphericAdministration (NOAA) climatological data points.

These changes to the NESC to add a new Clearance Zone 4 with appropriate conditions will bring the NESCrequirements in line with actual experience in Hawaii. These changes will also be useful be useful for otherisland systems, such as those in the U.S. Virgin Islands (18 degrees north latitude) and other islands that usethe NESC.

Local temperature data obtained from NOAA Climatological Data Annual Summary Hawaii and Pacific2006, Volume 102 Number 13.


Affirmative: (27) Bingel, Bullinger, Busel, Byrne, Clapp, Clem, Corzine, Denbrock, Erdle, Freimark, Fuller,Glaus, Guerry, Haire, Harrel, Heald, Jones, Kempner, Kluge, Lynch, Ng, Peters, Schwalm, Shultz,Soderberg, Jr., Standford, Wong




Negative: (0)

Abstention: (1) Berlinger

Revised Text

CP3430

Part: 2 Section: 23 Rule: 231 A

Also Part: 3 Section: 38 380 D SC7

Part: 3 Section: 38 384 C SC7

Submitter

Allen L. Clapp

Proposed Change

Revise Rule 231A to reflect bonding requirements, as follows:

A. From cClearances of supporting structures from fire hydrants

1. Basic clearance to aid fire fighters

Not less than 1.2 m (4 ft).

EXCEPTION 1: Where conditions do not permit, a clearance of not less than 900 mm (3 ft) isallowed.

EXCEPTION 2: Clearances in Rule 231A may be reduced by agreement with the local fireauthority and the pole owner.

2. Additional requirement

Supporting structures shall be so located that either:

a. The clearance between conductive (metal or concrete) supporting structure or a metallicgrounding conductor on the side of a nonconductive (wood or fiber-reinforced polymer)supporting structure and a fire hydrant shall be not less than 1.8 m (6 ft), or

b. The fire hydrant shall be bonded to the structure ground.

NOTE: A grounding conductor located on the opposite side of a nonconductive supportingstructure from a fire hydrant is positioned to limit the opportunity for simultaneous contactand is not considered to require bonding.

Revise Rule 380D to add a reference to Rule 384C, as follows:

D. Pad-mounted equipment, pedestals, and other aboveground enclosures, should be located not lessthan 1.2 m (4 ft) from fire hydrants. See Rule 384C for bonding requirements.



EXCEPTION: Where conditions do not permit a clearance of 1.2 m (4 ft), a clearance of not lessthan 900 mm (3 ft) is allowed.

Revise Rule 384C as follows to add clearances from utility apparatus to fire hydrants, conductive poles, andpole grounds.

C. Bonding of aboveground metallic apparatus

1. Bonding should be provided between all aboveground metallic power and communicationsapparatus (pedestals, terminals, apparatus cases, transformer cases, etc.) that are separated by adistance of 1.8 m (6 ft) or less.

2. In addition, bonding shall be provided between all such utility apparatus and (a) fire hydrants,(b) metal poles, (c) concrete poles, or (d) grounding conductors on nonconductive poleslocated within 1.8 m (6 ft) or less of the apparatus. For the purpose of this rule, pole groundsare not considered an aboveground metallic power apparatus and therefore ground wireslocated on the opposite side of a nonconductive pole are not required to be bonded to thecommunication apparatus.

3. Where the supply neutral or supply cable sheath or shield is bonded to the groundingcommunication cable sheath, shield, or grounded conductors at a structure within 7.6 m (25 ft)of the apparatus, such apparatus is considered to be bonded.

Supporting Comment

The same or greater voltage differential hazard exists between metallic utility apparatus and a fire hydrant,pole ground, or conductive pole as the potential hazard between supply and communication apparatus,especially where one circuit has been underground for long distances without bonding to overhead pole linegrounding conductors.

Fire hydrants are often connected to the electric supply utility wiring through bonds inside of buildings towater piping and present a significant potential voltage potential hazard when they can be simultaneouslycontacted with conductive aboveground supply or communication apparatus cases, unless they are bonded.


No action needed.


Reject.


Bonding communications pedestals and supply pad-mounted equipment to fire hydrants is not practical.Bonding communications pedestals and fire hydrants to pole grounds creates a greater hazard by extendingthe touch pole ground touch potential to the fire hydrants and pedestals that exists when the pole groundconducts lightning or fault surges to ground.


Affirmative: (18) Amrhyn, Bednarz, Bleakley, Crawford, Drzewiecki, Emery, Engdahl, Gill, Gunter, Henry,



Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White, Young

Negative: (1) Clapp

Abstention: (0)

Explanation of Vote

Clapp: (Negative) We already have a requirement to bond aboveground pad-mounted equipment enclosureslocated within touching range (defined as 6 ft). The voltage between a pad-mounted equipment enclosure anda pole ground or fire hydrant can be the same or greater than that between enclosures. The problem addressedby the affected rules is essentially the same as that addressed by Rule 092C3b, which requires bonding atcrossing structures. I have seen as much as 1600 V (small current) between a messenger on an overheadcommunication line that ran cross-country when that line hit a joint-use line running along a road—which iswhy you should never make or break a ground connection without wearing serious insulating gloves.

The problem addressed by the current rules is that, when communication is run for an extensive distanceseparate from power, the voltage drop on the relative grounding conductors can differ and cause a voltagedifferential between the two grounded enclosures, unless they are bonded together.

When a power pigmented transformer and a communication pedestal are fed from the same pole and locatednear the pole, there is rarely a significant voltage potential between the grounded enclosures. However, if oneor both are run for extensive distances underground (or aboveground) and not bonded to the other, significantvoltage differences can occur.

The same hazardous voltage differences can occur between an equipment enclosure and a pole ground or firehydrant.


Rejected.


It covers too many rules. It is not practical. Insufficient substantiation.


Affirmative: (19) Amrhyn, Austin, Bleakley, Bowmer, Cooke, Dyer, Gaunt, Guinn, Gunter, Hiu, Miller,Pehosh, Pool, Pregler, Pristach, Robeson, Slavin, Spence, Szendre

Negative: (1) Vencus

Abstention: (0)

Explanation of Vote

Vencus: (Negative) I agree with the original arguments in the CP.



Index

Revised Text, Index

CP3147

Submitter

Robert Molde

Proposed Change

Update the NESC Index to reflect changes that occurred in the 2007 NESC.

Supporting Comment

The Index has not been updated with all the Code changes.

Example 1: The Index states that Fire hydrants, clearances from, is stated in Rule 231A; page 85, but withthe Code changes it is also in Rule 380D; page 242.

Example 2: The Index states that Live parts, approach distance to, is stated in Rule 441A, and 441B; page264, but with the Code changes Rule 441A is on page 262.

Subcommittee Recommendation

Accept.



Negative: (0)

Abstention: (0)



Section 1. Introduction to the

National Electrical Safety Code®

New Text

CP3141

Section: 1 Rule: 010

Submitter

Bruce Freimark

Proposed Change

Revise Rule 010 as follows:

010. Purpose

The purpose of these rules is the practical safeguarding of persons during the installation, operation, ormaintenance of electric supply and communication lines and associated equipment.

These rules contain the basic provisions that are considered necessary for the safety of employees andthe public under the specified conditions. This Code is not intended as a design specification or as aninstruction manual. These rules are not designed to protect the general public from actions or activitiesby the general public that are not foreseeable or that a reasonable person would not undertake. The rulesset forth herein are not designed to establish a minimum standard of reliability regarding the delivery ofutility services to customers.

Supporting Comment

Regarding first proposed added sentence:

The rules are not designed to protect the general public from actions or activities by the general public thatare not foreseeable or that a reasonable person would not undertake.

In recent years, the utility industry has been plagued by lawsuits filed by plaintiffs who refuse to accept thatthey were injured due to their not applying “common sense” to avoid contact with energized lines, etc.

As an example, a farmer operating a hay baler stopped under an energized power line, climbed on top to cleardebris from the machinery and came into contact with the energized conductor. There was adequate clearancefor the equipment to safely pass under the line but not sufficient clearance with a person standing on top ofthe equipment. The Operating manual for the hay baler contained warnings regarding stopping in the vicinityof overhead lines when performing maintenance.

Regarding second proposed added sentence:

The rules set forth herein are not designed to establish a minimum standard of reliability regarding thedelivery of utility services to customers.



Overhead line facilities that are built to the criteria in the NESC, or to criteria that goes beyond that in theNESC, are still subject to damage from conditions that exceed the design criteria and/or from trees or otherwind-blown objects that may contact the line. The intent of this addition is to advise the public that thepurpose of the NESC does not include establishing minimum levels of reliability regarding the delivery ofservices to customers, for example the number and/or the duration of outages.


Reject.

Subcommittee Comment

Reference to reliability standards is inappropriate in a safety standard. No need to state what the Code is notfor.



Negative: (0)

Abstention: (0)

Revised Text

CP3407


Also Section: 1 011 SC1

Section: 2 Def utility SC1

Submitter

Allen L. Clapp

Proposed Change

Revise NESC Rule 010 Purpose, Rule 011 Scope, and the definition of utility as follows.

010. Purpose

The purpose of these rules is the practical safeguarding of persons and property during the installation,operation, or and maintenance of electric supply and communication lines and associated equipment.

These rules contain the basic provisions that are considered necessary for the safety of employees andthe public, utility lines, utility equipment, and facilities adjacent to or containing utility lines andequipment under the specified conditions. This Code is not intended as a design specification or as aninstruction manual.



The NESC is intended to provide a standard of safe practices that can be adopted by public utilities,private utilities, state or local utility commissions or public service commissions, or other boards orbodies having control over safe practices employed in the design, construction, operation, ormaintenance of electric supply, communication, lighting, signal, or railroad utility installations.

The National Electrical Safety Code (NESC) is American National Standard C2. It is a consensusstandard that has been prepared by the National Electrical Safety Code Committee under Proceduresapproved by the American National Standards Institute (ANSI). The NESC Committee is composed ofnational and international organizations and is certified by ANSI as having an appropriate balance of theinterests of members of the public, utility workers, regulatory agencies, and the various types of privateand public utilities.

NOTE: The NESC is used in whole or in part by statute, regulation, or consent as the standard (or basisof the standard) of safe practice for public and private utilities in every state of the United States, as wellvarious jurisdictions and industries in other countries.

011. Scope

A. Types of requirements

These rules cover supply and communication specify assumed loadings and factors related torequired strength of utility structures and supported facilities; clearances and spacings betweenfacilities of different utilities, facilities of the same utility, and utility facilities and public facilities;grounding; and other requirements related to the safety of utility lines, and equipment, andincluding associated safe work practices, to be employed by a public or private electric supply,communications, railway, or similar utility in the exercise of its function as a utility. They coversimilar systems under the control of qualified persons, such as those associated with an industrialcomplex or utility interactive system.

Utilities operating under the NESC are required to maintain control over the system to assure that(a) the system is engineered to meet the requirements of expected conditions and (b) the personnelinstalling, maintaining, and operating the system and its components are qualified to do so,adequately supervised, and use appropriate tools and safe work procedures, as specified in theserules.

B. Coverage of rules and types of utilities

1. Coverage of rules

The NESC covers the generation, transmission, and distribution of electricity, lumens, andsignals through public and private utility systems that are installed and maintained under thequalified control of utilities or their authorized representatives.

Where energy or signals are provided directly to ultimate consumers, the NESC covers utilityfacilities and functions up to the utility service point, where the energy or signals aretransferred onto the utilization wiring system of the ultimate customer.

The NESC also covers utility facilities and functions of electric generation utilities, electrictransmission utilities, and electric distribution utilities that (a) either generate electrical poweror accept electric power from another entity and (b) provide that power through a deliverypoint to another utility.

2. Types of utilities



Examples of utilities covered by the NESC include electric supply (electric power generation,transmission, or distribution), communication, lighting, traffic signal (or other signal),irrigation, railroad, and trolley utilities.

B. The NESC covers utility facilities and functions up to the service point.

NOTE: The National Electrical Code® (NEC®) (NFPA 70, 2005 Edition)1 covers utilizationwiring requirements beyond the service point.

C. Relationship to other national or international standardsNESC rules cover street and area lights(supplied by underground or overhead conductors) under the exclusive control of utilities(including their authorized contractors) or other qualified persons (such as those associated with anindustrial complex).

To the extent practical, the NESC has limited duplication of the provisions of other standards, suchas the National Electrical Code® (NEC®) (NFPA 70, 2008 Edition) of the International ElectricalCode Series of the National Fire Protection Association, by referencing such documents. However,where necessary, the NESC has required compliance with certain standards or portions ofstandards, as directly specified in the rules.

Where utilities provide service to the ultimate consumer (not itself or another utility), therequirements of the NESC are not intended to directly apply to the facilities on the load side of theservice point. Another standard, such as the NEC will apply to the facilities on the load side of theutility service point. However, the provisions of the NESC can be used to comply with such otherstandard, where that standard (a) references NESC requirements, (b) requires compliance withspecific NESC requirements, or (c) is silent on requirements for conditions covered by the NESC.

NOTE: Luminaires not under such exclusive control are governed by the requirements of the NEC.Lines and equipment that are not maintained under qualified control by a utility are subject to therequirements of other standards, such as the NEC (which applies to facilities on the load side of autility service point).

D. Additional coverage and limitations on coverage of rules

NESC rules cover utility facilities installed, maintained, and controlled by public or private utilitieson surface or underground mine sites, such as overhead or underground distribution systemsproviding service up to building or outdoor equipment locations.

NESC rules do not apply to facilities beyond utility service points to buildings or outdoorinstallations, nor do they apply to underground mine wiring.

EXCEPTION: Where NESC requirements are either referenced or required by (a) the NEC or otherstandards or (b) governmental regulations (such as state or local statutes, Occupational Safety andHealth Administration regulations, or Mine Safety and Health Administration regulations), NESCrequirements may be used to the extent so referenced or required.

NESC rules do not cover installations in mines, ships, railway rolling equipment, aircraft, orautomotive equipment., or utilization wiring except as covered in Parts 1 and 3.

Revise the definition of utility as follows.

utility. An organization responsible for the installationdesign, construction, operation, or maintenance of apublic or private electric supply, or communications, lighting, signal, or railroad utility systems.



1. public utility. A public utility is an entity that performs or provides one or more utility services formultiple customers (at retail, wholesale, or both), but some utilities are formed for singularpurposes, such as providing street and outdoor lighting or municipal traffic signal control. Publicutilities include investor-owned, municipality-owned, cooperative-owned utilities, public utilitydistricts, irrigation districts, lighting districts, traffic signal or other signal utilities, and similarutilities.

2. private utility. A private utility is an entity that performs or provides one or more utility services toits own facilities, such as a large industrial complex, large campus, military complex, railroadsystem, trolley system, or extensive gas or oil field through its own electric supply, communication,lighting, or signal system. Although many private utilities only operate a distribution level system,others operate generation and transmission systems.

Supporting Comment

This proposal is the result of discussions held by the NEC-NESC Task Force set up by IEEE and NFPA tomodify each document to (a) better state its application and (b) limit the opportunity for confusion as to whichcode applies to what facilities and work. This is one of several proposals being proposed by members of thetask force and others. The work of the task force is ongoing and is expected to produce further refinements inthe next few weeks for consideration by the NESC Subcommittee 1 this fall.

This proposal and others address most, if not all, of the issues that need to be addressed to clarify theapplication of the NESC versus the NEC. However, the proposals differ in the manner in which the issues areaddressed, in order to give NESC SC1 several options to consider.

Similar proposals will be made for change in the NEC after consideration of this and related proposals by theNESC this fall.


Accept as modified.

Revise NESC Rule 010 Purpose, Rule 011 Scope, and the definition of utility as follows.

010. Purpose

A. The purpose of the National Electrical Safety Code (NESC) these rules is the practical safeguardingof persons and property during the installation, operation, or and maintenance of electric supplyand communication lines and associated equipment. NESC rules are founded upon the fundamentalprinciples used for safety of public and private utility facilities and good engineering practicethroughout the world.

B. These NESC rules contain the basic provisions, under specified conditions, that are considerednecessary for the safety of the following: employee and public under the specified conditions.

1. The public,

2. Utility workers (employees and contractors),

3. Utility lines,

4. Electric supply and communication equipment connected to utility lines and structures, and



5. Other facilities or premises adjacent to or containing utility lines and equipment.

C. NESC rules are intended to provide a standard of safe practices that can be adopted by publicutilities, private utilities, state or local utility commissions or public service commissions, or otherboards or bodies having control over safe practices employed in the design, construction, operation,or maintenance of electric supply, communication, street and area lighting, signal, or railroad utilityinstallations.

D. This Code is not intended as a design specification or as an instruction manual.

E. The NESC is American National Standard C2. It is a consensus standard that has been prepared bythe National Electrical Safety Code Committee under procedures approved by the AmericanNational Standards Institute (ANSI). The membership of the NESC Committee is composed ofnational and international organizations and is certified by ANSI as having an appropriate balanceof the interests of members of the public, utility workers, regulatory agencies, and the various typesof private and public utilities.

NOTE: The NESC is used in whole or in part by statute, regulation, or consent as the standard (orbasis of the standard) of safe practice for public and private utilities in the United States, as wellvarious jurisdictions and industries in other countries.

011. Scope

A. Covered

These rules The NESC covers:

1. Ssupply and communication lines, equipment, structures, and associated work practicesemployed by a public or private electric supply, communications, railway, trolley, street andarea lighting, traffic signal (or other signal), irrigation, or similar utility in the exercise of itsfunction as a utility.

B2. The generation, transmission, and distribution of electricity, lumens, communication signals,and communication data through public and private utility systems that are installed andmaintained under the exclusive control of utilities or their authorized representatives.

3. Utility facilities and functions of utilities that (a) either generate energy or signals or acceptenergy or signals from another entity and (b) provide that energy or signals through a deliverypoint to another entity.

C4. NESC rules cover sStreet and area lights that provide a supply of lumens where these facilitiesare (supplied by underground or overhead conductors) installed and/or maintained under theexclusive control of utilities (including their authorized contractors) or other qualified persons)(such as those associated with an industrial complex).

NOTE: Luminaires not under such exclusive control are governed by the requirements of theNEC.

5. The NESC covers uUtility facilities and functions on the line side of up to the service point.located on public or private property in accordance with legally established easements orrights-of-way, contracts, other agreements (written or by conditions of service), or asauthorized by a regulating or controlling body.



Agreements to locate utility facilities on property are required where easements are either (a)not obtainable (such as locating utility facilities on existing rights-of-way of railroads or otherentities, military bases, federal lands, Native American reservations, lands controlled by a portauthority or other governmental agency) or (b) not necessary (such as locating facilitiesnecessary for requested service to a site).

NOTE: The National Electrical Code (NEC) (NFPA 70, 2005 Edition)1 covers utilizationwiring requirements beyond the service point.

6. Wiring within a supply station or in underground facility that is (a) installed in accordance withPart 1 or Part 3 of this Code and maintained under the exclusive control of utilities and (b)necessary for the operation of the supply station or underground facility.

7. Utility facilities installed, maintained, and controlled by utilities on surface or undergroundmine sites, including overhead or underground distribution systems providing service up tobuildings or outdoor equipment locations on the line side of the service point.

8. They cover sSimilar systems under the exclusive control of qualified persons and authorized bya regulating or controlling body, such as including those associated with an industrial complexor utility interactive system.

DB.Not covered. NESC rules do not cover:

1. Utilization equipment or premises wiring located beyond utility service points to buildings oroutdoor installations, or

2. Underground mine wiring or Iinstallations in mines, ships, railway rolling equipment, aircraft,or automotive equipment, or

3. Utilization wiring except as covered in Parts 1 and 3

4. Luminaires not installed or maintained under exclusive control by utilities, or

5. Industrial complex or utility interactive systems that are not controlled exclusively underutilities or qualified persons or are located on the premises wiring side of the service point.

NOTE: For installations in ships, refer to Title 46, Code of Federal Regulations, Parts 110–113.

The National Electrical Code® (NEC®) (NFPA 70, 2008 Edition) covers utilization wiringrequirements beyond the service point and luminaires that are not controlled exclusively underutilities. See Figure 011-1.

The following is a general illustration of where utility electric supply and premises wiring meetfor what is covered by this Code.



C. Types of requirements

1. These rules specify:

a. Loadings and factors related to required strength of utility structures and supportedfacilities;

b. Clearances and spacings between: (1) facilities of different utilities, (2) facilities of sameutility, and (3) utility facilities and public facilities;

c. Grounding; and

d. Other requirements related to the safety of utility lines and equipment, includingassociated safe work practices, to be employed by a utility in the exercise of its function asa utility up to the service point.

2. Utilities operating under the NESC are required to maintain control over the system up to theservice point to assure that:

a. The system is engineered to meet the requirements of expected conditions and

Figure 011-1—Utility electrical supply and premises wiring



b. The personnel installing, maintaining, and operating the system and its components arequalified to do so, adequately supervised under good engineering practice, and useappropriate tools and safe work procedures, as specified in these rules.

Revise the definition for utility as follows:

utility. An organization responsible for the engineering supervision (installationdesign, construction,operation, or and maintenance) of a public or private electric supply, or communications, area lighting, streetlighting, signal, or railroad utility systems.

1. public utility. A public utility is an entity that performs or provides one or more utility services forthe benefit of multiple customers (at retail, wholesale, or both), including utilities formed for asingular purpose, such as providing street and outdoor lighting or municipal traffic signal control.Public utilities include investor-owned, municipality/government-owned, cooperative-ownedutilities, public utility districts, irrigation districts, lighting districts, traffic signal or other signalutilities, and similar utilities.

2. private utility. A private utility is an entity that (a) performs or provides one or more utilityservices to its own facilities, such as a large industrial complex, large campus, military complex,railroad system, trolley system, or extensive gas or oil field through its own electric supply,communication, street and area lighting, or signal system and/or (b) generate or transmit power thatis delivered to another utility.

NOTE: Although many private utilities only operate a distribution level system, others operategeneration and transmission systems.

Supporting Comments

SC1 CPs for Rules 010 and 011 and related

This proposal is the result of discussions between July and November 2008 held by the NEC-NESC TaskForce set up by IEEE and NFPA to modify each document to (a) better state its application and (b) limit theopportunity for confusion as to which code applies to what facilities and work.

The current NESC requirements were initially established by the National Bureau of Standards (NBS) at therequest of the U.S. Congress to create national safety standards for public and private electric and supplyutility design, construction, maintenance, and operation. NBS was the first Secretariat for the NESC. Since1972 when the NBS ceased providing assistance to standards committees, the NESC Committee has utilizedthe services of the standards staff of the IEEE as the Secretariat for the NESC.

The initial standard was issued in 1916 for public review and comment. The 2nd Edition issued in 1918 wasthe first to be adopted by a state public service commission. By the 3rd Edition (1920–1922) and 4th Edition(1926–1928), the basic framework of the NESC was set. The NESC has been revised at appropriate timesthroughout its history by the NESC Committee as a consensus-based standard.

The National Electrical Safety Code Committee is accredited by the American National Standards Institute(ANSI) (formerly the American Standards Association and American Engineering Standards Committee) ashaving a balance of the interests involved.

The NESC is American National Standard C2. Until ANSI changed its standards nomenclature system to usedesignations made by a sponsoring organization, NFPA 70, the National Electrical Code (NEC), had beendesignated as ANSI C1. The NESC Committee is an independent committee not under the control of anystandards organization; the NESC procedures are accredited by ANSI.



Inclusion of requirements for similar items in both the NESC and the NEC

In a perfect world, the coverage of the NESC and the NEC could be cleanly separate. However, that cannotbe the case, since both codes must cover certain items. Service to farm buildings is an example. If the utilityprovides power to a central pole and then installs the service drops to each farm building, the service dropsare governed by the requirements of the NESC. However, if the central pole is a meter pole and the farmerinstalls the service drops from the meter pole to each building, the NEC requirements apply to the servicedrops.

Since both codes must include requirements for some of the same items, it is therefore necessary to carefullycraft the scope of each code to properly reflect the central differences between the codes, particularlyincluding the coverage of each code and the differences in exclusivity of control between facilities coveredby the NESC and those covered by the NEC.

This requires changes in both NESC rules and NESC definitions to appropriately reflect application of theNESC to current practices. Also required is a clear delineation between what is covered by the NESC andwhat is not covered by the NESC. Similar changes need to be made to the NEC for the same reasons.

To facilitate appropriate revisions to both the NESC and the NEC, IEEE (the NESC Secretariat) and theNational Fire Protection Association (NFPA—the Secretariat for the NEC) set up a joint task force to discussthe issues of scope similarities and differences between the two codes and prepare appropriate proposals. TheProposed Changes to the NESC that were accepted or accepted as modified by NESC Subcommittee 1 forinclusion in the Preprint were initially prepared by members of the joint task force for consideration by theNESC. Proposals for similar changes have been submitted in November 2008 by a joint NESC-NEC TaskForce for inclusion in the 2011 NEC.

Definitions of public and private utilities (re: CP3407)

Some of the features that distinguish utility installations from many other installations include that (a) thereis an organization responsible for the design, construction, operation, and maintenance of the facilities and(b) these activities are performed in accordance with either engineered standards or specifically engineereddesigns, and (c) these activities are supervised by appropriate personnel qualified to assure compliance. Inaddition, the utility maintains exclusive control over the facilities after initial installation.

This proposal includes a definition of utility that is broken down into sub-definitions of public utility andprivate utility. This breakdown of the definition of utility is made to limit the opportunity for confusion withthose two terms as they are used in other venues, such as rate regulation venues. This is not a change inapplication of the NESC; rather, it is a clear statement of the historic application of the NESC. Public utilitiesare utilities under qualified control that provide utility service to multiple customers, regardless of ownership.Private utilities are utilities under qualified control that provide utility services only to facilities of one ownerand recognized as such by regulatory bodies.

Public utilities include those that supply multiple services, such as power and lighting or telephone andtelevision signals. They also include those established to provide a single service, such as municipal trafficsignal control or lighting.

From its inception, the NESC has applied to the generation and delivery systems of private utilities up to thepoint of delivery to the utilization wiring system (i.e., the service point) of buildings or other installationsserved by the private utility system. For example, DuPont factory generation and delivery systems(distribution and transmission) are designed, installed, operated, and maintained to meet the requirements ofthe NESC ANSI C2. Former NESC Chair (1977–1984 Editions) Ralph Lee, known internationally for hispioneering work on grounding issues and work rules, was employed by DuPont. DuPont factory facilities onthe premises wiring side of the service point are installed to meet the NEC.



In each case, the public or private utility facilities are under the exclusive control of the utility and adhere tothe same standards.

The proposed definition of utility and its sub-definitions is made in order to limit the need to keep using theterms public or private whenever the term utility is used in the NESC. Whenever the term utility is used, itincludes both public utilities and private utilities.

Line of demarcation between the NEC and the NESC; service point vs. delivery point (re: CPs 3422and 3476)

When utilities deliver services to customers, application of the NESC stops at the service point at which theenergy or signals are delivered over to the premises wiring system. Utilization equipment and utilizationwiring on the premises wiring side of the service point is covered by the NEC.

It is recognized that, in some cases, a utility may accept energy or signals from a different utility or transfersuch signals to a different utility, instead of a customer. Such transfer point is not a service point, it is adelivery point and requires a new definition to clearly delineate the difference between transfer of energy orsignals between utilities at a delivery point and transfer of energy or signals between a utility and a customerat a service point.

Authorized person (re: CP3365)

The definition of authorized person is changed to reflect that the person actually performing specified dutiesin, on, or in the vicinity of utility facilities may be a person not in the direct employ of the utility, such as acontractor employee. It also recognizes that the personnel who check both utility vaults and premises wiringvaults in large buildings at specified intervals (usually to catch any water intrusion before it becomes aproblem, etc.) is usually a person on the electrical maintenance staff of the building who has been authorizedto make such checks (although they are not authorized to work on the utility equipment).

Exclusive control of utility (re: CP3418)

The definition of exclusive control is a general definition. The definition of exclusive control of utility is aspecific definition applicable to utility facilities.

Control is relative to control of, access to, and the right to work on energized facilities. The usual methodutilized by utilities to separate their facilities from the public is a spatial barrier (clearances) or a physicalbarrier (such as a pad-mounted transformer enclosure). This definition recognizes that supporting structuresand physical barriers may be within reach of the public.

Where the public has control of switching, such as for lighting served off of the premises wiring systeminstead of directly off of the utility system, the NEC would apply.

Lines (re: CP3435)

The definitions of communication lines and electric supply lines have been expanded to fully explain what isincluded in each definition. The traditional definitions had never been revised to include appropriateclassification of fiber optic cables and traffic signal light lines, as well as what constitutes a joint-use line forpurposes of applying appropriate NESC rules.

Rule 010. Purpose (re: CP3407)

This rule was revised to include the fact that many of its provisions are intended to safeguard property as wellas personnel, such as clearances to buildings from utility wires and equipment, strengths of supportingstructures, and grounding rules. Although the word “property” has not been used previously in this rule, it is



recognized that certain of the NESC rules have always had protection of certain kinds of utility and non-utilityproperty as a main focus. Clearances of wind-displaced, energized conductors from buildings, billboards, etc.,protect such property from accidental energization and protect the conductors from damage. The at-restconductor clearances are based upon accident data and provide adequate room for maintenance of suchproperty. NESC grounding and bonding rules, including the definition of effectively grounded, are designedto limit the likelihood of damage to connected equipment or nearby personnel due to surge voltages. Both theNESC and the NEC contain grounding and bonding requirements designed to limit the likelihood of electricalfires or undue voltages in served buildings or other structures.

In addition, the NESC covers work rules applicable to utility systems, including requirements forqualification, authorization, and direction.

The basis for the NESC requirements is a set of applicable fundamental principles recognized throughout theworld. Appropriate revision of NESC to reflect universal problems is promoted by participation byrepresentatives of the IEEE Power & Engineering Society and IEEE Industrial Application Society, as wellas representatives of other organizations with primary focus on electric supply or communication systems.Because of their universality, NESC requirements have been adapted for local weather conditions and usedby government and utility entities outside the U.S. on all continents in one manner or another. The NESC isused by almost every developing country whose electrification efforts have been aided by the U.S. AIDprogram.

The NESC is adopted for application to regulated utilities by state legislatures and public servicecommissions within the U.S. It is adopted by the American Public Power Association for use by membermunicipal utilities. It is adopted by the Rural Utilities Service of the U.S. Department of Agriculture forapplication to cooperative-owned electric supply and communication systems. It is also used by the U.S.Army Corps of Engineers and other military facility organizations. In addition, the NESC is required by theState of Tennessee to be used for the applicable facilities of industrial complexes. The NESC is adopted bythe governing bodies of unregulated public utilities and unregulated private utilities as the safety standard tobe met during design, construction, operation, and maintenance of their respective utility systems. Thegoverning bodies of unregulated private utilities also adopt the NEC as the safety standard applicable to theirutilization equipment and premises wiring systems.

Rule 011. Scope (re: CP3407)

The scope rule was revised to explicitly detail what the NESC does and does not cover, in order to clearlyindicate areas of responsibility that are different than (or similar to) those of the NEC. In particular, theserevisions stress the qualified control of utilities and more fully indicate the types of utility services to whichNESC requirements apply.

The application to facilities provided by utilities on mine sites is also added. On many mine sites of all types,and particularly on surface mine sites, the utilities install the distribution utility facilities throughout the siteto the various service points at the locations of buildings or major installations of outdoor electricalequipment. This usually includes overhead lines, but increasingly includes underground lines as well. TheNEC is applicable for the premise wiring systems for the utilization equipment beyond the service points atsuch sites.

The new Rule 011B. Not covered clearly indicates areas of responsibility that belong to the NEC or otherstandards and not to the NESC.

New Rule 011C is provided to describe the types of requirements covered by the NESC and the responsibilityof utilities to these rules.




Affirmative: (9) Bleakley, Clapp, Dagenhart, Denbrock, Engmann, Hooper, Hyland, Komassa, Tomaseski

Negative: (0)

Abstention: (0)

Revised Text

CP3415

Section: 1 Rule: 010 Purpose

Submitter

Neil F. LaBrake, Jr., PE

Proposed Change


010. Purpose

A. The purpose of these rules is the practical safeguarding of persons and property during theinstallation, operation, orand maintenance of electric supply and communication lines andassociated equipment.

B. These rules contain the basic provisions that are considered necessary for the safety of utilityworkers (employees and contractors) and the public under the specified conditions.

C. This Code is not intended as a design specification or as an instruction manual.

D. This Code serves the global needs of industry, government, and the public throughout the globalcommunity outside of the United States of America to be consistent with good engineeringpractice.

1. This National Electrical Safety Code (NESC) is American National Standard C2 (ANSI C2). Itis a consensus standard that is prepared by the National Electrical Safety Code Committeeunder procedures approved by the American National Standards Institute (ANSI). The NESCCommittee is composed of national and international organizations and is certified by ANSI ashaving an appropriate balance of the interests of members of the public, utility workers,regulatory agencies, and the various types of private and public utilities.

2. The NESC is intended to provide a standard of safe practices that can be adopted by publicutilities, private utilities, state or local utility commissions, or public service commissions, orother boards or bodies having control over safe practices employed in utility installations.

NOTE: The NESC is used in whole or in part by statute, regulation, or consent as the standard (orbasis of the standard) of safe practice for public and private utilities in every state of the UnitedStates, as well various jurisdictions and industries in other countries.



Supporting Comment

Editorially add outline numbering to Rule for organizational style to separate topics and provide ability toreference subsections and correlate this Rule with 90.1(B), and 90.1(C) of the NEC. The new proposedsubpart Rule D is intended to correlate with 90.1(D) in the NEC (see IEEE’s mission in their OperationsManual, December 2007, although IEEE is only the Secretariat for this ANSI document).

Added “property” in Rule 010A as another item the NESC safeguards and to correlate with NEC 90.1(A).

Added “utility workers” to Rule 010B along with the parenthetical description that these are the employeesand contractors covered by the NESC.

This is an action to harmonize the purpose and scope sections of two ANSI standards, the NESC and the NEC,to mitigate conflicts between documents as encountered in the NFPA Standards Council Appeals Hearingson the 2008 NEC adoption in July 2007. [Refer to Final Decision on Appeal number #07-24 (SC# 07-7-39)in the NFPA archives (http://www.nfpa.org/itemDetail.asp?categoryID=837&itemID=35006 and http://www.nfpa.org/assets/files/PDF/Standards%20Council/TranscriptSCMeetingJuly07.pdf) pertaining to thisissue.]

This action is a result of a meeting of a Task Group of the NESC and NEC Committees on July 10, 2008.


Accept in principle.


See CP3407.


Affirmative: (8) Bleakley, Christofersen, Clapp, Dagenhart, Denbrock, Hooper, Komassa, Tomaseski

Negative: (0)

Abstention: (0)

Revised Text

CP3008

Section: 1 Rule: 011 A

Submitter

Brian Erga

Proposed Change

A. These rules cover electric supply and communication lines, associated equipment, and associated



work practices employed by a public or private electric supply, communications, railway, orsimilar utility in the exercise of its function as a utility. They cover similar systems under thecontrol of qualified persons, such as those associated with an industrial complex or utilityinteractive system.

Supporting Comment

The addition of “electric” keeps the Code consistent throughout the document as noted in 012.A. and manyother locations. The term “associated” in front of “equipment” also makes Code consistent throughout as seenin the first paragraph of Rule 010.


Accept as modified.

Revise Rule 011A.

A. These rules cover (1) electric supply and communication lines, and equipment, and (2) associatedwork practices employed by a public or private electric supply, communications, railway, or similarutility in the exercise of its function as a utility.

These rules also They cover similar systems under the control of qualified persons, such as thoseassociated with an industrial complex or utility interactive system.


Electric supply lines and equipment, communication lines and equipment, and work practices associated witheach are covered by the NESC. The appropriate place for the word associated is in its present positionmodifying work practices.



Negative: (0)

Abstention: (0)

Revised Text

CP3203

Section: 1 Rule: 011 B

Submitter

James T. Collins



Proposed Change

Add the phrase “including electrical facilities installed by contractual or other agreement” to Rule 011B asfollows:

B. The NESC covers utility facilities and functions up to the service point.,including electricalfacilities installed by contractual or other agreement.

NOTE: The National Electrical Code® (NEC®) (NFPA 70, 2005 Edition) covers utilization wiringrequirements beyond the service point.

Supporting Comment

Recent changes to article 90.2(B)(5) of the NEC deleted the utility exclusion related to “by other agreements.”This change implies utilities should build to NEC requirements when facilities other than service drops andservice lateral are installed outside of a right-of-way or easement. There are property owners that will notgrant easements to utilities but contractual or other agreements between the property owner and the utilityallows utilities to install equipment (poles, primary wiring and transformers) across the property. Alsoeasements can not be obtained when installing equipment inside specially designed rooms (vaults) inbuildings but through special agreements utilities are granted rights to construct and maintain equipmentahead of the service point.




See CP3407.


Affirmative: (6) Clapp, Dagenhart, Denbrock, Hooper, Komassa, Tomaseski

Negative: (0)

Abstention: (0)

Revised Text

CP3416

Section: 1 Rule: 011 Scope

Submitter




Proposed Change


011. Scope

A. Covered. These rules cover supply and communication lines, equipment, and associated workpractices employed by a public or private electric supply, communications, railway, or similarutility in the exercise of its function as a utility.

1. They NESC covers similar systems under engineering supervision and the control of qualifiedpersons, such as those associated with an industrial complex or utility interactive system wherethese rules are recognized by other codes and standards and good engineering practice.

B2. The NESC covers utility facilities and functions of generation, transmission, and distributionof electricity, lumens, and signals located on the line side of up to the service point. installedby contractual or other agreement with the utility located on public and private property bylegally established easements or rights-of-way or other written agreements that are eitherdesignated by or recognized by public service commissions, utility commissions, or otherregulatory agencies having jurisdiction, or governing agencies where not regulated.

NOTE: The National Electrical Code® (NEC®) (NFPA 70, 2005 Edition)1 covers utilizationwiring requirements beyond the service point.

C3. NESC rules cover street and area lights to provide a supply of lumens where these facilities are(supplied by underground or overhead conductors) installed and/or maintained under theexclusive control of utilities (including their authorized contractors) or other qualified persons)(such as those associated with an industrial complex).

NOTE: Luminaires not under such exclusive control are governed by the requirements of theNEC.

4. NESC rules cover the lower voltage wiring within a supply station installed and/or maintainedunder the exclusive control of utilities that is necessary for the operation of the supply station.

DB. Not covered. NESC rules do not cover:

1. Installations in mines, ships, railway rolling equipment, aircraft, or automotive equipment, or

2. Utilization wiring requirements beyond the service point except as covered in Parts 1 and 3, or

3. Luminaires not installed or maintained under exclusive control by utilities, or

4. Industrial complex or utility interactive systems that are not controlled exclusively underutilities or qualified persons on the premises wiring side of the service point.

NOTE: For installations in ships, refer to Title 46, Code of Federal Regulations, Parts 110–113.

The National Electrical Code® (NEC®) (NFPA 70, 2008 Edition) covers utilization wiringrequirements beyond the service point and luminaires that are not controlled exclusively underutilities.

C. Types of requirements covered



1. These rules cover:

a. Minimum loadings and factors related to required strength of utility structures andsupported facilities;

b. Clearances and spacings between facilities of: different utilities, the same utility, andutility and public;

c. Grounding; and

d. Other requirements related to the safety of utility lines and equipment, includingassociated safe work practices, to be employed by and the function of a public or privateutility up to the service point.

2. Utilities operating under the NESC are required to maintain control over the supply system upto the service point to assure that:

a. The system is engineered to meet the requirements of expected conditions and

b. The personnel installing, maintaining, and operating the system and its components arequalified to do so, adequately supervised under good engineering practice, and useappropriate tools and safe work procedures, as specified in these rules.

Supporting Comment

Editorially add outline numbering to Rule for organizational style to separate topics and provide ability toreference subsections. Add text “Covered.” to Rule 011A to correlate with 90.2(A) of the NEC.

Added property text covered by the utility in proposed Rule 011A2 to correlate with the not covered items inNEC 90.2(B)(5). Included lumens as a service supplied by a utility.

Added “installed and/or maintained” in proposed Rule 011A3 to better describe the act of what is beingcontrolled exclusively under utilities. Included lumens as a service supplied by a utility.

The addition of proposed Rule 011A4 specifically applies to stations that are under NESC for such wiring ascontrols for electric operations. The text will help clarify jurisdictional issues relative to utilization wiring forsupply stations relative to the NEC. This will correlate with 90.2(B)(5)b in the NEC.

Add text “Not Covered.” to proposed Rule 011B to correlate with 90.2(B) of the NEC. And, added theinformational note in proposed Rule 011B1 to correlate with the Fine Print Note to NEC 90.2(B)(1).

In proposed Rule 011B2, the added text “requirements beyond the service point” correlates with the scope ofthe NEC where the NEC covers utilization and premises wiring up to the service point. This provides fordistinction between supply side facilities and premises wiring relative to the service point as defined in boththe NESC and NEC.

New Rule 011B3 provides correlation of not covered items for those that are covered in the NEC. Added“installed or maintained” to better describe the act of what is being controlled by utilities. This is derived fromformer informational note to Rule 011C.

New Rule 011B4 provides correlation of not covered items for those that are covered in the NEC. This isderived from second sentence of former Rule 011A. The added informational NOTE is derived from formerNOTES to Rules 011B and 011C to correlate with NEC 90.2(A).



New Rule 011C is provided to describe the types of requirements covered by the NESC and the responsibilityof utilities to these rules.

This is an action to harmonize the purpose and scope sections of two ANSI standards, the NESC and the NEC,to mitigate conflicts between documents as encountered in the NFPA Standards Council Appeals Hearingson the 2008 NEC adoption in July 2007. [Refer to Final Decision on Appeal numbers #07-24 (SC# 07-7-39)and #07-7 (SC# 07-7-5-m) in the NFPA archives (http://www.nfpa.org/itemDetail.asp?categoryID=837&itemID=35006 and http://www.nfpa.org/assets/files/PDF/Standards%20Council/TranscriptSCMeetingJuly07.pdf) pertaining to this issue.] Also, this action supportsthe NESC to resolve the conflict in 90.2(B)(5)b contained in the 2008 NEC caused by the removal of thewords “or by other agreements.”

This action is a result of a meeting of a Task Group of the NESC and NEC Committees on July 10, 2008.




See CP3407.



Negative: (0)

Abstention: (0)

Revised Text

CP3026

Section: 1 Rule: 013 A2c

Submitter

Ewell T. Robeson

Proposed Change

Revise Rule 013A2c as follows:

2. Types of construction and methods of installation other than those specified in the rules may beused experimentally to obtain information, if done where

a. Qualified supervision is provided,

b. Equivalent safety is provided, and



c. On joint use facilities, all affected parties joint users are notified agree.

Supporting Comment

Since equivalent safety is provided in item b), there is no need for agreement. Competition and innovationcan be stifled. For example if a utility wanted to “experiment” with plastic or steel distribution poles, thennotification is proper so that the joint users would know that their linemen may require steps to climb thepoles; they don’t need to agree since equivalent safety is already required by Rule 013A2b.


Accept as modified.





c. On joint use facilities, all affected utilities parties agree.


Affirmative: (7) Christofersen, Clapp, Dagenhart, Denbrock, Hooper, Hyland, Tomaseski

Negative: (2) Bleakley, Komassa

Abstention: (0)

Explanation of Vote

Bleakley: (Negative) Requiring agreement among the joint users may be used to stifle the use of newequipment or pole hardware designs by the same utility type joint user that compete with each other. Sinceonly agreement and not valid reasoning is required, it may be used by any joint user to stop innovation if itwill mean extra work or expense to accommodate the innovation. Since Rule 013A2b requires equivalentsafety to be provided, there is no safety gain by requiring agreement instead of notification. This is a safetycode, not a code of conduct.

Clapp: (Affirmative) The language requiring consent of joint users for experimentation on facilities uponwhich they were attached was specifically added to the Code to address previous problems that occurred whenone joint user mistakenly assumed that the experiment would not adversely affect any of the joint users. Theintention of the requirement is to assure that potential problems on the facilities of joint users areappropriately considered in the design of any experiment that has the to potential to adversely affect any joint-use facility. The intent was that the only reason for withholding permission would be related to the safety ofemployees, the public, lines, or equipment.

This proposed change leaves that language requiring permission to conduct the experiment on the joint usefacility intact; it merely changes the word “parties” to “utilities.” Thus, in the absence of a proposal to deletethe requirement to gain permission of joint users, I think the negative votes are not appropriate. However, I



recognize the concerns of the negative voters about the possibility of someone withholding permission for anexperiment on the basis of some competition-based concern (which is certainly not intended), instead of asafety-based concern. Such action is not intended by the rule. Therefore, I suggest that we should change thisrule to the language follows.

Rule 013A2c. On joint use facilities, all utilities with lines or equipment on or in the joint use facilities agreethat no adverse safety issue would be expected to result from the experiment.

Komassa: (Negative) Prefer original proposal.

Revised Text

CP3204

Section: 1 Rule: 013 A2c

Submitter

James T. Collins

Proposed Change





c. On joint use facilities, all affected parties agree.joint users are notified.

Supporting Comment

Since equivalent safety is provided in item b., there is no need for agreement. Competition and innovationcan be stifled. For example if a utility wanted to “experiment” with plastic or steel distribution poles, thennotification is proper so that the joint users would know that their linemen may require steps to climb thepoles; they don’t need to agree since equivalent safety is already required by Rule 013A2b.




See CP3026.




Affirmative: (7) Christofersen, Clapp, Dagenhart, Denbrock, Hooper, Hyland, Tomaseski

Negative: (2) Bleakley, Komassa

Abstention: (0)

Explanation of Vote

Bleakley: (Negative) See comment on CP3026.

Komassa: (Negative) See comment on CP3026.

Revised Text

CP3027

Section: 1 Rule: 013 B2

Submitter

Ewell T. Robeson

Proposed Change

Revise 013B2 as follows:

2. Existing installations, including maintenance replacements, that currently comply with prioreditions of the Code, need not be modified to comply with these rules except (a) as may be requiredfor safety reasons by the administrative authority or (b) as required by Rule 202 238C.

EXCEPTION 1: For safety reasons, the administrative authority may require compliance with theserules.

EXCEPTION 2: When a structure is replaced, requirement of current Rule 238C shall be met ifapplicable.

Supporting Comment

When the field user goes to the referenced Rule 202 as required by (b) above, Rule 202 then references Rule238C. A reference in a rule to another rule needs to take the field user directly to the rule that is applicable tolimit confusion; not to some intermediate rule first.


Accept as modified.



Proposed Change

Revise 013B2 as follows:

2. Existing installations, including maintenance replacements, that currently comply with prioreditions of the Code, need not be modified to comply with these rules except (a) as may be requiredfor safety reasons by the administrative authority or (b) as required by Rule 202.

EXCEPTION 1: For safety reasons, the administrative authority may require compliance with theserules.

EXCEPTION 2: When a structure is replaced, the current requirements of Rule 238C shall be met.


Affirmative: (8) Bleakley, Christofersen, Dagenhart, Denbrock, Hooper, Hyland, Komassa, Tomaseski

Negative: (1) Clapp

Abstention: (0)

Explanation of Vote

Clapp: (Negative) I agree with substituting 238C for 202, which was the primary purpose of this CP.However, I cannot support pulling that statement out into an EXCEPTION. Usually EXCEPTIONs are thingsthat you can do, if you desire, that are less restrictive than the general rule. As a result, people have a tendencyto ignore the EXCEPTIONs if they are planning to do what is required by the general rule. The originalpurpose of having this direction be part of the main rule is to assure that users see the requirement to meet238C when a structure is changed out. Thus, this direction needs to stay in the rule, not be put into anEXCEPTION.

Revised Text

CP3205


Submitter

James T. Collins

Proposed Change

Reformat rule to show exceptions in proper format.

B. Existing installations

1. ...



2. Existing installations, including maintenance replacements, that currently comply with prioreditions of the Code, need not be modified to comply with these rules. except (a) as may berequired for safety reasons by the administrative authority or (b) as required by Rule 202.

EXCEPTION 1: For safety reasons, the administrative authority may require compliance withthese rules.

EXCEPTION 2: When a structure is replaced, the requirements of current Rule 238C shall bemet, if applicable.

Supporting Comment

The current rule includes two exceptions. Reformatting the rule and revising the wording as shown willmore clearly indicate the intent of this rule.




See CP3027.



Negative: (0)

Abstention: (0)

New Text

CP3207

Section: 1 Rule: 014 A1

Submitter

James T. Collins

Proposed Change

Revise Rule 014A1 as follows:

A. Emergency installation

1. ...



a. The clearances required in 3 may be decreased for emergency installations. See Rule230A.

b. The burial depth requirements in Part 3 may be waived for the duration of the emergency.See Rule 311C.

Supporting Comment

Rule 311C was added in the 2007 Code, which mirrors Rule 230A2d for overhead that allow conductors orcables to be laid directly on grade during emergencies. Adding the reference to Rule 311C will take the userto the underground equivalent rule. Most cables laid on grade for emergencies are for underground cablefailures.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3028

Section: 1 Rule: 014 A1

Submitter

Ewell T. Robeson

Proposed Change


A. Emergency installations

1. The clearances required in Section 23 or burial depths required in Part 3 may be decreased foremergency installations. See Rules 230A and 311C.

Supporting Comment

Rule 311C was added in the 2007 Code, which mirrors Rule 230A2d for overhead that allow conductors orcables to be laid directly on grade during emergencies. Adding the reference to Rule 311C will take the userto the underground equivalent rule. Most cables laid on grade for emergencies are for underground cable



failures.




See CP3027.



Negative: (0)

Abstention: (0)

Revised Text

CP3425

Section: 1 Rule: 015 Intent

Submitter

Allen L. Clapp

Proposed Change

Revise the language of Rule 015, subsections C and D, as follows:

C. Footnotes to a table are designated by a circle surrounding the footnote number. Footnotes to atable have the same force and effect that is required or allowed by the rule that specifies the use ofthe table.

D. The word EXCEPTION indicates a specified option that may be substituted for one or more of therequirements stated in the rule or table, at the option of the utility. Exceptions to a rule have thesame force and effect required or allowed by the rule to which the exception applies.

NOTE: EXCEPTIONs recognize alternatives to generally applied requirements that are safe underthe specified conditions. In some cases, an EXCEPTION may merely be a less frequently used safeoption that may be preferable under the particular constraints of the site or work.

Supporting Comment

The revised form of 015C and 015D matches the form of the remainder of the rule. The additional NOTEaddresses questions that often arise as to the appropriateness of using an EXCEPTION, rather than the mainrule requirements, that the addition of 015D apparently did not cure.



Warning is one of the signal words used in ANSI Z535.2-1991, Standard for Environmental and FacilitySafety Signs. The preferred word is “safety” since the user is referred to the ANSI Z535 standards for thecorrect signal word.


Accept as modified.

Proposed Change

Revise the language of Rule 015, subsections C and D, as follows:

C. Footnotes to a table are designated by a circle surrounding the footnote number. Footnotes to atable have the same force and effect that is required or allowed by the rule that specifies the use ofthe table.

D. The word “EXCEPTION” indicates a specified option that may be substituted for one or more ofthe requirements stated in the rule or table, at the option of the utility. Exceptions to a rule have thesame force and effect that is required or allowed by the rule to which the exception applies.

NOTE: EXCEPTIONs recognize alternatives to generally applied requirements that are safe underthe specified conditions. In some cases, an EXCEPTION may merely be a less frequently used safeoption that may be preferable under the particular constraints of the site or work.


Affirmative (9) Bleakley, Christofersen, Clapp, Dagenhart, Denbrock, Hooper, Hyland, Komassa,Tomaseski

Negative: (0)

Abstention: (0)

New Text

CP3029


Submitter

Ewell T. Robeson

Proposed Change


016. Effective date

This edition may be used at any time on or after the publication date. Additionally, this edition shallbecome effective no later than the first day of the month after 180 days have elapsed following its



publication date for application to new installations and extensions where both design and approvalwere started after the expiration of that period, unless otherwise stipulated by the administrativeauthority. Example: If the NESC is published on August 1, 2011, then it will become effective onFebruary 1, 2012.

NOTE: A period of not less than 180 days is allowed for utilities and regulatory authorities to acquirecopies of the new edition and to change regulations, internal standards, and procedures as may berequired. There is neither an intention to require or imply that this edition be implemented before180 days from the publication date, nor an intention to prohibit earlier implementation.

Supporting Comment

Stating “180 days following its publication” creates a question as to what is the first day followingpublication. If the NESC is officially published on August 1, is August 1 the first day or is it August 2? Andat day 180, is it effective that day or the next? This proposal eliminates any potential for confusion.


Accept.


Affirmative (9) Bleakley, Christofersen, Clapp, Dagenhart, Denbrock, Hooper, Hyland, Komassa,Tomaseski

Negative: (0)

Abstention: (0)



Section 2. Definitions of special terms

New Text

CP3477

Section: 2 Def area lighting

Submitter

NESC Subcommittee 1

Proposed Change

Add a new definition for area lighting:

area lighting. An electrical installation that provides lumens on public or private property. Area lightinginstallations under the exclusives control of utility are covered by the NESC. All other area lightinginstallations are covered by the NEC.

Supporting Comment

This proposal is the result of discussions between July and November 2008 held by the NEC-NESC TaskForce set up by IEEE and NFPA to modify each document to (a) better state its application and (b) limit theopportunity for confusion as to which Code applies to what facilities and work.

The provision of lighting service is a provision of illumination, not electricity. It may be provided from adistribution system that also provides electricity to the same or other customers, or it may be provided froma dedicated system. This definition is added in support of the changes in Rule 011. If the lighting system isunder the exclusive control of a utility, then the NESC applies. If not, the NEC applies. This new definitionis also proposed for the 2011 NEC at this time.


Accept.


Affirmative (9) Bleakley, Clapp, Dagenhart, Denbrock, Engmann, Hooper, Hyland, Komassa, Tomaseski

Negative: (0)

Abstention: (0)



Revised Text

CP3453

Section: 2 Def effective ground

Submitter

Working Group 1.10

Proposed Change

effective ground/effectively grounded. Intentionally connected to earth through a ground connection orconnections of sufficiently low impedance and having sufficient current-carrying capacity to limit thebuildup of voltages to levels that which may result in undue hazard to persons or to connected equipment.Bonded to an effectively grounded neutral conductor or to a grounding system designed to minimize hazardto personnel and having resistances to ground low enough to permit prompt operation of circuit protectivedevices.

Supporting Comment

See new CP proposal on effectively grounded neutral conductor. With this new definition, the existingdefinition of effectively grounded can be simplified. This will also cover the requirements of Rules 96A and96D for delta or single–grounded systems.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3450

Section: 2 Def effectively grounded

Submitter

Working Group 1.10



Proposed Change

New definition.

effectively grounded neutral conductor: A conductor that is intentionally connected to the sourcetransformer neutral directly or through an impedance to limit phase to ground fault current and has aminimum of four grounds in each mile of line. The conductor shall be of sufficient size to carry the availablefault current and allow protective devices to operate promptly under fault conditions.

Supporting Comment

The term “neutral conductors that are effectively grounded” is used in Rule 230E1. Other variations of thisterm are used in the Code, but are not defined. The proposed definition meets current industry practices.


Accept.



Negative: (1) Bleakley

Abstention: (0)

Explanation of Vote

Bleakey: (Negative) The proposed definition for effectively grounded neutral conductor with suggestedrevision follows:

effectively grounded neutral conductor: A conductor that is intentionally connected to the sourcetransformer neutral directly or through an impedance to limit phase to ground fault current and has aminimum of four grounds in each mile of line. The conductor shall be of sufficient size to carry the availablefault current and allow protective devices to operate promptly under fault conditions.

The phrase “a minimum of” should be replaced with the phrase “not less than.”

The use of the word “minimum” was generally changed to “not less than” to alleviate the questions aboutwhether the rule is requiring 4 and only 4 grounds in each mile or not less than 4 grounds in each mile. Seethe wording in Rule 96C.

New Text

CP3478

Section: 2 Def engineering supervision



Submitter

NESC Subcommittee 1

Proposed Change

Add a new definition for engineering supervision.

engineering supervision: Technical supervision for applying engineering principles and practices in thedesign, construction, maintenance, operation, and performance of an installation, equipment, or system.

Supporting Comment


Some of the features that distinguish utility installations from many other installations include that (a) thereis an organization responsible for the design, construction, operation, and maintenance of the facilities (seethe definition of utility), (b) these activities are performed in accordance with either engineered standards orspecifically engineered designs, and (c) these activities are supervised by appropriate personnel qualified toassure compliance with these engineered standards or designs. In addition, the utility maintains exclusivecontrol over the facilities after initial installation.

What constitutes “expertise” and establishment of credentials and the nature of engineering from beginningto end of a structure, equipment, or system installation? By law, many governmental jurisdictions requireengineers to be licensed in order to practice to demonstrate their professional service to the protection ofpublic health, safety, and welfare. Engineering supervision of a structure, equipment, or system installationbegins with the initial engineering design, continues with construction and establishment and overseeing ofongoing operation and maintenance, and ends with final retirement and removal.

Having an engineer oversee the installation and maintenance of an installation does not eliminate commonpractice of having technical persons perform and oversee portions of the work according to their individualexpertise. All it means is that they will be working under the oversight of an engineer. This brings the NESCin compliance with existing state law and provides an opportunity for the engineer to verify that the correctpersons are overseeing each portion of a project. This new definition is also proposed for the 2011 NEC atthis time.


Accept.



Negative: (0)

Abstention: (0)



New Text

CP3476

Section: 2 Def premises wiring

Submitter

NESC Subcommittee 1

Proposed Change

The following changes are based upon language presently in the National Electrical Code NFPA 70-2008.

Add a new definition for premises to be used with a new definition of premises wiring.

premises. The land and buildings of a user located on the user side of the service point (sometimes calledthe utility-user network point of demarcation for communication wiring) to electric supply, communicationor signal premises wiring.

Add a new definition for premises wiring to be used to support the present definition of service point andhelp differentiate application of the NESC from that of the NEC.

premises wiring (system). Interior and exterior wiring, including power, lighting, control, communication,and other signal circuit wiring together with all their associated hardware, fittings, and wiring devices, bothpermanently and temporarily installed either (a) from the service point or premises power source to theoutlets or (b) where there is no service point, from and including the non-utility power source to the outlets.

Such wiring does not include wiring internal to appliances, luminaires, motors, controllers, motor controlcenters, and similar equipment, nor does it include utility equipment and wiring on the utility side of theservice point.

Revise the definition of service point to aid in differentiating application of the NESC from that of the NECby adding a NOTE taken verbatim from the NEC Handbook. The definition remains unchanged in both theNEC and the NESC.

service point. The point of connection between the facilities of the serving utility and the premises wiring.

NOTE: The service point is the point of demarcation between the serving utility and the premises wiring.The service point is the point on the wiring system where the serving utility wiring ends and the premiseswiring begins. The serving utility generally specifies the location of the service point based on theutility’s condition of service.

Because the location of the service point is generally determined by the utility, the service-dropconductors and the service-lateral conductors may or may not be part of the service covered by the NEC.For these types of conductors to be covered, they must be physically located on the premises wiring sideof the service point. If the conductors are located on the utility side of the service point, they are notcovered by the NEC definition of service conductors and are therefore not covered by the NEC.

Based on the definitions of the terms service point and service conductors, any conductor on the servingutility side of the service point generally is not covered by the NEC. For example, a typical suburbanresidence has an overhead service drop from the utility pole to the house. If the utility specifies that the



service point is at the point of attachment of the service drop to the house, the service-drop conductorsare not considered service conductors because the service drop is not on the premises wiring side of theservice point. Alternatively, if the utility specifies that the service point is “at the pole,” the service-dropconductors are considered service conductors, and the NEC would apply to the service drop.

Exact locations for a service point may vary from utility to utility, as well as from occupancy tooccupancy.

Supporting Comment


These definitions are necessary to appropriately revise the scope and coverage of the NESC to clearlydelineate facilities covered by the NESC versus those covered by the NEC.

The new definitions of premises and premises wiring support the definition of service point that is currentlyin both the NESC and the NEC. The new NOTE added under the definition of service point is copied directlyfrom the 2008 NEC Handbook.

Emphasis was added in several places by bolding or italicizing text.

The changes presently shown above in this document show changes to the NESC language that are proposed.In order to indicate how this language was developed, the changes below show the proposal language as ithas been revised from the NEC language.

premises. The land and buildings of a user located on the user side of the service point (sometimes calledthe utility-user network point of demarcation for communication wiring) to electric supply, communicationor signal premises wiring.

It is recognized that the definition of premises may, at first, appear odd, since it only includes the land andbuildings located on the user side of the service point. This is taken directly from language used in NECarticles 100 and 800. In essence, the utility facilities on the line side of the service point are not included inthe premises, similar to the manner in which the NEC considers that a utility vault inside a building isconsidered to be outside the building.

premises wiring (system). Interior and exterior wiring, including power, lighting, control, communication,and other signal circuit wiring together with all their associated hardware, fittings, and wiring devices, bothpermanently and temporarily installed either (a) from the service point or premises power source to theoutlets or (b) where there is no service point, from and including the non-utility power source to the outlets.This includes (a) wiring from the service point or power source to the outlets or (b) wiring from andincluding the power source to the outlets where there is no service point.

service point. The point of connection between the facilities of the serving utility and the premises wiring.

NOTE: The service point is the point of demarcation between the serving utility and the premiseswiring. The service point is the point on the wiring system where the serving utility ends and thepremises wiring begins. The serving utility generally specifies the location of the service point.

Because the location of the service point is generally determined by the utility, the service-dropconductors and the service-lateral conductors may or may not be part of the service covered by theNEC. For these types of conductors to be covered, they must be physically located on the premises



wiring side of the service point. If the conductors are located on the utility side of the service point, theyare not covered by the NEC definition of service conductors and are therefore not covered by the NEC.

Based on the definitions of the terms service point and service conductors, any conductor on the servingutility side of the service point generally is not covered by the NEC. For example, a typical suburbanresidence has an overhead service drop from the utility pole to the house. If the utility specifies that theservice point is at the point of attachment of the service drop to the house, the service-drop conductorsare not considered service conductors because the service drop is not on the premises wiring side of theservice point. Alternatively, if the utility specifies that the service point is “at the pole,” the service-dropconductors are considered service conductors, and the NEC would apply to the service drop.

Exact locations for a service point may vary from utility to utility, as well as from occupancy tooccupancy.

The preceding language relating to service point is taken directly from the NEC and the NEC Handbook.

This will provide clarity where the NEC applies to premises wiring meeting the supply facilities underexclusive control of utilities at the service point and to separately derived systems that are not connected to aservice point. The location of the service point and utility equipment to provide electric service to premiseswiring is dependent upon the serving public or private utility’s local requirements under conditions ofservice (e.g., tariffs with service applications). These new definitions are also proposed for the 2011 NEC atthis time.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3365

Section: 2 Def authorized person

Submitter

Allen L. Clapp

Proposed Change

Add the following new definition of authorized person.

authorized person. A person who has been authorized by the entity controlling utility facilities to performspecified duties in, on, or in the vicinity of utility facilities, as applicable.



Supporting Comment

This definition is required for use with Rule 224A and other rules. Even though a person may be qualified towork on or around utility facilities, they may not do so until authorized to do so by the entity controlling thosefacilities. For example, a person qualified to install communication cables in the supply space on a pole lineis prohibited from doing so by Rule 224A until they are authorized by the supply utility to do so.


Accept as modified.

Add the following new definition of authorized person.

authorized person. A person who has been authorized by the controlling utility or its designatedrepresentative to perform specified duties in, on, or in the vicinity of utility facilities, as applicable.


This proposal is the result of the work of the NESC-NEC Task Force set up by IEEE and NFPA tocoordinate the scope and application of each Code. This definition is necessary to support other definitionsand rules dealing with exclusive control by utilities, including its authorized representatives.



Negative: (0)

Abstention: (0)

New Text

CP3206

Section: 2 Def clearance

Submitter

James T. Collins

Proposed Change

Revise the definition of clearance as follows:

clearance. The clear distance between two objects measured surface to surface, and usually filled with a gassuch as air.



Supporting Comment

The 2007 NESC incorporated a number of changes where separation was replaced with clearance when airfilled the space between surfaces. The definitions are practical equivalents since both measure the samedistance with the same units. Both terms indicate a distance measured surface to surface, but separation isdefined as: “The distance between two objects, measured surface to surface, and usually filled with a solid orliquid material.” No mention is made of the medium for clearance. Rather than undoing what was done in2007, we should further differentiate between in the terms. The proposed revision will distinguish betweenclearance and separation.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3022

Section: 2 Def communication lines

Submitter

Ewell T. Robeson

Proposed Change

Revise the definition of communication lines as follows:

lines.

1. communication lines.

a. communication lines located in the communication space. The conductors and theirsupporting or containing structures that are used for public or private signal or communicationsservice, and which operate at potentials not exceeding 400 V to ground or 750 V between anytwo points of the circuit, and the transmitted power of which does not exceed 150 W. Whenoperating at not more than 90 V ac or 150 V dc, no limit is placed on the transmitted power ofthe system. Under specified conditions, communication cables may include communicationcircuits exceeding the preceding limitation where such circuits are also used to supply powersolely to communications equipment.



NOTE: Telephone, telegraph, railroad-signal, data, clock, fire, police-alarm, cable-television,and other systems conforming with the above are included. Lines used for signaling purposes,but not included under the above definition, are considered as supply lines of the same voltageand are to be so installed.

b. communication lines located in the supply space. Communication lines located in the supplyspace and meeting Rule 224A may (a) operate at any voltage, (b) include supply circuits of anyvoltage, or c) be included within a supply conductor or cable operating at any voltage.

2. electric supply lines. Those conductors used to transmit electric energy and their necessarysupporting or containing structures. Signal lines of more than 400 V are always supply lines withinthe meaning of the rules, and those of less than 400 V may be considered as supply lines, if so runand operated throughout. Syn: supply lines.

Supporting Comment

The major reason for the separation between communication and supply facilities is because of thedifference in the type of work and exposure to hazards. This is not dependent on how the facility is used.Therefore a supply worker is qualified to work on any type of cable regardless of use. This change proposalwould allow combination cables for both supply and communication, as long as the worker is qualified todo such work on the facilities having the higher hazard.

As Allen Clapp had suggested in his comment 5038 for this CP, it appears that the presenter is saying thatwhen a communication circuit is located in the supply space, where only qualified personnel are allowed towork, then there is no need for a voltage limitation. The proposal above is the same as Allen suggested in hiscomment and I remember that most of the committee felt that it was a good suggestion, but was notappropriate for a CP at that time, but would be for the 2012 NESC.




See CP3208.



Negative: (0)

Abstention: (0)

Revised Text

CP3208

Section: 2 Def communication lines



Submitter

James T. Collins

Proposed Change

Revise the definition of communication lines as follows:

lines.

1. communication lines.

a. located in the communication space. The conductors and their supporting or containingstructures that are used for public or private signal or communications service, and whichoperate at potentials not exceeding 400 V to ground or 750 V between any two points of thecircuit, and the transmitted power of which does not exceed 150 W. When operating at notmore than 90 V ac or 150 V dc, no limit is placed on the transmitted power of the system.Under specified conditions, communication cables may include communication circuitsexceeding the preceding limitation where such circuits are also used to supply power solely tocommunications equipment.

NOTE: Telephone, telegraph, railroad-signal, data, clock, fire, police-alarm, cable-television,and other systems conforming with the above are included. Lines used for signaling purposes,but not included under the above definition, are considered as supply lines of the same voltageand are to be so installed.

b. located in the supply space. Communication lines located in the supply space and meetingRule 224A may (a) operate at any voltage, (b) include supply circuits of any voltage, or (c) beincluded within a supply conductor or cable operating at any voltage.

2. electric supply lines. Those conductors used to transmit electric energy and their necessarysupporting or containing structures. Signal lines of more than 400 V are always supply lines withinthe meaning of the rules, and those of less than 400 V may be considered as supply lines, if so runand operated throughout. Syn: supply lines.

Supporting Comment

CP2788 for the 2007 Code had the following proposal rejected:

Add to Rule 220B2e as follows:

EXCEPTION: When communication circuits are constructed and maintained by qualified supply personnel,any communication circuit may be included in a supply cable.

The major reason for the separation between communication and supply facilities is because of thedifference in the type of work and exposure to hazards. This is not dependent on how the facility is used.Therefore a supply worker is qualified to work on any type of cable regardless of use. This change proposalwould allow combination cables for both supply and communication, as long as the worker is qualified to dosuch work on the facilities having the higher hazard.

As Allen Clapp had suggested in his comment 5038 for this CP, it appears that the presenter is saying thatwhen a communication circuit is located in the supply space, where only qualified personnel are allowed towork then there is no need for a voltage limitation. The proposal above is the same as Allen suggested in his



comment and I remember that most of the committee felt that it was a good suggestion, but was notappropriate for a CP at that time, but would be for the 2012 NESC.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3366

Section: 2 Def conduit

Submitter

Allen L. Clapp

Proposed Change

Add the following subdefinitions under conduit.

rigid conduit. Rigid conduit may be composed of metal, PVC, concrete, or other materials. Rigid conduitmay have some flexure, but is not considered as flexible conduit. If buried, rigid conduit is installed insections in prepared trenches.

flexible conduit. Flexible conduit is intentionally manufactured to be more flexible than rigid conduit, inorder to make curved runs. If buried, flexible conduit is generally installed in the same manner as rigidconduit.

direct-buried flexible conduit. Direct-buried flexible conduit is designed to be plowed into the ground inthe same manner as direct-buried cable. At the time of plowing, it may contain one or more cables or it maybe empty.

Supporting Comment

These definitions allow Sections 32 and 35 to appropriately distinguish between conduits for purposes ofapplication of those sections.


Accept as modified.




1. rigid conduit. Conduit composed of metal, PVC, concrete, or other materials. Rigid conduit mayhave some flexure, but is not considered as flexible conduit.

NOTE: If buried, rigid conduit is generally installed in sections in prepared trenches.

2. flexible conduit. Conduit intentionally manufactured to be more flexible than rigid conduit, inorder to make curved runs or limit joints.

NOTE: If buried, flexible conduit is generally installed in prepared trenches.

3. direct-buried flexible conduit. Conduit designed to be plowed into the ground in the same manneras direct-buried cable.

NOTE: At the time of plowing, it sometimes contains one or more cables.


Affirmative: (8) Christofersen, Clapp, Dagenhart, Denbrock, Hooper, Hyland, Komassa, Tomaseski

Negative: (1) Bleakley

Abstention: (0)

Explanation of Vote

Bleakley: (Negative) The proposed definitions are for terms not used in the Code. CP3370 was rejected bySC 7.

Revised Text

CP3433

Section: 2 Def elec supply station

Submitter

Allen L. Clapp

Proposed Change

Revise the definitions to include switching station.

electric supply station. Any building, room, or separate space within which electric supply equipment islocated and the interior of which is accessible, as a rule, only to qualified persons. This includes generatingstations, switching stations, and step-up and step-down substations, including their associated generator,storage battery, transformer, and switchgear rooms or enclosures, but does not include facilities such as pad-mounted equipment and installations in manholes and vaults.



1. generating station. A plant wherein electric energy is produced by conversion from some otherform of energy (e.g., chemical, nuclear, solar, mechanical, or hydraulic) by means of suitableapparatus. This includes all generating station auxiliaries and other associated equipment requiredfor the operation of the plant. Not included are stations producing power exclusively for use withcommunications systems.

2. substation. An enclosed assemblage of equipment, e.g., switches, circuit breakers, buses, andtransformers, under the control of qualified persons, through which electric energy is passed for thepurpose of switching or modifying its characteristics to increase or decrease voltage or controlfrequency or other characteristics.

3. switching station. An enclosed assemblage of equipment, e.g., switches, circuit breakers, buses,and control systems, usually with station service transformer(s) and without line transformers,under the control of qualified persons, through which electric energy is passed for the purpose ofswitching electric power between lines.

Supporting Comment

This definition change should answer recent questions about where switching stations without line voltagetransformation fit into the Code scheme. In many areas, local definitions do not include switching stationsunder the definition of substation, since pure switching stations do not change system voltage.


Accept as modified.

Revise the definitions to include switching station.

electric supply station. Any building, room, or separate space within which electric supply equipment islocated and the interior of which is accessible, as a rule, only to qualified persons. This includes generatingstations and substations, including their associated generator, storage battery, transformer, and switchgearrooms or enclosures, but does not include facilities such as pad-mounted equipment and installations inmanholes and vaults.

1. generating station. A plant wherein electric energy is produced by conversion from some otherform of energy (e.g., chemical, nuclear, solar, mechanical, or hydraulic) by means of suitableapparatus. This includes all generating station auxiliaries and other associated equipment requiredfor the operation of the plant. Not included are stations producing power exclusively for use withcommunications systems.

2. substation. An enclosed assemblage of equipment, e.g., switches, circuit breakers, buses, andtransformers, under the control of qualified persons, through which electric energy is passed for thepurpose of switching or modifying its characteristics to increase or decrease voltage or controlfrequency or other characteristics.

3. switching station. See: substation.



Negative: (0)



Abstention: (0)

New Text

CP3418

Section: 2 Def exclusive control of utility

Submitter: Neil F. LaBrake, Jr., PE

Proposed Change

Add the following definition to Section 2 as follows:

exclusive control of utility. Separated from public access by a spatial or a physical barrier and accessibleonly to qualified personnel authorized by the serving utility.

Supporting Comment

New term to be used for both the NESC and the NEC intended to correlate the purpose and scope of bothdocuments. This action is intended to harmonize the purpose and scope sections of two ANSI standards, theNESC and the NEC and to mitigate conflicts between documents as encountered in the NFPA StandardsCouncil Appeals Hearings on the 2008 NEC adoption in July 2007. [Refer to Final Decision on Appealnumber #07-24 (SC# 07-7-39) in the NFPA archives (http://www.nfpa.org/itemDetail.asp?categoryID=837&itemID=35006 and http://www.nfpa.org/assets/files/PDF/Standards%20Council/TranscriptSCMeetingJuly07.pdf) pertaining to this issue.]

This action is a result of a meeting of Task Group of the NESC and NEC Committees on July 10, 2008.


Accept as modified.

Proposed Change


exclusive control of utility. Where (a) energized facilities are separated from public access by a spatial or aphysical barrier and accessible only to qualified personnel authorized by the serving utility, and (b) theutility is responsible for connection/disconnection of such facilities to/from energized sources of energy orsignals.

Supporting Comment

This modified proposal is the result of discussions between July and November 2008 held by the NEC-NESC Task Force set up by IEEE and NFPA to modify each document to (a) better state its application and(b) limit the opportunity for confusion as to which Code applies to what facilities and work.

A central issue to the application of the NESC is the exclusive control of a utility. When exclusive control ofan installation is maintained by a utility, the NESC applies. Otherwise, the NEC applies. This definition isadded to support the language in various rules and correlate the purpose and scope of both the NESC and



NEC documents in clarifying its meaning. This new definition is also proposed for the 2011 NEC at thistime.



Negative: (0)

Abstention: (0)

New Text

CP3417

Section: 2 Def exclusive control

Submitter


Proposed Change


exclusive control. Generally covers installation, ownership, restricted access, operation, and maintenanceby qualified and authorized persons.

Supporting Comment




Accept.



Negative: (0)



Abstention: (0)

Revised Text

CP3435

Section: 2 Def lines

Submitter

Allen L. Clapp

Proposed Change

Revise the definition of lines as follows. Delete the definition of joint use.

joint use. Simultaneous use by two or more kinds of utilities.

lines.

1. communication lines. The conductors and their supporting or containing structures, equipment,and apparatus that are used for public or private signal or communications service, and whichoperate at potentials not exceeding 400 V to ground or 750 V between any two points of the circuit,and the transmitted power of which does not exceed 150 W. When operating at not more than 90 Vac or 150 V dc, no limit is placed on the transmitted power of the system. Under specifiedconditions, communication cables may include communication circuits exceeding the precedinglimitation where such circuits are also used to supply power solely to communications equipment.Fiber-optic cables are considered as communication lines, regardless of whether they are installedin the communication space or supply space in accordance with applicable rules,

NOTE: Public and private tTelephone, telegraph, railroad-signal, data, clock, fire, police-alarm,cable-television, and other systems conforming with the above are included. Lines used forsignaling purposes, but not included under the above definition, are considered as supply lines ofthe same voltage and are to be so installed. Traffic signal light lines are considered as supply lines,not communication lines.

2. electric supply lines. Those wires, conductors, and cables used to transmit electric or light energyand their necessary supporting or containing structures, equipment, and apparatus that are used toprovide public or private electric supply or lighting service.

Signal lines of more than 400 V and traffic signal lines of any voltage are always considered assupply lines within the meaning of the rules, and those signal lines of less than 400 V may beconsidered as supply lines, if so run and operated throughout.

Although fiber-optic lines are considered as communication lines, regardless of whether they areinstalled in the communication space or supply space in accordance with applicable rules, electricsupply conductors to light amplifiers, etc., are considered as supply lines, unless contained within acommunication cable in accordance with the definition of communication lines and applicablerules.



3. joint-use lines. Joint-use lines are overhead or underground lines containing or supporting supplyconductors or cables in a supply space and communication conductors or cables within acommunication space separated from each other in accordance with applicable rules.

Lines either (a) containing or supporting facilities delivering two or more types of service withinthe same category of lines, such as electricity and lighting supply service or telephone and CATVcommunication service, or (b) having two or more of the same type of utility lines by the same ordifferent owners are not considered as joint-use lines, unless also accompanied by one or morelines of the other category.

An overhead structure with communication conductors or cables located in the supply space inaccordance with applicable rules is not considered as a joint-use structure, unless communicationconductors or cables are also present in a separate communication space on the structure.

Syn: supply lines.

Supporting Comment

This proposal is (1) partly a companion to other proposals dealing with the scope of the NESC and the NECand (2) partly in response to recent questions about exactly what constitutes joint-use lines.


Accept as modified.

Revise the definition of lines and change the definition of joint use as follows:

joint use. Simultaneous use by two or more kinds of utilities.

lines.

1. communication lines. The conductors and their supporting or containing structures, equipment,and apparatus that are used for public or private signal or communications service, and whichoperate at potentials not exceeding 400 V to ground or 750 V between any two points of the circuit,and the transmitted power of which does not exceed 150 W. When operating at not more than 90 Vac or 150 V dc, no limit is placed on the transmitted power of the system. Under specifiedconditions, communication cables may include communication circuits exceeding the precedinglimitation where such circuits are also used to supply power solely to communications equipment.Fiber-optic cables are considered as communication lines, regardless of whether they are installedin the communication space or supply space in accordance with applicable rules,

NOTE: Public and private tTelephone, telegraph, railroad-signal, data, clock, fire, police-alarm,cable-television, and other systems conforming with the above are included. Lines used forsignaling purposes, but not included under the above definition, are considered as supply lines ofthe same voltage and are to be so installed. Traffic signal light lines are considered as supply lines,not communication lines.

2. electric supply lines. Those wires, conductors, and cables used to transmit electric or light energyand their necessary supporting or containing structures, equipment, and apparatus that are used toprovide public or private electric supply or lighting service.



Signal lines of more than 400 V and traffic signal lines of any voltage are always considered assupply lines within the meaning of the rules, and those signal lines of less than 400 V may beconsidered as supply lines, if so run and operated throughout.

Although fiber-optic lines are considered as communication lines, regardless of whether they areinstalled in the communication space or supply space in accordance with applicable rules, electricsupply conductors to light amplifiers, etc., are considered as supply lines, unless contained within acommunication cable in accordance with the definition of communication lines and applicablerules.

3. joint-use lines. Overhead or underground lines containing or supporting facilities of two or moreutilities. Lines containing or supporting facilities delivering two or more types of service by thesame owner, such as electricity and lighting supply service or telephone and CATV communicationservice, are not considered as joint-use lines, unless also accompanied by one or more lines ofanother utility.

Syn: supply lines.



Negative: (0)

Abstention: (0)

Revised Text

CP3367

Section: 2 Def open conductors

Submitter

Allen L. Clapp

Proposed Change

Revise the definition of open conductor and add the following definition of bare conductor.

2. bare conductor. A metal conductor without a covering.

11.10. open conductor. A type of electric supply or communication line construction in which theconductors are (a) bare, covered, or insulated, (b) do not have grounded shielding, and (c) areindividually supported at the structure either directly or with insulators. Syn: open wire.


Accept as modified.

Revise the definition of open conductor and add the following definition of bare conductor.



2. bare conductor. A metallic conductor without a covering.

11.10. open conductor. A type of electric supply or communication line construction in which theconductors are (a) bare, covered, or insulated and without (b) do not have grounded shielding, and(c) are individually supported at the structure either directly or with insulators. Syn: open wire.



Negative: (0)

Abstention: (0)

Revised Text

CP3025

Section: 2 Def random separation

Submitter

Ewell T. Robeson

Proposed Change

Revise the definition of random separation as follows:

random separation. Installed with less than 300 mm (12 in) no deliberate separation.

Supporting Comment

Revise the definition of random separations to conform and be consistent with the definition as found in thetitle of Rule 354, page 237.




See SC action on CP3209.



Negative: (1) Clapp



Abstention: (0)

Explanation of Vote

Clapp: (Negative) See comment on CP3209.

Revised Text

CP3209

Section: 2 Def random separation

Submitter

James T. Collins

Proposed Change

Revise the definition of random separation as follows:

random separation. Installed with no deliberate separation. less than 300 mm (12 in) separation.

Supporting Comment

Revise the definition of random separation to conform and be consistent with the definition as found in thetitle of Rule 354, page 237.


Accept.



Negative: (1) Clapp

Abstention: (0)

Explanation of Vote

Clapp: (Negative) The term “no deliberate separation” was intentionally added in the past to indicate thatthe cables do not have to be separated from one another and, therefore, should be left in the rule, since theintent is to allow these items to touch, as opposed to still keeping some clearance between the cables that isless than 12 in. If the desire is to add the 12 in language, it should be added without deleting the reference tono deliberate separation. I suggest the following would be better if the 12 in language is absolutely necessary(which I do not object to, but do not see the need for): “Installed with less than 12 in of separation andwithout deliberate separation.”



New Text

CP3419

Section: 2 Def restricted access

Submitter


Change Proposal


restricted access. Areas where exclusive control are not maintained.

Supporting Comment




Accept as modified.

Add the following definitions to Section 2 as follows:

restricted access. Where exclusive control is maintained.



Negative: (0)

Abstention: (0)

New Text

CP3211

Section: 2 Def spacing



Submitter

James T. Collins

Proposed Change

Add the definition of spacing.

spacing. The distance between two objects measured center to center.

Supporting Comment:

The terms clearance and separation are often confused with the term spacing.

Clearance and separation both indicate a distance measured surface to surface, but spacing is measuredcenter to center. Spacing is a term used throughout the NESC and is not currently defined. Adding thedefinition will help alleviate any confusion.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3212

Section: 2 Def supported facility

Submitter

James T. Collins

Proposed Change

Add a new definition.

supported facility. Any component of an overhead line system that is supported on, but is not intended toprovide structural strength to, the supporting structure or mechanical support system.

NOTE: Examples of supported facilities include, but are not limited to, components such as conductors,line hardware, equipment hanger brackets, and switches.



Supporting Comment

This change proposal relates to IR 549. The term supported facilities often confuses Code users as to what isa structural component and what is a supported facility. The addition of this definition will give guidance asto how the term is to be understood and applied.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3210

Section: 2 Def supporting structure

Submitter

James T. Collins

Proposed Change

Add note to definition of supporting structure to make clear that a multiple pole line structure is considereda single structure.

supporting structure. The main supporting unit (usually a pole or tower) used to support supply and/orcommunication conductors, cables, and equipment.

NOTE: A supporting structure may consist of a single or multiple pole arrangement that supports supplyand/or communication conductors, cables, and equipment at a line location.

1. readily climbable. A supporting structure having sufficient handholds or footholds so that thestructure can be climbed easily by an average person without using a ladder, tools or devices, orextraordinary physical effort.

2. not readily climbable. A supporting structure not meeting the definition of a readily climbablestructure, including but not limited to the following:

a. supporting structures, including poles and tower legs, with handholds or footholds arranged sothat there is not less than 2.45 m (8 ft) between either: (1) the lowest handhold or foothold andground or other accessible surface, or (2) the two lowest handholds or footholds. Diagonal



braces on towers are not considered to be handholds or footholds except at their points ofattachment.

b. guy wires

Supporting Comment

Questions have arisen as to whether clearances for wires supported on different poles of a multi-polestructure should be treated as being supported on different structures (Rule 233) or on same structures (Rule235). The NESC does not explicitly specify that a multiple pole structure is one structure as intended forclearance determination purposes.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3364

Section: 2 Def supporting structure

Submitter

Allen L. Clapp

Proposed Change

Revise the definition of supporting structure as follows.

supporting structure. The main supporting unit (usually a pole or tower, and including guys and braces)used to support supply and/or communication conductors, cables, and equipment.

1. readily climbable. A supporting structure having sufficient handholds or footholds so that thestructure can be climbed easily, though its entire length or a substantial portion thereof, by anaverage person without using a ladder, tools or devices, or extraordinary physical effort.

2. not readily climbable. A supporting structure not meeting the definition of a readily climbablestructure, including but not limited to the following:

a. supporting structures, including poles and tower legs, with handholds or footholds arranged sothat there is a gap between handholds and footholds of not less than 2.45 m (8 ft) between



either: (1) the lowest handhold or foothold and ground or other permanently accessible surface,or (2) the two lowest handholds or footholdsa higher set of handhold and foothold, providingthat the required gap starts not more than 1.8 m (6 ft) aboveground or other permanentlyaccessible surface. Diagonal braces on towers are not considered to be handholds or footholdsexcept at their points of attachment.

b. guy wires

Supporting Comment

These changes (a) clean up and complete the language of the definition and (b) restore the 2002 requirementto have the required gap start not less than the 6 ft level aboveground. The required gap has two missions.One is to limit the opportunity for unauthorized personnel to climb up to the supported electrical orcommunication lines or equipment. The other is to limit the opportunity for unauthorized personnel to climbhigh enough above grade to create a fall hazard. OSHA investigated this issue thoroughly and concludedthat there is such a high probability that the result of a fall from a height greater than 6 ft will result inserious permanent injury, including paraplegia and quadriplegia, that fall protection is required for personnelworking above that level. The NESC adopted the same limit in the 2002 Edition. The overall revision of thedefinitions in this area in the 2007 Edition omitted the 6 ft limit on climbing. It should be replaced.


Reject.



Negative: (1) Clapp

Abstention: (0)

Explanation of Vote

Clapp: (Negative) The 2002 Edition deliberately adopted the maximum starting point height for the required8 ft gap at 6 ft above the permanent support (ground) level to recognize that the data in the OSHA hearingsthat led to the OSHA 6 ft starting point for requiring fall protection indicates that a fall from heights abovethe 6 ft level brings with it a significantly increased probability of permanent injury, including paraplegiaand quadriplegia. If the structure is readily climbable to a level above 6 ft, it should carry a safety signwarning against climbing the structure, as required by Rule 217. Thus, the 6 ft limitation placed in the Codein the 2002 Edition should be returned and kept in the Code.

New Text

CP3420

Section: 2 Def supervised installation

Submitter




Proposed Change


supervised installation. Conditions of maintenance and engineering supervision ensure that only qualifiedpersons monitor and service the system. A private electric supply, communications, or railway exercising itsfunction as a utility covering similar systems under the control of qualified persons, such as those associatedwith an industrial complex or utility interactive system.

Supporting Comment




Accept as modified.


supervised installation. Where conditions of maintenance and supervision ensure that only qualifiedpersons monitor and service the system.


Affirmative: (7) Bleakley, Clapp, Dagenhart, Denbrock, Hooper, Komassa, Tomaseski

Negative: (0)

Abstention: (0)

New Text

CP3023

Section: 2 Def surge (lightning) arrester

Submitter

Ewell T. Robeson



Proposed Change

New definition.

surge (lightning) arrester. A protective device for limiting surge voltages.

Supporting Comment

The terms surge arrester and lightning arrester are used interchangeably throughout the NESC. A definitionwill help avoid confusion in the interpretation in the use of these terms.


Accept as modified.

Add new definition.

surge arrester. A protective device for limiting surge voltages.

lightning arrester. See: surge arrester.



Negative: (0)

Abstention: (0)

Revised Text

CP3421

Section: 2 Def utility

Submitter


Proposed Change

Delete the existing definition and add the following new definition to Section 2 as follows:

utility. A public organization typically designated or recognized by governmental law or regulation bypublic service/utility commissions responsible for the installation, operation, or maintenance of electricsupply (such as generation, transmission, or distribution systems) or communication systems (such astelephone, CATV, Internet, satellite, or data services) to the service point.



Supporting Comment

Revised term to be used for both the NESC and the NEC intended to correlate the purpose and scope of bothdocuments. This action is intended to harmonize the purpose and scope sections of two ANSI standards, theNESC and the NEC and to mitigate conflicts between documents as encountered in the NFPA StandardsCouncil Appeals Hearings on the 2008 NEC adoption in July 2007. [Refer to Final Decision on Appealnumber #07-24 (SC# 07-7-39) in the NFPA archives (http://www.nfpa.org/itemDetail.asp?categoryID=837&itemID=35006 and http://www.nfpa.org/assets/files/PDF/Standards%20Council/TranscriptSCMeetingJuly07.pdf) pertaining to this issue.]





See CP3407.


Affirmative: (7) Bleakley, Clapp, Dagenhart, Denbrock, Hooper, Komassa, Tomaseski

Negative: (0)

Abstention: (0)

Revised Text

CP3422

Section: 2 Def utilization equipment

Submitter


Proposed Change

Delete the existing definition and add the following new definition to Section 2 as follows:

utilization equipment. Equipment, devices, and connected wiring that utilize electric energy for electronic,electromechanical, chemical, heating, lighting, testing, or similar purposes on the premises wiring side ofthe service point.

Supporting Comment

This definition as proposed correlates with the same defined term in the NEC Article 100.



Revised term to be used for both the NESC and the NEC intended to correlate the purpose and scope of bothdocuments. This action is intended to harmonize the purpose and scope sections of two ANSI standards, theNESC and the NEC and to mitigate conflicts between documents as encountered in the NFPA StandardsCouncil Appeals Hearings on the 2008 NEC adoption in July 2007. [Refer to Final Decision on Appealnumber #07-24 (SC# 07-7-39) in the NFPA archives (http://www.nfpa.org/itemDetail.asp?categoryID=837&itemID=35006 and http://www.nfpa.org/assets/files/PDF/Standards%20Council/TranscriptSCMeetingJuly07.pdf) pertaining to this issue.]



Accept as modified.

Revise the existing definition of utilization equipment and add the following new definition of delivery pointto Section 2 as follows:

utilization equipment. Equipment, devices, and connected wiring that utilize An electrical installation thatuses electric or light energy for electronic, electromechanical, chemical, heating, lighting, testing,communication, signaling, or similar purposes on the premises wiring side of the service point and are not apart of supply equipment, supply lines, or communication lines.

NOTE: Utilization equipment and premises wiring on the load side of the service point is intended to beperformed under the NEC, regardless of whether a utility has exclusive control.

delivery point. The point at which one utility delivers energy or signals to another utility.

Supporting Comment

This modified proposal is the result of discussions between July and November 2008 held by the NEC-NESCTask Force set up by IEEE and NFPA to modify each document to (a) better state its application and (b) limitthe opportunity for confusion as to which Code applies to what facilities and work.

These definitions are intended to support other NESC rules and definitions and to reflect similar issues in theNEC. These changes help to give clarity to the rules and definitions that differentiate between application ofthe NESC and application of the NEC clarifying the demarcation point relative to equipment operated bypremises wiring and that the NEC covers utilization equipment. This revised “utilization equipment” term isalso proposed for the 2011 NEC at this time.



Negative: (0)

Abstention: (0)



Revised Text

CP3368

Section: 2 Def conductor, vertical, lateral

Submitter

Allen L. Clapp

Proposed Change

Revise the definition of lateral conductor as follows and add a new definition for vertical conductor.

8. lateral conductor. A wire or cable entirely supported on one structure and extending in a generalhorizontal, vertical, or diagonal direction at an angle to the general direction of the line conductorsto makeconnections to line conductors, service drops, equipment, or other facilities supported on the same structure,and entirely supported on one structure. Lateral conductors may be attached directly to the structure orsupported away from the structure.

11. vertical conductor. Either a wire or cable riser attached to a pole or a vertical portion of a lateralconductor.

Supporting Comment

The two terms vertical and lateral conductors are typically used together in the clearances rules to refer tojumpers and to risers on poles. It has caused confusion, since the definitions did not match the usage. Therevision of the present definition of lateral conductor and the new definition of vertical conductor shouldlimit further confusion.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3434

Section: 2 Def vault



Submitter

Allen L. Clapp

Proposed Change

Revise the definition of vault.

vault. A structurally solid enclosure, including all sides, top, and bottom, that is (1) associated with anunderground electric supply or communication system, (2) located either (a) above or below ground or (b) ina building, but not in an electric supply station, and (3) where entry is limited to personnel qualified toinstall, maintain, operate, or inspect the equipment or cable enclosed. The enclosure may have openings forventilation, personnel access, cable entrance, and other openings required for operation of equipment in thevault.

Supporting Comment

This change should settle the ongoing confusion about whether a so-called vault room in a power plant issubject to the vault rules in Part 3 and vice versa.


Accept as modified.

Revise the definition for vault as follows:

vault. A structurally solid enclosure, including all sides, top, and bottom, that is (1) associated with anunderground electric supply or communication system, (2) located either (a) above or below ground or (b) ina building, and (3) where entry is limited to personnel qualified to install, maintain, operate, or inspect theequipment or cable enclosed. The enclosure may have openings for ventilation, personnel access, cableentrance, and other openings required for operation of equipment in the vault.



Negative: (0)

Abstention: (0)




Revised Text

CP3359

Section: 3 NFPA 70

Submitter

Percy E. Pool

Proposed Change

In Section 3, References, change reference to NEC to read:

NFPA 70, 2005 2008 Edition, National Electrical Code® (NEC®). [Rules 11, 099, 124, and 127]

Supporting Comment

This CP shows that the current edition of the National Electrical Code (NEC) is dated 2008. This CP alsoadds a reference to Rule 099 where the NEC is mentioned. See page 29.

Note that it may be necessary to change the date from “2008” to “2011” since the NEC is in a 3-year cycleand the next NESC will be issued in 2012.


Accept.



Negative: (0)

Abstention: (0)



Section 9. Grounding methods for electric supply

and communications facilities

Revised Text

CP3219


Submitter

James T. Collins

Proposed Change

Add new sentence to Rule 091.

Rule 091. Scope

Section 9 of this Code covers methods of protective grounding of supply and communicationconductors and equipment. The rules requiring grounding are in other parts of this Code. For rulesrequiring conductors or equipment to be effectively grounded, methods described in this section shall beused and the ground connection or connections shall have sufficiently low impedance and current-carrying capacity to limit the buildup of voltages to levels below that which may result in undue hazardto persons or to connected equipment.

These rules do not cover the grounded return of electric railways nor those lightning protection wiresthat are normally independent of supply or communication wires or equipment.

Supporting Comment

Other parts of the NESC specify to use methods found in Section 9 to effectively ground conductors orequipment. There is not a statement in Section 9 which specifically states which methods can be used toeffectively ground conductors or equipment. The addition of this sentence will specify that using themethods in Section 9 need to be used as long as the definition for effectively grounded is met.


Accept as modified.

Proposed Change

Add new sentence to Rule 091.

Rule 091. Scope

Section 9 of this Code covers methods of protective grounding of supply and communicationconductors and equipment. The rules requiring grounding are in other parts of this Code. For rules



requiring conductors or equipment to be effectively grounded, methods described in this section shall beused and the definition of effectively grounded shall be met.

These rules do not cover the grounded return of electric railways nor those lightning protection wiresthat are normally independent of supply or communication wires or equipment.


Affirmative: (13) Bowles, Bowmer, Dagenhart, Dixon, Gaunt, Maxwell, Molde, Montambo, Pool, Reese,Robeson, Saint, Zipse

Negative: (0)

Abstention: (0)

New Text

CP3213

Section: 9 Rule: 092 A

Submitter

James T. Collins

Proposed Change

Revise Rule 092A as follows:

A. Direct-current systems that are to be grounded as required by other parts of this Code

Supporting Comment

This CP relates to IR 547.

This addition will clarify that Section 9 rules cover methods of grounding (how to) and not what is to begrounded that is required by other rules in the Code. See also Rule 092E for similar language.


Reject.


It is already covered in the scope.


Affirmative: (12) Bowles, Bowmer, Dagenhart, Dixon, Gaunt, Maxwell, Molde, Montambo, Pool,Robeson, Saint, Zipse



Negative: (1) Reese

Abstention: (0)

Explanation of Vote

Reese: (Negative) Addition of this language will add clarity and consistency to the Code. The clarification isthat this section is not requiring grounding, only if it is to be grounded these are the methods to use.

Revised Text

CP3214


Submitter

James T. Collins

Proposed Change

Revise Rule 092B as follows:

B. Alternating current systems that are to be grounded as required by other parts of this Code

Supporting Comment




Reject.




Affirmative: (12) Bowles, Bowmer, Dagenhart, Dixon, Gaunt, Maxwell, Molde, Montambo, Pool, Robeson,Saint, Zipse

Negative: (1) Reese

Abstention: (0)



Explanation of Vote


Revised Text

CP3215

Section: 9 Rule: 092 C

Submitter

James T. Collins

Proposed Change

Revise Rule 092C as follows:

C. Messenger wires and guys that are to be grounded as required by other parts of this Code

Supporting Comment




Reject.





Negative: (1) Reese

Abstention: (0)

Explanation of Vote




Revised Text

CP3068

Section: 9 Rule: 092 C2

Submitter

Mickey Gunter

Proposed Change

Revise Rule 092C2 as follows:

2. Guys

Guys that are required to be effectively grounded shall be connected to one or more of thefollowing:

a. An effectively grounded metallic supporting structure.

b. An effective ground on a nonmetallic supporting structure.

c. A line conductor that meets the definition of “effectively grounded” and has at least fourground connections in each mile of line in addition to the ground connections at individualservices.

Supporting Comment

The present wording of “a” implies that a grounded supporting structure meets the definition of effectivelygrounded. Also the present wording of “c” implies that a multi-grounded neutral meets the definition of aneffectively grounded conductor. Just because a pole is grounded, or that a line conductor that has at least 4grounds in each mile of line (multi-rounded neutral) doesn’t mean they are “effectively grounded” as per therequirements of Rule 215C2. If the present wording in “c” remains, then we are saying that a multi-groundedneutral is considered to be effectively grounded and we need to state this in other parts of Section 9.


Reject.


CP not necessary; see action on CP3219.



Negative: (0)



Abstention: (0)

Revised Text

CP3216

Section: 9 Rule: 092 C2

Submitter

James T. Collins

Proposed Change


2. Guys

Guys that are required to be effectively grounded shall be connected to one or more of thefollowing:

a. An effectively grounded metallic supporting structure.

b. An effective ground on a nonmetallic supporting structure.

c. An effectively grounded line conductor that has at least four ground connections in each mileof line in addition to the ground connections at individual services.

Supporting Comment

The present wording of “a” implies that a grounded supporting structure meets the definition of effectivelygrounded. Also the present wording of “c” implies that a multi-grounded neutral meets the definition of aneffectively grounded conductor. Just because a pole is grounded, or that a line conductor that has at leastfour grounds in each mile of line (multi-grounded neutral) doesn’t mean they are “effectively grounded” asper the requirement of Rule 215C2. If the present wording in “c” remains, then we are saying that a multi-grounded neutral is considered to be effectively grounded which contradicts the definition for multi-grounded/multiple grounded systems.


Reject.


CP not necessary, see action on CP3219.





Negative: (0)

Abstention: (0)

Revised Text

CP3030

Section: 9 Rule: 093 D1, D2, D3

Submitter

Ewell T. Robeson

Proposed Change

Rewrite 93D1 and 93D3; 93D2 becomes new 93D3 and 93D4 stays the same:

D. Guarding and protection

1. The grounding conductors for single-grounded systems and those exposed to mechanicaldamage shall be guarded. However, grounding conductors need not be guarded where notreadily accessible to the public nor where grounding multi-grounded circuits or equipment.

32. Where guarding is required, grounding conductors shall be protected by guards suitable for theexposure to which they may reasonably be subjected. The guards should extend for not lessthan 2.45 m (8 ft) above the ground or platform from which the grounding conductors areaccessible to the public.

3. Where guarding is not required, grounds shall be protected by being substantially attachedclosely to the surface of the pole or other structure in areas of exposure to mechanical damageand, where practical, on the portion of the structure having least exposure.

4. Guards used for grounding conductors of lightning-protection equipment shall be ofnonmetallic materials if the guard completely encloses the grounding conductor or is notbonded at both ends to the grounding conductor.

Change to read as follows:


1. Single-grounded systems: Guarding is required for grounding conductors of single-groundedsystems unless the installation is not readily accessible to the public.

2. Multi-grounded systems: Grounding conductors of multi-grounded systems need not beguarded. However, grounding conductors of multi-grounded circuits, shield wires, orequipment, installed in areas of exposure to mechanical damage, shall be protected by beingsubstantially attached closely to the surface of the pole or other structure and where practical,located on the portion of the structure having least exposure.

3. Where guarding is required, grounding conductors shall be protected by guards suitable for theexposure to which they may reasonably be subjected. The guards should extend for not less



than 2.45 m (8 ft) above the ground or platform from which the grounding conductors areaccessible to the public.

4. Guards used for grounding conductors of lightning-protection equipment shall be ofnonmetallic materials if the guard completely encloses the grounding conductor or is notbonded at both ends to the grounding conductor.

Supporting Comment

A recent check of Midwest utilities revealed that not everyone interpreted this rule uniformly.

The proposed change in wording is offered to make the meaning of this rule clearer. This is not intended tochange the intent of the existing rule.

Rule 93D1 is confusing because it begins with single-point ground system and then seems to expand itscoverage to any system that is exposed to mechanical damage. The next sentence in the same rulecontradicts this by saying grounding conductors of multi-grounded systems need not be guarded.

Existing Rule 93D1, sentence 1, states guarding is only required in special circumstances. The secondsentence clearly says “grounding conductors need not be guarded where not readily accessible to the publicnor where grounding multi-grounded circuits or equipment.” Yet many people reading this rule areuncertain if guarding is required for multi-grounded systems where the ground conductor may not be placedin a location remote from possible mechanical damage.

WUA believes the proposed wording more clearly conveys the intended message.

Existing items 1 and 3 become 1 and 2. The change clearly makes a distinction between single and multi-grounded systems. There is no change to the wording of items 2 and 4, except item 2 is renumbered to 3.


Accept as modified.

Rewrite 93D1, add a new 93D2, 93D2 becomes new 93D3, rewrite 93D and it is the new 93D4; and 93D4becomes new 93D5:


1. The grounding conductors for single-grounded systems and those exposed to mechanicaldamage shall be guarded. However, grounding conductors need not be guarded where notreadily accessible to the public nor where grounding multi-grounded circuits or equipment.Single-grounded systems: Guarding is required for grounding conductors of single-groundedsystems unless the installation is not readily accessible to the public.

2. Multi-grounded systems: Grounding conductors of multi-grounded systems need not beguarded.

3. 2.Where guarding is required, grounding conductors shall be protected by guards suitable for theexposure to which they may reasonably be subjected. The guards should extend for not lessthan 2.45 m (8 ft) above the ground or platform from which the grounding conductors areaccessible to the public.

4. 3.Where guarding is not required grounding conductors, installed in areas of exposure tomechanical damage, grounds shall be protected by being substantially attached closely to the



surface of the pole or other structure in areas of exposure to mechanical damage and, wherepractical, on the portion of the structure having least exposure.

5. 4.Guards used for grounding conductors of lightning-protection equipment shall be ofnonmetallic materials if the guard completely encloses the grounding conductor or is notbonded at both ends to the grounding conductor.



Negative: (0)

Abstention: (0)

Revised Text

CP3405


Submitter

Helen Chen

Proposed Change

Revise Rule 094B7 as follows:

Directly embedded steel poles shall constitute an acceptable electrode, if all of the following requirements aremet:

a) Backfill around the pole is native earth, concrete, or conductive ground (not gravel)

b) Not less than 942.5 in2 1.5 m (5.0 ft) of the embedded length is exposed directly to the earth,without nonconductive covering

c) The pole diameter is not less than 125 mm (5 in), and

d) The metal thickness is not less than 6 mm (1/4 in)

NOTE 1: directly embedded steel poles having a nonconductive covering below ground that limitsthe length of direct exposure to earth to less than 1.5 m (5.0 ft) are not considered as an acceptableelectrode. Aluminum installed belowground is not considered as an acceptable electrode.

NOTE 2: There are structural and corrosion concerns that should be investigated prior to usingmetal poles as grounding electrodes. See Sections 25 and 26.

EXCEPTION: Other lengths or configurations may be used if their suitability is supported by aqualified engineering study.



Supporting Comment

The intent of 094B7 b and c should be focused on the surface area required for a suitable ground and couldbe argued that it need not be different than ground rods or butt plates. In the interest of compromise the valuerepresented by the length and diameter previously represented in 7b and 7c is 942.5 in2. This equates to30 in exposure for a 14 in diameter section or 30 in exposure for a 10 in diameter section. The ¼ inminimum thickness required by 7d seems arbitrary and aimed at the fear of corrosion effects. A paperentitled “Grounding Equivalency of Steel Poles” by J. Patrick Donohoe (1999) is attached for reference andprovides a study of the performance of steel pole embedded section in comparison with ground rod providedthere is at least 2 ft of bare length exposure.

The reference to weathering steel would, again, seem aimed at the fear of corrosion effects. NOTE 2 alreadydirects the reader to Sections 25 and 26 for consideration of other structural and corrosion issues that mayneed to be considered with the use of steel pole sections as ground.


Reject.


It is incomplete. The reference to weathering steel is left out of the CP.



Negative: (0)

Abstention: (0)

Revised Text

CP3217


Submitter

James T. Collins

Proposed Change


2. Driven Rods

a. Driven rods may be sectional; the total length shall be not less than 2.44 m (8 ft). Iron, zinc-coated steel, or steel rods shall have a cross-sectional dimension diameter of not less than



15.87 mm (5/8 in or 0.625 in). Copper-clad, stainless steel, or stainless steel-clad rods shallhave a cross-sectional dimension diameter of not less than 12.7 mm (1/2 in or 0.5 in).

b. Longer rods or multiple rods may be used to reduce the ground resistance. Spacing betweenmultiple rods should be not less than 1.8 m (6 ft).

EXCEPTION: Other dimensions diameters or configurations may be used if their suitability issupported by a qualified engineering study.

Supporting Comment

Diameter is the appropriate term for this rule. The clarification is justified since there are other types ofdimensions such as area, radius, and circumference. The term “cross-sectional” is not needed.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3363

Section: 9 Rule: 094 B2a

Submitter

Nelson Bingel

Proposed Change

Driven rods may be sectional; the total length shall be not less than 2.44 (8 ft). Iron, zinc-coated steel or steelrods shall have a cross-sectional dimension of not less than 15.87 mm (0.625 in). Copper- clad coated(10 mils minimum per UL 467), zinc coated steel (hot-dip galvanized per ASTM A-123), solid stainlesssteel (ANSI Type 304), or stainless steel-clad (15 mils minimum per UL 467 of ANSI Type 304 stainless-steel) rods shall have a cross-sectional dimension of not less than 12.7 mm (0.5 in).

Supporting Comments

The change of moving “zinc-coated” is simply maintaining all coated and/or clad rod electrodes in therespective category.



Without clarification of the coating process for zinc, copper, and stainless, it is left up to the discretion of themanufacturer. The addition of UL 467, ASTM A-123, etc., clearly specifies the type and/or process to whicheach type of coating needs to conform to. Confidence may be rendered that each product is to be produced tospecific criteria currently accepted by the domestic electric utilities.


Reject.


Inappropriate to include manufacturing specifications.


Affirmative: (12) Bowles, Bowmer, Dagenhart, Dixon, Gaunt, Maxwell, Molde, Pool, Reese, Robeson,Saint, Zipse

Negative: (1) Montambo

Abstention: (0)

Explanation of Vote

Montambo: (Negative) Without proper engineering definition of what a copper-coated (one mil or 100 mils?),zinc-coated (zinc paint or hot-dip galvanized?) and stainless-steel (clad, solid, and of what type?) rodelectrode is, it is therefore left up to the manufacturer or distributor to provide.

While copper-coated products most often include 10 mils of copper, there is NO guarantee. Likewise withzinc-coated products, some galvanize to ASTM A123 while others to A153, each offering two distinct coatingthicknesses. And there are a variety of stainless-steel products from which to choose if no specific type ismentioned. This is altogether too vague to be left up to unqualified judgment.

My recommendation is for the committee to reconsider its vote in view of the above issues and vote toapprove both CPs. While I would agree that the NESC may not be the most appropriate place to define someof this criteria, until there is a more appropriate place, it should be added in this paragraph.

Revised Text

CP3361


Submitter

Nelson Bingel



Proposed Change

a. Driven rods may be sectional; the total length shall be not less than 2.44 m (8 ft). Iron, zinc-coatedsteel, or steel rods shall have a cross-sectional dimension of not less than 15.87 mm (0.625 in).Copper-clad, stainless steel, or stainless steel-clad rods shall have a cross-sectional dimension ofnot less than 12.7 mm (0.5 in). All ground rods shall be permanently and legibly marked with themanufacturer’s identification and catalog number or equivalent designation, starting within the top6 in of the drive, or chamfer end, of the ground rod electrode.

Supporting Comments

The need for permanent marking on ground rod electrodes is now more critical than ever. To maintaintraceability, the only way to effectively brand a product in the event a need arises to go back to the originalmanufacturer is to permanently mark the product. Current IOU specifications mandate marking for thispurpose as do most IOUs. With the number of non-compliant products commercially available in thedomestic market, follow-up to assure compliance is critical. The following provides additional justificationfor this addition to Rule 094.

Paragraph 10 of the last issued ANSI C135.30-1988 document states…“Each shipment shall be marked withthe manufacturer’s name and catalog number.” The IEEE PC135.30/D1.1 group developing an updatedground rod specification voted for and supports the addition of this marking on each rod electrode.

Rural Utilities Services (was REA) also mandates all rods be marked with manufacturer’s designation to bein compliance. This is intended to provide for traceability.

It is difficult for any individual to 1) verify compliance to a specification without a permanent certificationmarking on the product (e.g., diameter, length, coating thickness, material characteristics), 2) providetraceability of a product to a manufacturer and/or 3) have confidence that the product has been inspected byan independent firm to assure compliance to a minimum national standard.

Regardless of whether the issue is intended fraud or just a manufacturer offering ground rods withdimensions, coating thickness, etc., that are different from commercially accepted standards, it is critical thatthe integrity of the utility infrastructure be maintained through the use of ground rods with consistentattributes to limit the opportunity for corrosion, assure that fittings will work appropriately, etc. Thus,marking the rods include both the manufacturer and catalog number or equivalent designation is a necessarypart of assuring that only compatible and durable ground rods and allied connectors will be used.


Reject.


This is a commercial issue.



Negative: (0)



Abstention: (0)

Revised Text

CP3362


Submitter

Nelson Bingel

Proposed Change

a. Driven rods may be sectional; the total length shall be not less than 2.44 (8 ft). Iron,zinc coated steel orsteel rods shall have a cross-sectional dimension of not less than 15.87 mm (0.625 in). Copper-clad,zinc coated steel, stainless steel, or stainless steel-clad rods shall have a cross-sectional dimension ofnot less than 12.7 mm (0.5 in).

Supporting Comments

The 2007 NESC does not clearly differentiate between bare steel or coated steel for 5/8 in nominal diameterrod electrodes in the 2nd and 3rd sentences. Zinc-coated steel rods are required to be not less than 15.87 mm(0.625 in) while copper-coated steel rods are required to be “not less than 12.7 mm (0.5 in).” There is noquestion that a coated steel rod provides incremental protection versus bare steel rod. This discrepancy ofbare and coated appears to have originated before galvanized ground rod electrodes were available andretained in the Code ever since.

It is equally important to recognize that while the diameter may be important for component compatibilityreasons, once any coating type has been compromised, the minor difference in diameter of any steel rod corebecomes fundamentally insignificant. This is pure engineering fact. During the last Code cycle ground roddimensional characteristics referenced in “Rule-017” were eliminated affecting only zinc-coated rods, withthe diameter changing in “Rule 094” from 0.604–0.614 in to 0.625–0.640 in. Copper-coated rods effectivelycontinued to maintain a diameter of 0.555–0.565 in (dimensions in common use today). This is inconsistentwith sound engineering principles.

Implementation of the CP will allow the NESC and NEC to, for the first time, harmonize domestic utility andelectrical ground rod electrode criteria. Galvanized steel rod electrodes have been used successfully since theearly 1930s (galvanized pipe-type electrodes since the turn of the last century) and are the principal rodelectrodes for the Canadian residential market as well as much of the European market. A large number ofdomestic utilities (IOU, MUNI, COOP, etc.) and residential markets also utilize galvanized rods. Both copperand galvanized coatings exhibit great performance in most soil types, with the selection of the coating left tosound engineering evaluation of the specific soil conditions in the specific area of installation.


Reject.


There is continuing disagreement on the technical aspects of this CP, particularly with the reduction from



0.625 in to 0.5 in. There is insufficient technical substantiation.




Abstention: (0)

Explanation of Vote

Montambo: (Negative) Rejection of CP3362 provides no benefit of a “coated product” versus a bare steel rodelectrode, which violates sound engineering practices. In fact, a bare 0.625 in diameter electrode fullycomplies with 094B2a. Yet galvanized coatings that have been used to protect steel for decades for manyapplications is given NO benefit to resist corrosion than a bare steel rod. This is technically unsoundreasoning.

Coatings do provide incremental protection to the electrode, thus the CP recommending moving the words“zinc-coated” to the second sentence in line with coated alternatives is technically substantiated based uponthe many applications presently experienced in the electrical industry. Galvanized electrodes have beenapproved by standards engineers worldwide, and used successfully by IOUs and RUS in the U.S. for over 75years.

Concern regarding the slightest difference in rod electrode diameter is NOT a legitimate issue, norfundamentally significant, as it relates to “service life.” Of more significance are soil resistivity and otherimportant characteristics including pH, moisture, stray current, chlorides, etc. Proper rod selection involvesconsideration of ALL factors using sound engineering principles in a comprehensive technical analysis.

My recommendation is for the committee to reconsider its position on the negative vote on this CP, andreview the technical merits described above.

Revised Text

CP3218


Submitter

James T. Collins

Proposed Change

Revise Rule 094B7, EXCEPTION, and NOTE 1 as follows:

7. Directly embedded metal poles

Directly embedded steel poles shall constitute an acceptable electrode, if all of the followingrequirements are met:



a. Backfill around the pole is native earth, concrete, or conductive grout (not gravel) and

b. Not less than 1.5 m (5.0 ft) of the embedded length is exposed directly to the earth, withoutnonconductive covering

c. The pole diameter is not less than 125 mm (5 in), and

d. The metal thickness is not less than 6 mm (1/4 in)

If a supplemental ground electrode is to be installed with an embedded steel pole being used asan electrode, the supplemental electrode should be installed 1.83 m (6 ft) from the metal pole.

EXCEPTION: Other lengths, or configurations, or type metal may be used if their suitability issupported by a qualified engineering study.

NOTE 1: Directly embedded steel poles having a nonconductive covering below ground thatlimits the length of direct exposure to earth to less than 1.5 m (5.0 ft) are not considered as anacceptable electrode. Aluminum installed belowground is not considered as an acceptableelectrode. Weathering steel may not be an acceptable material for this application.

Supporting Comment

The requirements specified in 094B7c and 094B7d are not needed. A small steel pole with a 5 in diameterwith 5 ft of pole exposed directly to the earth has over 6 times the surface area as a 1/2 in stainless steelgrounding electrode. The 1/4 in thickness requirement does not affected the exposed surface area. Also,companies use steel poles which have a thickness of 3/8 in.

Adding other type metal to the EXCEPTION will allow new poles manufactured using new material to beused as an electrode if a qualified engineering study is performed.

The addition of the sentence concerning a supplemental grounding electrode is needed to clarify where asupplemental grounding electrode is to be installed, if needed. Since the steel pole is used as a groundingelectrode, it should meet other rules concerning grounding electrodes.

The first sentence in NOTE 1 is a repeat of Rule 094B7b and can be deleted.


Accept as modified.

Revise Rule 094B7, EXCEPTION, and NOTE 1 as follows:


Directly embedded steel poles shall constitute an acceptable electrode, if all of the followingrequirements are met:

a. Backfill around the pole is native earth, concrete, or conductive grout other conductivematerial (not gravel)

b. Not less than 1.5 m (5.0 ft) of the embedded length is exposed directly to the earth, withoutnonconductive covering




d. The metal thickness is not less than 6 mm (1/4 in)

If a supplemental ground electrode is to be installed with an embedded steel pole being used as anelectrode, the supplemental electrode should be installed not less than 1.83 m (6 ft) from the metalpole.

EXCEPTION: Other lengths, or configurations, or type metal may be used if their suitability issupported by a qualified engineering study.

NOTE 1: Directly embedded steel poles having a nonconductive covering below ground that limitsthe length of direct exposure to earth to less than 1.5 m (5.0 ft) are not considered as an acceptableelectrode. Aluminum installed belowground is not considered as an acceptable electrode.Weathering steel may not be an acceptable material for this application.




Abstention: (0)

Explanation of Vote

Montambo: (Negative) Allowing exposed steel surface of an embedded steel pole to act as a groundingelectrode, with or without a supplemental electrode placed at 6 ft from the metal pole, may very well resultin a “cell” due to the cathodic/anodic relationship of different materials within reasonable distance of theexposed pole.

If a copper-coated ground rod electrode is selected as a supplemental electrode, the steel pole will besacrificed to the copper-coated rod. If however a galvanized rod electrode is selected, then the galvanizedrod will be sacrificed to the “exposed” buried pole steel.

It will be important to isolate the steel pole from “any” buried adjacent materials to avoid this cell, anddegradation of the pole steel and its structural integrity.

My recommendation, based upon the variety of soils and conditions where rods and/or embedded steel polesare installed nationwide, is to encourage SC2 to change their vote to reject acceptance of CP3218 and 3031based upon sound engineering principles.

Deleted Text

CP3031


Submitter

Ewell T. Robeson



Proposed Change

Revise Rule 094B7, NOTE 1 as follows:

NOTE 1: Directly embedded steel poles having a nonconductive covering below ground that limits thelength of direct exposure to earth to less than 1.5 m (5.0 ft) are not considered as an acceptable electrode.Aluminum installed belowground is not considered as an acceptable electrode. Weathering steel may not bean acceptable material for this application.

Supporting Comment

Delete the first sentence of NOTE 1; it is redundant, wordy language already covered in 094B7b.




See action on CP3218.




Abstention: (0)

Explanation of Vote

Montambo: (Negative) See comment for CP3318.

Deleted Text

CP3348


Submitter

Mike Gall

Proposed Change





Directly embedded metal poles shall constitute an acceptable electrode, if all of the followingrequirements are met:

a. Backfill around the pole is native earth, concrete, or conductive grout (not gravel)

b. Not less than 1.5 m (5 ft) of the embedded length is exposed directly to earth, withoutnonconductive covering A minimum of 0.046 mm2 (0.5 ft2) is exposed directly to earthwithout nonconductive covering and


dc. The metal thickness is not less than 6mm (¼ in) 4.76 mm (3/16 in)

NOTE 1: Directly embedded steel poles having a nonconductive covering belowground thatlimits the length of direct exposure to earth to less than 1.5 m (5.0 ft) are not considered as anacceptable electrode. Aluminum installed belowground is not considered an acceptableelectrode. Weathering steel may not be an acceptable material for this application.

NOTE 2: There are structural and corrosion concerns that should be investigated prior to usingmetal poles as grounding electrodes. See Sections 25 and 26.


Supporting Comment

This appears to be directed towards small distribution poles, however the concept of using the uncoatedbottom section of larger poles has been used for many years now.

The intent of 7b, 7c needs to focus on surface area required for a suitable ground. The criteria should not beany different than ground rods or butt plates. 7d: 6 mm (1/4 in) minimum thickness appears to be arbitrary.4.76 mm (3/16 in) is more common industry practice. The removal of the statement about weathering steelis appropriate since this has been used for over 20 years with no evidence on any problems. I have beeninvolved in weathering steel research of transmission structures throughout the U.S. and have foundweathering steel performs very well in this application. Unfortunately there’s a significant amount of outdatedmis-information on corrosion of weathering steel that’s not related to this utility application. If there wereconcerns, I would expect to see it addressed in ANSI 48-05 of which I am a member. This is also true aboutNOTE 2, which references Sections 25 and 26 but offers no guidance. This current statement implies there’sa problem with direct embedded steel structures. Structural and/or corrosion concerns in using a foundationtype for a steel structure would seem to be outside the scope of this subcommittee.


Reject.


Disagreement on removing weathering steel from the rule. See action on CP3218.


Affirmative: (13) Bowles, Bowmer, Dagenhart, Dixon, Gaunt, Maxwell, Molde, Montambo, Pool, Reese,



Robeson, Saint, Zipse

Negative: (0)

Abstention: (0)

Revised Text

CP3350


Submitter

Robert Molde

Proposed Change


Directly embedded galvanized or stainless steel poles shall constitute an acceptable electrode, if allof the following requirements are met:

a. Backfill around the pole is native earth, crushed gravel with fines included, concrete, orconductive grout. (not Washed gravel or washed stone are not acceptable backfill materialsunless the water table is above the exposed portion of the pole).

b. Not less than 1.5 m (5.0 ft) of embedded length is exposed to the earth, without nonconductivecovering

b. Not less than 0.45 m2 (5.0 ft2) of the embedded pole surface, without nonconductive coating, isexposed directly to the backfill, and the exposed area shall extend not less than 5 ft belowground-line.


d. The metal thickness is not less than 6 mm (1/4 in) 4.5 mm (3/16 in)

e. Weathering steel and aluminum are not acceptable materials for this application.

NOTE 1: Directly embedded steel poles having a nonconductive covering below ground thatlimits the length area of direct exposure to earth to less than 1.5 m (5.0 ft) 0.45 m2 (5.0 sf) arenot considered as an acceptable electrode. Aluminum installed below ground is not consideredas an acceptable electrode. Weathering steel is not an acceptable material for this application.

NOTE 1 2: Bonding a metallic structure to the neutral and exposing the bare metal to the soilelectrolyte can aggravate corrosion or compromise a cathodic protection system. This shouldbe considered when using the structure as a ground. There are structural and corrosionconcerns that should be investigated prior to using metal poles as grounding electrodes. SeeSections 25 and 26.




Supporting Comment

The word “galvanized” must be added because later the rule states weathering steel cannot be used. Saying“steel pole” are acceptable is contradictory.

Part b

There are two concerns in establishing good earth grounding—contact surface and embedment depth

The surface area of a 5/8 in by 8 ft ground rod equals 1.3 ft2. The current Rule 094B7 requires an exposedlength of 5 ft and a minimum diameter of 5.0 in, which equates to 6.5 ft2 of exposed area for a steel pole,substantially more then the single ground rod. The proposed change (5.0 ft2) would require the steel pole tohave nearly 4 times as much contact area with the soil as a typical ground rod with a length of 8 ft. This is nochange from the current requirement of length and diameter and, therefore, requires no further justification.

A minimum bury depth is still required to provide contact with moist conductive earth. The change clearlystates the “expose area shall extend not less than 5 ft below ground-line.”

This is improved wording especially for larger diameter poles. As proposed, a large diameter pole with 5 ft2

of exposed metal surface buried adequately (5 or more ft) belowground would not need to have 5 ft of exposedlength. Length is not a relevant measure of contact with earth. There are utilities that are leaving the bottomfoot or two uncoated.

Part d

Why is a minimum thickness required?

If it is for loss of section due to corrosion, the requirement belongs under strength requirements.

If it is for conductivity, there really shouldn’t be any question regarding the conductivity of a steel pole. Steelpoles have been successfully used as grounding conductors for years even where copper ground rods aredriven along side. It is common practice to have grounding nuts welded to the pole at equipment mounts andat ground line. In this manner, the pole is used as the grounding conductor. Therefore, the thicknessrequirement is reduced to 3/16 in.

The thickness requirement could possibly be eliminated entirely.

NOTE 1

This should be a rule. The current text is more than explanatory.

NOTE 2

Notes are explanatory so NESC should be as clear as possible and provide appropriate clarification or purposeregarding the rule.

EXCEPTION

Delete the EXCEPTION because it is redundant. This is covered under Rule 013. Rule 013 is there so thisexception does not need to be added to every rule.






See CP3218.



Negative: (1) Reese

Abstention: (0)

Explanation of Vote

Reese: (Negative) While I agree with parts of this change proposal, I disagree with other parts.

— Crushed gravel with fines included should not be considered an acceptable backfill.

— Washed gravel or washed stone should never be acceptable as a backfill because the water table fluc-tuates greatly.

— The exception should remain to allow other methods that have been supported by a study.

New Text

CP3424

Section: 9 Rule: 096 E

Submitter

Tim Rasmussen

Proposed Change

Add a Rule 96E that reads as follows:

E. Multi-grounded system transition to uni-grounded system (or hybrid grounded system)

Where there is a transition from a multi-grounded system to a uni-grounded system, line reclosersmay be used in lieu of extension of the system neutral or installation of a device to obtain magneticseparation between the two systems.



Supporting Comment

At present, when a neutral is extended to at least one transformer location on a uni-grounded system, thenthat neutral must be extended to all transformer locations. This is currently the only allowed alternative sincesubstation line-to-ground fault protection is dependent on a multiplicity of grounds to guarantee properoperation.

This revision proposes another alternative, which is to allow the use of modern line reclosers instead ofextending the neutral in these instances. Modern line reclosers have high-speed ground fault detectingcapabilities and are able to sense even low amperage ground faults, thereby establishing the requiredovercurrent protection.


Reject.


It may violate Rule 215B5 and is in conflict with Rule 96C. Down wire detection is difficult under presenttechnology.



Negative: (0)

Abstention: (0)

Revised Text

CP3032


Submitter

Ewell T. Robeson

Proposed Change

B. Electrode connection

The grounding conductor shall preferably be made of copper (or other material that will not corrodeexcessively under the prevailing conditions of use) and shall not be less AWG No. 14 6 in size. Thegrounding conductor shall be attached to the electrode by means of a bolted clamp or other suitablemethods.



Supporting Comment

In our service area (Progress Energy), the bonding conductor typically used by the telephone companies hasbeen a #6 bare copper conductor. On occasion, when the neutral of our direct buried service cable is cut, theneutral current has returned to our source through the telephone grounding conductor. In most cases verylittle, if any, damage was done to the customer’s residence or telephone facilities.

Recently, a number of house fires have occurred where our service neutral failed due to a previous dig-in. Ourinvestigations found that in most cases, the traditional telephone company was not connected to the residence.The local CATV company was providing telephone service. In all of the cases where fires had occurred, theCATV company had installed a #14 copper insulated grounding conductor to the customer’s ground rod. Ineach case, the results were the same when our service neutral failed. The #14 conductor would overheateventually causing a fire potential.

All installations where the fires occurred met the present requirements of the NESC and NEC. However,communication services to residence have changed. Where the CATV companies are now providing both TVand telephone service, we no longer have the parallel paths of the telephone and CATV grounding conductors.As presented above, the #14 grounding conductor alone is not adequate to protect the customer’s facility.

Both the NEC and the NESC require a minimum size of #6 copper bonding conductor between separateground rods when the electrical and communications services have separate ground rods. Allowing a #14bonding conductor when a common ground rod is used seems to be a contradiction to requiring #6 whenseparate ground rods are used.

A similar CP request is also being presented to NFPA 70 (NEC) to increase the minimum size bondingconductor to #6 copper.


Accept.


Affirmative: (11) Bowles, Dagenhart, Dixon, Gaunt, Maxwell, Molde, Montambo, Reese, Robeson, Saint,Zipse

Negative: (2) Pool, Bowmer

Abstention: (0)

Explanation of Vote

Bowmer: (Negative) I oppose the change requested by this CP3032 because of three main reasons.

A) The use of 14-AWG bonding conductors is sufficient and safe based on the decades long safe history ofusing a 14-AWG bonding conductor in the telecommunications industry.

B) Using a 6-AWG bonding conductor will be less safe than using a 14-AWG conductor since this will resultin higher fault currents being more widely distributed into places and equipment where it does not belong.This will result in placing electrical heat energy into telecom plant components and possibly onto customerpremises equipment.



C) The evidence presented does not identify the conductor size as being the root cause of the fire problem—changing the conductor size will not solve problem.

Related observations:

1) The concern raised in CP3032 belongs more appropriately within NEC jurisdiction. Article 820 cover inCATV plant where Section 820.100(A)(3) states: “The grounding conductor shall not be smaller than 14AWG. It shall have a current carrying capacity approximately equal to that of the outer conductor of thecoaxial cable. The grounding conductor shall not be required to exceed 6 AWG.”

2) The current Rule 99B (NESC) allows 6 AWG to be used and is adequate.

3) My analysis of the available evidence suggests that the root cause of the fires lies in one or more of thefollowing—the insulation on the bonding conductor, the CATV coaxial cable, and equipment within theCATV box mounted on the side of the house. The root cause is not in the size of the grounding conductor.

4) In the CATV system described there was reportedly an insulated #14 AWG bonding conductor, a CATVbox, a splitter inside the box, and coaxial cable drop cables. Since the ampacity of the coaxial cable and itsshield is much smaller than the #14 AWG, increasing the size of the ground wire will not prevent the problem.The ampacity of a #14 AWG ground wire is 20 A to 25 A. The ampacity of a #6AWG ground wire is 65 to75 A. The ampacity of coaxial drop cables are between 5 to 6 A (Series 59) to 10 to 13 A (Series 11) withcurrent on both conductors. The ampacity of shield alone will be some fraction of that value. The problemand the solution lies in (a) the safe performance of the splitter when a foreign current is coming up the groundconnection and (2) the fire resistance CATV enclosure material (is it listed for application). Thesecomponents should be fire-resistant and in the telecom best practices these components should meetfunctional performance requirements both for fire resistance of the materials and resistance to fault currentsappearing on the bond wire.

5) Permitting higher fault currents on the bonding conductor may interfere with the automatic operation ofprotection devices.

My recommendation is for the committee to reconsider its position on the vote for CP3032 in light of theabove arguments and observations.

I appreciate the authors field problem and his frustration at the lack of response from the CATV company.However, I do not think the CP3032 is the correct way to fix the problem.

The NESC relies on and assumes that honest open communication and technical cooperation between powerand telecommunications occurs to make a safe, reliable network for their employees and the public. If this isnot forthcoming, then changes to the NESC rules will not make it happen.

Pool: (Negative) This proposal is not enforceable. Communications equipment installed on houses is doneper requirements of the National Electrical Code (NEC). Inspectors (City or County) inspect theseinstallations for compliance with NEC rules. Further Rule 99 should be applicable to small huts (such asrepeater and regenerator stations) and not houses.

I believe that the proposal addresses the symptoms and not the cause of the problem. Increasing the groundingconductor size will not resolve the problem but transfer the overheating to some other portion of the plant,i.e., coax/service wire shield. The real source of the problem is inadequate physical protection of the buriedpower service from dig-ins and corrosion.

The size of the grounding conductor falls under the purview of the NEC. NEC Section 820.100(A)(3)addresses the size of the grounding conductor. It states that the grounding conductor should “... have acurrent-carrying capacity approximately equal to that of the outer conductor of the coaxial cable.”



New Text

CP3356

Section: 9 Rule: 099 D

Submitter

Percy E. Pool

Proposed Change

Change Rule 099C to read:

A bond not smaller than AWG No. 6 copper or equivalent shall be placed between the communicationgrounding electrode and the supply system neutral grounding electrode where separate electrodes are used atthe structure or building being served. All separate electrodes shall be bonded together except whereseparation is required per Rule 97.

Supporting Comment

The word “building” is not necessary. The word “structure” is sufficiently clear.


Reject.


Section 9 contains only grounding methods. This CP proposes a grounding requirement. Also, this CP is inconflict with Rule 384C.


Affirmative: (11) Bowles, Dagenhart, Dixon, Gaunt, Maxwell, Molde, Montambo, Reese, Robeson, Saint,Zipse

Negative: (2) Pool, Bowmer

Abstention: (0)

Explanation of Vote

Bowmer: (Negative) I consider the change suggested by CP3356 is useful and worth adding to promote thebonding of telecom and power equipment with 6 ft of one another.

Pool: (Negative) This CP is intended to make clear that all electrodes are to be bonded together regardless ofwhether the electrode is used to ground cases or housings or is a vertical pole ground as long as they are 1.8m or less from one another. A vertical pole ground within 1.8 m of an aboveground metallic apparatuspresents the same hazard as two aboveground metallic apparatus separated by less than 1.8 m.



Aboveground communications apparatus (such as pedestals and housings) are typically grounded. Thus theyhave a grounding electrode (ground rod). Similarly, power apparatus (such as transformer cases) are alsoconnected to a grounding electrode. The vertical pole ground also terminates at a grounding electrode. If anyof these are within 1.8 m of each other they must be bonded together in order to minimize a voltage differencebetween them. Common bonding is necessary for personnel safety.

Common bonding between communications and power apparatus, and including pole grounds helps to reducepotential differences between metallic parts that could be touched simultaneously. The intent of this new ruleis to limit the possibility of technicians (both power and communications) or the general public to contact twometallic surfaces that may be at different voltage levels and thus receive an electrical shock.



Part 1. Rules for the Installation and Maintenance of Electric Supply Stations and Equipment

Revised Text

CP3220

Part: 1 Section: 10 Rule: 110 B2 EXCEPTION 3

Submitter

James T. Collins

Proposed Change

Revise as follows:

EXCEPTION 3: Stored mMaterial, equipment, and vehicles related to station, transmission, anddistribution construction, operations, or and maintenance work in progress may be temporarily locatedin a storage space meeting all of the following requirements:

Supporting Comment

This is in reference to IR 546.

A restriction on equipment and vehicles in stations would have a significant negative impact on stationoperations. Here are a few of the issues from an operations perspective:

Site show-up—The Memorandum of Agreement with IBEW allows qualified workers to report directly to aworksite at the start of their shift instead of first reporting to a work headquarters. The work location is oftenin the vicinity of, and not directly at, the station, so the employee’s personal vehicle may be left unattended.Also, when off-duty, show-up personnel leave their company vehicle staged at the site. If not allowed withinthe fence, the company would not be able to provide secure parking for these vehicles, making site show-upimpossible in many cases.

Pre-staging equipment for planned work—Often for maintenance or construction work, especially whereclearances must be taken during night or weekend hours, or on an “on call” basis, company vehicles are pre-staged at a site for efficient start of work when the clearance is granted.

Take-home vehicles—Many field employees use take-home work vehicles for faster emergency response toproblems. This also allows them to work from home saving travel time and fuel required to go to a workheadquarters every day. Some who live in deed restricted neighborhoods or have limited parking at home,must park the work vehicle in a nearby substation.


Accept.




Affirmative: (7) Comans, Dietzman, Konz, Saint, Tomaseski, Winoski, Zaczek

Negative: (2) Engmann, Christofersen

Abstention: (0)

Explanation of Vote

Christofersen: (Negative) Vehicles should be a subset of material and equipment. Clarification of theequipment or material essential for maintenance or construction is beyond the scope of the NESC.

Engmann: (Negative) The inclusion of the word “operations” may produce an effect that is counter to theintent of the proposed change. The EXCEPTION will require that any operations vehicle that is parked in asubstation, e.g., a vehicle that enters the substation as part of a routine patrol, shall meet the all of therequirements of (a) – (f), regardless of the length of time that the vehicle is in the substation. More seriously,it violates the intent of the rule to limit combustible material in the substation. Convenience will becomesufficient reason to add any quantity of vehicle fuel to the contents of the substation.

Revised Text

CP3347

Part: 1 Section: 11 Rule: 110 A2

Submitter

Alton Comans

Note: This change proposal is being submitted to document the previously approved TIA 2007-1, adoptedFebruary 5, 2007.

TENTATIVE INTERIM AMENDMENT

Tentative Interim Amendment 2007-1to the

National Electrical Safety Code

ANSI C2-2007

Rule 110A2: Delete the last part of the first sentence and replace with the new underlined material. DeleteEXCEPTION 1 and replace with item a), item b), new material, and accompanying NOTE. Change theoriginal EXCEPTION 2 to EXCEPTION.

2. Safety clearance zone

Fences or walls, when installed as barriers for unauthorized personnel, shall be located such thatexposed live parts are outside the safety clearance zone as illustrated in Figure 110-1 and shown inTable 110-1 depending on the type of barrier, as follows:



EXCEPTION 1: Where a fence, partition, or wall with no openings though which sticks or otherobjects can be inserted is utilized, live parts complying with the requirements of this code may beinstalled within the safety clearance zone if they are below the horizontal line projected from thetop of the fence or wall.

a. A metal chain-link fence or equivalent barrier, as illustrated in Figure 110-1, shall have an R-value equal to or greater than that specified in Table 110-1.

b. Where an impenetrable barrier is used, such as a fence, partition, or wall with no openingsthrough which sticks or other objects can be inserted, the sum of the values of R1 and H(barrier height) as illustrated in Figure 110-2 shall be equal to or greater than the sum ofDimension (R) as specified in Table 110-1 plus 1.5 m (5.0 ft). The lower 0.6 m (2 ft) of anysection utilizing an impenetrable barrier may be constructed of metal chain-link fence fabric.

NOTE: An impenetrable barrier does not have to cover the entire wall or fence, only thoseportions that would not be in compliance with the dimensions of Figure 110-1 and Table 110-1.

All exposed live parts installed shall meet the requirements of Rule 124 and Rule 125.

EXCEPTION 2: The safety clearance zone requirement is not applicable to internal fences withinan electric supply station perimeter.

Rule 110: Add Figure 110-2, Safety clearance to electric supply station impenetrable fence, afterFigure 110-1.

H + R1 > R + 1.5 m (5.0 ft)

Figure 110-2—Safety clearance to electric supply station impenetrable fence

Supporting Comment

Rationale for the proposed TIA—Fence safety clearance zone Rule 110A2

EXCEPTION 1 was included in this rule to allow a method to deal with live parts which violate the fence



safety clearance zone rule. The requirement for an impenetrable fence (defined as a fence with no openingsthrough which sticks or other objects can be inserted) was added so the possibility of a rod or stick beinginserted through the fence could be eliminated; however, requiring the impenetrable fence to be of an equalheight as the violating live part is excessive.

There is no valid safety reason that the total distance from the ground line (where a person would be standing)over top of the impenetrable fence to the offending live part should be greater than the distance from the samepoint on the ground to a point 1.5 m (5.0 ft) vertically on an open-mesh fence and then through the fence tothe live part. As long as the total possible reach distance to the live part over the fence is the same or greaterthan is required by Rule 110A2 through the fence at the 5.0 ft height, there is no compromise in safety.

Figure 1 illustrates a live part, at a height of 13.0 ft and 5.0 ft inside the substation fence. At the 13.8 kVvoltage class, this live part would be in violation of Rule 110A2.

To correct this violation, using the wording of Rule 110A2, EXCEPTION 1, will require an impenetrablefence height of 13.0 ft. Construction of impenetrable fences of this height, especially in areas of high windloading is sometimes not practical and places a burden that was not intended by this rule. The fact that animpenetrable fence is being used to correct a safety clearance zone violation normally indicates that theavailable space is limited. The required supporting foundation for a solid fence in an extreme wind loadingarea can be substantial and cannot always be practically installed.

Figure 2 illustrates the required fence height for the same condition under the proposed TIA. The revisedmethod results in a required impenetrable fence height of only 9.0 ft.



Calculation of the required fence height using this method is an iterative process, because R1 cannot bereadily calculated until a trial height for the fence is selected. However, for any voltage class a series of arcscan be constructed with various fence heights which will quickly give a graphical solution. Modern computeraided drafting techniques can quickly give the required height.

For the two examples given, the ground line moment for the foundation reaction is twice as much for the13.0 ft fence as for the 9.0 ft fence. An increase in the design ground line moment by a factor of 2.0 willsignificantly increase the size of the fence supporting columns and the fence foundation. As stated earlier, ifthe fence is being installed in an area of restricted or confined space and the design extreme wind loading issubstantial, such as hurricane exposure regions, the design and installation of the fence may be impractical.

This proposed TIA does recognize that as a live part approaches the vertical plane of the fence, the fence doesneed to be higher; indeed for a live part very close to the fence the fence height will approach the same heightas the live part.

Having been in attendance during the meeting when Rule 110A2 was adopted, and having been involved inthe discussion that crafted the wording, I submit that EXCEPTION 1 to this rule was not intended to placethis stringent a requirement. It was not recognized at the time this was done that the requirement for theimpenetrable fence to be at the same height as the offending live part would create this degree of difficulty.The TIA as proposed will correct this.


Accept as modified.

Rule 110A2: Delete the last part of the first sentence and replace with the new underlined material. DeleteEXCEPTION 1 and replace with item a), item b), new material, and accompanying NOTE. Change theoriginal EXCEPTION 2 to EXCEPTION.



2. Safety clearance zone

Fences or walls, when installed as barriers for unauthorized personnel, shall be located such thatexposed live parts are outside the safety clearance zone as illustrated in Figure110-1 and shown inTable 110-1 depending on the type of barrier, as follows:

EXCEPTION 1: Where a fence, partition, or wall with no openings though which sticks or otherobjects can be inserted is utilized, live parts complying with the requirements of this code may beinstalled within the safety clearance zone if they are below the horizontal line projected from thetop of the fence or wall.

a. A metal chain-link fence or equivalent barrier, as illustrated in Figure 110-1, shall have an R-value equal to or greater than that specified in Table 110-1.

b. Where an impenetrable barrier is used, such as a fence, partition, or wall with no openingsthrough which sticks or other objects can be inserted, the sum of the values of R1 and H(barrier height) as illustrated in Figure 110-2 shall be equal to or greater than the sum ofdimension (R) as specified in Table 110-1 plus 1.5 m (5.0 ft). The impenetrable barrier doesnot have to cover the entire wall or fence, only those portions that would not be in compliancewith the dimensions of Figure 110-1 and Table 110-1, having a width such that the minimumdistance from the outer edge of impenetrable barrier to the nearest live parts shall be equal toor greater then the dimension (R).

EXCEPTION 2: The safety clearance zone requirement is not applicable to internal fences withinan electric supply station perimeter.

Rule 110: Add Figure 110-2, Safety clearance to electric supply station impenetrable fence, afterFigure 110-1.

H + R1 > R + 1.5 m (5.0 ft)

Figure 110-2—Safety clearance to electric supply station impenetrable fence




Affirmative: (8) Comans, Dietzman, Engmann, Konz, Saint, Tomaseski, Winoski, Zaczek

Negative: (1) Christofersen

Abstention: (0)

Explanation of Vote

Christofersen: (Negative) Would accept if the 2 ft lower section may be constructed of chain-link fencefabric.

Revised Text

CP3222


Submitter

James T. Collins

Proposed Change

Revise Rule 110B2, EXCEPTION 1, as follows:

EXCEPTION 1: Material, equipment, and vehicles Equipment or material essential for maintenance ofthe installed equipment may be stored if guarded or separated from live parts as required by Rule 124.

Supporting Comment



Site show-up—The Memorandum of Agreement with IBEW allows qualified workers to report directly to aworksite at the start of their shift instead of first reporting to a work headquarters. The work location is oftenin the vicinity of, and not directly at, the station, so the employee’s personal vehicle may be left unattended.Also, when off-duty, show-up personnel leave their company vehicle staged at the site. If not allowed withinthe fence, the company would not be able to provide secure parking for these vehicles, making site show-upimpossible in many cases.

Pre-staging equipment for planned work—Often for maintenance or construction work, especially whereclearances must be taken during night or weekend hours, or on an “on call” basis, company vehicles are pre-staged at a site for efficient start of work when the clearance is granted.

Take-home vehicles—Many field employees use take-home work vehicles for faster emergency response toproblems. This also allows them to work from home saving travel time and fuel required to go to a workheadquarters every day. Some who live in deed restricted neighborhoods or have limited parking at home,



must park the work vehicle in a nearby substation.


Accept.



Negative: (1) Christofersen

Abstention: (0)

Explanation of Vote


Revised Text

CP3221


Submitter

James T. Collins

Proposed Change

EXCEPTION 2: Materials, equipment, and vehicles related to station, transmission and distributionconstruction, operations, or maintenance work may be stored in the station if located in an areaseparated from the station electric supply equipment by a fence meeting the requirements of Rule 110A.

Supporting Comment



Site show-up—The Memorandum of Agreement with IBEW allows qualified workers to report directly to aworksite at the start of their shift instead of first reporting to a work headquarters. The work location is oftenin the vicinity of, and not directly at the station, so the employee's personal vehicle may be left unattended.Also, when off-duty, show-up personnel leave their company vehicle staged at the site. If not allowed withinthe fence, the company would not be able to provide secure parking for these vehicles, making site show-upimpossible in many cases.

Pre-staging equipment for planned work—Often for maintenance or construction work, especially where



clearances must be taken during night or weekend hours, or on an “on call” basis, company vehicles are pre-staged at a site for efficient start of work when the clearance is granted.

Take-home vehicles—Many field employees use take-home work vehicles for faster emergency response toproblems. This also allows them to work from home saving travel time and fuel required to go to a workheadquarters every day. Some who live in deed restricted neighborhoods or have limited parking at home,must park the work vehicle in a nearby substation.


Accept.




Abstention: (0)

Explanation of Vote


Engmann: (Negative) See response to CP3220. Note that it appears that the inclusion of “operations” requiresthat all of the vehicles listed in the CP, e.g., “site show-up,” shall be separated from the substation by a fence,screen, partition.

Revised Text

CP3463


Submitter

Subcommittee 3

Proposed Change

Add to existing Rule 111A.

A. Under normal conditions

1. Outdoor lighting is not required at unattended stations. Permanent or portable lighting may beused during such times that personnel perform work in the station at night.

2. Rooms and spaces shall have means provisions for artificial illumination while attended.Illumination levels not less than those listed in Table 111-1 are recommended for safety to bemaintained on the task.



Supporting comment

Clarification of the rule in response to IR 542.


Accept.


Affirmative: (7) Christofersen, Dietzman, Konz, Saint, Tomaseski, Winoski, Zaczek

Negative: (0)

Abstention: (0)

Revised Text

CP3474

Part: 1 Section: 11 Rule: 111 Table 111-1

Submitter

NESC SC3

Proposed Change

Table 111-1—Illumination levels

Location lux footcandles

Generating station (interior)

Highly critical areas occupied most of the time 1 270 25

Areas occupied most of the time 2 160 15

Critical areas occupied infrequently 3 110 10

Areas occupied infrequently 4 55 5

Air-conditioning equipment, air preheater and fan floor, ash sluicing 55 5

Auxiliaries, battery areas, boiler feed pumps, tanks, compressors, gage area

110 10

Boiler platforms 55 5

Burner platforms 110 10

Cable room, circulator, or pump bay 55 5



Chemical laboratory 270 25

Coal conveyor, crusher, feeder, scale area, pulverizer, fan area, transfer tower

55 5

Condensers, de-aerator floor, evaporator floor, heater floors 55 5

Control rooms Vertical face of switchboards Simplex or section of duplex operator:

Type A—Large centralized control room 1.68 m (66 in) above floor 270 25

Type B—Ordinary control room 1.68 m (66 in) above floor 160 15

Section of duplex facing away from operator 270 15

Bench boards (horizontal level) 270 25

Area inside duplex switchboards 55 5

Rear of all switchboard panels (vertical) 55 5

Dispatch boards

Horizontal plane (desk level) 270 25

Vertical face of board [1.22 m (48 in) above floor, facing operator]:

System load dispatch room 270 25

Secondary dispatch room 160 15

Hydrogen and carbon dioxide manifold area 110 10

Precipitators 55 5

Screen house 110 10

Soot or slag blower platform 55 5

Steam headers and throttles 55 5

Switchgear, power 110 10

Telephone equipment room 110 10

Tunnels or galleries, piping 55 5

Turbine bay sub-basement 110 10

Turbine room 160 15

Visitors’ gallery 110 10

Water treating area 110 10

Generating station (exterior)

Building pedestrian main entrance 110 10

Critical areas 5 55 5

Areas occupied occasionally by pedestrians 6 22 2

Table 111-1—Illumination levels (continued)




Areas occupied occasionally by vehicles 7 11 1

Areas occupied infrequently 8 5.5 0.5

Remote areas 9 2.2 0.2

Catwalks 22 2

Cinder dumps 2.2 0.2

Coal unloading

Dock (loading or unloading zone) 55 5

Barge storage area 5.5 0.5

Car dumper 55 5

Tipple 22 2

Conveyers 22 2

Entrances Generating or service building

Main 110 10

Secondary 22 2

Gate house

Pedestrian entrance 110 10

Conveyor entrance 55 5

Fence 2.2 0.2

Fuel-oil delivery headers 55 5

Oil storage tanks 11 1

Open yard 2.2 0.2

Platforms—boiler, turbine deck 55 5

Roadway

Between or along buildings 11 1

Not bordered by buildings 5.5 0.5

Substation

Control building interior 110 10

General exterior horizontal and equipment vertical 22 2

Specific vertical (on disconnects) 22 2

Remote areas 10 2.2 0.21 Such as: Chemical laboratory, large centralized control room 1.68 m (66 in) above floor, section of duplex facing away from operator,bench boards (horizontal level), dispatch boards—horizontal plane (desk level), dispatch boards—vertical face of board [1.22 m (48 in)above floor, facing operator]—system load dispatch room.2 Such as: Ordinary control room 1.68 m (66 in) above floor, secondary dispatch room, turbine room.

Table 111-1—Illumination levels (continued)




Supporting Comment

This working group was formed to simplify and update Table 111-1. This table is two pages long and hasmuch too much detail for generating stations and not enough detail for substations and nothing for substationcontrol buildings. This CP does not change any of the illumination levels. Details of generation items aregrouped with others with the same illumination level and detailed in a footnote instead of in the table.Additional illumination levels have been added for substations including the control building interior.


Accept.


Affirmative: (6) Christofersen, Comans, Dietzman, Engmann, Harrison, Zaczek

Negative: (2) Winoski, Konz

Abstention: (0)

Explanation of Vote

Konz: (Negative) While we like the idea of cleaning up this table, we are not in favor of adding requirementsto substations. If they would have been left alone, we would have supported this.

Winoski: (Negative) We are in agreement that the tables need to be updated. We are not in favor of adding inrequirements for the light levels of remote areas of substations.

New Text

CP3149

Part: 1 Section: 11 Rule: 114

3 Such as: Auxiliaries, battery areas, boiler feed pumps, tanks, compressors, gage area, burner platforms, hydrogen and carbon dioxidemanifold area, screen house, power switchgear, telephone equipment room, turbine bay sub-basement, visitors’ gallery, water treatingarea4 Such as: Air-conditioning equipment, air preheater and fan floor, ash sluicing, boiler platforms, cable room, circulator, or pump bay,coal conveyor, crusher, feeder, scale area, pulverizer, fan area, transfer tower, condensers, de-aerator floor, evaporator floor, heaterfloors, area inside duplex switchboards, rear of all switchboard panels (vertical), precipitators, soot or slag blower platform, steamheaders and throttles, piping tunnels or galleries.5 Such as: Coal unloading dock (loading or unloading zone), coal unloading car dumper, gate house conveyor entrance, fuel-oil deliveryheaders, platforms—boiler, turbine deck. 6 Such as: Catwalks, coal unloading tipple, conveyers, secondary building entrances. 7 Such as: Oil storage tanks, roadway between or along buildings. 8 Such as: Coal unloading barge storage area, roadway not bordered by buildings.9 Such as: Cinder dumps, fence, open yard.10 Such as: fence, open yard.



Submitter

David J. Marne, P.E.

Proposed Change


Fire-extinguishing equipment approved for the intended use shall be conveniently located andconspicuously marked.

EXCEPTION: This rule does not apply to unmanned, outdoor substations that do not contain a controlbuilding or similar building.

Supporting Comment

The design of a rural substation without a control building does not lend itself to placement of a fireextinguisher. Typically a vehicle-mounted fire extinguisher would be used in a rural substation if a fire wasencountered.


Reject.


This rule is not intended to require permanent fire extinguishers or fire extinguishment systems in all electricsupply stations or in all areas of large, complex stations.


Affirmative: (9) Christofersen, Comans, Dietzman, Engmann, Konz, Saint, Tomaseski, Winoski, Zaczek

Negative: (0)

Abstention: (0)

New Text

CP3044


Submitter

Jack Christofersen

Proposed Change

Replace Rule 121; insert new rule.



121. Inspections, tests, and maintenance

A. In-service equipment

1. Initial compliance with rules

Equipment shall comply with the safety rules of the National Electrical Safety Code whenplaced in service.

2. Inspection

a. Accessible equipment shall be inspected while in service at such intervals as experience hasshown to be necessary.

NOTE: It is recognized that inspections may be performed in a separate operation or whileperforming other duties, as desired.

b. New equipment in electrical supply stations shall be inspected before being placed inservice.

3. Tests

a. When considered necessary, equipment shall be subjected to practical tests to determinerequired maintenance.

b. New equipment in electrical supply stations shall be inspected and tested in accordancewith standard industry practices before being placed in service.

4. Performing or scheduling maintenance; recording of condition affecting compliance with thisCode

Any condition affecting compliance with this Code revealed by inspection or tests, if notpromptly corrected, shall be recorded and scheduled for maintenance, replacement, or removalfrom service; such records shall be maintained until the conditions are corrected.

5. Remedying condition affecting compliance with this Code

Equipment with any recorded condition affecting compliance with this Code that couldreasonably be expected to endanger life or property shall be promptly repaired, disconnected,or isolated. Other conditions shall be scheduled for maintenance or replacement on anappropriate schedule.

NOTE: It is recognized that many conditions found during inspections or tests are not expectedto have an immediate or life-endangering impact and should be scheduled for maintenanceduring ordinary maintenance cycles. Often an identified maintenance item is not critical or time-sensitive and may best wait to be scheduled for maintenance the next time other work isscheduled for that work area, particularly if such maintenance requires personnel to work inenergized areas.

B. Equipment that is out of service

1. Equipment infrequently used

Equipment infrequently used shall be inspected or tested as necessary before being placed back



into service. Idle equipment that is energized but not connected to a load shall be inspected andmaintained at such intervals as experience has shown to be appropriate.

NOTE: Such idle equipment includes, but is not limited to, emergency or redundant equipmenton standby service and equipment installed in anticipation of new loads or similar installations.

2. Equipment temporarily out of service

Equipment temporarily out of service shall be maintained in a safe condition.

3. Equipment permanently abandoned

Equipment permanently abandoned shall be removed or maintained in a safe condition.

Delete old rule.

121. Inspections

A. In-service equipment

Electric equipment shall be inspected and maintained at such intervals as experience has shown tobe necessary. Equipment or wiring found to be defective shall be put in good order or permanentlydisconnected.

B. Idle equipment

Infrequently used equipment or wiring shall be inspected and tested before use to determine itsfitness for service. Idle equipment energized but not connected to a load shall be inspected andmaintained at such intervals as experience has shown to be necessary.

C. Emergency equipment

Equipment and wiring maintained for emergency service shall be inspected and tested at suchintervals as experience has shown to be necessary to determine its fitness for service.

D. New equipment

New equipment shall be inspected and tested before being placed in service. New equipment shallbe tested in accordance with standard industry practices.

Supporting Comment

This revises Rule 121 to be consistent with other parts of the code.

Working Group 1.11, Inspection rules—For the 2012 Edition of SC2, SC3, SC4, SC7, and SC5 to addresstheir own inspection rules with the intent to have uniform language for station, overhead line, andunderground line inspection rules where the requirements are the same.

Chair: Jack Christofersen

Each SC chair to assign SC members to the WG. Allen Clapp suggested this WG at our October 2003 SC1meeting to revise. Rule 121 to have inspections consistent with other parts of the code. This should onlyrequire a change proposal for the 2012 Edition.




Reject.


The need for “recorded” documentation for the electrical supply stations as presented in the CP is notappropriate for safety code. The SC feels that Part B3, which states, “Equipment permanently abandoned,”shall be removed or maintained in a safe condition is not necessary.




Abstention: (0)

Explanation of Vote

Christofersen: (Negative) Rule 121 is inconsistent with inspection rules of other parts of the Code and needsrevision. Also, I am not in agreement with the Rejection relative to not recording defects, schedulingmaintenance or defective equipment not being maintained safely.

Engmann: (Negative) Rule 121 is inconsistent with inspection Rules of other parts of the Code and needsrevision. Also, I am not in agreement with the Rejection relative to not recording defects, schedulingmaintenance or defective equipment not being maintained safely.

New Text

CP3398


Submitter

Jack Christofersen

Proposed Change

Add new text to Rule 124A1.

124. Guarding live parts

A. Where required

1. Guards shall be provided around all live parts operating above 300 V phase-to-phase withoutan adequate insulating covering, unless their location gives sufficient horizontal or verticalclearance or a combination of these clearances to limit the likelihood of accidental humancontact. Clearances from live parts to any permanent supporting surface for workers shall



equal or exceed either of those shown in Table 124-1 and illustrated in Figure 124-1. Theclearance can be achieved by meeting the horizontal clearance, the vertical clearance, or a“taut string distance” equal to the required vertical clearance as illustrated in Figure 124-3.

Figure 124-3—“Taut String” measurement

EXCEPTION: Where supplemental protection is used in accordance with Rule 124C3, therequirements to guard do not apply.


Accept as modified.

Add new text to Rules 124A1 and124C1.

124. Guarding live parts

A. Where required

Guards shall be provided around all live parts operating above 300 V phase-to-phase without anadequate insulating covering, unless their location gives sufficient horizontal or vertical clearanceor a combination of these clearances to limit the likelihood of accidental human contact, and thelocation of the live parts is in compliance with the Safety Clearance Zone requirements of Rule110A2. Clearances from live parts to any permanent supporting surface for workers shall equal orexceed either of those shown in Table 124-1 and illustrated in Figure 124-1.

EXCEPTION: Where supplemental protection is used in accordance with Rule 124C3, therequirements to guard do not apply.

C. Types of guards

1. Location or physical isolation

Live parts in compliance with the Safety Clearance Zone requirements of having clearancesequal to or greater than specified in Table 124-1 are guarded by location. Parts are guarded by



isolation when all entrances to enclosed spaces, runways, fixed ladders, and the like are keptlocked, barricaded, or roped off, and safety signs are posted at all entrances.


Affirmative: (6) Christofersen, Comans, Dietzman, Engmann, Saint, Zaczek

Negative: (1) Winoski

Abstention: (0)

Explanation of Vote

Comans: (Affirmative) One concern I still have is that this wording may lead someone to believe that if theyviolate the safety clearance zone that the live parts can be guarded, which is something we may want.However, I am not sure that the guarding method as described in 124C2 is sufficient for the 10 ft stick issueof Rule 110A2, as Rule 124C2 only requires the guard to be to the height needed to comply with Table 124-1.

Winoski: (Negative) We feel that in light of all the discussions that have been unable to succinctly addressdesired changes to 124A1 that the existing language in 124A1 is acceptable.

Revised Text

CP3150


Submitter


Proposed Change


3. Each portion of parts of indeterminate potential, such as telephone wires exposed to induction fromhigh-voltage lines, ungrounded neutral connections, ungrounded frames, ungrounded parts ofinsulators or surge arresters, or ungrounded instrument cases connected directly to a high-voltagecircuit, shall be guarded in accordance with Rule 124A1 on the basis of the maximum voltage thatmay be present on the surface of that portion. The vertical clearance above grade any permanentsupporting surface for workers to of the bottom of such part shall be not less than 2.60 m (8.5 ft)unless it is enclosed or guarded in accordance with Rule 124C.

Supporting Comment

Rule 124A1 uses the wording “any permanent supporting surface for workers.” Rule 124A3 should use thesame wording. Measurements should not be made to grade if a concrete slab above grade exists.




Accept as modified.


3. Each portion of parts of indeterminate potential, such as telephone wires exposed to induction fromhigh-voltage lines, ungrounded neutral connections, ungrounded frames, ungrounded parts ofinsulators or surge arresters, or ungrounded instrument cases connected directly to a high-voltagecircuit, shall be guarded in accordance with Rule 124A1 on the basis of the maximum voltage thatmay be present on the surface of that portion. The vertical clearance above grade any permanentsupporting surface for workers to of the bottom of such part shall be not less than 2.60 m (8.5 ft)unless it is enclosed or guarded in accordance with Rule 124C or Rule 124D.


Affirmative: (9) Christofersen, Comans, Dietzman, Engmann, Konz, Saint, Tomaseski, Winoski, Zaczek

Negative: (0)

Abstention: (0)

New Text

CP3369

Part: 1 Section: 12 Rule: 124 D

Submitter

Allen L. Clapp

Proposed Change

Add a new Rule 124D as follows and renumber the remaining sections of Rule 124.

D. Taut-string distances

Vertical clearances to energized parts or parts of indeterminate potential that are set back from theedge of equipment or other barrier to clear reaching distance (such as bushings on the top of a largetransformer) may be composed of the vertical distance of the top of the equipment or barrier abovethe nearest permanent supporting surface (such as a step, foundation pad, etc.) plus the shortestdiagonal or horizontal clearance from the edge of the top side of the equipment or barrier to thepart. See Figure 124-2.



Figure 124-2—Taut-string measurement of vertical clearance to energized parts of equipment or behind barriers

Supporting Comment

The question of measurement to bushings set back on the top of equipment or behind barriers has continuedto be asked. This question has been answered in other Code documents and in the NESC Handbook, but thiswill put it up front in the Code for all to see.


Accept as modified.

Add a new Rule 124D as follows and renumber the remaining sections of Rule 124.

D. Taut-string distances

1. Vertical clearances to energized parts or parts of indeterminate potential as required by Rule124A that are set back from the edge of equipment or other barriers to clear reaching distancemay be composed of the vertical distance of the top of the equipment or barrier above thenearest permanent supporting surface (such as a step, foundation pad, etc.) plus the shortestdiagonal or horizontal clearance from the edge of the top side of the equipment or barrier to thepart with a vertical component of the taut string distance not less than 1.5 m. or 5 ft, as shownin Figure 124-3.



Figure 124-3—Taut-string measurement of vertical clearance to energized parts of equipment or behind barriers



Negative: (0)

Abstention: (1) Christofersen

Explanation of Vote

Christofersen: (Abstain) Minimum of 8.6 ft required to live parts unless guarded. A verification is requiredthat a 5 ft clearance is an adequate guard.

Revised Text

CP3426


Submitter

Allen L. Clapp

Proposed Change

Revise Rule 125 to appropriately reflect working room requirements and to coordinate with NECrequirements for similar work. Delete Rule 125A5.



125. Working space about electric equipment

Access and working space shall be provided and maintained about electric equipment to permit readyand safe operation and maintenance of such equipment.

NOTE: Requirements for working space about installed equipment may not be sufficient to allowinstallation or replacement of the equipment.

A. Clear spaces for working

Working space required by this section shall not be used for storage. When normally enclosedenergized parts are exposed for inspection or servicing, the working space, if in a passageway orgeneral open space, shall be guarded.

B. Access and entrance to working space

At least one entrance shall be provided to give access to the working space about electricequipment.

C. Width of working space

The width of the working space in front of the electric equipment shall be not less than 750 mm(30 in) wide the width of the opening in the equipment, whichever is greater.

D. Depth of working space

The depth of the working space shall be measured from (a) the energized parts, if such are exposedon the outside of a board or enclosure or (b) the enclosure front or opening, if energized parts arenormally enclosed.

Concrete, brick, or tile walls and conductive enclosures or racks shall be considered as groundedfor purposes of using Table 125-1.

A. Working space (1. 600 V or less)

Access and working space shall be provided and maintained about electric equipment to permitready and safe operation and maintenance of such equipment.

1. Clear spaces

Working space required by this section shall not be used for storage. When normally enclosedenergized parts are exposed for inspection or servicing, the working space, if in a passagewayor general open space, shall be guarded.

2. Access and entrance to working space

At least one entrance shall be provided to give access to the working space about electricequipment.

3. Working space

The depth of the working space in the direction of access to energized parts operating at 600 Vor less that require examination, adjustment, servicing, or maintenance while energized shallbe not less than indicated in Table 125-1. In addition to the dimensions shown in Table 125-1,



the working space shall be not less than 750 mm (30 in) wide in front of the electric equipment.Distances shall be measured from the energized parts if such are exposed or from the enclosurefront or opening if such are enclosed. Concrete, brick, or tile walls shall be consideredgrounded.

2. Over 600 V

The depth of the working space in the direction of access to energized parts operating greaterthan 600 V that require examination, adjustment, servicing, or maintenance while energizedshall be not less than the sum of the depth of working space required in Table 125-1 for parts of600 V plus the guard zone of Table 124-1 for the applicable voltage.

34. Headroom for working space about switchboards or control centers

The headroom of working spaces about switchboards or control centers shall be not less than2.13 m (7 ft). Headroom about other equipment shall also consider requirements for movementof workers or parts during operation or maintenance.

5. Front working space

In all cases where there are energized parts normally exposed on the front of switchboards ormotor control centers, the working space in front of such equipment shall not be less than 900mm (3 ft).

B. Working space over 600 V

Working space shall be in accordance with Table 124-1.

Supporting Comment

Rule 125A5 should be deleted. It is confusing and can lead a user to install a switchboard or motor controlcenter in violation of Table 125-1. The 3 ft clearance of Rule 125A5 is only good up to 150 V. This rule canbe read to allow 3 ft working clearance in front of switchboards and motor control centers having voltages upto 600 V, which is not the intent of the rule. Table 125-1 says all that needs to be said.

The remainder of the changes to Rule 125A are intended to make the rule more complete and to match therequirements of the NEC, which require a width of working space no smaller than the width of the openingin equipment or 30 in, whichever is greater.

The present Rule 125B is unenforceable and unintelligible. Nothing in Table 124-1 addresses workingclearances. Neither the horizontal nor vertical clearances for personnel areas are appropriate for workingclearances, nor is the guard zone of Table 124-1.


Reject.


The CP did not improve the existing wording.




Affirmative: (8) Christofersen, Comans, Dietzman, Konz, Saint, Tomaseski, Winoski, Zaczek

Negative: (1) Engmann

Abstention: (0)

Explanation of Vote

Engmann: (Negative) The merit of the CP was lost in the wording.

Revised Text

CP3442


See CP3442 General section.



Part 2.Safety Rules for the Installation and Maintenance of Overhead Electric Supply and Communication Lines

Sections 20–27

Revised Text

CP3427


Submitter

Allen L. Clapp

Proposed Change

Revise Rule 202 to appropriately address the strength for maintenance replacement structures.

202. Application of rules

The general requirements for application of these rules are contained in Rule 13. However, when asupporting structure is replaced, (a) the arrangement of equipment shall conform to the current editionof Rule 238C and (b) the strength of the supporting structure and its components shall meet therequirements of Sections 24, 25, 26, and 27 of the current edition.

Supporting Comment

There may be many reasons to continue using a previous edition when a structure must be maintained, asallowed under Rule 013B2 and Rule 013B3, because of clearance or other issues limiting application of thecurrent edition. However, there is no reason not to install replacement structures to meet current strengthsand loadings requirements and every reason to do so.


Accept in part.

Revise Rule 202

202. Application of rules

The general requirements for application of these rules are contained in Rule 13. However, when asupporting structure is replaced, the arrangement of equipment shall conform to the current edition ofRule 238C.


Insufficient substantiation.




Affirmative: (19) Amrhyn, Bednarz, Bleakley, Bullinger, Clapp, Drzewiecki, Engdahl, Gill, Gunter, Henry,Hooper, Komassa, Marne, Neubauer, Reding, Slavin, Steiner, White, Young

Negative: (0)

Abstention: (0)

Revised Text

CP3224


Submitter

James T. Collins

Proposed Change


4. Inspection Record of defects

Any conditions defects affecting compliance with this Code revealed by inspection or tests, if notpromptly corrected, shall be recorded; such records shall be maintained until the conditions defects arecorrected.

Supporting Comment

The word “defects” suggests something tangible or physical such as a bad pole, crossarm, equipment, etc.The word “conditions” is more inclusive and lets users know the intent of this rule also includes clearances,spacing, etc. It is difficult to equate a clearance violation with being a defect.




See CP3097.



Negative: (0)



Abstention: (0)

Revised Text

CP3097


Submitter

Ewell T. Robeson

Proposed Change


4. Inspection rRecords of defects

Any conditions or defects affecting compliance with this Code revealed by inspection or tests, if notpromptly corrected, shall be recorded; such records shall be maintained until the conditions or defectsare corrected.

Supporting Comment

The word “conditions” is more inclusive and lets users know the intent of this rule also includes clearances,spacing, etc. The word “defects” suggests something tangible or physical such as a bad pole, crossarm,equipment, etc. While a “defect” should be considered to be a subset of “condition,” the proposed wordingmakes the intent of the Code clear to the users. Some Code users may not equate a clearance violation withbeing a defect.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3098




Submitter

Ewell T. Robeson

Proposed Change


5. Corrections Remedying defects

Lines and equipment with recorded conditions or defects that could reasonably be expected to endangerlife or property shall be promptly corrected repaired, disconnected, or isolated.

Supporting Comment

The word “conditions” is more inclusive and lets users know the intent of this rule also includes clearances,spacing, etc. The word “defects” suggests something tangible or physical such as a bad pole, crossarm,equipment, etc. While a “defect” should be considered to be a subset of “condition,” the proposed wordingmakes the intent of the Code clear to the users. Also using the word “corrected” mirrors the language of Rule214A4 and is more inclusive than “repaired.”


Accept as modified.



a. Lines and equipment with recorded conditions or defects that could reasonably be expected toendanger life or property shall be promptly corrected repaired, disconnected, or isolated.

b. Other conditions or defects shall be designated for correction.



Negative: (0)

Abstention: (0)

Revised Text

CP3225




Submitter

James T. Collins

Proposed Change

Revise wording for correction of non-critical defects.

214. Inspection and tests of lines and equipment

A. When in service


Lines and equipment with recorded conditions revealed by inspections defects that couldreasonably be expected to endanger life or property shall be promptly corrected repaired,disconnected, or isolated.

Supporting Comment

The word “defects” suggests something tangible or physical such as a bad pole, crossarm, equipment, etc. Theword “conditions” is more inclusive and lets users know the intent of this rule also includes clearances,spacing, etc. It is difficult to equate a clearance violation with being a defect. Also using the word “corrected”mirrors the language of Rule 214A4 and is more inclusive than “repaired.”




See CP3098.



Negative: (0)

Abstention: (0)

Deleted Text

CP3461




Submitter

SC4

Proposed Change


B. Circuits

1. Common neutral

A conductor used as a common neutral for primary and secondary circuits shall be effectivelygrounded as specified in Section 9.

Supporting Comment

This change is made to coordinate with the changes made in the rest the rule. Also, it is redundant with Rule215A


Accept.


Affirmative: (20) Amrhyn, Bednarz, Bleakley, Bullinger, Clapp, Crawford, Drzewiecki, Engdahl, Gill,Gunter, Henry, Hooper, Komassa, Marne, Neubauer, Reding, Slavin, Steiner, White, Young

Negative: (0)

Abstention: (0)

Revised Text

CP3464


Submitter

SC4

Proposed Change


B. Circuits

1. Common neutral



A conductor used as a common neutral for primary and secondary circuits shall be effectivelygrounded as specified in Section 9.

Supporting Comment

This change is made to coordinate with the changes made in the rest the rule. Also, it is redundant with Rule215A


Accept.


Affirmative: (21) Amrhyn, Bednarz, Bleakley, Bowmer, Bullinger, Clapp, Crawford, Drzewiecki, Engdahl,Gill, Gunter, Henry, Hooper, Komassa, Marne, Neubauer, Reding, Slavin, Steiner, White, Young

Negative: (0)

Abstention: (0)

Revised Text

CP3226


Submitter

James T. Collins

Proposed Change


2. Other neutrals

Primary line, secondary line, and service neutral conductors shall be effectively grounded asspecified in Section 9.

EXCEPTION: Circuits designed for ground-fault detection and impedance-current-limitingdevices.

Supporting Comment

Since there is a definition of “grounded” and “effectively grounded,” which are different, adding the word“effectively” will clarify the intent of the type grounding required by this rule. This will also be consistentwith underground Rule 314C1.

The term “effectively grounded” or the specific steps on how to effectively ground lines and equipment are



not in Section 9. The language “as specified in Section 9” needs to be deleted to limit confusion for the fielduser.

Subcommittee RecommendationAccept.



Negative: (0)

Abstention: (0)

Revised Text

CP3227


Submitter

James T. Collins

Proposed Change


3. Other conductors

Line or service conductors, other than neutral conductors, that are intentionally grounded, shall beeffectively grounded as specified in Section 9.

Supporting Comment

Since there is a definition of “grounded” and “effectively grounded,” which are different, adding the word“effectively” will clarify the intent of the type grounding required by this rule. Also it will make it consistentwith underground Rule 314C2.

The term “effectively grounded” or the specific steps on how to effectively ground lines and equipment arenot in Section 9. The language “as specified in Section 9” needs to be deleted to limit confusion for the fielduser.


Accept as modified.




3. Other conductors

Line or service conductors, other than neutral conductors, that are may be intentionally grounded,shall be grounded specified in Section 9.


Subcommittee 4 is requesting comments as to whether SC4 should require these items to be effectivelygrounded or grounded. For example, SC 4 is soliciting feedback as to whether a corner grounded delta phaseconductor can be or should be effectively grounded.



Negative: (0)

Abstention: (0)

Revised Text

CP3228


Submitter

James T. Collins

Proposed Change


4. Surge arresters

Where the operation of surge arresters is dependent upon grounding, they shall be effectivelygrounded in accordance with the methods outlined in Section 9.

Supporting Comment

Since there is a definition of “grounded” and “effectively grounded,” which are different, adding the word“effectively” will clarify the intent of the type grounding required by this rule. Also it will make it consistentwith underground Rule 314C3.

The term “effectively grounded” or the specific steps on how to effectively ground lines and equipment arenot in Section 9. The language “as specified in Section 9” needs to be deleted to limit confusion for the fielduser.




Accept as modified.


4. Surge arresters

Where the operation of surge arresters is dependent upon grounding, they shall be effectivelygrounded in accordance with the methods outlined in Section 9.



Negative: (0)

Abstention: (0)

New Text

CP3357

Part: 2 Section: 21 Rule: 215 C

Submitter

Percy E. Pool

Proposed Change

Add new item 9 to Rule 215C to read:

9. Bonding shall be provided between a pole ground and all aboveground metallic power andcommunications apparatus (pedestals, terminals, apparatus cases, transformer cases, etc.) that areseparated by a distance of 1.8 m (6 ft) or less from the pole ground.

Supporting Comment

Common bonding between pole grounds and communications and power apparatus helps to reduce potentialdifferences between metallic parts that could be touched simultaneously.

The intent of this CP is to limit the possibility of technicians (both power and communications) or the generalpublic to contact two metallic surfaces that may be at different voltage levels and thus receive an electricalshock.


Reject.




It creates a greater safety hazard to both personal and communication equipment. The current rules do notprohibit the bonding of communication and supply equipment when companies feel such bonding can beaccomplished and provide for a safe environment.


Affirmative: (15) Bednarz, Bleakley, Bullinger, Drzewiecki, Engdahl, Gill, Gunter, Hooper, Komassa,Marne, Neubauer, Reding, Slavin, Steiner, White

Negative: (4) Young, Henry, Clapp, Amrhyn

Abstention: (0)

Explanation of Vote

Amrhyn: (Negative) This rationale gives the reason(s) for rejecting the SC4 vote to reject CP3357. The CPmakes it necessary to bond all aboveground power and communication apparatus and a grounding conductorthat are separated by 6 ft or less. Further, in the first sentence of paragraph 1, “should” is changed to “shall”in order to make the rule mandatory. Assuring that conductive cases of all utilities in close proximity be atthe same potential for personal electrical protection of employees and the public, special importance isassigned to this CP because possible exposure to children of faulted electrical equipment is a possibility.

Clapp: (Negative) Communication pedestals fed from nearby poles are rarely the issue; they are usuallyalready bonded to the pole ground through their internal grounding connections.

The problem is the communication pedestal served by cables that have run for long distances without bondingto the power system grounds and then is located next to a power system ground wire. I have seen over 1600 Vpresent when overhead communication ran cross country and contacted a power pole along the road. This iswhy the present Rule 92C3b requires bonding at the common structure when crossing systems connect. Giventhe capacitive nature of underground cables, the voltage difference may be even higher for the situationcovered by this rule.

As similar problem exists if power is underground and communication is overhead.

The proposed change is consistent with Rule 92C3b and Rule 384C and should be adopted for the safety ofthe public and communication workers that must work around these pedestals.

Henry: (Negative) Throughout the Code, a telecommunications plant is required to be grounded to a multi-grounded neutral when supply and communications are in close vicinity. Not following this when a pedestalis within 6 ft of a pole ground could create a potential safety hazard to workers and the public.

Young: (Negative) I voted against the rejection because I am concerned about buried cable running under andparallel to a pole line with power on it. If a telecom pedestal was within 6 ft of pole ground, there is thepotential for someone to be at different voltage levels and receive a shock.



Revised Text

CP3480


Submitter

Subcommittee 4

Proposed Change

The Working Group recommends the following changes to Rule 215C:

215. Grounding of circuits, supporting structures, and equipment

C. Non-current-carrying parts

1. General (retain)

2. Anchor guys and span guys

Anchor guys and span guys shall be effectively grounded as specified in Rule 92C.

EXCEPTION: Where one or more guy insulators meeting the requirements of Rules 279A1279A and 215C4 or 215C5 are inserted in an anchor guy or span guy, the guy is not required tobe grounded.

NOTE: For the purpose of this rule, if a span guy and its associated anchor guy are bondedtogether, they may be considered as one guy.

3. Span wires carrying luminaires or traffic signals (retain)

4. Span wires carrying trolley or electric railway contact conductors

Span wires carrying trolley or electric railway contact conductors shall be effectively groundedat the structures.

EXCEPTION: Where one or more span-wire insulators meeting the requirements of Rules279B and 215C6 are inserted in a contact conductor span wire, the span wire is not required tobe grounded.

4. Use of insulators in anchor guys, span guys, and span wires supporting luminaires or trafficsignals

Where insulators are used in lieu of grounding in anchor guys, span guys, or in span wiressupporting luminaires or traffic signals in accordance with Rule 215C2 or 215C3, insulatorsshall be installed as follows:

a. All guy insulators or span-wire insulators shall be located at a position such that thebottom of the insulator shall be not less than 2.45 m (8 ft) above the ground if the guy orspan wire is broken below the insulator. Insulator(s) shall be positioned so as to limit thelikelihood of any portion of an anchor guy, including any portion of the insulator(s)



attached to that portion of the anchor guy, becoming energized within 8 ft of ground in theevent that the anchor guy (1) becomes slack or (2) breaks at or near the ground line.

b. Insulators shall be so placed that, in case any guy or span-wire contacts, or is contacted by,an energized conductor or part, the voltage will not be transferred to other facilities on thestructure(s). Insulators shall be positioned so as to limit the likelihood of an anchor guybecoming a conductive path between: (1) an energized conductor or rigid live part and (2)a conductor of another circuit, rigid part, or equipment in the event that the anchor guybecomes slack.

c. Insulators shall be so placed that in case any guy or span wire sags down upon another,positioned so as to limit the likelihood that the insulators will not become ineffective in theevent that any anchor guy sags down upon another anchor guy, span guy, or span wire.

5. Use of insulators in span guys and span wires supporting luminaries and traffic signals

Where insulators are used in lieu of grounding in span guys or in span wires supportingluminaires and traffic signals in accordance with Rule 215C2 or Rule 215C3, insulators shallbe installed as follows:

a. Insulator(s) shall be positioned so as to limit the likelihood of any portion of a span guy ora span wire becoming energized within 8 ft of ground in the event that the span guy orspan wire becomes slack.

b. Insulators shall be positioned so as to limit the likelihood of a span guy or a span wirebecoming a conductive path between: (1) any energized conductor or rigid live part and(2) a conductor of another circuit, rigid part, or equipment in the event that the span guy orspan wire becomes slack.

c. Insulators shall be positioned so as to limit the likelihood that the insulators will becomeineffective in the event that any span guy or span wire sags down upon another anchorguy, span guy or span wire.

6. Use of insulators in span wires supporting energized trolley or electric railroad contactconductors

a. All span wires supporting energized trolley or electric railroad contact conductors,including bracket span wires, shall have a suitable insulator (in addition to an insulatedhanger if used) inserted between each point of support of the span wire and the luminaireor trolley or electric railroad contact conductor supported.

EXCEPTION 1: Single insulators, as provided by an insulated hanger, may be permittedwhen the span wire or bracket is supported on wood poles supporting only trolley, railwayfeeder, or communication conductors used in the operation of the railway concerned.

EXCEPTION 2: Insulators are not required if the span wire is effectively grounded.

EXCEPTION 3: This rule does not apply to insulated feeder taps used as span wires.

b. In case insulated hangers are not used, the insulator shall be located so as to limit thelikelihood of having that in the event of a broken wire, the energized part of the span wirewithin 8 ft of cannot be reached from the ground in the event of a broken wire.

7. Insulators used to limit galvanic corrosion (retain)



8. Multiple messengers on the same structure (retain)

Supporting Comment

Working Group 4.14 Report

Working Group 4.14 considered the existing Rule 215C text, Tentative Interim Amendment 2007-4, anddiscussion at the September 2008 Subcommittee 4 meeting. The Working Group recommends the abovechanges to Rule 215C:

This revision is based on the following considerations:

— Anchor guys, span guys, and span wires supporting luminaires or traffic signals are normallygrounded; use of insulators is the exception except where BIL is of concern. Conversely, span wiressupporting rail contact conductors are normally insulated; grounding is the exception.

— Anchor guys should be treated separately and should include consideration of insulators attached toportions of guys that may become energized, as in TIA 2007-4.

— Span guys and span wires supporting luminaires and traffic signals can be treated in a similar man-ner. While span wires supporting luminaires may be somewhat archaic, except perhaps for someforms of decorative lighting, the luminaire provisions have been retained.

Some comments on specific Rule 215C revisions are as follows:

— C2: Anchor guys and span guys are both treated in this rule because of the NOTE which states that aspan guy and an anchor guy can be considered as one guy if they are bonded together. “As specifiedin rule 92C” was added to ensure that users would not consider (electrical) connection to an anchorrod as an acceptable means of grounding an anchor guy. Rule 279A1 was expanded to Rule 279Abecause the former reference was limiting; Rule 279A2b (BIL insulation) is also applicable.

— C4: The existing rule is deleted. Span wires carrying railroad contact conductors are more appropri-ately covered in C6 and existing rule C6 is complete. This rule now covers anchor guys.

— C5: This rule now covers span guys and span wires supporting luminaires and traffic signals.— C6 title and C6a (energized): While most contact conductors are energized, some may not be. Con-

sider a trolley-bus (trackless trolley) with dual contact conductors: the return path conductor may notbe energized and could be grounded.

— C6a (remainder): Revised to cover applicable items. These revisions should have been made duringthe last revision cycle.

— C6b: Wording updated.

Minority Comments

Neubauer: Rule 215C4a

I support the WG 4.14 Report except that it does not have language in proposed Rule 215C4a that would limitthe possibility of the guy being energized by a slack energized conductor.

My reasoning is that if a guy is not “effectively grounded” per definition it cannot be assumed to have a“sufficiently low impedance and current-carrying capacity to limit the buildup of voltages to levels below thatwhich may result in undue hazard to persons.” Existing Rule 215C1 requires all metal supporting structures,etc., to be effectively grounded. One of the reasons is to protect against a voltage transfer to the equipmentdue to any cause. Question 1, why should this reasoning not apply to guys?

The Report states, in proposed Rule 215C4a, that the insulator should be placed to limit the likelihood that if



a guy goes slack or breaks it will not be energized less than 8 ft above the ground. Question 2, why beconcerned about this if the guy is not effectively grounded? If not effectively grounded, an intact guy mayhave close to infinity impedance to ground. If this is the case and a slack conductor contacts the guy beneaththe insulator the guy could be energized. Why be concerned only if it breaks or goes slack?

I have seen many conductors fall off their support. If they were to fall on an effectively grounded guy or aninsulated guy where the insulator was long enough to prevent the conductor from contacting the metal portionof the guy or the insulator was located mid guy where the voltage could not be any closer than 8 ft to theground, a hazard would be minimized. If the BIL of the structure is an issue and the utility does not want touse a long enough insulator, see Figure 279-1.

If it is a problem designing to “limit the likelihood,” then require the sag calculations be performed todetermine how far down the conductor will sag if it falls off its support and insulate to protect against that orground the guy. But don’t increase the hazard to the public.

Bednarz: Rule 215C4a

I agree with all of the Task Force’s Draft 3 proposed revisions of Rule 215C except the phrase “including anyportion of the insulator(s) attached to that portion of the anchor guy,” which is now included in 215C4a andcauses the entire insulator to be treated as an energized conductor.

It is my understanding that this additional text resulted from a concern about the possibility of someone 1)contacting a fiberglass strain insulator and receiving an electrical shock, 2) if the guy wire above the insulatorbecame energized, 3) when the guy fails at the ground line.

I disagree with using this rationale for including this clause in the proposed rule. I believe it will cause manymore design problems, questions, and IRs than we can imagine.

The selection of fiberglass guy strain insulators as the lower insulator in an insulated guy is seldom made.The vast majority of insulators used in this application are class 54 (johnny ball) insulators.

Guy strain insulators normally are not attached to or contacted by energized conductors and I am not awareof any electrical accident resulting from a person touching a fiberglass guy strain insulator when the upperportion of the guy wire became energized. This is an event that is not normally encountered or reasonablyanticipated.

However, should this occur, I see no difference in:

— Contacting the fiberglass insulator of a guy that has failed at ground line such that the lower portionof guy wire is ungrounded and the energized guy wire and insulator live parts are 8 ft abovegroundor,

— Contacting the bottom end of the guy wire containing a class 54 insulator (johnny ball) located at anylevel above 8 ft under the same conditions; energized guy wire above the insulator and failed andungrounded guy wire at ground line.

The second scenario is more prevalent.

Unless there is sufficient documentation of accidents resulting from this scenario, we should not write codeto cover all hypothetical situations.

I recommend deleting this phrase entirely so that only the energized components of the guy are required tocomply with the 8 ft rule.



Clapp Comments on WG 4.14 Report

Part 1—Support for Working Group Report

I support the working group report and proposal for sending out for public comment in the 2012 Preprint.However, I have reservations about two areas. First, I think that we can combine some of the text and makeportions easier to read and understand. Second, I am concerned that now may be the time to make a significantchange to the requirements for support of contact conductors for some electric bus systems.

My following comments and proposals on each of these subjects have been discussed with members of theworking group and several members supported adding these to the Preprint in the form of this comment, inorder to solicit comment on these options.

Part 2—Consolidation of text

The following proposed revision combines two subparagraphs from the Working Group proposal to try tosimplify the requirements and save some words. This proposal retains the language of the Working Groupproposal for the last section; suggested changes to that section are addressed in of my comments.

Clapp suggested revision of Working Group 4.14 draft

215. Grounding of circuits, supporting structures, and equipment

C. Non-current-carrying parts

1. General (retain)

2. Anchor guys and span guys

Anchor guys and span guys shall be effectively grounded as specified in Rule 92C.

EXCEPTION: Where one or more guy insulators meeting the requirements of Rules 279A1 279Aand 215C4 or 215C5 are inserted in an anchor guy or span guy, the guy is not required to begrounded.

NOTE: For the purpose of this rule, if a span guy and its associated anchor guy are bonded together,they may be considered as one guy.

3. Span wires carrying luminaires or traffic signals (retain)

4. Span wires carrying trolley or electric railway contact conductors

Span wires carrying trolley or electric railway contact conductors shall be effectively grounded atthe structures.

EXCEPTION: Where one or more span-wire insulators meeting the requirements of Rules 279Band 215C6 are inserted in a contact conductor span wire, the span wire is not required to begrounded.

4. Use of insulators in span wires supporting luminaires or traffic signals, anchor guys, and span guys,and span wires supporting luminaires or traffic signals



Where insulators are used in lieu of grounding in span wires supporting luminaires or trafficsignals, anchor guys, and span guys in accordance with Rule 215C2 or 215C3, insulators shall beinstalled as follows:

a. All guy insulators or span-wire insulators shall be located at a position such that the bottom ofthe insulator shall be not less than 2.45 m (8 ft) above the ground if the guy or span wire isbroken below the insulator. Insulator(s) shall be positioned so as to limit the likelihood of anyportion of a span wire supporting luminaires or traffic signals, an anchor guy, or a span guy,including any portion of the insulator(s) attached to that portion of such anchor span wire orguy, becoming energized within 8 ft of ground in the event that (1) an anchor guy becomesslack or breaks at or near the ground line or (2) a span wire or span guy becomes slack orbreaks at or near its connection at the next pole.

b. Insulators shall be so placed that, in case any guy or span-wire contacts, or is contacted by, anenergized conductor or part, the voltage will not be transferred to other facilities on thestructure(s). Insulators shall be positioned so as to limit the likelihood of a span wiresupporting luminaires or traffic signals, an anchor guy, or a span guy, becoming a conductivepath between: (1) an energized conductor or rigid live part and (2) a conductor of anothercircuit, rigid part, or equipment in the event that the such anchor span wire or guy becomesslack.

c. Insulators shall be so placed that in case any guy or span wire sags down upon another,positioned so as to limit the likelihood that the insulators will not become ineffective in theevent that any anchor guy sags down upon another anchor guy, span guy or span wire.

5. Use of insulators in span guys and span wires supporting luminaires and traffic signals

Where insulators are used in lieu of grounding in span guys or in span wires supporting luminairesand traffic signals in accordance with Rule 215C2 or Rule 215C3, insulators shall be installed asfollows:

a. Insulator(s) shall be positioned so as to limit the likelihood of any portion of a span guy or aspan wire, including any portion of the insulator(s) attached to that portion of the span guy orspan wire, becoming energized within 8 ft of ground in the event that the span guy or span wirebecomes slack.

b. Insulators shall be positioned so as to limit the likelihood of a span guy or a span wirebecoming a conductive path between: (1) any energized conductor or rigid live part and (2) aconductor of another circuit, rigid part, or equipment in the event that the span guy or spanwire becomes slack.

c. Insulators shall be positioned so as to limit the likelihood that the insulators will becomeineffective in the event that any span guy or span wire sags down upon another anchor guy,span guy or span wire.

5. Use of insulators in span wires supporting energized trolley or electric railroad contact conductors

a. All span wires supporting energized trolley or electric railroad contact conductors, includingbracket span wires, shall have a suitable insulator (in addition to an insulated hanger if used)inserted between each point of support of the span wire and the luminaire or trolley or electricrailroad contact conductor supported.



EXCEPTION 1: Single insulators, as provided by an insulated hanger, may be permitted whenthe span wire or bracket is supported on wood poles supporting only trolley, railway feeder, orcommunication conductors used in the operation of the railway concerned.



b. In case insulated hangers are not used, the insulator shall be located so as to limit the likelihoodof having that in the event of a broken wire, the energized part of the span wire within 8 ft ofcannot be reached from the ground in the event of a broken wire.

7. Insulators used to limit galvanic corrosion (retain)

8. Multiple messengers on the same structure (retain)

Part 3—Revision of requirements for support of electrified contact conductors

I originally was trying in the following proposal to consolidate and simplify the present rules. The more Ilooked at it, the more convinced I became that we should consider changing the requirements for safe supportof some electrified contact conductors. Unlike energized power lines that are suspended in the air as singleconductors and do not received wear that might bring them down, all electrified contact conductors wear asa result of the passage of the pickup system employed to transfer electricity from the contact conductor downto the trolley, railway, or bus wiring. As a result, the presence of electrified contact conductors creates thepotential hazard of public contact with fallen, energized conductors.

Many trolley and electric railway contact conductors are suspended in one of two cases:

(1) From insulated hangers attached throughout the span to a grounded catenary span wire that is attacheddirectly to supporting structures, or

(2) From conductive hangers attached throughout the span to an energized catenary span wire that is itselfhung from insulators at supporting structures.

In Case 1, the span wire itself should be grounded—and we should say that! In Case 2, the energized catenaryspan wire is not necessarily insulated—and we should not require it to be insulated! In both Case 1 and Case2, it is practical to set the hanger spacing close enough to limit the opportunity for a broken contact conductorto fall and hang down below 8 ft above grade.

However, some contact conductors are single conductors suspended from insulators or structures and are notsuspended from a catenary conductor (usually for electric busses that do not ride on rails). As a result, if theybreak due to wear, they fall down low enough to be contacted by personnel on the ground.

I considered the fact that some commuter units run on rails in dedicated rights-of-way that limit public access.At first thought, it may seem that there is no need to worry about falling contact conductors in such cases.However, the very conductor that breaks may leave passengers stranded on a train and those passengers mayhave to walk for some distance down the right-of-way to get out and find other transportation. In such a case,it would not be appropriate to have energized conductors hanging in their way. As a result, no exemption fromrequiring frequent support of contact conductors is proposed in the following proposal. Changes are madethroughout the present 215C6 as a result of the considerations discussed below.

This proposal would simplify the language, but it would also require the use of catenary support with frequentsuspension points for all electrified contact conductors. This will change some electric bus suspensionsystems.



Paragraph 6a is no longer needed, if the new language is adopted. In the proposal, EXCEPTION 1 to 6adoesn’t seem to make a lot of sense and should be deleted. Who cares whether the pole is wood, concrete,metal, FRP, etc.? Why does it apply on when supporting such conductors? EXCEPTION 2 to 6a also makesno sense. There had better be an insulator there, if the span wire is grounded—otherwise the system shortsout and the train doesn’t move! EXCEPTION 3 to 6a is confusing as it stands and is not necessary if theproposed new language is adopted. Paragraph 6b is not needed with

Clapp suggested revision of 215C6

4. Use of insulators in sSpan wires supporting energized trolley or electric railroad contact conductors

Energized contact conductors shall be supported by either (a) insulated hangers to an effectivelygrounded catenary span wire that is directly attached to supporting structures or (b) conductivehangers attached to an energized catenary span wire that is attached to supporting structures withinsulators. In all cases, the contact conductor hangers shall be attached to the catenary span wire atsuitable locations throughout the span such that, if the contact conductor breaks, no portion of theenergized contact conductor shall be less than 2.45 m (8 ft) aboveground.

a. All span wires supporting energized trolley or electric railroad contact conductors, includingbracket span wires, shall have a suitable insulator (in addition to an insulated hanger if used)inserted between each point of support of the span wire and the luminaire or trolley or electricrailroad contact conductor supported.

EXCEPTION 1: Single insulators, as provided by an insulated hanger, may be permitted whenthe span wire or bracket is supported on wood poles supporting only trolley, railway feeder, orcommunication conductors used in the operation of the railway concerned. Clapp Comment:Why wood only? Why only supporting such conductors?



b. In case insulated hangers are not used, the insulator shall be located so as to limit the likelihoodof having that in the event of a broken wire, the energized part of the span wire within 8 ft ofcannot be reached from the ground in the event of a broken wire.

Working Group

The Working Group members were: Keith Reese-Secretary, Jay Bednarz, Charles Bleakley, Allen Clapp,Eric Engdahl, Mickey Gunter, Ernie Neubauer and Don Hooper-Chair. The contributions and participationof all members is deeply appreciated.

Respectfully submitted, Don Hooper


Accept.


Affirmative: (21) Amrhyn, Bednarz, Bleakley, Bowmer, Bullinger, Clapp, Crawford, Crowell, Drzewiecki,Engdahl, Gunter, Hooper, Komassa, Marne, Neubauer, Oswald, Reding, Schwarz, Slavin, White, Young



Negative: (0)

Abstention: (0)

Explanation of Vote

Bowmer: (Affirmative) The proposed CP recommended by the Working Group does greatly improve Rule215C and should be in the Preprint.

However, I am concerned that two guys that share an anchor may be treated very differently under the rule(current rule as well as newly proposed one).

For example, consider one guy is attached to the pole at the level of the power supply lines and one guy isattached at the level of the communications plant.

The top guy has an insulator in place and therefore does not have to be effectively grounded.

The bottom guy has no insulator and therefore needs to be “effectively grounded,” which means that a bondneeds to be added from the guy to the strand or to the multi-ground neutral on the pole.

The different treatment of these two guys that are connected at the anchor does not seem warranted.

The new definition of “effectively grounded” may also influence how Rule 215C is applied.

Revised Text

CP3466

Part: 2 Section: 21 Rule: 215 C1

Submitter

SC4

Proposed Change

Revise Rule 215C1 EXCEPTION 3 as follows:

EXCEPTION 3: This rule does not apply to equipment cases, frames, equipment hangers, conduits,messengers, raceways, and cable sheaths enclosing or supporting only communication conductors,provided they are not exposed to contact with open supply conductors of over 300 V.

Supporting Comment

SC 7 CP3429 Rule 314B approved the deletion of the reference to exposure to over 300 V. Similar referencesshould be deleted from Rule 215C1, EXCEPTION 3. This is also consistent with the elimination of thevoltage exposure of over 300 V from 215C2 in the 2007 Code.


Accept.




Affirmative: (19) Amrhyn, Bednarz, Bleakley, Bowmer, Clapp, Crawford, Drzewiecki, Emery, Engdahl,Gunter, Hall, Hooper, Komassa, Marne, Neubauer, Reding, Slavin, White, Young

Negative: (0)

Abstention: (0)

Revised Text

CP3065

Part: 2 Section: 21 Rule: 215 C1 EXCEPTION 1

Submitter

Ewell T. Robeson

Proposed Change

Revise EXCEPTION 1 to Rule 215C1 as indicated:

EXCEPTION 1: This rule does not apply when both of the following conditions are met:

1. to f Frames, cases, and hangers of equipment and switch handles and operating rods that are 2.45 m(8 ft) or more above readily accessible surfaces or are otherwise isolated or guarded, and

2. where t The practice of not grounding such items has been a uniform practice over a well-definedoperating area.

Supporting Comment

The above change is proposed to eliminate questions posed in IR 550.


Accept as modified.

Revise EXPECTION 1 to Rule 215C1 as indicated:

EXCEPTION 1: This rule does not apply when both of the following conditions are met:

1. to f Frames, cases, and hangers of equipment and switch handles and operating rods that are 2.45 m(8 ft) or more above readily accessible surfaces or are otherwise isolated or guarded, and

2. where t The practice of not grounding such items has been a uniform practice over a well-definedoperating area.

NOTE: Items listed in EXCEPTION 1 must be grounded unless both criteria in EXCEPTION 1apply (isolated or guarded in a well-defined area). If the decision is made to ground all new items



above the 2.45 m (8 ft) level, the rules do not require retrofitting existing ungrounded items. Goodpractice then is to ground existing ungrounded items whenever significant work is done onsupporting structures.


Affirmative: (21) Amrhyn, Bednarz, Bleakley, Bowmer, Bullinger, Clapp, Crawford, Drzewiecki, Emery,Engdahl, Gill, Gunter, Henry, Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White, Young

Negative: (0)

Abstention: (0)

Revised Text

CP3229

Part: 2 Section: 21 Rule: 215 C5a

Submitter

James T. Collins

Proposed Change

Revise Rule 215C5a as follows:

5. Use of insulators in anchor guys, span guys, and span wires supporting luminaires or traffic signals

Where insulators are used in lieu of grounding in anchor guys, span guys, or in span wiressupporting luminaires or traffic signals in accordance with Rule 215C2 or 215C3, insulators shallbe installed as follows:

a. All guy insulators or span-wire insulators shall be located at a position such that, if the guy orspan wire becomes broken or is exposed to contact with energized conductors the bottom ofthe insulator shall be not less than 2.45 m (8 ft) above the ground if the guy or span wire isbroken below the insulator.

(1) Any part of the guy or span wire that may become energized due to contact with anenergized conductor or part shall be not less than 2.45 m (8 ft) aboveground and,

(2) The entire insulator attached to any portion of the guy or span wire that may becomeenergized shall be not less than 2.45 m (8 ft) aboveground.

RECOMMENDATION: If it is impractical for guys or span wires to meet the intent ofRule 215C5a due to excessive exposure to energized conductors or parts, it isrecommended they be effectively grounded in lieu of using insulators.

NOTE: Nothing in this rule limits guys and span wires from being both insulated andeffectively grounded.



Supporting Comment

This is in response to TIA 2007-4.

AEGIS Insurance Company, which underwrites insurance for utilities concerning personal injury or deathand damage claims occurring on utility facilities, has expressed their concern to me many times with thewording, or lack of wording, of Rule 215C5. AEGIS has had numerous claim settlements involving accidentsin which the guy insulator was installed too high up on the guy, where guy insulators were installed at the topwith the lower portion of the guy ungrounded. Rule 215C5a is carefully worded to keep the insulator frombeing installed too low, but neither Rules 215C5b nor 215C5c address the concern of it being installed toohigh. Several years ago, a utility in Georgia had a guy insulator installed too high in a transmission guy. Anaccident to a pedestrian occurred due to the lower portion of the guy contacting an energized supply conductorbecause the guy was slack; the lower portion was not grounded and was exposed to energized supplyconductors. This installation, in the literal sense, did not violate Rule 215C5. Anchor guys are maybe the mostpotential hazardous installation on a utility system; a conductive wire at ground level, exposed to the public,and the other end in an energized area. So we need to make sure our wording is as good as we can make it sothat the field users clearly understand the intent of the rule. One can argue of course that a utility should knowbetter, but utilities today have many inexperienced field “engineers” using the NESC as written and use therules literally sometimes.




See CP3099.


Affirmative: (19) Amrhyn, Bleakley, Bullinger, Clapp, Crawford, Drzewiecki, Engdahl, Gill, Gunter,Henry, Hooper, Komassa, Marne, Neubauer, Reding, Slavin, Steiner, White, Young

Negative: (1) Bednarz

Abstention: (0)

Explanation of Vote

Bednarz: (Negative) See comment on CP3099.

Revised Text

CP3099

Part: 2 Section: 21 Rule: 215 C5a

Submitter

Ewell T. Robeson



Proposed Change


5. Use of insulators in anchor guys, span guys, and span wires supporting luminaries or traffic signals

Where insulators are used in lieu of grounding in anchor guys, span guys, or in span wiressupporting luminaries or traffic signals in accordance with Rule 215C2 or 215C3, insulators shallbe installed as follows:

a. All guy insulators or span-wire insulators shall be located at a position such that, if the guy orspan wire becomes broken or is exposed to contact with slack energized conductors: thebottom of the insulator shall be not less than 2.45 m (8 ft) above the ground if the guy or spanwire is broken below the insulator.


(2) The entire insulator attached to any portion of the guy or span wire that may becomeenergized, shall be not less than 2.45 m (8 ft) aboveground.

NOTE: Nothing in this rule limits guys and span-wires from being both insulated andeffectively grounded.

Supporting Comment

AEGIS Insurance Company, which underwrites insurance for utilities concerning personal injury or deathand damage claims occurring on utility facilities, has expressed their concern to me many times with thewording, or lack of wording, of Rule 215C5. AEGIS has had numerous claim settlements involving accidentsin which the guy insulator was installed too high up on the guy, where guy insulators were installed at the topwith the lower portion of the guy ungrounded. Rule 215C5a is carefully worded to keep the insulator frombeing installed too low, but neither Rules 215C5b nor 215C5c address the concern of it being installed toohigh. Several years ago, a utility in Georgia had a guy insulator installed too high in a transmission guy. Anaccident to a pedestrian occurred due to the lower portion of the guy contacting an energized supply conductorbecause the guy was slack; the lower portion was not grounded and was exposed to energized supplyconductors. This installation, in the literal sense, did not violate Rule 215C5.

Anchor guys are maybe the most potential hazardous installation on a utility system; a conductive wire atground level, exposed to the public, and the other end in an energized area. So we need to make sure ourwording is as good as we can make it so that the field users clearly understand the intent of the rule. One canargue of course that a utility should know better, but utilities today have many inexperienced field “engineers”using the NESC as written and use the rules literally sometimes.

The RECOMMENDATION was added to bring to the attention to the field user that some guy installationssuch as span guys may have excessive exposure such that it may not be practical to insulate them andgrounding may be the better option. The added note is to clarify that this rule does not limit both the groundingand insulating of guys together.


Accept as modified.



Editor’s note: SC4 WG 4.14 was established to further review this CP and rule; see SC4 CP3480 along withWG 4.14’s report and recommendation for the final action taken on this CP and rule.



Where insulators are used in lieu of grounding in anchor guys, span guys, or in span wiressupporting luminaries or traffic signals in accordance with Rule 215C2 or 215C3, insulators shallbe installed as follows:

a. All guy insulators or span-wire insulators shall be located at a position such that, if the guy orspan wire becomes broken or slack, or is exposed to contact with slack energized conductors:the bottom of the insulator shall be not less than 2.45 m (8 ft) above the ground if the guy orspan wire is broken below the insulator.


(2) The entire insulator attached to any portion of the guy or span wire that may becomeenergized shall be not less than 2.45 m (8 ft) aboveground.

NOTE: Nothing in this rule limits different portions of guys and span wires from beinginsulated or effectively grounded.


Affirmative: (19) Amrhyn, Bleakley, Bullinger, Clapp, Crawford, Drzewiecki, Engdahl, Gill, Gunter,Henry, Hooper, Komassa, Marne, Neubauer, Reding, Slavin, Steiner, White, Young

Negative: (1) Bednarz

Abstention: (0)

Explanation of Vote

Bednarz: (Negative) This CP as modified makes it impractical to protect against the failure of anchor guys atany point of the guy. It also includes span guys that are not part of the problem that TIA 2007-4, April 11,2008, tried to address and which cannot meet the requirements of (1) and (2).

This modified proposal and other related CPs should be rejected and it is recommended to revise the TIA byexcluding insulated span guys from the clearance provisions of 215C5a and changing the guy failure scopeback to the 2007 NESC verbiage of “is broken below the insulator” similar to the following:

Rule 215C5a: Modify a. by rearranging it into (1) and (2), which should be added beneath a.


Where insulators are used in lieu of grounding in anchor guys, span guys, or in span wires supportingluminaries or traffic signals in accordance with Rule 215C2 or 215C3, insulators shall be installed asfollows:



a. All anchor guy insulators or span-wire insulators shall be located at a position such that the bottomof the insulator shall be not less than 2.45 m (8 ft) above the ground if the guy or span wire is brokenbelow the insulator if the anchor guy or span wire becomes broken at any point below the insulator,or if energized conductors, guys, or span wires become slack:

(1) Any part of the anchor guy or span wire that may become energized due to contact with anenergized conductor or part shall be not less than 2.45 m (8 ft) above the ground, and

(2) The entire insulator attached to any portion of the anchor guy or span wire that may becomeenergized shall be not less than 2.45 m (8 ft) above the ground

Revised Text

CP3069


Submitter

Mickey Gunter

Proposed Change


8. Multiple messengers on the same structure

Communication cable messengers exposed to power contacts, power induction, or lightning, shallbe bonded together at intervals specified in Rule 092C1.

Supporting Comment

The correct rule to reference for grounding intervals is 092C1.


Accept.



Negative: (0)

Abstention: (0)



Revised Text

CP3230


Submitter

James T. Collins

Proposed Change


8. Multiple messengers on the same structure

Communication cable messengers exposed to power contacts, power induction, or lightning, shallbe bonded together at intervals specified in Rule 092C1.

Supporting Comment

The correct rule to reference for grounding intervals is 092C1.




See CP3069.



Negative: (0)

Abstention: (0)

Revised Text

CP3231




Submitter

James T. Collins

Proposed Change

C. Locking

Switch-operating mechanisms that are accessible to unauthorized persons shall have provisions forlocking in each operational position and shall be locked or otherwise secured except duringoperation or testing.

NOTE: See Rule 444C.

Supporting Comment

The 2007 Edition of the NESC states that switch operating mechanisms be capable of being locked but doesnot require this feature to be used. Security of the installation is implied by the present wording, but safety ofworkers and others warrants a more explicit statement of the rule’s intent, which is to prevent tampering withinstallations by unauthorized persons.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3232

Part: 2 Section: 21 Rule: 217 A1a

Submitter

James T. Collins

Proposed Change

Delete Rule 217A1a and renumber Rules 217A1b and c to a and b, respectively. Move the second sentenceand NOTE of Rule 217A1a to Rule 231B1 (separate CP3241).

A. Supporting structures



1. Protection of structures

a. Mechanical damage

Appropriate physical protection shall be provided for supporting structures subject tovehicular traffic abrasion that would materially affect their strength.

This rule does not require protection or marking of structural components located outsideof the traveled ways of roadways or established parking areas.

NOTE: Experience has shown that it is not practical to protect structures from contact byout-of control vehicles operating outside of established traveled ways.

Supporting Comment

Rule 217A1a was added in 1990 and directly conflicts with Rules 231B1 and 231B2, of which the currentlanguage was added in 1984. Rules 231B1 and B2 say that if an ordinary vehicle is located on the traveledway, then a structure shall be a sufficient distance away so that the vehicle is not making contact with astructure; otherwise it is a Code violation. Of course Rule 217A1a says that if a vehicle is subject to vehicleabrasion, then we shall provide mechanical protection for the structure, even though the structure is probablyin violation of Rules 231B1 or B2. So if a utility provides mechanical protection to a structure that is beinghit by ordinary vehicles located on the traveled way, is the utility negligent because it was meeting one ruleand at the same time knowing it was violating another rule?




See CP3064.



Negative: (0)

Abstention: (0)

Deleted Text

CP3064


Submitter

Ewell T. Robeson



Proposed Change

Delete rule 217A1a and re-number 217A1b and c to a and b respectively. Move the second sentence andNOTE of rule 217A1a to Rule 231B1 (separate CP3241).




Appropriate physical protection shall be provided for supporting structures subject tovehicular traffic abrasion that would materially affect their strength.


NOTE: Experience has shown that it is not practical to protect structures from contact byout-of control vehicles operating outside of established traveled ways

Supporting Comment

Rule 217A1a was added in 1990 and directly conflicts with rules 231B1 and 231B2, of which the currentlanguage was added in 1984. Rules 231B1 and B2 say that if an ordinary vehicle is located on the traveledway, then a structure shall be a sufficient distance away so that the vehicle is not making contact with astructure; otherwise it is a Code violation. Of course rule 217A1a says that if a structure is subject to vehicleabrasion, then we shall provide mechanical protection for the structure, even though the structure is probablyin violation of rules 231B1 or B2. So if a utility provides mechanical protection to a structure that is beinghit by ordinary vehicles located on the traveled way, is the utility negligent because it was meeting one ruleand at the same time knowing it was violating another rule?


Accept as modified.

Revise rule 217A1a and the NOTE of rule 217A1a to Rule 231B1 (separate CP3241).




Appropriate physical protection shall be provided for supporting structures in parking lots,in alleys, or next to driveways subject to vehicular traffic abrasion that would materiallyaffect their strength.


NOTE: Experience has shown that it is not practical to protect structures from contact byout-of control vehicles operating outside of established traveled ways. See Rule 231B forstructure clearances to roadways.





Negative: (0)

Abstention: (0)

Revised Text

CP3442

Part: 2 Section: 21 Rule: 217 A1c

See CP3442 in the General section.

Also Section: 3 Z535 references SC1

Part: 1 Section: 11 110 A1 SC3







Revised Text

CP3467


Submitter

SC4

Proposed Change

Revise rule 217A2a as follows:

2. Readily climbable supporting structures

a. Readily climbable supporting structures, such as closely latticed poles, towers, or bridgeattachments, carrying open supply conductors energized at more than 300 V, which areadjacent to roads, regularly traveled pedestrian thoroughfares, or places where personsfrequently gather (such as schools or public playgrounds), shall be equipped with barriers toinhibit climbing by unqualified persons or posted with appropriate safety signs.



Supporting Comment

SC 7 CP3429 Rule 314B approved the deletion of the reference to exposure to over 300 V. Similar referencesshould be deleted from Rule 217A1a. This is also consistent with the elimination of the voltage exposure ofover 300 V from 215C2 in the 2007 Code.


Accept.


Affirmative: (18) Amrhyn, Bednarz, Bleakley, Bowmer, Clapp, Crawford, Drzewiecki, Emery, Engdahl,Gunter, Hall, Hooper, Komassa, Marne, Neubauer, Slavin, White, Young

Negative: (0)

Abstention: (0)

Revised Text

CP3233

Part: 2 Section: 21 Rule: 217 A2b

Submitter

James T. Collins

Proposed Change

Revise rule, add new EXCEPTION 1, and renumber existing exceptions as follows:

b. Steps

Steps permanently installed on supporting structures shall be not less not be closer than 2.45 m(8 ft) from the ground or other accessible surface.

EXCEPTION 1: Where work activities require that temporarily installed steps less than 2.45 m(8 ft) from the ground or other accessible surface be left unattended for short time periods in areaswhere persons frequently gather (such as schools or public playgrounds), barriers to inhibitclimbing by unqualified persons shall be placed.

EXCEPTION 1 2: This rule does not apply where supporting structures are isolated.

EXCEPTION 2 3: This rule does not apply where access to the supporting structure is limited by afence meeting the height requirements of Rule 110A1.



Supporting Comment

The danger associated with having pole or structure steps located within 8 ft of the ground or anotheraccessible surface is independent of whether the steps are to be permanently affixed to the structure orwhether they will be temporary. The issue is whether the opportunity exists for an unauthorized person toclimb the structure. The current rule ignores the situation where unattended temporarily installed steps maybe accessible to unauthorized persons. In fact, it might be argued that temporarily installed steps canconstitute “attractive nuisance” situations where unauthorized persons are attracted to the structure. Unlessthe structure is inaccessible or qualified workers are present to prevent unauthorized persons from climbing,the only difference in the potential hazard presented by permanent versus temporary steps is the duration ofthe exposure. The proposed revision will make clear that it is not acceptable to have either unattendedpermanent or temporary steps in place below 8 ft or without the required separation between the two loweststeps.

Further, adding the proposed EXCEPTION gives reasonable latitude for workers to perform their dutieswithout requiring unrealistic measures to prevent unauthorized persons from climbing structures.


Accept.


Affirmative: (18) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Drzewiecki, Engdahl, Gill, Gunter, Henry,Hooper, Komassa, Neubauer, Reding, Slavin, Steiner, White, Young

Negative: (1) Marne

Abstention: (0)

Explanation of Vote

Marne: (Negative) I don’t like the wording “left unattended for short time periods.” I envision the crewputting up some cones and ribbon and then going to lunch. I think steps down to the ground level (eventemporary) need to be attended by someone on the crew.

Revised Text

CP3428


Also Part: 2 Section: 21 217 A4 SC4

Submitter

Allen L. Clapp

Proposed Change

Combine and revise the present Rules 217A4 and 217A5 into a new Rule 217A4, as follows.



4. Obstructions

Signs, posters, notices, and other attachments shall not be placed on supporting structures withoutconcurrence of the owner. Supporting structures should be kept free from other climbing hazardssuch as tacks, nails, vines, and through bolts not properly trimmed.

5. Decorative lighting

Attachment of decorative lighting on structures shall not be made without the concurrence of theowners and occupants.

4. Attachments to supporting structures of utility lines

No attachment of any kind (including, but not limited to, utility facilities, signs, posters, notices,basketball goals, fence wire, tacks, nails, vines, or other facilities) shall be made to a supportingstructure of a utility line (including lighting and metering structures) without the concurrence of thestructure owner.

a. No attachment shall cause any portion of the resulting installation to be in noncompliance withthe clearance, grounding, strength, or other requirements of the NESC.

b. Holiday or seasonal attachments, including decorative lighting, shall not be made on utilitysupporting structures without the concurrence of both the structure owner and occupants of thespace in which the attachment is made.

c. Attachments shall neither obstruct the climbing space nor present a climbing hazard to utilitypersonnel. Through-bolts shall be properly trimmed. Vines, nails, tacks, or other items whichmay interfere with climbing should be removed before climbing.

Supporting Comment

Recent years have shown the variety of unauthorized additions made by customers or other utilities to utilitypoles has increased to the detriment of the safety of the physical infrastructure and the ability of line workersto perform necessary repair and maintenance. Whereas there used to be few utilities attaching to poles, newones spring up on a frequent basis and try to use existing infrastructure supports to carry their facilities. Poleshave been overloaded and have fallen as a result of the overloading. Unauthorized personnel have beeninjured installing attachments in the wrong place or with the wrong methods. Any attachment has the potentialto interfere with the existing facilities, if not controlled.

The number of customer-owned facilities found to be attached to utility poles without authorization hasincreased. Such items as satellite dish antennas, flags, decorations, customer circuits running to outbuildingsfrom the utility-served structure, etc., have presented safety issues for pedestrians and safety issues for theintegrity of the utility poles themselves. Customer-owned dish antennas and the like are not now covered bythe NESC in an appropriate manner; some customers have argued that the clearances of Table 235-6 that wereintended for utility antennas should apply to customer-owned antennas installed by nonqualified personnel,which is not the case.

This is the first extensive update of this rule in modern times.


Accept as modified.



Combine and revise the present Rules 217A4 and 217A5 into a new Rule 217A4, as follows.

4. Obstructions

Signs, posters, notices, and other attachments shall not be placed on supporting structures withoutconcurrence of the owner. Supporting structures should be kept free from other climbing hazardssuch as tacks, nails, vines, and through bolts not properly trimmed.

5. Decorative lighting

Attachment of decorative lighting on structures shall not be made without the concurrence of theowners and occupants.

4. Attachments, decorations, and obstructions

No attachment of any kind to a supporting structure of a utility line (including lighting and meteringstructures) shall be allowed without the concurrence of the structure owner. Non-utility attachmentsshall also have concurrence of the occupant(s) of the space in which the attachment is made.

a. No attachment shall cause any portion of the resulting installation to be in noncompliance withthe clearance, grounding, strength, or other requirements of the NESC.

b. Attachments shall neither obstruct the climbing space nor present a climbing hazard to utilitypersonnel. Through-bolts shall be properly trimmed. Vines, nails, tacks, or other items whichmay interfere with climbing should be removed before climbing.


Affirmative: (17) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Drzewiecki, Engdahl, Gill, Gunter, Henry,Hooper, Marne, Neubauer, Reding, Steiner, White, Young

Negative: (2) Slavin, Komassa

Abstention: (0)

Explanation of Vote

Komassa and Slavin: (Negative) The original rules are sufficient.

Revised Text

CP3151


Submitter




Proposed Change


2. Where an anchor is located in an established parking area, the guy shall either be protected fromvehicle contact or marked.

3. This rule does not require protection or marking of anchor guys located outside of the traveledways of roadways or established parking areas.

NOTE: Experience has shown that it is not practical to protect guys from contact by out of controlvehicles operating outside of established traveled ways.

Supporting Comment

The wording in Rule 217C3 should only apply to 217C2 and not to the entire Rule 217C. This change matchesthe formatting used in Rule 217A1a, which contains similar wording.


Accept as modified.

Revise Rule 217C as follows: make C3 part of C2. Move paragraph directly under C2.

2. Where an anchor is located in an established parking area, the guy shall either be protected fromvehicle contact or marked.

3. This rule does not require protection or marking of anchor guys located outside of the traveledways of roadways or established parking areas.

NOTE: Experience has shown that it is not practical to protect guys from contact by out of controlvehicles operating outside of established traveled ways. See Rule 231B for clearances of structuresadjacent to roadways.



Negative: (0)

Abstention: (0)

Revised Text

CP3234




Submitter

James T. Collins

Proposed Change

C. Protection and marking of guys

1. The ground end of anchor guys exposed to pedestrian traffic shall be provided with a substantialand conspicuous marker.

NOTE: Visibility of markers can be improved by the use of color or color patterns that providecontrast with the surroundings.

2. …

3. This rule does not require protection or marking of anchor guys located outside of the traveledways of roadways or established parking areas except as required in Rule 217C1.

NOTE: Experience has shown that it is not practical to protect guys from contact by out of controlvehicles operating outside of established traveled ways.

Supporting Comment

In its 2007 form, Rule 217C3 contradicts Rule 217C1 in that anchor guys subject to pedestrian traffic and ofcourse located outside traveled ways, etc., shall be marked. The proposed revision will eliminate thecontradiction.




See CP3151.



Negative: (0)

Abstention: (0)

New Text

CP3343




Submitter

Thomas E. Sullivan

Proposed Change

218. Vegetation management

A. General

1. Vegetation that may damage ungrounded supply conductors should be pruned or removed.Vegetation management should be performed as experience has shown to be necessary.

NOTE 1: Factors to consider in determining the extent of vegetation management requiredinclude, but are not limited to: line voltage class, species’ growth rates and failurecharacteristics, right-of-way limitations, the vegetation’s location in relation to the conductors,the potential combined movement of vegetation and conductors during routine winds, andsagging of conductors due to elevated temperatures or icing.

NOTE 2: It is not practical to prevent all tree-conductor contacts on overhead distributionsystems. Some level of incidental contact by new growth will occur.

Supporting Comment

Many state and local regulatory bodies still interpret the language in A1 to be a “no touch” rule forvegetation. This interpretation causes electric utilities to carry out unnecessary pruning and removal ofvegetation. There is no safety reason for a “no touch” rule. The NESC Code should clearly state that someincidental contact by vegetation will occur.


Accept as modified.

Add NOTE 2 to Rule 218:

218. Vegetation management

A. General

1. Vegetation that may damage ungrounded supply conductors should be pruned or removed.Vegetation management should be performed as experience has shown to be necessary.

NOTE 1:…

NOTE 2: It is not practical to prevent all tree-conductor contacts on overhead lines. Some levelof incidental contact by new growth may occasionally be expected; such contact is notexpected to result in conductor damage.


SC4 considered the report from Working Group 4.11. SC4 accepts the rationale behind the change proposalincluded in the WG 4.11 report. See the Working Group 4.11 Report below. The purpose of this rule is to



limit the likelihood of conductor damage. However, SC4 prefers the above change proposal as modified. SC4believes that it is not appropriate to specify vegetation clearances in the NESC. Any specified clearancewould be too restrictive for some species in areas and not restrictive enough for others. Experience withexpected growth habits of different species in specific areas should be considered.

Scope: Communicate with organizations and agencies significantly involved in establishing and/orimplementing utility vegetation management practices and or policies. Determine vegetation managementpractices and/or policies necessary within the NESC for the safety of employees and the public. Develop arecommendation and rationale for revision to Rule 218 to accomplish the above for the 2012 Edition.

Members: Eric Engdahl (chair), Don Hooper, and Keith Reese (Tom Phillips was listed in error as amember in the 2007 NESC. Phil Givens was an original member but withdrew and was replaced by DonHooper.)

Recommended changes for 2012 NESC, Rule 218:

218. Vegetation management requirements

A. General

1. Vegetation that may damage ungrounded supply conductors should be pruned or removed.Vegetation management should be performed as experience has shown to be necessary

NOTES: Factors to consider in determining the extent of vegetation management requiredinclude, but are not limited to: line voltage class, species’ growth rates and failurecharacteristics, right-of-way limitations, the vegetation’s location in relation to the conductors,the potential combined movement of vegetation and conductors during routine winds, andsagging of conductors due to elevated temperatures or icing.

a. ANSI A-300 Performance Standards for the Care and Maintenance of Tree, Shrubs, andother Woody Plants and ANSI Z133.1- Pruning, Trimming, Repairing, Maintaining, andRemoving Tree and Cutting Brush-Safety Requirements contain information regardingvegetation management.

b. See Rule 214A2 for vegetation inspection.

2. Where pruning or removal is not practical, the conductor should be separated from the treewith suitable materials or devices to avoid conductor damage by abrasion and grounding of thecircuit through the tree

B. At line crossings, railroad crossings and limited-access highway crossings

The crossing span and the adjoining span on each side of the crossing should be kept free fromoverhanging or decayed trees or limbs that otherwise might fall into the line.

Supporting Comment

The NESC is not a prescriptive Code and the general rules need not contain requirements such as “Vegetationmanagement should be performed as experience has shown to be necessary.” Rule 218 is to state therelationship/conditions that provide safe conditions when considering overhead conductors and vegetation.The Code user is to determine the best means to comply with the stated requirements. The vegetationinspection requirements need to be specifically stated in Rule 218 to make it clear that the vegetationinspection requirements are limited to the requirements of Rule 218; that is, vegetation that could damageconductors.



Background information: The NESC sets overhead conductor and cable safety requirements for employeeand the public by applying a combination of following concepts:

— Recognizing and defining the nature of the human activities under and in the vicinity of the overheadconductors and cables.

— Energized conductors and cables are isolated from persons or objects associated with human activityby 1) insulation, 2) barriers, or 3) physical isolation (clearance).

— The NESC recognizes that OSHA and other regulatory statutes already limit activities in the vicinityof overhead supply conductors.

NESC Rule 218 considers and applies all three of the above stated concepts when defining the safe specifiedconditions for electric supply and communication equipment in the vicinity of vegetation and when notsetting specific conductor-to-vegetation clearances. The recommend changes to NECS Rule 218 are foundedon the following:

1. The clearance requirements of Section 23 provide for worker and public safety by the safety-by-positionconcept. Vegetation generally is not considered a readily accessible structure and routine, normal day-in, day-out human activities do not occur in vegetation. The tables in Rule 232 identify the “nature of surfaceunderneath wires, conductors, or cables” and provide for adequate physical separation between humans andconductors for day-in, day-out activities and, thus, vegetation is not specifically identified. In a similarmanner, Rule 234 does not identify vegetation as a clearance consideration for “clearances to otherinstallations.” Furthermore, no evidence has been presented that current or future operating conditions ortechnologies will alter this experience.

2. The safe conditions of Section 23 could be compromised if the mechanical integrity of the overheadconductors were reduced to the point that the conductors could not support the specified NESC loadings orthe electrical loads associated with clearance calculations. Therefore, Rule 218 states that vegetation that maydamage ungrounded supply conductors should be pruned or removed and its the users’ responsibility tomaintain the conductor such that they will withstand the applicable mechanical and electrical loads. The Codeis not concerned with incidental vegetation conductor contact. Extensive operating experience has shown thatincidental conductor-vegetation contact in and of itself does not create unsafe condition for workers or thepublic nor does the incidental contact with vegetation materially impact the condition of the conductor.Consequently, the Code does not mandate that vegetation must be pruned or removed nor are specificclearances considered necessary.

3. Part 2 of the NESC recognizes that other standards are already in force and that safe approach distances toenergized conductors are addressed by NESC Part 4, OSHA, and other industry standards such as ANSIZ133.1. Corporations, businesses and individuals undertaking activities in the general vicinity of overheadconductors are already required to take responsibility to maintain the separation between themselves and theirtools and the overhead conductors as mandated by these standards.

4. NESC requirements for vegetation management have not materially changed since the 3rd Edition NESCand experience in the ensuing 60+ years has shown that specific conductor vegetation clearances are notrequired to provide for employee or public safety. Neither historical field experience nor the human activitywithin/around vegetation support or draws attention to the need for specific conductor vegetation clearancesin Rule 218. The safety aspect of the Code that is related to vegetation does not depend on the clearancebetween conductors and vegetation but on the clearance between conductors and persons. Part 4 of the NESCestablishes the safe approach distances for qualified electric workers and ANSI Z133.1 and OSHA rulescontain the safe working distances for unqualified workers performing vegetation clearing, or other tasks, inthe general area of energized conductors.

Rule 218 relationships to and with other industry standards



1. Industry standards, such as ANSI Z133.1 (Pruning, Trimming, Repairing, Maintaining, and RemovingTrees and Cutting Brush—Safety Requirements), OSHA, and the NERC’s Vegetation Standard, areconsistent with the current and historical NESC position that specific conductor-to-vegetation clearances arenot necessary to define safe operating conditions for overhead supply lines. The stated purpose of ANSIZ133.1 is “…to provide safety criteria for workers and the public….” and provides the safe approachdistances for both qualified line-clearance tree trimmers and for persons other than qualified line-clearancetree trimmers. The rules of NESC Part 4 follow the same approach to provide for worker and public safety.Like the NESC, ANSI Z133.1 does not consider it necessary to specify conductor-to-vegetation clearancesbut only specifies conductor-to-person clearances.

2. OSHA provides for worker and public safety in a manner consistent and in accord with the NESC. OSHAsubpart 1910.269(I)(2) provides minimum approach distance tables and states, “The employer shall ensurethat no employee approaches or takes any conductive object closer to exposed energized parts than set forthin Table R-6 though Table R-10….” OSHA makes it very clear that these minimum approach distances alsocover line-clearance tree-trimming operations. Subpart 1910.269(a)(1)(i)E)(1) states, “Entire 1910.269 ofthis Part, except paragraph (r)(1) of this section, applies to line-clearance tree-trimming operations performedby qualified employees (those who are knowledgeable in the construction and operations of electric powergeneration, transmission, or distribution equipment involved, along with the associated hazards).”

3. The NERC Transmission Vegetation Program (FAC-003-01) is clearly a reliability standard with thepurpose, in part, “To improve the reliability of the electric transmission systems by preventing outages fromvegetation located on transmission rights-of-way….” Thus, while FAC-003-01 does provide minimumconductor-to-vegetation clearances, these clearances are to address reliability and to create operatingconditions not prone to widespread area outages. The established NERC vegetation clearances are notintended to address worker or public safety. FAC-003-01 conductor-to-vegetation clearances are currentlybased upon the insulating distances contained in IEEE Std 516 but FAC-003-01 is in the process of beingrevised to eliminate the reference to IEEE Std 516 and to set the conductor-to-vegetation clearances basedupon established sparkover science. These revisions have not been implemented as of May 6, 2008.

Summary of state requirements as known by WG 4.11

New Jersey

General: Requires a vigorous program including both an annual inspection and a minimum four-yearvegetation management cycle.

Distribution: Based on interference with energized conductors and references NESC.

Transmission: Contains additional reliability-based requirements including limited growth in the right-of-way.

Revisions are being considered; now open for public review and comment.

New York

Distribution: NESC

Transmission: Requires enhanced reliability-based right-of-way management practices.

California

Uses General Orders—not NESC.

Is concerned with last year’s southern California wildfires.



California Dept. of Forestry and Fire Protection report issued.

California PSC’s Consumer Protection Safety Division is conducting its own investigation; report due July31, 2008. Report is expected to contain reliability-based recommendations for preventing a recurrence offuture wildfires due to the same cause(s).


Affirmative: (17) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Drzewiecki, Engdahl, Gill, Henry,Hooper, Komassa, Marne, Neubauer, Reding, Slavin, Steiner, Young

Negative: (2) White, Gunter

Abstention: (0)

Explanation of Vote

Gunter: (Negative) The added NOTE adds nothing to the Rule and suggests it is OK for trees to contactoverhead lines.

White: (Negative) I understand that incidental contact with new tree growth may happen. However, I do notbelieve it is appropriate to add a NOTE to the rule stating that such contact is allowed. Contact with newgrowth during winter months, when the vegetation is dry, may cause sparks to drop on dry ground vegetationcausing a fire.

Revised Text

CP3152


Submitter


Proposed Change


B. At line crossings, railroad crossings and limited-access highway crossings

At crossings, as defined in Rule 241C, tThe crossing span and the adjoining span on each side ofthe crossing should be kept free from overhanging or decayed trees or limbs that otherwise mightfall into the line.

Supporting Comment

The current rule does not address a change made in the 2007 Edition, which added navigable waterwaysrequiring waterway crossing permits to the list of items considered a crossing.






See CP3063.



Negative: (0)

Abstention: (0)

Revised Text

CP3236


Submitter

James T. Collins

Proposed Change

Revise Rule 218B Title as follows

B. At line crossings, railroad crossings, and limited-access highway crossings, or navigable waterwaysrequiring crossing permits


Supporting Comment

Since “navigable waterways requiring crossing permits” was added to the at crossings lists (see Rule 241Cand Table 242-1) in 2007, it needs to be added to Rule 218B for tree trimming at line crossings to beconsistent.




See CP3063.





Negative: (0)

Abstention: (0)

New Text

CP3063


Submitter

Ewell T. Robeson

Proposed Change

Revise Rule 218B title as follows:

B. At line crossings, railroad crossings, and limited-access highway crossings, or navigable waterwaysrequiring crossing permits


Supporting Comment

Since “navigable waterways requiring crossing permits” was added to the at crossings lists (see Rule 241Cand Table 242-1) in 2007, it needs to be added to Rule 218B for tree trimming at line crossings to beconsistent.


Accept.



Negative: (0)

Abstention: (0)



Revised Text

CP3235


Submitter

James T. Collins

Proposed Change

Revise title to include a voltage range over 50 kV.

C. Relative levels: Supply lines of different voltage classifications (0 to 750 V, over 750 V to 8.7 kV,over 8.7 kV to 22 kV, and over 22 kV to 50 kV, and over 50 kV)

Supporting Comment

Prior to 2007 the title of the rule referenced voltage classifications of voltages as indicated in Table 235-5. In2007 the title was revised to list the voltage ranges covered in Table 235-5, but voltages above 50 kV wererange of voltages.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3237


Submitter

James T. Collins



Proposed Change

Make the second sentence of the rule an EXCEPTION.

221. Avoidance of conflict

Two separate lines, either of which carries supply conductors, should be so separated from each otherthat neither conflicts with the other.

EXCEPTION: If this elimination of conflict is not practical, the conflicting line or lines should beseparated as far as practical and shall be built to the grade of construction required by Section 24 for aconflicting line, or the two lines shall be combined on the same structures.

Supporting Comment

The current rule actually states an exception in its text, but the EXCEPTION is not identified as such. Thisrevision places the exception in the proper format. In addition, the revised wording will more clearly definethe condition under which the exception applies.


Accept as modified.

Make the second sentence of the rule an EXCEPTION.

221. Avoidance of conflict

Two separate lines, either of which carries supply conductors, should be so separated from each otherthat neither line conflicts with the other.

EXCEPTION: If this elimination of conflict is not practical, the conflicting line or lines should beseparated as far as practical and shall be built to the grade of construction required by Section 24 for aconflicting line, or the two lines shall be combined on the same structures.



Negative: (0)

Abstention: (0)

Revised Text

CP3358

Part: 2 Section: 22 Rule: 223A



Submitter

Percy E. Pool

Proposed Change

Change NOTE in Rule 223A to read:

NOTE: Additional information may be obtained from the latest issue of IEEE Stds 487™-2000 [B34]and 1590™-2003 [B54].

Supporting Comment

This CP changes the wording of the NOTE in Rule 223A to minimize future changes to the NOTE just toupdate the reference dates. The latest issue of IEEE 487 is dated 2007. IEEE 1590 is presently under revision.

It is becoming customary not to include dates of references with the understanding that the latest edition ofthe referenced document (including any amendments or corrigenda) applies. Typically for dated references,only the edition cited applies.


Accept as modified.

Change NOTE in Rule 223A to read:

NOTE: Additional information may be obtained from IEEE Stds 487™-2000 2007 [B34] and 1590™-2003 [B54].


SC4 believes references should be specific as done elsewhere in the Code.



Negative: (0)

Abstention: (0)

Revised Text

CP3070




Submitter

Mickey Gunter

Proposed Change

Revise rule 230A2a as follows:

a. Open supply conductors of 0 to 750 V and supply cables meeting Rule 230C; and communicationconductors and cables, guys, messengers, and neutral conductors meeting Rule 230E1 shall besuspended not less than 4.8 m (15.5 ft) above areas where trucks are expected, or 2.70 m (9 ft)above areas limited to pedestrians or restricted traffic only where vehicles are not expected duringthe emergency, unless Section 23 permits lesser clearances.

For the purpose of this rule, trucks are defined as any vehicle exceeding 2.5 m (8 ft) in height.Areas not subject to truck traffic are areas where truck traffic is neither normally encountered norreasonably anticipated or is otherwise limited.

Spaces and ways subject to pedestrians or restricted traffic only are those areas where riders onhorseback or other large animals, vehicles, or other mobile units exceeding 2.5 m (8 ft) in heightare prohibited by regulation or permanent terrain configurations or are otherwise neither normallyencountered nor reasonably anticipated or are otherwise limited.

Supporting Comment

Adding the language “or other large animals” will make it consistent with previous code changes in Footnote9 of Table 232-1 and Footnote 5 of Table 232-2.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3238


Submitter

James T. Collins



Proposed Change

Revise Rule 230A2a as follows

a. Open supply conductors of 0 to 750 V and supply cables meeting Rule 230C; and communicationconductors and cables, guys, messengers, and neutral conductors meeting Rule 230E1 shall besuspended not less than 4.8 m (15.5 ft) above areas where trucks are expected, or 2.70 m (9 ft)above areas limited to pedestrians or restricted traffic only where vehicles are not expected duringthe emergency, unless Section 23 permits lesser clearances.

For the purpose of this rule, trucks are defined as any vehicle exceeding 2.5 m (8 ft) in height.Areas not subject to truck traffic are areas where truck traffic is neither normally encountered norreasonably anticipated or is otherwise limited.

Spaces and ways subject to pedestrians or restricted traffic only are those areas where riders onhorseback or other large animals, vehicles, or other mobile units exceeding 2.5 m (8 ft) in height areprohibited by regulation or permanent terrain configurations or are otherwise neither normallyencountered no reasonably anticipated or are otherwise limited.

Supporting Comment

Adding the language “or other large animals” will make it consistent with previous code changes in Footnote9 of Table 232-1 and Footnote 5 of Table 232-2.

Subcommittee RecommendationAccept in principle.


See CP3070.



Negative: (0)

Abstention: (0)

Revised Text

CP3153


Submitter




Proposed Change


3. Measurement of clearance and spacing

Unless otherwise stated, all clearances shall be measured from surface to surface and all spacingsshall be measured center to center. For clearance measurements, live metallic hardware electricallyconnected to supply line conductors and communication equipment electrically connected tocommunication line conductors shall be considered a part of the line conductors. Metallic bases ofpotheads, surge arresters, and similar devices shall be considered a part of the supporting structure.

Supporting Comment

Communication equipment is often attached to the conductor out in the span (splice boxes, power supplies,communication antennas, etc.). The change clarifies that measurements for clearances need to be made tothe communication equipment attached to the communication line conductor as well as the live metallichardware attached to the supply line conductor.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3062


Submitter

Ewell T. Robeson

Proposed Change


4. Rounding of calculation results

Unless otherwise specified in a table or rule within Section 23, clearances that require a calculation,that requires a calculation, shall have the resultant of the calculation shall be rounded up to the



same level of decimal places as the basic value shown in the rule or table, regardless of the numbersof significant digits of individual values required to be used in the calculation.

If a calculated clearance is allowed a reduction by footnotes or exceptions, the resultant calculationshall be rounded up before the reduction is applied and the resultant calculation after the reductionis applied shall also be rounded up.

EXCEPTION 1: When calculating an actual clearance, the resultant calculation shall be roundeddown.

EXCEPTION 2: Rules or tables with values in millimeters are shown in units of 5 mm; as a result,resultants of calculations to be expressed in millimeters shall be rounded up to the next multiple of5 mm.

Supporting Comment

When calculating a clearance required by a rule or table, the clearance calculation resultant must be roundedup so that the resultant value will not be less than the stated rule value.

However, when an actual clearance is being calculated such as checking to see if a clearance over a road meetsthe required clearance, where additional sag due to maximum conductor temperature or ice loading issubtracted from a given clearance, the resultant value should be rounded down so that the resultant value willnot be greater than the actual clearance value.

The best way to illustrate the proposed second paragraph is to give an example:

Example: Using Table 239-1 (in), calculate the clearance of a span guy from a 19.8 kV phase to phase voltagelateral conductor.

Rounding up the initial resultant calculation before the allowed reduction:

6 + 0.4 x (19.8 – 8.7) = 6 + 0.4 x 11.1 = 6 + 4.44 = 10.44 = 11 (rounded up)

Taking the 25% reduction: 11 x 75 = 8.25 = 9 (rounded up)

Not rounding up the initial resultant calculation before the reduction:

6 + 0.4 x (19.8 – 8.7) = 6 + 0.4 x 11.1 = 6 + 4.44 = 10.44 (not rounded up)

Taking the 25% reduction: 10.44 x 75 = 7.83 = 8 (rounded up)

As you can see, if you don’t round up the initial resultant calculation before the reduction, the value after the25% reduction is taken can be lower than the resultant calculation that is rounded up in the initial calculation.

Some field users may think that the resultant calculation is after the reduction is applied. This change shouldassure that the maximum clearance is obtained.


Accept as modified.





Unless otherwise specified in a table or rule within Section 23, clearance specifications that requirea calculation to determine the required clearance, that requires a calculation, shall have the resultantof the calculation shall be rounded up to the same level of decimal places as the basic value shownin the rule or table, regardless of the numbers of significant digits of individual values required tobe used in the calculation.

If a calculated clearance is allowed a reduction by FOOTNOTE or EXCEPTIONs, the resultantcalculation shall be rounded up before the reduction is applied and the resultant calculation after thereduction is applied shall also be rounded up.

EXCEPTION 1: When determining a clearance at specified conditions based on fieldmeasurements the resultant calculation shall be rounded down.



Affirmative: (19) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Drzewiecki, Emery, Engdahl, Gill,Gunter, Henry, Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White, Young

Negative: (0)

Abstention: (0)

Revised Text

CP3239


Submitter

James T. Collins

Proposed Change

Revise Rule 230A4 as follows


Unless otherwise specified in a table or rule within Section 23, clearances that require a calculation,that requires a calculation, shall have the resultant of the calculation shall be rounded up to thesame level of decimal places as the basic value shown in the rule or table, regardless of the numbersof significant digits of individual values required to be used in the calculation.



If a calculated clearance is allowed a reduction by footnotes or exceptions, the resultant calculationshall be rounded up before the reduction is applied and the resultant calculation after the reductionis applied shall also be rounded up.

EXCEPTION 1: When calculating an actual clearance, the resultant calculation shall be roundeddown.


Supporting Comment

When calculating a clearance required by a rule or table, the clearance calculation resultant must be roundedup so that the resultant value will not be less than the stated rule value. However, when an actual clearance isbeing calculated such as checking to see if a clearance over a road meets the required clearance, whereadditional sag due to maximum conductor temperature or ice loading is subtracted from a given clearance,the resultant value should be rounded down so that the resultant value will not be greater than the actualclearance value.

The best way to illustrate the proposed second paragraph is to give an example:

Example: Using Table 239-1 (in), calculate the clearance of a span guy from a 19.8 kV phase to phase voltagelateral conductor.

Rounding up the initial resultant calculation before the allowed reduction:

6 + 0.4 x (19.8 – 8.7) = 6 + 0.4 x 11.1 = 6 + 4.44 = 10.44 = 11 (rounded up)

Taking the 25% reduction: 11 x 75 = 8.25 = 9 (rounded up)

Not rounding up the initial resultant calculation before the reduction:

6 + 0.4 x (19.8 – 8.7) = 6 + 0.4 x 11.1 = 6 + 4.44 = 10.44 (not rounded up)

Taking the 25% reduction:10.44 x 75 = 7.83 = 8 (rounded up)

As you can see, if you don’t round up the initial resultant calculation before the reduction, the value after the25% reduction is taken can be lower than the resultant calculation that is rounded up in the initial calculation.Some field users may think that the resultant calculation is after the reduction is applied. This change shouldassure that the maximum clearance is obtained.

Example for EXCEPTION 1: A vertical clearance of 21.0 ft is measured under ambient conditions over aroadway. To determine if the clearance meets Code, the additional maximum sag has to be calculated as perRule 232A and is determined to be 2.55 ft.

Thus: 21.0 ft – 2.55 ft = 18.45 ft = 18.5 ft (rounded up according to the present rule). Rounding up causes thestated clearance to be greater than the actual clearance. Rounding down to 18.4 ft causes the stated clearanceto be less than the actual clearance. Rounding up can falsely state what the actual clearance is whereas theactual clearance may be a code violation.






See CP3062.



Negative: (0)

Abstention: (0)

Revised Text

CP3454


Also Part: 2 Section: 25 251 B SC5


New Text

CP3393


Submitter

Nelson Bingel

Proposed Change

Revise Rule 230B2 as follows.

2. Table 230-1 shows the radial thickness of ice to be used in calculating sags for clearance purposesabove all areas except roads, buildings, and bridges; for clearances above roads, buildings, andbridges, use the greater of the radial ice loadings specified in Table 230-1 or in Rule 250D.

See applicable clearance rules in Section 23.

Supporting Comment

We need to revisit the ice loading used for vertical clearances aboveground. The present ones have served us



well for lines along roadways and within the rights-of-way where they did not cross a traveled way of aroadway or driveway, primarily because vehicular traffic under the line at that location is virtually nil duringthe icing event. They also have mostly served well across roads, since the majority of road crossings are fromone side of the road to the other with a short span with sags that do not change much with ice loading.

However, there have been some notable exceptions that stopped traffic. Where the span across a road ordriveway is long, and the line is located in one of the areas where greater ice loadings are expected under Rule250D (or the new rime ice/hoar frost loadings whenever they arrive), the greater ice loading of any of the iceloading cases should be used to determine clearance requirements across roads, driveways, and parking lots.

While the same may also be said for some pastures where a farmer’s truck rolls or bales of hay to livestockin the pastures until the ice disappears, that may be harder to specify clearly and may need to await a lateredition.

Rule 230B ice loadings for clearances purposes should be greater for road, driveway, and line crossings thanfor along roads—use the present ones over fields and the increased ones in Section 25 over roads and at linecrossings.


Reject.


Existing rule is sufficient. See Appendix B.


Affirmative: (18) Amrhyn, Bednarz, Bleakley, Crawford, Drzewiecki, Emery, Engdahl, Gill, Gunter,Henry, Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White, Young

Negative: (1) Clapp

Abstention: (0)

Explanation of Vote

Clapp: (Negative) Long spans crossing roads have caused and will cause blockage of traffic along roadsduring major ice storms unless realistic ice loading is used. The issue with building is leaving room forpeople to scrape off excess snow loads.

New Text

CP3240

Part: 2 Section: 23 Rule: 230 B4b

Submitter

James T. Collins



Proposed Change

Add note to rule as follows:


The horizontal load shall be the horizontal wind pressure determined under Rule 230B1 and Table230-2, applied at right angles to the direction of the line using the projected area of the conductor ormessenger and conductors, spacers, or equipment that it supports, ice covered where required byRule 230B1 and Table 230-2.

NOTE: The projected area upon which the wind load is based is the rectangle defined by a widthequal to the diameter of the conductor or messenger, plus ice if appropriate, multiplied by the lengthof the conductor or messenger upon which the wind blows. See Rule 252B2 for force coefficientvalues of different surface shapes.

Supporting Comment

This proposal would define the term “projected area” as it is used in the rule to specify the area upon whichwind pressure is applied in calculating wind loads on conductors. On occasion, infrequent or non-technicalcode users have questioned this term.


Accept as modified.


The horizontal load shall be the horizontal wind pressure determined under Rule 230B1 and Table230-2, applied at right angles to the direction of the line using the projected area of the conductor ormessenger and conductors, spacers, or equipment that it supports, ice covered where required byRule 230B1 and Table 230-2.

NOTE: The projected area of the conductor or messenger is equal to the diameter of the conductoror messenger, plus ice if appropriate, multiplied by the span length (see Rule 252B4). See Rule251A2 for force coefficient values of different surface shapes.



Negative: (0)

Abstention: (0)

Revised Text

CP3154

Part: 2 Section: 23 Rule: 230 I



Submitter


Proposed Change

Revise the note to Rule 230I as follows:

NOTE: See Rule 13 to determine the applicable addition. See Rule 214 for inspection requirements.

Supporting Comment

Rule 230I makes it sound like clearance does not need to be met after an extreme storm because of thewording “as a result of.” Noting the inspection requirements makes clear the intent that sometime after thestorm, clearances must be brought back into Code compliance.


Reject.


Insufficient substantiation.


Affirmative: (18) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Drzewiecki, Emery, Engdahl, Gill,Gunter, Henry, Hooper, Komassa, Neubauer, Slavin, Steiner, White, Young

Negative: (1) Marne

Abstention: (0)

Explanation of Vote

Marne: (Negative) See supporting comment. The committee assumed the change implies that an inspectionmust be made after a storm. This was not the intent.

Revised Text

CP3437


Also Part: 2 Section:23 230 B1 SC4











Revised Text

CP3430


Also Part: 3 Section: 38 380 D SC7



Revised Text

CP3241


Submitter

James T. Collins

Proposed Change

Revise Rule 231B1 as follows

B. From streets, roads, and highways

1. Where there are curbs: supporting structures, support arms, anchor guys, or equipmentattached thereto, up to 4.6 m (15 ft) above the road surface shall be located a sufficient distancefrom the street side of the curbs to avoid contact by ordinary vehicles using and located on thetraveled way. For a redirectional curb, paved or concrete swale-type curbs, such distance shallbe not less than 150 mm (6 in). For paved or concrete swale-type curbs, such facilities shall belocated behind the curb.

This rule does not require protection or marking of structural components located outside ofthe traveled ways of roadways or established parking areas.

NOTE: Experience has shown that it is not practical to protect structures from contact by out-of-control vehicles operating outside of established traveled ways.



Supporting Comment

The requirement of Rule 231B1 is “sufficient distance,” not 6 in as implied in the second sentence. The 6 inrequirement just places a lower boundary value on the rule, but is not the rule requirement. It is human natureto gravitate to a value and this is what most field users and students do when asked a question about this rule.Their answer is typically that a structure has to be 6 in away to meet the rule. The “sufficient distance”language was added in the 1984 Code, but the 6 in requirement was left in as a lower boundary, thus creatingconflict between “sufficient distance” and 6 in. We need to delete the reference to 6 in so as to limit confusionfor the field user. Since sufficient distance is the rule, then it should not matter the actual distance from thecurb as long as the structure is a “sufficient distance” away to keep an ordinary vehicle located on the travelway from striking the structure.

For example, we gave the following question to be answered on a test as true or false at a recent NESC schoolfor field users:

A street with re-directional curbs has a pole set 8 in behind the street side of the curb. An ordinary vehiclelocated on the traveled way scrapes the pole and damages the vehicle. The driver sues the utility pole ownerfor damages. Since the pole was located more than 6 in behind the street side of the curb, there is no NESCviolation and therefore no basis for a lawsuit.

Eleven (11) of twelve (12) students answered true and missed the question.


Accept as modified.

Revise Rule 231B1 as follows

B. From streets, roads, and highways

1. Where there are curbs: supporting structures, support arms, anchor guys, or equipmentattached thereto, up to 4.6 m (15 ft) above the road surface shall be located behind the curb andat a sufficient distance from the street side of the curbs to avoid contact by ordinary vehiclesusing and located on the traveled way. For a redirectional curb such distance shall be not lessthan 150 mm (6 in). For paved or concrete swale-type curbs, such facilities shall be locatedbehind the curb. This rule does not require protection or marking of structural componentslocated outside of the traveled ways of roadways or established parking areas.

NOTE: Experience has shown that it is not practical to protect structures from contact by out-of-control vehicles operating outside of established traveled ways.



Negative: (0)

Abstention: (0)



New Text

CP3120

Part: 2 Section: 23 Rule: 232 C1b

Submitter

Bruce Freimark

Proposed Change

Revise Rule 232C1b as indicated:

b. For voltages exceeding 50 kV, the additional clearance specified in Rule 232C1a shall be increased3% for each 300 m (1000 ft) or portion thereof in excess of 1000 m (3300 ft) above mean sea level.

EXAMPLES:

(1) At a conductor elevation between 1000.1 m and 1300 m (3301 ft and 4300 ft) the additionalclearance specified in Rule 232C1a are multiplied by 1.03.


Supporting Comment

While working with IEEE staffers on a computer application to automate the calculation of many of theNESC clearances it became apparent that these individuals had not written the program as intended by theNESC. The addition of the proposed words should clarify the intent to all readers of the NESC.


Accept as modified.

Revise Rule 232C1b as indicated:

b. For voltages exceeding 50 kV, the additional clearance specified in Rule 232C1a shall be increasedat a rate of 1% per 100 m (330 ft) 3% for each 300 m (1000 ft) in excess of 1000 m (3300 ft) abovemean sea level.


Affirmative: (16) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Emery, Gill, Gunter, Henry, Hooper,Komassa, Marne, Neubauer, Slavin, White, Young

Negative: (3) Steiner, Engdahl, Drzewiecki

Abstention: (0)



Explanation of Vote

Drzewiecki: (Negative) I do not believe we should be addressing voltage adders in such small increments.Next thing you know, we will be applying finite elements mathematics to determine the values. I believe otherdocuments including IEEE Std 516, the NESC work rules, and OSHA work rules all apply voltage adders inlarger 1000 ft increments in one form or another. By having to calculate such a small adder, it makes the Codemore cumbersome and less of a “practical” Code.

Engdahl: (Negative) This change proposal does not add clarity to the Code nor does it help address theinconsistencies between the clearance rules of Section 23 and the work rules of Section 43 when applyingelevation adders. Moving the application of elevation adders to an “at the rate of” will force designers to eitherincrease clearances by factions of inches for specific elevations or simply to apply the “at the rate of” over afixed elevation increment, which is basically the current block method. This level of design detail is nottechnically supported nor has field experience indicated that the current application of elevation adders is notproviding for safe clearances.

Steiner: (Negative) I agree with the original change proposal position, which considers a discrete stepfunction of 1000 ft increments when applying the voltage adders. The adders are similar to other industryaccepted standards and rules. I do not believe such small increments are necessary or practical in such code.I also support the examples as stated.

New Text

CP3155


Submitter


Proposed Change

Add an EXAMPLE to Rule 232C1b as follows:

EXAMPLE: Calculation of percent increase required by Rule 232C1b for an elevation of 1450 m(4800 ft).

SI units: (1450 – 1000) x (3% / 300) = 4.5%

Customary units: (4800 – 3300) x (3% / 1000) = 4.5%

Applied to the additional clearance specified in Rule 232C1a.

Supporting Comment

Clarification is needed on how the “3% for each 300 m (1000 ft) above 1000 m (3300 ft)” requirement isapplied. I’ve encountered professional engineers in the industry using at least two different methods.

There are three ways to interpret the “3% for each 1000 ft in excess of 3300 ft” requirement.

1. Use a “1000 ft block” method starting at 1 ft over 3300 ft (i.e., 3% added for 1 ft to 1000 ft over, 6% added



for 1001 ft to 2000 ft over, etc.). In this case the answer to the proposed example would be 6%.

2. Use a “1000 ft block” method starting at 1000 ft in excess of 3300 ft (i.e., no percentage is applied 1 ft to999 ft over, 3% is added for 1000 ft to 1999 ft, 6% is added for 2000 ft to 2999 ft, etc.). In this case the answerto the proposed example would be 3%.

3. Use a “prorated” percentage of 3% per 1000 ft. (This is the method used in the proposed example.)

I believe the third method (the “prorated” method discussed in item 3 above) is the correct method. This isthe method used in the Rural Utilities Service (RUS) Transmission Design Manual. I believe the “1000 ftblock” methods are not what the Code intends, but some designers have applied this method. Adding theexample clarifies the intended prorated method.




See CP3120.


Affirmative: (15) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Emery, Gill, Henry, Hooper, Komassa,Marne, Neubauer, Slavin, White, Young

Negative: (4) Steiner, Gunter, Engdahl, Drzewiecki

Abstention: (0)

Explanation of Vote

Drzewiecki: (Negative) See comment on CP3120.

Engdahl: (Negative) See comment on CP3120.

Gunter: (Negative) See comment on CP3120.

Steiner: (Negative) See comment on CP3120.

New Text

CP3121

Part: 2 Section: 23 Rule: 232 D3b

Submitter

Bruce Freimark



Proposed Change

Revise Rule 232D3b as indicated:

b. The value of D shall be increased 3% for each 300 m (1000 ft) or portion thereof in excess of 450 m(1500 ft) above mean sea level.

EXAMPLES:

(1) At a conductor elevation between 450.1 m and 750 m (1501 ft and 2500 ft), the value of Dshall be multiplied by 1.03.

(2) At a conductor elevation between 750.1 m and 1050 m (2501 ft and 3500 ft), the value of Dshall be multiplied by 1.06.

Supporting Comment



Accept as modified.

Revise Rule 232D3b as indicated:

b. The value of D shall be increased at the rate of 1% per 100 m (330 ft) 3% for each 300 m (1000 ft)in excess of 450 m (1500 ft) above mean sea level.


Affirmative: (18) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Drzewiecki, Emery, Gill, Gunter, Henry,Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White, Young

Negative: (1) Engdahl

Abstention: (0)

Explanation of Vote

Engdahl: (Negative) See negative comment on CP3120.

Revised Text

CP3100




Submitter

Ewell T. Robeson

Proposed Change

Revise column 4 category as follows:

Supply

cables over

750 V

meeting

Rule 230C2

or 230C3;

open supply

conductors,

0 to

750 V 3;

Ungrounded guys meeting Rules 279A1 and 215C5

exposed to

over 300 V

to 750 V 14

Supporting Comment

Rule 215C2 now requires all guys to be effectively grounded or insulated. Since we no longer haveungrounded guys, the ungrounded guy item needs to be changed to reflect this.


Accept as modified.

Revise Table 232-1, column 4 category as follows:

Supply

cables over

750 V

meeting

Rule 230C2

or 230C3;

open supply

conductors,



0 to

750 V 3;

Ungrounded portions of guys

meeting Rules 215C5 and 279A1

exposed to

over 300 V

to 750 V 14, 6


Affirmative: (18) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Drzewiecki, Emery, Engdahl, Gunter,Henry, Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White, Young

Negative: (0)

Abstention: (0)

Revised Text

CP3096


Submitter

Ewell T. Robeson

Proposed Change


Open

supply

conductors,

over 750 V

to 22 kV;

ungrounded guys meeting

Rules 279A1 and 215C5

exposed to

750 V to

22 kV 14



Supporting Comment



Accept as modified.

Revise Table 232-1, column 5, and add new Footnote 6 category as follows:

Open

supply

conductors,

over 750 V

to 22 kV;

ungrounded portions of guys


exposed to

750 V to

22 kV 14, 6

6 These clearance values also apply to guy insulators.



Negative: (0)

Abstention: (0)

Revised Text

CP3004


Submitter

Karen M. Lloyd



Proposed Change





Supporting Comment


Reject.


The equipment is not standard use on highways. Rule 12C and Footnote 26 of Table 232-1 adequately takecare of such requirements when they are needed.



Negative: (0)

Abstention: (0)



Revised Text

CP3117


Submitter

Ewell T. Robeson

Proposed Change


Insulated

communication

conductors and

cable;

messengers;

overhead shield/

surge-protection

wires; grounded

guys;



exposed to

0 to 300 V 11, 15

neutral

conductors

meeting Rule

230E1;

supply cables

meeting

Rule 230C1

Supporting CommentRule 215C2 now requires all guys to be effectively grounded or insulated. Since we no longer haveungrounded guys, the ungrounded guy item needs to be changed to reflect this.




Accept as modified.

Revise Table 232-1 column 2 category as follows:

Insulated

communication

conductors and

cable;

messengers;

overhead shield/

surge-protection

wires; grounded

guys;



exposed to 0 to 300 V 11, 15 , 6

neutral

conductors

meeting

Rule

230E1; supply

cables meeting

Rule 230C1



Negative: (0)

Abstention: (0)

Revised Text

CP3242

Part: 2 Section: 23 Rule: 232 Table 232-1 Column 2



Submitter

James T. Collins

Proposed Change


Insulated

communication

conductors and

cable;

messengers;

overhead shield/

surge-protection

wires; grounded

guys;

ungrounded insulated guys

exposed to

0 to 300 V 11, 15

neutral

conductors

meeting Rule

230E1; supply

cables meeting

Rule 230C1

Supporting Comment





See CP3096.





Negative: (0)

Abstention: (0)

Revised Text

CP3243


Submitter

James T. Collins

Proposed Change

Revise column 4 category as follows

Supply

cables over

750 V

meeting

Rule 230C2

or 230C3;

open supply

conductors,

0 to

750 V 3;

Ungrounded insulated guys

exposed to

over 300 V

to 750 V 14

Supporting Comment

Rule 215C2 now requires all guys to be effectively grounded or insulated. Since we no longer haveungrounded guys, this category needs to be changed to reflect this.






See CP3096.



Negative: (0)

Abstention: (0)

Revised Text

CP3244


Submitter

James T. Collins

Proposed Change


Open

supply

conductors,

over 750 V

to 22 kV;


exposed to

750 V to

22 kV 14

Supporting Comment







See CP3096.



Negative: (0)

Abstention: (0)

Revised Text

CP3245

Part: 2 Section: 23 Rule: 232 Table 232-1 Footnote 1

Submitter

James T. Collins

Proposed Change

Add existing Footnote 1 to last column category of Table 232-1 and add omitted language to Table 232-1(m) to be consistent with Table 232-1 (ft) as follows:

ft m

Trolley and Trolley and

electrified railroad electrified railroad

contact conductors contact conductors

and associated span or and associated span or

messenger wires 1 messenger wires 1

Supporting Comment

Footnote 1 is still in the Code for Table 232-1, but it was not referenced in the table rows or columns. In wasreferenced in the above category in the 1993 Code, but was missing in the 1997 and subsequent Codes. I foundnothing in the 1997 Preprint authorizing its removal, so I believe in is just an editorial error. Also the language“or messenger wires” is missing from the m table; it was in the 2002 Code and appears to be an editorial erroralso.






See CP3071.



Negative: (0)

Abstention: (0)

Revised Text

CP3071


Submitter

Mickey Gunter

Proposed Change

Add existing Footnote 1 to last column category of Table 232-1 and add omitted language to Table 232-1(m) to be consistent with Table 232-1 (ft) as follows:

ft m

Trolley and Trolley and

electrified railroad electrified railroad

contact conductors contact conductors

and associated span or and associated span or

messenger wires 1 messenger wires 1

Supporting Comment

Footnote 1 is still in the Code for Table 232-1, but it was not referenced in the table rows or columns. It wasreferenced in the above category in the 1993 Code, but was missing in the 1997 and subsequent Codes. I foundnothing in the 1997 Preprint authorizing its removal, so I believe in is just an editorial error. Also the language“or messenger wires” is missing from the m Table; it was in the 2002 Code and appears to be an editorial erroralso.




Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3250


Submitter

James T. Collins

Proposed Change

Revise Table 232-1, Footnote 10, m and ft, as follows:

10Where a supply or communication line along a road is located relative to fences, ditches, embankments,etc., so that the ground under the line would not be expected to be traveled except by pedestrians, theclearances may be reduced to the following values:

(ft)

(a) Insulated communication conductor and

communication cables. 9.5

(b) Conductors of other communication circuits 9.5

(c) Supply cables of any voltage meeting Rule 230C1,

supply cables limited to 150 V to ground meeting

Rule 230C2 or 230C3, and neutral conductors

meeting Rule 230E1 9.5

(d) Insulated supply conductors limited to

300 V to ground 12.5 10.5

(e) Insulated supply cables limited to 150 V to ground

meeting Rule 230C2 or 230C3 10.0

(e f) Guys 9.5



Supporting Comment

Footnote 10 allows value reductions for ground under lines that are expected to be traveled by pedestriansonly. Since row 5 is for spaces and ways subject to pedestrians only, Footnote 10 needs to have similar valuesas row 5 so there will not be inconsistency.

For example: Footnote 8 in row 5, columns 3 and 4, allows a cable limited to 300 V to ground to be reducedfrom 12 ft to 10.5 ft (assuming the house is not high enough). Footnote 10 allows a reduction from 14 ft to12.5 ft.


Reject.


See CP3101.



Negative: (0)

Abstention: (0)

Revised Text

CP3101


Submitter

Ewell T. Robeson

Proposed Change

Revise Table 232-1, Footnote 10, m and ft as follows:

10 Where a supply or communication line along a road is located relative to fences, ditches, embankments,etc., so that the ground under the line would not be expected to be traveled except by pedestrians, theclearances may be reduced to the following values:

(ft)











300 V to ground 12.5



(e f) Grounded gGuys, guys meeting

rules 279A1 and 215C5 exposed to 0 to 300 V 9.5

Supporting Comment

Footnote 10 allows value reductions for ground under lines that are expected to be traveled by pedestriansonly. Since row 5 is for spaces and ways subject to pedestrians only, footnote 10 needs to have similar valuesas row 5 so there will not be inconsistency.

For example: Footnote 8 in row 5, columns 3 and 4 allows a 230C3 cable limited to 300 V to ground to bereduced from 12 ft to 10.5 ft (assuming the house is not high enough). Footnote 10 allows a reduction from14 ft to 12.5 ft.


Accept as modified.

Revise Table 232-1, Footnote 10, m and ft, as follows:

10Where a supply or communication line along a road is located relative to fences, ditches, embankments,etc., so that the ground under the line would not be expected to be traveled except by pedestrians, theclearances may be reduced to the following values:

(ft)









300 V to ground 12.5





(e f) Grounded gGuys, ungrounded portions of guys meeting

Rules 279A1 and 215C5 exposed to 0 to 300 V 9.5



Negative: (0)

Abstention: (0)

Revised Text

CP3103


Submitter

Ewell T. Robeson

Proposed Change

Revise Footnote 14 in Table 232-1 as follows:

14Ungrounded guys and ungrounded Pportions of span guys between guy insulators shall have clearancesbased on the highest voltage to which they may be exposed due to a slack conductor or guy.

Supporting Comment



Accept as modified.


14Ungrounded guys and ungrounded The portion(s) of span guys between guy insulators and the portion(s)of anchor guys above guy insulators shall have clearances based on the highest voltage to which they may beexposed due to a slack conductor or guy.





Negative: (0)

Abstention: (0)

Revised Text

CP3251


Submitter

James T. Collins

Proposed Change



Supporting Comment

According to Rule 215C2, there are no more ungrounded guys and this footnote needs to reflect this change.




See CP3103.



Negative: (0)

Abstention: (0)

Revised Text

CP3252




Submitter

James T. Collins

Proposed Change


15Anchor guys insulated in accordance with Rules 279A1 and 215C5 may have the same clearance asgrounded guys.

Supporting Comment

According to Rule 215C2, guys are to be effectively grounded or insulated according to Rules 279A1 and215C5. Footnote 15 needs to reflect this change.




See CP3102.



Negative: (0)

Abstention: (0)

Revised Text

CP3102


Submitter

Ewell T. Robeson

Proposed Change


15Anchor guys meeting insulated in accordance with Rules 279A1 and 215C5 may have the same clearanceas grounded guys.



Supporting Comment

Using the verbiage “meeting” rather than “insulated in accordance with” better clarifies the intent of thisfootnote.


Accept as modified.


15The portion of Aanchor guys below the lowest insulator meeting insulated in accordance with Rules279A1 and 215C5 may have the same clearance as grounded guys.

Add Footnote 15 designator after Footnote 14 to the end of each column heading 4 and 5.



Negative: (0)

Abstention: (0)

Revised Text

CP3246


Submitter

James T. Collins

Proposed Change

Revise Footnote 7 of Table 232-1 as follows:

7Where the height of a residential building does not permit its service drop(s) to meet these values, Ttheclearances over residential driveways only may be reduced to the following:

Supporting Comment

The height of a building should have nothing to do with a clearance; a clearance should be based on activityunder the line, cable or conductor type, and voltage. When this change was made from attachment point toheight, it was argued that electricians were determining the height of a utilities service drop, but with the useof the word height, we are now allowing an architect or house builder to determine the service drop clearance.I don’t believe many utility field engineers or line personnel have the expertise or time to determine whetheror not a building is high enough to accommodate a service attachment point. The Uniform System of



Clearances developed in 1990 (see Appendix A) were based on a reference height, and a mechanical andelectrical component to reflect activity under the line, type cable or conductor, and voltage. The use of heightas a requirement is highly subjective, almost impossible for the utility to determine or enforce, and increasesconflicts with electricians and local inspectors for the field user.




See CP3073.


Affirmative: (14) Amrhyn, Bednarz, Bleakley, Drzewiecki, Emery, Engdahl, Gunter, Henry, Komassa,Marne, Slavin, Steiner, White, Young

Negative: (3) Neubauer, Crawford, Clapp

Abstention: (0)

Explanation of Vote

Clapp: (Negative) See Comment on CP3073.

Crawford: (Negative) See Comment on CP3073.

Neubauer: (Negative) See Comment on CP3073.

Revised Text

CP3073


Submitter

Mickey Gunter

Proposed Change


7Where the height of a residential building does not permit its service drop(s) to meet these values, Ttheclearances over residential driveways only may be reduced to the following:

Supporting Comment

The height of a building should have nothing to do with a clearance; a clearance should be based on activity



under the line, cable or conductor type, and voltage. When this change was made from attachment point toheight, it was argued that electricians were determining the height of a utilities service drop, but with the useof the word height, we are now allowing an architect or house builder to determine the service drop clearance.I don’t believe many utility field engineers or line personnel have the expertise or time to determine whetheror not a building is high enough to accommodate a service attachment point. The Uniform System ofClearances developed in 1990 (see Appendix A) were based on a reference height, and a mechanical andelectrical component to reflect activity under the line, type cable or conductor, and voltage. The use of heightas a requirement is highly subjective, almost impossible for the utility to determine or enforce, and increasesconflicts with electricians and local inspectors for the field user.


Accept.


Affirmative: (14) Amrhyn, Bednarz, Bleakley, Drzewiecki, Emery, Engdahl, Gunter, Henry, Komassa,Marne, Slavin, Steiner, White, Young

Negative: (3) Neubauer, Crawford, Clapp

Abstention: (0)

Explanation of Vote

Clapp: (Negative) The height restriction was added in Footnote 7 of Table 232-1 in the 1990 Edition as a partof the overall coordination of clearance requirements. It resulted from a compromise that occurred whenSubcommittee 4 came within one vote of prohibiting service drops that could not meet the values required inTable 232-1. This drastic action was considered because of hundreds of service drops that had recently beentorn down by moving vans, ambulances, and delivery trucks pulling into driveways by residences.

It was recognized that the reduced clearances allowed by Footnote 7 of Table 232-1 will allow normallyexpected residential vehicles to safely traverse underneath them but that moving vans, ambulances, anddelivery vans could not. As a result, application of Footnote 7 reduced clearances were limited by applyingthem only to houses (residential buildings) that were so low that there was no place on the building to attacha service drop and meet the table clearances. In essence, this footnote only applies to flat-roofed residences(of which few are built) and so-called hip roofed houses where all roof edges are sloping and the gutter edgeis at the same level on all sides (many of which also use underground service).

Multi-story houses and gable-ended houses have enough height to allow attachment at a level that can usuallyachieve the full clearances required by Table 232-1.

The front end of most driveways at residences is for general use by the residential vehicles as well as movingvans, ambulances, and delivery vans. Footnote 7 does not apply above such areas; it only applies if there is aportion of a driveway at a residence that is not for general use, such as running from the house to a rear-lotlocated detached garage.

At the time of the 1990 changes, the subcommittee believed that these limitations on application of thereduced clearances would limit teardowns of new service drops—and it seems to have done so. The changeproposed here and supported by the majority is a giant step backward and can only cause increases in servicedrop contacts by moving vans, ambulances, and delivery vehicles.

Many utilities have prepared information packets that they give to electricians and house designers to indicate



acceptable locations for service drop attachments on various styles of single and multiple story houses. Thisinformation allows electricians to install service weatherheads at appropriate locations to meet both NESCand NEC requirements. This is all that is required to solve the problem that apparently is attempting to beaddressed by this proposal. Not only is the change not needed, it is counterproductive to safety.

Crawford: (Negative) The rule should not be changed to remedy the incorrect application of clearances bynon-utility personnel; NESC clearances can be adequately conveyed by service guidelines publications. Theincreased clearances should be kept due to the oversized vehicles that are commonly parked in residentialdriveways.

Neubauer: (Negative) I agree with the comment that the height of a house should have nothing to do with aclearance of a service drop. However, after listening to the discussion this was put in as a compromise in thepast. These clearances are too low to be allowed over most portions of driveways, removing the height ofhouse could allow more safety hazards than the present wording.

Revised Text

CP3249


Submitter

James T. Collins

Proposed Change


8Where the height of a residential building does not permit its service drop(s) to meet these values, theclearances may be reduced to the following:

(ft)

(a) Insulated supply service drops limited to 300 V to ground 10.5

(b) Insulated drip loops of supply service drops limited to 300 V to ground 10.5

(c) Supply service drops limited to 150 V to ground and meeting

Rule 230C1 or 230C3 10.0

(d) Drip loops only of supply service drops limited to 150 V to

ground and meeting Rule 230C1 or 230C3 10.0

Supporting Comment

In row 5, column 2, of Table 232-1, the clearance for a 230C1 supply cable of any voltage allowed overspaces and ways subject to pedestrians only is 9.5 ft. Footnotes 8 (c) and (b) allow a reduction for a 230C1cable from 12 ft to 10.0 ft over spaces and ways subject to pedestrians only. This presents a contradictionbetween row 5, column 2, and row 5, column 3 Footnote 8, and needs to be corrected.






See CP3074.



Negative: (0)

Abstention: (0)

Revised Text

CP3248


Submitter

James T. Collins

Proposed Change




(b) Insulated drip loops of supply service drops limited to 300 V to

ground 10.5


Rule 230C1 or 230C3 10.0



Supporting Comment

In row 5, column 2, of Table 232-1, the clearance for a 230C1 supply cable of any voltage allowed over spacesand ways subject to pedestrians only is 9.5 ft. Footnotes 8 (c) and (b) allow a reduction for a 230C1 cablefrom 12 ft to 10.0 ft over spaces and ways subject to pedestrians only. This presents a contradiction between



row 5, column 2, and row 5, column 3 Footnote 8, and needs to be corrected.




See CP3074.



Negative: (0)

Abstention: (0)

Revised Text

CP3247


Submitter

James T. Collins

Proposed Change

Revise Footnote 8 of Table 232-1 as follows




ground 10.5


Rule 230C1 or 230C3 10.0



Supporting Comment

In row 5, column 2, of Table 232-1, the clearance for a 230C1 supply cable of any voltage allowed over spaces



and ways subject to pedestrians only is 9.5 ft. Footnotes 8 (c) and (b) allow a reduction for a 230C1 cablefrom 12 ft to 10.0 ft over spaces and ways subject to pedestrians only. This presents a contradiction betweenrow 5, column 2, and row 5, column 3 Footnote 8, and needs to be corrected.




See CP3074.


Affirmative: (17) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Drzewiecki, Emery, Engdahl, Gunter,Henry, Komassa, Marne, Neubauer, Slavin, Steiner, White, Young

Negative: (0)

Abstention: (0)

Revised Text

CP3074


Submitter

Mickey Gunter

Proposed Change


8Where the height of a residential building does not permit its service drop(s) to meet these values, Ttheclearances for residential service drop(s) only may be reduced to the following:



ground 10.5


Rule 230C1 or 230C3 10.0





Supporting Comment

The height of a building should have nothing to do with a clearance; a clearance should be based on activityunder the line, cable or conductor type, and voltage. When this change was made from attachment point toheight, it was argued that electricians were determining the height of a utilities service drop, but with the useof the word height, we are now allowing an architect or house builder to determine the service drop clearance.I don’t believe many utility field engineers or line personnel have the expertise or time to determine whetheror not a building is high enough to accommodate a service attachment point. The Uniform System ofClearances developed in increases conflicts with electricians and local inspectors for the field user.

1990 (see Appendix A) were based on a reference height, and a mechanical and electrical component toreflect activity under the line, type cable or conductor, and voltage. The use of height as a requirement ishighly subjective, almost impossible for the utility to determine or enforce, and increases conflicts withelectricians and local inspectors for the field user.

Also, in row 5, column 2, of Table 232-1, the clearance for a 230C1 supply cable of any voltage allowed overspaces and ways subject to pedestrians only is 9.5 ft. Footnotes 8 (c) and (d) allow a reduction for a 230C1cable from 12 ft to 10.0 ft over spaces and ways subject to pedestrians only. This presents a contradictionbetween row 5, column 2, and row 5, column 3 Footnote 8, and needs to be corrected.


Accept.


Affirmative: (15) Amrhyn, Bednarz, Bleakley, Crawford, Drzewiecki, Emery, Engdahl, Gunter, Henry,Komassa, Marne, Slavin, Steiner, White, Young

Negative: (2) Neubauer, Clapp

Abstention: (0)

Explanation of Vote

Clapp: (Negative) The height restriction was added in Footnote 7 of Table 232-1 in the 1990 Edition as a partof the overall coordination of clearance requirements. It resulted from a compromise that occurred whenSubcommittee 4 came within one vote of prohibiting service drops that could not meet the values required inTable 232-1. This drastic action was considered because of hundreds of service drops that had recently beentorn down by moving vans, ambulances, and delivery trucks pulling into driveways by residences.

It was recognized that the reduced clearances allowed by Footnote 7 of Table 232-1 will allow normallyexpected residential vehicles to safely traverse underneath them but that moving vans, ambulances, anddelivery vans could not. As a result, application of Footnote 7 reduced clearances were limited by applyingthem only to houses (residential buildings) that were so low that there was no place on the building to attacha service drop and meet the table clearances. In essence, this footnote only applies to flat-roofed residences(of which few are built) and so-called hip roofed houses where all roof edges are sloping and the gutter edgeis at the same level on all sides (many of which also use underground service).

Multi-story houses and gable-ended houses have enough height to allow attachment at a level that can usuallyachieve the full clearances required by Table 232-1.



The front end of most driveways at residences is for general use by the residential vehicles as well as movingvans, ambulances, and delivery vans. Footnote 7 does not apply above such areas; it only applies if there is aportion of a driveway at a residence that is not for general use, such as running from the house to a rear-lotlocated detached garage.

At the time of the 1990 changes, the subcommittee believed that these limitations on application of thereduced clearances would limit teardowns of new service drops—and it seems to have done so. The changeproposed here and supported by the majority is a giant step backward and can only cause increases in servicedrop contacts by moving vans, ambulances, and delivery vehicles.

Many utilities have prepared information packets that they give to electricians and house designers to indicateacceptable locations for service drop attachments on various styles of single and multiple story houses. Thisinformation allows electricians to install service weatherheads at appropriate locations to meet both NESCand NEC requirements. This is all that is required to solve the problem that apparently is attempting to beaddressed by this proposal. Not only is the change not needed, it is counterproductive to safety.

Neubauer: (Negative) I agree with the comment that the height of a house should have nothing to do with aclearance of a service drop. However, after listening to the discussion this was put in as a compromise in thepast. These clearances are too low to be allowed over most portions of driveways, removing the height ofhouse could allow more safety hazards than the present wording.

Deleted Text

CP3468


Submitter

SC4

Proposed Change

Delete Footnote 25 and add a note to bottom of Table 232-1 (ft).

Table 232-1—Vertical clearance of wires, conductors, and cables aboveground, roadway, rail, or water surfaces 25

(Voltages are phase to ground for effectively grounded circuits and those other circuits where all ground faults are cleared by promptly de-energizing the faulted section, both initially and following subsequent breaker

operations. See the definitions section for voltages of other systems.See Rules 232B1, 232C1a, and 232D4.)

25The clearance values shown in this table are computed by adding the applicable Mechanical and Electrical(M & E) value of Table A-1 to the applicable Reference Component of Table A-2a of Appendix A.

NOTE: The clearance values shown in this table are computed by adding the applicable Mechanical andElectrical (M & E) value of Table A-1 to the applicable Reference Component of Table A-2a of AppendixA.



Supporting Comment

By definition footnotes have the same force and effect required or allowed by the rule that specifies the useof a table. Footnote 25 contains references to Appendix A. Appendices are not part of the Code and isincluded for information only. A note added to the bottom of the table is more appropriate.


Accept.


Affirmative: (19) Amrhyn, Bednarz, Bleakley, Bowmer, Clapp, Crawford, Drzewiecki, Emery, Engdahl,Gill, Gunter, Hall, Hooper, Komassa, Marne, Neubauer, Reding, Slavin, White

Negative: (0)

Abstention: (0)

Revised Text

CP3472

Part: 2 Section: 23 Rule: 232 Table 232-1, 2, 4

Also Part: 2 Section: 23 233 Table 233-2 2SC4

Part: 2 Section: 23 234 Table 234-1, 2, 3 SC4

Part: 2 Section: 23 235 Table 235-2, 3, 5, 6 SC4

Submitter

NESC SC4

Proposed Change

Add a reference to Rule 232A in the headings of Tables 232-1, 232-2, and 232-4.

Add a reference to Rule 233A in the headings of Tables 233-1 and 233-2.

Add a reference to Rule 234A in the headings of Tables 234-1, 234-2, and 234-3.

Add a reference to Rule 235A in the headings of Tables 235-2, 235-3, 235-5, 235-6, and 235-8.

All would be added to the end of the list in each table.

Supporting Comment

The rules that require the use of these tables must be used in accordance with requirements contained in the application subsection (the A rule) for each rule.




Accept.


Affirmative: (17) Amrhyn, Bednarz, Bleakley, Bowmer, Clapp, Crawford, Drzewiecki, Emery, Engdahl,Gunter, Hall, Hooper, Komassa, Marne, Neubauer, Slavin, White

Negative: (0)

Abstention: (0)

New Text

CP3377


Also Part: 2 Section: 23 232 Table 232-1 Footnote 26 SC4

Submitter

Nelson Bingel

Proposed Change:

Apply the existing Footnote 26 to row 2 and 3 of Table 232-1.

26 When designing a line to accommodate oversized vehicles, these clearance values shall be increased bythe difference between the known height of the oversized vehicle and 4.3 m (14 ft).

Duplicate Footnote 26 to Table 232-1 as Footnote 10 to Table 232-2 and apply it to rows 1a, 1b, 1c, and 2a.

10 When designing a line to accommodate oversized vehicles, these clearance values shall be increased bythe difference between the known height of the oversized vehicle and 4.3 m (14 ft.).

Supporting Comment

Footnote 26 to Table 232-1 needs to be added to additional rows and to Table 232-2, since other clearancecategories, such as roads in some manufacturing areas, can have oversized equipment like forklifts or largehauler trucks intended to be under the line on a regular basis.


Accept as modified.

Revise row 4 in Table 232-1, row 1c as shown in Table 232-2, and add new Footnote 3 to Table 232-2.

Table 232-1, row 4



4. Other land traversed by vehicles, such as cultivated, grazing, forest, orchards, industrial areas, commercialareas, etc. 26

Table 232-2, row 1c

c. Other land traversed by vehicles such as cultivated land, grazing land, forest, orchard, industrial areas,commercial areas, etc.3

New Footnote 3 in Table 232-2

3 When designing a line to accommodate oversized vehicles, these clearance values shall be increased by thedifference between the known height of the oversized vehicle and 4.3 m (14 ft).



Negative: (0)

Abstention: (0)

New Text

CP3075


Submitter

Mickey Gunter

Proposed Change

Add new Footnote 3 (currently not used) to row 1c category of Table 232-2 as follows:

c. Other land traversed by vehicles such as cultivated land, grazing land, forest, orchard, etc. 3

3When designing a line to accommodate oversized vehicles, these clearance values shall be increased by thedifference between the known height of the oversized vehicle and 14 ft.

Supporting Comment

Existing Footnote 3 is currently not used in Table 232-2. Adding Footnote 3 to row 1c category of Table 232-2 will make it consistent with Footnote 26 in Table 232-1, which will give the field user guidance on how tohandle oversized vehicles that you typically find in cultivated land, etc.






See CP3377.



Negative: (0)

Abstention: (0)

New Text

CP3253


Submitter

James T. Collins

Proposed Change

Add new Footnote 3 (currently not used) to row 1c category of Table 232-2 as follows:

c. Other land traversed by vehicles such as cultivated land, grazing land, forest, orchard, etc. 3

3When designing a line to accommodate oversized vehicles, these clearance values shall be increased by thedifference between the known height of the oversized vehicle and 14 ft.

Supporting Comment

Existing Footnote 3 is currently not used in this Table 232-2. Adding Footnote 3 to row 1c category ofTable 232-2 will make it consistent with Footnote 26 in Table 232-1, which will give the field user guidanceon how to handle oversized vehicles that you typically find in cultivated land, etc.




See CP3377.





Negative: (0)

Abstention: (0)

Deleted Text

CP3469


Submitter

Subcommittee 4

Proposed Change

Delete Footnote 8 and add a NOTE to bottom of Table 232-2 (ft).

Table 232-2—Vertical clearance of equipment cases, support arms, platforms, braces and unguarded rigid live parts aboveground, roadway, or water surfaces 8

(Voltages are phase to ground for effectively grounded circuits and those other circuits where all ground faults are cleared by promptly de-energizing the faulted section, both initially and following subsequent breaker

operations. See the definitions section for voltages of other systems.See Rules 232B1, 232B3, 232C1a, and 232D4.)

8The clearance values shown in this table are computed by adding the applicable Mechanical and Electrical(M & E) value of Table A-1 to the applicable Reference Component of Table A-2a of Appendix A.

NOTE: The clearance values shown in this table are computed by adding the applicable Mechanical andElectrical (M & E) value of Table A-1 to the applicable Reference Component of Table A-2a ofAppendix A.

Supporting Comment

By definition footnotes have the same force and effect required or allowed by the rule that specifies the useof a table. Footnote 8 contains references to Appendix A. Appendices are not part of the Code and is includedfor information only. A note added to the bottom of the table is more appropriate.


Accept.



Negative: (0)

Abstention: (0)



New Text

CP3157


Submitter


Proposed Change

Revise Footnote 1 to Table 232-4 as follows:

1 Limited by Rule 232D4. Increase clearance due to elevation as specified in Rule 232C1b.

Supporting Comment

Table 232-4 (and Rule 232D3a) increase clearance for elevations greater than 1500 ft. When limited by Rule232D4 it is appropriate to use an increase in clearance for elevations greater than 3300 ft as specified in Rule232C1b. This change to the footnote removes confusion as to which elevation should be used when theclearance is limited by Rule 232D4.


Accept as modified.

Revise Footnote 1 and 2 to Table 232-4 as follows:

1 Shall be not less than that required Limited by Rule 232D4, including the altitude correction for linesabove 1000 m (3300 ft) elevation as specified in Rule 232C1b. 2 Shall be not less than that required Limited by Rules 232A and 232B.



Negative: (0)

Abstention: (0)

New Text

CP3134




Submitter

Bruce Freimark

Proposed Change

Revise the heading of Table 232-4 as indicated:

Table 232-4—Electrical component of clearance in Rule 232D3a[Add 3% for each 300 m (1000 ft) or portion thereof in excess of 450 m (1500 ft) above mean sea level;

NOTE: See examples presented under Rule 232D3b. Increase clearance to limit electrostatic effects in accordance with Rule 232D3c.]

Supporting Comment



Accept as modified.


Table 232-4—Electrical component of clearance in Rule 232D3a[This clearance shall be increased Add at the rate of 1% per 100 m (330 ft) 3% for each 300 m (1000 ft) in

excess of 450 m (1500 ft) above mean sea level. Increase clearance to limit electrostatic effects in accordance with Rule 232D3c.]


Affirmative: (17) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Drzewiecki, Emery, Gunter, Henry,Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White, Young


Abstention: (0)

Explanation of Vote


New Text

CP3061




Submitter

Ewell T. Robeson

Proposed Change

Create a new Rule 233B2 as indicated:

B. Horizontal clearance

1. Clearance requirements

The horizontal clearance between crossing or adjacent wires, conductors, or cables carried ondifferent supporting structures shall be not less than 1.50 m (5 ft). For voltages between the wires,conductors, or cables exceeding 22 kV, additional clearance of 10 mm (0.4 in) per kV over 22 kVshall be provided.

EXCEPTION: The horizontal clearance between anchor guys of different supporting structuresmay be reduced to 150 mm (6 in) and may be reduced to 600 mm (2 ft) between other guys, spanwires, and neutral conductors meeting Rule 230E1.

2. For voltages exceeding 50 kV, the additional clearance specified in Rule 233B1 shall be increased3% for each 300 m (1000 ft) or portion thereof in excess of 1000 m (3300 ft) above mean sea level.

23. Alternate clearances for voltages exceeding 98 kV ac to ground or 139 kV dc to ground

The clearances specified in Rule 233B1 may be reduced for circuits with known switching-surgefactors, but shall be not less than the alternate clearance derived from the computations required inRules 235B3a and 235B3b.

Supporting Comment

Rule 233C, which provides the vertical clearance requirements between wires carried on different supportingstructures, contains an adjustment for high elevations in Rule 233C2b.

Rule 233B, which provides the horizontal clearance requirements between wires carried on differentsupporting structures, does not contain an adjustment for high elevations. This CP will rectify this omission.


Accept as modified.

Create a new Rule 233B2 as indicated:



The horizontal clearance between crossing or adjacent wires, conductors, or cables carried ondifferent supporting structures shall be not less than 1.50 m (5 ft). For voltages between the wires,conductors, or cables exceeding 22 kV, additional clearance of 10 mm (0.4 in) per kV over 22 kVshall be provided.




2. For voltages exceeding 50 kV, the additional clearance specified in Rule 233B1 shall be increasedat the rate of 1% per 100 m (330 ft) in excess of 1000 m (3300 ft) above mean sea level.

23. Alternate clearances for voltages exceeding 98 kV ac to ground or 139 kV dc to ground




Negative: (0)

Abstention: (0)

New Text

CP3076


Submitter

Mickey Gunter

Proposed Change




The horizontal clearance between crossing or adjacent wires, conductors, or cables carried ondifferent supporting structures shall be not less than 1.50 m (5 ft). For voltages between the wires,conductors, or cables exceeding 22 kV, additional clearance of 10 mm (0.4 in) per kV in excess ofover 22 kV shall be provided.

The voltage between line conductors of different circuits shall be the greater of the following:

a. The phasor difference between the conductors involved

NOTE: A phasor relationship of 180° is considered appropriate where the actual phasorrelationship is unknown.

b. The phase-to-ground voltage of the higher-voltage circuit



Supporting Comment

Since this rule deals with the clearance between conductors, similar language as in Rule 235A3 needs to beadded so as to give guidance on how to calculate the voltage between conductors of different circuits as isrequired in Rule 233B1.

Also the word crossing is not appropriate for horizontal conductors and should be deleted, and replacing“over” with “in excess of” will be consistent with the language added in the 2007 Code.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3077


Submitter

Mickey Gunter

Proposed Change




The horizontal clearance between crossing or adjacent wires, conductors, or cables carried ondifferent supporting structures shall be not less than 1.50 m (5 ft). For voltages between the wires,conductors, or cables exceeding 22 kV, additional clearance of 10 mm (0.4 in) per kV over inexcess of 22 kV shall be provided.

Supporting Comment

The use of the verbiage “over” was replaced with “in excess of” in the 2007 Code and revising it in this rulewill make it consistent with other rules and tables. Also it is hard to image that two horizontal lines arecrossing each other.






See CP3076.



Negative: (0)

Abstention: (0)

Revised Text

CP3159


Submitter


Proposed Change



a. The horizontal clearance between crossing or adjacent wires, conductors, or cables carried ondifferent supporting structures shall be not less than 1.50 m (5 ft). For voltages between the wires,conductors, or cables exceeding 22 kV, additional clearance of 10 mm (0.4 in) per kV over 22 kVshall be provided. All clearances for lines over 50 kV shall be based on the maximum operatingvoltage.

b. For voltages exceeding 50 kV, the additional clearance specified in Rule 233B1a shall be increased3% for each 300 m (1000 ft) in excess of 1000 m (3300 ft) above mean sea level.

EXCEPTION: The horizontal clearance between anchor guys of different supporting structures maybe reduced to 150 mm (6 in) and may be reduced to 600 mm (2 ft) between other guys, span wires,and neutral conductors meeting Rule 230E1.

Supporting Comment

The requirements for greater than 50 kV and for elevation should be added for consistency with otherclearance rules throughout Section 23.




Accept as modified.



a. The horizontal clearance between crossing or adjacent wires, conductors, or cables carried ondifferent supporting structures shall be not less than 1.50 m (5 ft). For voltages between the wires,conductors, or cables exceeding 22 kV, additional clearance of 10 mm (0.4 in) per kV over 22 kVshall be provided. All clearances for lines over 50 kV shall be based on the maximum operatingvoltage.

b. For voltages exceeding 50 kV, the additional clearance specified in Rule 233B1a shall be increasedat the rate of 1% per 100 m (330 ft) in excess of 1000 m (3300 ft) above mean sea level.




Negative: (0)

Abstention: (0)

Revised Text

CP3254


Submitter

James T. Collins

Proposed Change




The horizontal clearance between crossing or adjacent wires, conductors, or cables carried ondifferent supporting structures shall be not less than 1.50 m (5 ft). For voltages between the wires,



conductors, or cables exceeding 22 kV, additional clearance of 10 mm (0.4 in) per kV in excess ofover 22 kV shall be provided.

The voltage between line conductors of different circuits shall be the greater of the following:

a. The phasor difference between the conductors involved

NOTE: A phasor relationship of 180° is considered appropriate where the actual phasorrelationship is unknown.

b. The phase-to-ground voltage of the higher-voltage circuit

When the circuits have the same nominal voltage, either circuit may be considered to be thehigher-voltage circuit.

Supporting Comment

The use of the verbiage “over” was replaced with “in excess of” in the 2007 Code and revising it in this rulewill make it consistent with other rules and tables. Also it is hard to image that two horizontal lines arecrossing each other.

Since this rule deals with the clearance between conductors, similar language as in Rule 235A3 needs to beadded so as to give guidance on how to calculate the voltage between conductors of different circuits as isrequired in Rule 233B1.




See CP3076.



Negative: (0)

Abstention: (0)

Revised Text

CP3391


Submitter

Nelson Bingel



Proposed Change


The horizontal clearance between crossing or adjacent wires, conductors, or cables carried on differentsupporting structures shall be not less than 1.50 m (5 ft). the vertical clearance required by Rule 233C1and Table 233-1 plus 1.0 m (3 ft). For voltages between the wires, conductors, or cables exceeding22 kV, additional clearance of 10 mm (0.4 in) per kV over 22 kV shall be provided.

EXCEPTION: The horizontal clearance between anchor guys of different supporting structures may bereduced to 150 mm (6 in) and may be reduced to 600 mm (2 ft) between other guys, span wires, andneutral conductors meeting Rule 230E1.

Supporting Comment

The present Code establishes a basic vertical clearance of 2 ft between items of the same type at crossings.Where the crossing items are not of the same type, the vertical clearance increases to:

4 ft (where power secondary is above communication)5 ft (where power primary is above communication)or 6 ft (where power is above trolley conductors).

The basic horizontal clearance of 5 ft includes an extra 3 ft to allow for differential movement in conductorsor cables of parallel lines supported on different supporting structures. This takes into account bothdifferential gust deflection on cables and conductors and differential deflection of the two differentsupporting structure systems.

However, the horizontal clearance fails to recognize the additional desired clearances where the potentialconflict is between power and communication or power and trolley conductors.

Therefore, it is appropriate to revise the horizontal clearances of Rule 233 to be 3 ft greater than that requiredfor vertical clearance by Table 233-1 (i.e., 5 ft for items of the same type next to one another, 7 ft for powersecondary next to communication, 8 ft for power primary next to communication, and 9 ft for power next totrolley conductors). Although the last three combinations are relatively rare, they do occur and should beappropriately recognized in the same manner as crossing clearances.


Reject.


Insufficient justification that the existing clearances are not adequate.


Affirmative: (16) Amrhyn, Bednarz, Bleakley, Crawford, Drzewiecki, Emery, Engdahl, Gunter, Henry,Hooper, Komassa, Marne, Slavin, Steiner, White, Young

Negative: (2) Neubauer, Clapp



Abstention: (0)

Explanation of Vote

Clapp: (Negative) The original Code requirements were set with the assumption that communication cablesand trolley contact conductors would not be located at the same level as supply conductors on an adjacentpole line. As a result, there is a clearance increment added for vertical clearances in Table 233-1 where powersecondary or primary is above (or below) communication of trolley contact conductors, but there is no suchdifferentiation for horizontal clearances between conductors and cables on adjacent pole lines.

Today, as a result of the need for additional cables and supply line circuits, and the ever-shrinking availabilityof rights-of-way, more separate pole lines are being placed in tandem in the same right-of-way. It is now nolonger unusual to see communication cables on one line (on a separate line or underbuilding another set ofcircuits) at the same level as supply line conductors.

Similarly, with the advent of commuter light rail raised above roadways on pylons, it is not unusual to seetrolley contact conductors at the same level as adjacent supply lines or communication lines.

As a result, it is now time to require the same differentiation between horizontal clearances as is used in Table233-1 for vertical clearances.

The present horizontal clearance requirement of 5 ft in Rule 233B1 is based upon the basic clearance of 2 ftused in Table 233-1 for clearances between the same class of items plus a 3 ft adder to recognize the additionalclearance required during storm loadings when the structures may deflect at different rates and gust-inducedwaves run up and down the conductors.

This clearance proposal would still require 5 ft for the majority of places where this rule applies, i.e., a powerline running along next to another power line.

In most cases, communication is attached directly to the pole and supply conductors are held away from thepole by crossarms. As a result, even though the clearance required between power and communication wouldbe increased with the proposed changes, they would rarely control placement of the pole lines.

In the case of overhead commuter light rail lines supported on pylons, this proposal would increase theclearances to supply line conductors running on adjacent power lines. However, this clearance is appropriate,since it is needed to get a bucket up between the lines to work on each type of facilities.

This proposal should be adopted.

Neubauer: (Negative) I agree in principle with Mr. Bingel’s supporting comments.

I also believe the NESC should address new conditions as they arrive. As rights-of way are becoming moredifficult to obtain, we are seeing more parallel lines. The necessary clearances should be addressed.

Because of this I supported this CP and voted not to reject.

Revised Text

CP3104




Submitter

Ewell T. Robeson

Proposed Change

Revise as indicated:

2. Alternate clearances for voltages exceeding for different circuits where one or both circuits exceed98 kV ac to ground or 139 kV dc to ground


Supporting Comment

The present title does not reflect that two circuits are involved and that only one circuit may qualify as being 98 kV ac to ground or 139 kV dc to ground


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3122


Submitter

Bruce Freimark

Proposed Change

Revise the Rule 233C2b as indicated:

b. For voltages exceeding 50 kV, the additional clearance specified in Rule 233C2a shall be increased3% for each 300 m (1000 ft) or portion thereof in excess of 1000 m (3300 ft) above mean sea level.



EXAMPLES:



Supporting Comment

While working with IEEE staffers on a computer application to automate the calculation of many of theNESC clearances, it became apparent that these individuals had not written the program as intended by theNESC. The addition of the proposed words should clarify the intent to all readers of the NESC.


Accept as modified.

Revise the Rule 233C2b as indicated:

b. For voltages exceeding 50 kV, the additional clearance specified in Rule 233C2a shall be increasedat the rate of 1% per 100 m (330 ft) 3% for each 300 m (1000 ft) in excess of 1000 m (3300 ft)above mean sea level.




Abstention: (0)

Explanation of Vote


New Text

CP3123

Part: 2 Section: 23 Rule: 233 C3b(2)

Submitter

Bruce Freimark

Proposed Change

Revise the Rule 233C3b(2) as indicated:



(2) The value of D calculated by Rule 233C3b(1) shall be increased 3% for each 300 m (1000 ft) orportion thereof in excess of 450 m (1500 ft) above mean sea level.

EXAMPLES:

i. At a conductor elevation between 450.1 m and 750 m (1501 ft and 2500 ft) the value of D shallbe multiplied by 1.03.

ii. At a conductor elevation between 750.1 m and 1050 m (2501 ft and 3500 ft) the value of Dshall be multiplied by 1.06.

Supporting Comment



Accept as modified.

Revise the Rule 233C3b(2) as indicated:

(2) The value of D calculated by Rule 233C3b(1) shall be increased at the rate of 1% per 100 m (330 ft)3% for each 300 m (1000 ft) in excess of 450 m (1500 ft) above mean sea level.




Abstention: (0)

Explanation of Vote


Revised Text

CP3297


Submitter

James T. Collins



Proposed Change

Make editorial corrections to Table 235-6. Revise footnote reference format to place the reference inside ofassociated punctuation.

Table 233-1 (m) and (ft):

Col. 2, Heading. Reference to Footnote 7 associated with communication guys.

Col. 3, Heading. Reference to Footnote 7 associated with supply guys.

Col. 5, Heading. Reference to Footnote 6 associated with 750 V.

Col. 1, Row 1. Reference to Footnote 7 associated with supply guys.

Col. 1, Row 2. Reference to Footnote 7 associated with communications guys.

Supporting Comment

Placements of footnote references in several code tables are incorrect in that they are placed after associatedpunctuation. For examples of proper placement of similar references, see Tables 234-1, 234-2, and 234-3.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3158


Submitter


Proposed Change

Revise Footnote 1 to Table 233-2 (ft and m) as follows:

1 Limited by Rule 233C3c. Increase clearance due to elevation as specified in Rule 233C2b.



Supporting Comment

Table 233-2 [and Rule 233C3b(1)] increase clearance for elevations greater than 1500 ft. When limited byRule 233C3c it is appropriate to use an increase in clearance for elevations greater than 3300 ft as specifiedin Rule 233C2b. This change to the footnote removes confusion as to which elevation should be used whenthe clearance is limited by Rule 233C3c.


Accept as modified.

Revise Footnote 1 to Table 233-2 (ft and m) as follows:

1 Shall be not less than that required Limited by Rule 233C3c, including the altitude correction for linesabove 1000 m (3300 ft) elevation as specified in Rule 233C2b.



Negative: (0)

Abstention: (0)

New Text

CP3135


Also Part: 2 Section: 23 233 Table 233-2 SC4

Submitter

Bruce Freimark

Proposed Change

Revise the heading of Table 233-2 (m and ft) as indicated:

mTable 233-2—

Clearance between supply wires, conductors, and cables in Rule 233C3b(1)[Add 3% for each 300 m or portion thereof in excess of 450 m above mean sea level.

NOTE: See the examples presented under Rule 233C3b(2).]



ftTable 233-2—

Clearance between supply wires, conductors, and cables in Rule 233C3b(1)[Add 3% for each 1000 ft or portion thereof in excess of 1500 ft above mean sea level.

NOTE: See examples presented under Rule 233C3b(2).]

Supporting Comment



Accept as modified.

Revise the heading of Table 233-2 (m and ft) as indicated:

mTable 233-2—

Clearance between supply wires, conductors, and cables in Rule 233C3b(1)(This clearance shall be increased Add 3% for each 300 m at the rate of 1% per 100 m

in excess of 450 m above mean sea level.)

ftTable 233-2—

Clearance between supply wires, conductors, and cables in Rule 233C3b(1)(This clearance shall be increased Add 3% for each 15oo ft at the rate of 1% per 330 ft

in excess of 1500 ft above mean sea level.)




Abstention: (0)

Explanation of Vote


New Text

CP3412




Submitter

Wade Shultz

Proposed Change

Add statement explain that two clearance conditions are to be satisfied.

234. Clearance of wires, conductors, cables, and equipment from buildings, bridges, railcars, swimming pools, and other installations

A. Application

In each of Rules 234B, 234C, and 234D, horizontal clearance requirements are specified for twoconditions: 1) the conductor without wind displacement (at rest), and 2) the conductor with winddisplacement. In each case, the clearance requirements for both conditions shall be satisfied.

1. Vertical and horizontal clearances (no wind displacement)

The vertical and horizontal clearances specified …

Supporting Comment

No additional requirement is imposed by this revision. This statement should be added to clarify that both oftwo conditions of horizontal clearance are required to be satisfied. It is often assumed by some users that thehorizontal clearance requirement is the default clearance (at rest) as presented in the tables. Unless the casualuser is careful in reading the entire rule, the requirement for the wind displaced clearance is often overlooked.The proposed introductory statement will make clear that both horizontal clearance requirements must besatisfied.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3380




Submitter

Nelson Bingel

Proposed Change

Revise rule to include clearance to midspan poles in skip-span construction.

B. Clearances of wires, conductors, and cables from other supporting structures

Wires, conductors, or cables of one line passing near a lighting support, traffic signal support, or asupporting structure of a second line, or a midspan pole in skip-span construction, without beingattached thereto, shall have clearance from any part of such structure not less than the following:

Supporting Comment

There is a need to directly identify the clearance requirements in Rule 234B as being applicable forclearances to midspan poles in skip-span construction. The present rule is worded to only apply to poles ofanother line. There is an old IR that says to use 234B, but this needs to be obvious.


Accept as modified.

Revise rule 234B to include clearance to intermediate poles in skip-span construction and add a note.


Wires, conductors, or cables of one line passing near a lighting support, traffic signal support, or asupporting structure of a second line, or intermediate poles in skip-span construction, without beingattached thereto, shall have clearance from any part of such structure not less than the following:

NOTE: Skip-span construction: Lines where upper conductors are not attached to intermediate poles.



Negative: (0)

Abstention: (0)

Revised Text

CP3255

Part: 2 Section: 23 Rule: 234 B1a



Submitter

James T. Collins

Proposed Change

Revise the clearance value in Rules 234B1a to conform to Rule 230A4, rounding of calculation results, asfollows:


1. Horizontal clearances

a. A horizontal clearance, without wind, of 1.50 m (5.0 ft) for voltages up to 50 kV.

Supporting Comment

This change will match the horizontal clearance values in the tables that are specified with one decimalplace.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3295


Submitter

James T. Collins

Proposed Change

Add a new note to Rule 234C1 as follows:

1. Vertical and horizontal clearances

a. Clearances



Unguarded or accessible wires, conductors, cables, or rigid live parts may be located adjacentto buildings, signs, billboards, chimneys, radio and television antennas, tanks, and otherinstallations and any projections therefrom. The vertical and horizontal clearances of suchrigid and nonrigid parts shall be not less than the values given in Table 234-1 when at restunder the conditions specified in Rule 234A1. These facilities may be installed beside, over orunder buildings, building projections and other installations, as illustrated in Figures 234-1(a),234-1(b), and 234-1(c).

NOTE: A flag and flag pole is considered to be a type of sign.

Supporting Comment

Flags and flag poles are considered to be a type of sign and should be referenced as such in this rule.




See CP3124.



Negative: (0)

Abstention: (0)

New Text

CP3376

Part: 2 Section: 23 Rule: 234 C3c

Submitter

Nelson Bingel

Proposed Change

Add the following EXCEPTION to Rule 234C3c.

EXCEPTION: For open supply circuits of 0 to 750 V and supply cables of all voltages meeting Rule230C.1, 2, or 3, this clearance may be reduced to 25 mm (1 in). No clearance is specified for phaseconductors of such cables where they are physically restrained by a suitable bracket from abrasionagainst the pole.



Supporting Comment

Rule 234C3c was recently changed to directly specify 3 in as the clearance a wire attached to a building mustbe held off the surface. Previously, the clearance was required to be not less than that required by Table 235-6 and Rule 235I for clearance to supports. This made the user have to go elsewhere in the Code to find therequirement. Unfortunately, Footnote 8 of Table 235-6, which recognizes that the secondary attachment formultiplex cables to poles or houses does not always give a full 3 in of clearance, was not also transferred withthe 3 in requirement. This EXCEPTION to the 3 in needs to be brought into this rule.


Accept as modified.

Add the following exception to Rule 234C3c.

EXCEPTION: For open supply circuits of 0 to 750 V and supply cables of all voltages meeting Rule230C1, 2, or 3, the clearance at the point of attachment may be reduced to 25 mm (1 in). No clearance isspecified for phase conductors of such cables where they are physically restrained by a suitable bracketfrom abrasion against the served structure.



Negative: (0)

Abstention: (0)

New Text

CP3406

Part: 2 Section: 23 Rule: 234 C3d

Submitter

Robert Molde

Proposed Change

d. Service-drop conductors, including drip loops, shall have a clearance of not less than the following:

(1) 3.0 m (10 ft) vertical clearance from the highest point of roofs, balconies, porches, or attacheddecks over which they pass. 3.0 m (10 ft) vertical clearance from the highest point of selfcontained spas or hot tubs with a maximum width, length or diameter of 96 in.

Supporting Comment

It is common for home owners to install backyard self-contained spas/hot tubs under existing overhead utility



service conductors. Often the only remedy to avoid this conflict is to re-install the service conductorsunderground. Per the IEEE NESC Handbook, 6th Edition, page 398, “…Spas, whirlpools, hot tubs, Jacuzzis,and similar installations that are not suitable for swimming are not considered as swimming pools and are notcovered by Rule 234E….” The reason for the higher clearance requirements for pools is to protect the user ofskimmer poles or rescue poles from contacting energized overhead conductors with theses devices. Spas andhot tubs due to their much smaller size do not typically require the use of these devices.

Although we are not aware of industry size limits on spas or hot tubs they are typically sized 8 ft x 8 ft orsmaller. Spa or hot-tub covers normally have hinged sections that fold-up. It seems unlikely that someonewould hold a folded spa cover longer than 8 ft vertically above the top of a spa or hot tub.


Reject.


See CP3465.



Negative: (0)

Abstention: (0)

Revised Text

CP3256

Part: 2 Section: 23 Rule: 234 C3d(1)

Submitter

James T. Collins

Proposed Change

Revise Rule 234C3d(1) as follows:

d. Service-drop conductors, including drip loops shall have a clearance of not less than the following:

(1) 3.0 m (10 ft) vertical clearance from the highest point of roofs, balconies, porches, or attacheddecks over which they pass.

EXCEPTION 1: For clearances above railings, walls, or parapets around balconies, decks, orroofs, use the clearances required for Table 234-1, row 1b(1). For such clearances where anoutside stairway exists to provide access to such balconies, decks, or roofs, use the clearancesrequired for Table 234-1, row 2b(2).



EXCEPTION 2: Where the voltage between conductors meeting Rule 230D does not exceed300 V, or where the voltage of cables meeting Rule 230C2 or 230C3 does not exceed 750 V, orwhere the cable meets Rule 230C1, and the roof, or balcony, porch, or attached deck is notreadily accessible, the clearance over the roof, or balcony, porch, or attached deck includingthe drip loop shall be not less than either of the following:

(a) 900 mm (3 ft)

(b) 457 mm (18 in) for a horizontal distance of 1.8 m (6 ft) from an approved raceway orsupport located not more than 1.2 m (4 ft) from the edge of the roof and not less than 900mm (3 ft) for the remainder of the horizontal distance that the cable or conductor passesover the roof or balcony.

Supporting Comment

EXCEPTION 1 was added to mirror Footnote 14 of Table 234-1 that was added in the 2007 Code. Thisfootnote should also be applicable to service drops passing over balconies or decks attached to a building.Since porches and decks are generally accessible, this language needs to be deleted from the exceptions.




See CP3079.



Negative: (0)

Abstention: (0)

New Text

CP3079

Part: 2 Section: 23 Rule: 234 C3d(1)

Submitter

Mickey Gunter

Proposed Change

Revise Rule 234C3d(1) as follows:



d. Service-drop conductors, including drip loops shall have a clearance of not less than the following:

(1) 3.0 m (10 ft) vertical clearance from the highest point of roofs, balconies, porches, or attacheddecks over which they pass

EXCEPTION 1: For clearances above railings, walls, or parapets around balconies, decks, orroofs, use the clearances required for row 1b(1), Table 234-1. For such clearances where anoutside stairway exists to provide access to such balconies, decks, or roofs, use the clearancesrequired for row 2b(2), Table 234-1.

EXCEPTION 2: Where the voltage between conductors meeting Rule 230D does not exceed300 V, or where the voltage of cables meeting Rule 230C2 or 230C3 does not exceed 750 V, orwhere the cable meets Rule 230C1, and the roof or, balcony, porch, or attached deck is notreadily accessible, the clearance over the roof or, balcony, porch, or attached deck includingthe drip loop shall be not less than either of the following:

(a) 900 mm (3 ft)

(b) 457 mm (18 in) for a horizontal distance of 1.8 m (6 ft) from an approved raceway orsupport located not more than 1.2 m (4 ft) from the edge of the roof and not less than 900mm (3 ft) for the remainder of the horizontal distance that the cable or conductor passesover the roof or balcony

Supporting Comment

EXCEPTION 1 was added to mirror footnote 14 of Table 234-1 that was added in the 2007 Code. Thisfootnote should also be applicable to service drops passing over balconies or decks attached to a building.

The language “porch or attached deck” was deleted from the existing exception because porches and decksare generally accessible and not appropriate in new EXCEPTION 2.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3465

Part: 2 Section: 23 Rule: 234 E1



Submitter

Subcommittee 4

Proposed Change

Add a new note at the end of the rule after the EXCEPTION 2 to Rule 234E1.

NOTE: For NESC clearance purposes, spas (including whirlpools, hot-tubs, jacuzzis, or other similarinstallations not suitable for swimming) are not considered as swimming pools covered by rule 234E,Table 234-3. Note that this rule and table refers to swimming areas and swimming pools. Table 234-3clearances allow for use of skimmer and rescue poles.

Spas, etc., not suitable for swimming, are usually installed as part of a building or as a similarinstallation. Clearances for such installations are found in Table 234-1. Vertical clearance should befrom the highest point of the installation upon which people can stand. See part 1, buildings, in Table234-1 for installations that are part of buildings, such as a raised spa on an open deck. See part 2, otherinstallations, in Table 234-1 for free-standing installations.

For portable wading pools see Table 232-1.

Supporting Comment

This was prepared in response to CP3406 and addresses IR 521.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3146

Part: 2 Section: 23 Rule: 234 Figure 234-4(b)

Submitter

Robert Molde



Proposed Change

Revise Figure 234-4(b) so that the vertical clearance requirements surrounding the grain bins are referencedto grade instead of to the grain bins. Please see the attached proposed revision of Figure 234-4(b).

Supporting Comments

The clearances for grain bins from Rule 234F2 are diagrammed in Figure 234-4(b). The clearancerequirements both above and surrounding the grain bins are referenced to the grain bins themselves and areindependent of any surrounding variations in ground elevation until the area where vertical clearancerequired by Rule 232 aboveground, roadway, etc., is reached.

The clearances intended by Rule 234F2 and Figure 234-4(b) are achieved when the surrounding grade isrelatively flat, but may not be achieved where there is a significant variation in grade surrounding the grainbins. The intention of this Change Proposal is to reference the intended clearances to the surrounding groundelevation and therefore maintain the intended clearances that would be achieved if the surrounding groundelevation were level.

Interestingly, the NESC Handbook, 6th Edition, published by Standards Information Network IEEE Press,has an extensive discussion of this rule and figure. Figure H-234-4(b) on page 404 of the Handbook showsthat the vertical clearance line adjacent to the grain bin and extending out distance “H” should follow thegrade level. However, this is not what is shown in NESC Figure 234-4(b). This Change Proposal wouldagree with the Handbook by having the required vertical clearance (V + 18 ft) measured from the grounduntil the horizontal distance “H” is reached. This Change Proposal then goes beyond the Handbook andchanges the areas of 1.5:1.0 sloped clearances so that they are also referenced from the ground. Thismaintains the clearances in the present NESC as they would be over level ground. Once calculated for agiven location, the required clearance is easily measured because it is measured from the ground.

In redrawing Figure 234-4(b) for this Change Proposal, an inconsistency between the elevation and planviews of the existing figure was eliminated. In the present figure, the plan view shows the sloped clearancearea on the non-loading side of the grain bin beginning at the side of the grain bin, while the elevation viewshows the sloped clearance area on the non-loading side of the grain bin beginning at an undefined distanceaway from the grain bin. In this Change Proposal the sloped clearance area on the non-loading side of thegrain bin is shown beginning at the grain bin as in the plan view of the existing Figure.

In the redrawn Figure 234-4(b) the plan view was shifted to the right so that it aligns vertically with theelevation view per common drafting practice.

In summary, this Change Proposal amends Figure 234-4(b) so that the required clearances surrounding agrain bin filled by portable augers, conveyors, or elevators are measured from the surrounding groundinstead of a being referenced from the grain bin itself. This is consistent with other areas of the NESC whererequired vertical clearances are measured from ground, roadway, or other surfaces. It also makes theclearance envelope conform to the terrain as it does in other parts of the NESC and permits requiredclearances to be measured directly from the ground.




Accept as modified.

Revise Figure 234-4(b) so that the vertical clearance requirements surrounding the grain bins are referencedto grade instead of to the grain bins. Please see the attached proposed revision of Figure 234-4(b).

Replace the letter V with B and H with A and modified figured as shown.

Add under V and H: D is a variable horizontal dimension.

Add labels “Follows the ground slope” and “Flat” above the figure.




Affirmative: (18) Amrhyn, Bednarz, Bleakley, Bowmer, Clapp, Crawford, Drzewiecki, Emery, Engdahl,Gunter, Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White, Young

Negative: (0)

Abstention: (0)

Follows the ground slope Flat



Revised Text

CP3257

Part: 2 Section: 23 234 Figure 234-4(b)

Submitter

James T. Collins

Proposed Change

Redraw Figure 234-4(b) for consistency and ease of understanding.

Supporting Comment

The current drawing does not follow basic engineering drawing and drafting rules and therefore allowedinconsistency to creep in. These reasons created more confusion in trying to understand the rule.




See CP3146.



Vote on Subcommittee 4 Recommendation


Negative: (0)

Abstention: (0)

New Text

CP3125

Part: 2 Section: 23 234 G2

Submitter

Bruce Freimark

Proposed Change

Revise the Rule 234G2 as indicated:

2. For voltages exceeding 50 kV, the additional clearance specified in Rule 234G1 shall be increased3% for each 300 m (1000 ft) or portion thereof in excess of 1000 m (3300 ft) above mean sea level.

EXAMPLES:

(a) At a conductor elevation between 1000.1 m and 1300 m (3301 ft and 4300 ft) the additionalclearance specified in Rule 234G1 are multiplied by 1.03.

(b) At a conductor elevation between 1300.1 m and 1600 m (4301 ft and 5300 ft) the additionalclearance specified in Rule 234G1 are multiplied by 1.06.

Supporting Comment



Accept as modified.

Revise the Rule 234G2 as indicated:

2. For voltages exceeding 50 kV, the additional clearance specified in Rule 234G1 shall be increasedat the rate of 1% per 100 m (330 ft) 3% for each 300 m (1000 ft) in excess of 1000 m (3300 ft)above mean sea level.






Abstention: (0)

Explanation of Vote


New Text

CP3126

Part: 2 Section: 23 234 H3b

Submitter

Bruce Freimark

Proposed Change

Revise the Rule 234H3b as indicated:

b. The value of D shall be increased 3% for each 300 m (1000 ft) or portion thereof in excess of 450 m(1500 ft) above mean sea level.

EXAMPLES:

(1) At a conductor elevation between 450.1 m and 750 m (1501 ft and 2500 ft) the value of D shallbe multiplied by 1.03.

(2) At a conductor elevation between 750.1 m and 1050 m (2501 ft and 3500 ft) the value of Dshall be multiplied by 1.06.

Supporting Comment



Accept as modified.

Revise the Rule 234H3b as indicated:



b. The value of D shall be increased at the rate of 1% per 100 m (330 ft) 3% for each 300 m (1000 ft)in excess of 450 (1500 ft) above mean sea level.




Abstention: (0)

Explanation of Vote


Deleted Text

CP3057

Part: 2 Section: 23 234 Table 234-1

Submitter

Ewell Robeson

Proposed Change

Delete Footnote 11 of Table 234-1, m and ft.

11 Where available space will not permit this value, the clearance may be reduced to 7.0 ft for conductorslimited to 8.7 kV to ground.

Supporting Comment

Clearances should be based on voltage, type cable or conductor, and activity, not available space (seeAppendix A, Uniform system of clearances adopted in the 1990 Edition). If a conductor at 7.2 kV is unsafeat rest at less than 7.5 ft from a building, then it is certainly unsafe at 7.0 ft; available space should have noaffect on whether something is safe or not. There are many overhead construction alternatives to obtain theproper clearance if space is not available; one could even argue that underground is an option when it comesto safety. Whether an area has “available” space or not can be highly subjective and ambiguous.


Accept.





Negative: (0)

Abstention: (0)

Revised Text

CP3058


Submitter

Ewell Robeson

Proposed Change


Unguarded

rigid live

parts, over

750 V to

22 kV;

ungrounded

equipment

cases,

750 V

to 22 kV;

ungrounded guys

insulated according to


exposed to

over 750 V

to 22 kV 5

Supporting Comment



Accept as modified.



Revise Table 234-1 column 6 category and add footnote 16 as follows:

Unguarded

rigid live

parts, over

750 V to

22 kV;

ungrounded

equipment

cases,

750 V

to 22 kV;

ungrounded portions of

guys meeting

Rules 215C5 and 279A1

exposed to

over 750 V

to 22 kV 5, 16




Negative: (0)

Abstention: (0)

Revised Text

CP3059


Submitter

Ewell Robeson

Proposed Change




Unguarded

rigid live parts,

0 to 750 V;

noninsulated

communication

conductors;

ungrounded

equipment

cases, 0 to

750 V; and

ungrounded guys insulated

according to


exposed to

open supply

conductors of

over 300 V to

750 V 5

Supporting Comment



Accept as modified.


Unguarded

rigid live parts,

0 to 750 V;

noninsulated

communication

conductors;

ungrounded

equipment

cases, 0 to

750 V; and




guys meeting


exposed to

open supply

conductors of

over 300 V to

750 V 5, 16



Negative: (0)

Abstention: (0)

Revised Text

CP3060


Submitter

Ewell Robeson

Proposed Change


Insulated

communication

conductors and

cables; messengers;

overhead shield/

surge-protection

wires;

grounded guys;

ungrounded guys insulated

according to




exposed to

0 to 300 V 13

neutral

conductors meeting Rule

230E1; supply

cables meeting

Rule 230C1

Supporting Comment



Accept as modified.


Insulated

communication

conductors and

cables; messengers;

overhead shield/

surge-protection

wires;

grounded guys;



exposed to

0 to 300 V 13, 16

neutral

conductors

meeting Rule

230E1; supply

cables meeting

Rule 230C1





Negative: (0)

Abstention: (0)

New Text

CP3124


Also Part: 2 Section: 23 234 C

Submitter

Bruce Freimark

Proposed Change


C. Clearances of wires, conductors, cables, and rigid live parts from buildings, signs, billboards,chimneys, radio and television antennas, tanks, flagpoles and flags, banners, and other installationsexcept bridges

1. Vertical and horizontal clearances

a. Clearances

Unguarded or accessible wires, conductors, cables, or rigid live parts may be locatedadjacent to buildings, signs, billboards, chimneys, radio and television antennas, tanks,flagpoles and flags, banners, and other installations and any projections therefrom. Thevertical and horizontal clearances of such rigid and nonrigid parts shall be not less than thevalues given in Table 234-1 when at rest under the conditions specified in Rule 234A1.These facilities may be installed beside, over or under buildings, building projections andother installations, as illustrated in Figures 234-1(a), 234-1(b), and 234-1(c).

b. Horizontal clearances under wind displacement conditions

When the following conductors and cables are displaced from rest under the windconditions of Rule 234A2, horizontal clearances from such conductors or cables tobuildings, signs, billboards, chimneys, radio and television antennas, flagpoles and flags,banners, and other installations shall be not less than those shown below:



1 Does not include neutral conductors meeting Rule 230E1.See Footnotes 9 and 10 to Table 234-1.

Revise Table 234-1 as indicated to apply the present clearances for signs, chimneys, etc., to banners,flagpoles and flags as follows, also adding new Footnote 16:

16 It is presumed that a flag or banner is fully extended but that there is no deflection or displacement of the flagpoleor other supporting structure due to wind and that the conductors, cables, or rigid live parts are not displaced by thewind. The specified clearance is measured to the point of maximum displacement of the banner or flag towards theoverhead utility facility.

Supporting Comment

The NESC does not presently address clearances to flags, flagpoles, and banners. This clearance question hasoccurred occasionally at our utility. This situation should be addressed in the NESC to provide a standardizedmethod and clearances.

Note that the above change has the flag or banner fully extended, which would occur under a mild wind ofless than 20 mph. Such a wind has an effective pressure of approximately 1 psf, which should cause negligibledeflection of the supporting flagpole or displacement of the conductors away from the flag or banner.


Accept.



Negative: (0)

Abstention: (0)

Conductor or cable

Horizontal clearance required when displaced by wind

(m) (ft)

Open supply conductors, 0 to 750 V 1 1.1 3.5

230C2 cable, above 750 V 1.1 3.5

230C3 cable, above 750 V 1.1 3.5

Open supply conductors, over 750 V to 22 kV 1.4 4.5

2. Signs, chimneys, billboards, radio and television antennas, banners, flagpoles and flags, tanks, and other installations not classified as buildings or bridges 16



New Text

CP3397


Submitter

Nelson Bingel

Proposed Change

Revise Table 234-1 to add new Footnote 16 (Footnote 26 of Table 232-1) and add a new Footnote 16designator to the headings of row 1b(4).

16



16 When designing a line to accommodate oversized vehicles, these clearance values shall be increased by the difference between theknown height of the oversized vehicle and 14 ft.

Supporting Comment

Footnote 26 to Table 232-1 needs to be added to Tables 234-1 since other clearance categories, such as roadsin some manufacturing areas, can have oversized equipment like forklifts or large hauler trucks intended tobe under the line on a regular basis.


Accept as modified.

Revise Table 234-1 to add new Footnote 16 (Footnote 26 of Table 232-1) and add a new Footnote 16designator to the headings of row 1b(4).

Title of row of 1b(2)

(2) Over or under balconies, porches, decks, and roofs readily accessible to pedestrians 3

Title of row 1b(3)

(3) Over roofs, ramps, decks, and loading docks accessible to vehicles but not subject to truck traffic 6

Title of row 1b(4)

(4) Over roofs, ramps, decks, and loading docks accessible to truck traffic 6, 16



16 When designing a line to accommodate oversized vehicles, these clearance values shall be increased by the difference between theknown height of the oversized vehicle and 14 ft.



Negative: (0)

Abstention: (0)

16



Revised Text

CP3258

Part: 2 Section: 23 234 Table 234-1 Column 2

Submitter

James T. Collins

Proposed Change


Insulated

communication

conductors and

cables; messengers;

overhead shield/

surge-protection

wires;

grounded guys;


exposed to 0 to 300 V 13;

neutral

conductors

meeting Rule

230E1; supply

cables meeting

Rule 230C1

Supporting Comment

Rule 215C2 now requires all guys to be effectively grounded or insulated. Since we no longer haveungrounded guys, this category needs to be changed to reflect this. Also add “overhead shield/” to beconsistent with other tables (see Table 232-1).






See CP3060.



Negative: (0)

Abstention: (0)

Revised Text

CP3259


Submitter

James T. Collins

Proposed Change


Unguarded

rigid live parts,

0 to 750 V;

noninsulated

communication

conductors;

ungrounded

equipment

cases, 0 to

750 V; and

ungrounded insulated

guys exposed to

open supply

conductors of

over 300 V to

750 V 5



Supporting Comment





See CP3059.



Negative: (0)

Abstention: (0)

Revised Text

CP3260


Submitter

James T. Collins

Proposed Change


Unguarded

rigid live

parts, over

750 V to

22 kV;

ungrounded

equipment

cases, 750 V

to 22 kV;




exposed to

over 750 V

to 22 kV 5

Supporting Comment





See CP3058.


Affirmative: (17) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Drzewiecki, Emery, Engdahl, Gunter,Henry, Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White

Negative: (0)

Abstention: (0)

Deleted Text

CP3262

Part: 2 Section: 23 234 Table 234-1 Footnote 11

Submitter

James T. Collins

Proposed Change

Delete Footnote 11 of Table 234-1, m and ft.

11Where available space will not permit this value, the clearance may be reduced to 7.0 ft for conductorslimited to 8.7 kV to ground.

Supporting Comment

This CP is in response to IR 543.

Clearances should be based on voltage, type cable or conductor, and activity, not available space (seeAppendix A, Uniform system of clearances adopted in the 1990 Edition). If a conductor at 7.2 kV is unsafe



at rest at less than 7.5 ft from a building, then it is certainly unsafe at 7.0 ft; available space should have noaffect on whether something is safe or not. There are many overhead construction alternatives to obtain theproper clearance if space is not available; one could even argue that underground is an option when it comesto safety. Whether an area has “available” space or not can be highly subjective and ambiguous.




See CP3057.


Affirmative: (17) Amrhyn, Bednarz, Bleakley, Clapp, Crawford, Drzewiecki, Emery, Engdahl, Gunter,Henry, Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White

Negative: (0)

Abstention: (0)

Revised Text

CP3105


Submitter

Ewell Robeson

Proposed Change


13The anchor end of guys meeting insulated in accordance with Rules 279A1 and 215C5 may have the sameclearance as grounded guys.

Supporting Comment



Accept as modified.




13The portion of anchor guys below the lowest insulator meeting insulated in accordance with Rules 279A1and 215C5 may have the same clearance as grounded guys.



Negative: (0)

Abstention: (0)

Revised Text

CP3263


Submitter

James T. Collins

Proposed Change


13The anchor end of guys insulated in accordance with Rules 279A1 and 215C5 may have the sameclearance as grounded guys.

Supporting Comment

Rule 215C2 now requires all guys to be effectively grounded or insulated. Adding these specific rulereferences will clarify the rules to be met for an insulated guy.




See CP3105.



Negative: (0)

Abstention: (0)



New Text

CP3078


Submitter

Mickey Gunter

Proposed Change

Revise Table 234-1, Footnote 14 as follows:

14For clearances above railings, walls, or parapets around balconies, decks, or roofs, use the clearancesrequired for row 1b(1). For such clearances where an outside stairway exists to provide access to suchbalconies, decks, or roofs, use the clearances required for row 2b(2).

Supporting Comment

This footnote has always been confusing. As I remember the reason for this footnote was to allow a reducedclearance over a railing, parapet, etc., if the balcony, deck, etc., had access via an outside stairway such thatsomeone could access the balcony, deck, etc., from the stairway without having to climb over the railing,parapet, etc., then lesser clearances over the railings, parapets, etc., are allowed. Just because an outsidestairway exists, it doesn’t mean it is there to provide access. This language will clarify the intent of the rule.


Accept as modified.

Revise Rule 234C3d(2) and Table 234-1, Footnote 14, as follows:

Rule 234C3d(2)

(2) 900 mm (3 ft) in any direction from windows, doors, porches, decks, fire escapes, or similarlocations.

EXCEPTION 1: This does not apply to service-drop conductors meeting Rule 230C3 above the toplevel of a window.

EXCEPTION 2: This does not apply to windows that are not designed to open.






Negative: (0)

Abstention: (0)

Revised Text

CP3264


Submitter

James T. Collins

Proposed Change

Revise Table 234-1, Footnote 14, as follows:


Supporting Comment

This footnote has always been confusing. As I remember the reason for this footnote was to allow a reducedclearance over a railing, parapet, etc., if the balcony, deck, etc. had access via an outside stairway such thatsomeone could access the balcony, deck, etc., from the stairway without having to climb over the railing,parapet, etc., then lesser clearances over the railings, parapets, etc., are allowed. Just because an outsidestairway exists, it doesn’t mean it is there to provide access. This language will clarify the intent of the rule.




See CP3078.


Affirmative: (23) Amrhyn, Bednarz, Bleakley, Bowmer, Bullinger, Clapp, Crawford, Drzewiecki, Emery,Engdahl, Gill, Gunter, Hall, Henry, Hooper, Komassa, Marne, Neubauer, Reding, Slavin, Steiner, White,Young

Negative: (0)

Abstention: (0)



Revised Text

CP3296


Submitter

James T. Collins

Proposed Change


4The required clearances shall be to the closest approach of motorized signs, fully extended flags, or movingportions of installations covered by Rule 234C.

Supporting Comment

Flags and flag poles are considered to be a type of sign and should be referenced as such in this footnote.


Reject.


See CP3124.



Negative: (0)

Abstention: (0)

Revised Text

CP3106


Submitter

Ewell Robeson



Proposed Change



Supporting Comment



Accept as modified.


5Ungrounded guys and ungrounded The portion(s) of span guys between guy insulators and the portion(s) ofanchor guys above guy insulators shall have clearances based on the highest voltage to which they may beexposed due to a slack conductor or guy.



Negative: (0)

Abstention: (0)

Revised Text

CP3261


Submitter

James T. Collins

Proposed Change





Supporting Comment

Rule 215C2 now requires all guys to be effectively grounded or insulated. Since we no longer haveungrounded guys, this footnote needs to be changed to reflect this.

Adding the word “span” to guys will clarify the intent is for span guys, which makes it consistent withFootnote 14 of Table 232-1. Anchor guys are already covered in Footnote 13 of Table 234-1.




See CP3106.



Negative: (0)

Abstention: (0)

Deleted Text

CP3470


Submitter

Subcommittee 4

Proposed Change

Delete Footnote 12 and add a NOTE to bottom of Table 234-1.ft

Table 234-1—Clearance of wires, conductors, cables, and unguarded rigid live parts adjacent but not

attached to buildings and other installations except bridges 12 (Voltages are phase to ground for effectively grounded circuits and those other circuits where all ground faults

are cleared by promptly de-energizing the faulted section, both initially and following subsequent breaker operations. See the definitions section for voltages of other systems. Clearances are with no wind

displacement except where stated in the footnote below.See Rules 234C1a, 234C2, and 234H.)

12The clearance values shown in this table are computed by adding the applicable Mechanical and Electrical(M & E) value of Table A-1 to the applicable Reference Component of Table A-2b of Appendix A.



NOTE: The clearance values shown in this table are computed by adding the applicable Mechanical andElectrical (M & E) value of Table A-1 to the applicable Reference Component of Table A-2b of AppendixA.

Supporting Comment

By definition footnotes have the same force and effect required or allowed by the rule that specifies the useof a table. Footnote 12 contains references to Appendix A. Appendices are not part of the Code and isincluded for information only. A NOTE added to the bottom of the table is more appropriate.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3107


Submitter

Ewell Robeson

Proposed Change


Unguarded rigid

live parts, 0 to

750 V; noninsulated

communication

conductors; supply

cables of 0 to 750 V

meeting Rule

230C2 or 230C3 7,

ungrounded



equipment cases,

0 to 750 V;

ungrounded guys meeting Rules

279A1 and 215C5

exposed to open

supply conductors

over 300 V to

750 V 4

Supporting Comment



Accept as modified.

Revise Table 234-2 column 2 category and add a new Footnote 11 as follows:

Unguarded rigid

live parts, 0 to

750 V; noninsulated

communication

conductors; supply


meeting Rule

230C2 or 230C3 7,

ungrounded

equipment cases,

0 to 750 V;


guys meeting


exposed to open

supply conductors

over 300 V to

750 V 4, 11






Negative: (0)

Abstention: (0)

Revised Text

CP3108


Submitter

Ewell Robeson

Proposed Change


Unguarded

rigid live parts,

over 750 V to

22 kV,

ungrounded

equipment

cases, 750 V to

22 kV;



exposed to

open supply

conductors of

over 750 V to

22 kV 4

Supporting Comment





Accept as modified.


Unguarded

rigid live parts,

over 750 V to

22 kV,

ungrounded

equipment

cases, 750 V to

22 kV;



exposed to

open supply

conductors of

over 750 V to

22 kV 4, 11



Negative: (0)

Abstention: (0)

Revised Text

CP3265


Submitter

James T. Collins

Proposed Change




Unguarded rigid

live parts, 0 to

750 V; noninsulated

communication

conductors; supply


meeting Rule

230C2 or 230C3 7,

ungrounded

equipment cases,

0 to 750 V;


exposed to open

supply conductors

over 300 V to

750 V 4

Supporting Comment





See CP3107.



Negative: (0)

Abstention: (0)



Revised Text

CP3266


Submitter

James T. Collins

Proposed Change


Unguarded

rigid live parts,

over 750 V to

22 kV,

ungrounded

equipment

cases, 750 V to

22 kV;


exposed to

open supply

conductors of

over 750 V to

22 kV 4

Supporting Comment





See CP3108.





Negative: (0)

Abstention: (0)

Revised Text

CP3114


Submitter

Ewell Robeson

Proposed Change


4 Ungrounded guys and ungrounded Pportions of span guys between guy insulators shall have clearancesbased on the highest voltage to which they may be exposed due to a slack conductor or guy.

Supporting Comment



Accept as modified.


4 Ungrounded guys and ungrounded The portion(s) of span guys between guy insulators and the portion(s)of anchor guys above guy insulators shall have clearances based on the highest voltage to which they may beexposed due to a slack conductor or guy.



Negative: (0)

Abstention: (0)



Revised Text

CP3267


Submitter

James T. Collins

Proposed Change



Supporting Comment

Rule 215C2 now requires all guys to be effectively grounded or insulated. Since we no longer haveungrounded guys, this category needs to be changed to reflect this. Adding the word “span” to guys willclarify the intent is for span guys, which makes it consistent with Footnote 14 of Table 232-1.




See CP3114.



Negative: (0)

Abstention: (0)

Revised Text

CP3109




Submitter

Ewell Robeson

Proposed Change


Insulated

communication

conductors and

cables;

messengers;

overhead shield/

surge-protection

wires; grounded

guys;



exposed to

0 to 300 V 3;

neutral

conductors

meeting Rule

230E1; supply

cables meeting

Rule 230C1

Supporting Comment



Accept as modified.

Revise Table 234-3 column 2 category and add new Footnote 5 as follows:

Insulated

communication

conductors and



cables;

messengers;

overhead shield/

surge-protection

wires; grounded

guys;



exposed to

0 to 300 V 3, 5;

neutral

conductors

meeting Rule

230E1; supply

cables meeting

Rule 230C1




Negative: (0)

Abstention: (0)

Revised Text

CP3110


Submitter

Ewell Robeson

Proposed Change


Unguarded



rigid live parts,

0 to 750 V;

noninsulated

communication

conductors;

supply cables of

0 to 750 V

meeting Rule

230C2 or

230C3;

ungrounded

ungrounded guys meeting Rules

279A1 and 215C5

exposed to

open supply

conductors of

over 300 V to

750 V 3

Supporting Comment



Accept as modified.


Unguarded

rigid live parts,

0 to 750 V;

noninsulated

communication

conductors;

supply cables of

0 to 750 V

meeting Rule

230C2 or



230C3;



exposed to

open supply

conductors of

over 300 V to

750 V 3, 5



Negative: (0)

Abstention: (0)

Revised Text

CP3111


Submitter

Ewell Robeson

Proposed Change


Unguarded

rigid live

parts over

750 V to

22 kV;


Rules 279A1and 215C5

exposed to

over 750 V

to 22 kV 2



Supporting Comment



Accept as modified.


Unguarded

rigid live

parts over

750 V to

22 kV;



exposed to

over 750 V

to 22 kV 2, 5



Negative: (0)

Abstention: (0)

Revised Text

CP3268


Submitter

James T. Collins

Proposed Change


Insulated



communication

conductors and

cables;

messengers;

overhead shield/

surge-protection

wires; grounded

guys;


exposed to

0 to 300 V 3;

neutral

conductors

meeting Rule

230E1; supply

cables meeting

Rule 230C1

Supporting Comment

Rule 215C2 now requires all guys to be effectively grounded or insulated. Since we no longer haveungrounded guys, this category needs to be changed to reflect this. Also add “overhead shield/” to beconsistent with other tables (see Table 232-1).




See CP3109.



Negative: (0)

Abstention: (0)



Revised Text

CP3269


Submitter

James T. Collins

Proposed Change


Unguarded

rigid live parts,

0 to 750 V;

noninsulated

communication

conductors;

supply cables of

0 to 750 V

meeting Rule

230C2 or

230C3;

ungrounded insulated guys exposed to

open supply

conductors of

over 300 V to

750 V 3

Supporting Comment





See CP3110.





Negative: (0)

Abstention: (0)

Revised Text

CP3270


Submitter

James T. Collins

Proposed Change


Unguarded

rigid live

parts over

750 V to

22 kV;


exposed to

over 750 V

to 22 kV 2

Supporting Comment





See CP3111.





Negative: (0)

Abstention: (0)

Revised Text

CP3112


Submitter

Ewell Robeson

Proposed Change



Supporting Comment



Accept as modified.


2 Ungrounded guys and ungrounded The portion(s) of span guys between guy insulators and the portion(s)of anchor guys above guy insulators shall have clearances based on the highest voltage to which they may beexposed due to a slack conductor or guy.



Negative: (0)

Abstention: (0)



Revised Text

CP3271


Submitter

James T. Collins

Proposed Change



Supporting Comment

Rule 215C2 now requires all guys to be effectively grounded or insulated. Since we no longer haveungrounded guys, this category needs to be changed to reflect this. Adding the word “span” to guys willclarify the intent is for span guys, which makes it consistent with Footnote 14 of Table 232-1. Anchor guysare already covered in Footnote 3 of Table 234-3.




See CP3112.



Negative: (0)

Abstention: (0)

Revised Text

CP3113




Submitter

Ewell Robeson

Proposed Change


3Anchor guys meeting insulated in accordance with Rules 279A1 and 215C5 may have the same clearanceas grounded guys.

Supporting Comment



Accept as modified.


3The portion of Aanchor guys below the lowest insulator meeting insulated in accordance with Rules 279A1and 215C5 may have the same clearance as grounded guys.



Negative: (0)

Abstention: (0)

Revised Text

CP3272


Submitter

James T. Collins

Proposed Change


3Anchor guys insulated in accordance with Rules 279A1 and 215C5 may have the same clearance asgrounded guys.



Supporting Comment

According to Rule 215C2, guys are to be effectively grounded or insulated according to Rules 279A1 and215C5. Adding the reference to the specific rules for insulated guys will clarify the rules required for aninsulated guy.




See CP3113.



Negative: (0)

Abstention: (0)

Revised Text

CP3471


Submitter

Subcommittee 4

Proposed Change

Delete Footnote 1 and add a new NOTE 2 to bottom of Table 234-3.ft

Table 234-3—Clearance of wires, conductors, cables, and unguarded rigid live parts

over or near swimming pools 1 (Voltages are phase to ground for effectively grounded circuits and those other circuits where all ground faults

are cleared by promptly de-energizing the faulted section, both initially and following subsequent breaker operations. See the definitions section for voltages of other systems.

Clearances are with no wind displacement.See Rules 234E1, 234E2, and 234H4.)

1The clearance values shown in this table are computed by adding the applicable Mechanical and Electrical(M & E) value of Table A-1 to the applicable Reference Component of Table A-2b of Appendix A.

NOTE 1: A, B, and V are shown in Figure 234-3.



NOTE 2: The clearance values shown in this table are computed by adding the applicable Mechanical andElectrical (M & E) value of Table A-1 to the applicable Reference Component of Table A-2b of AppendixA.

Supporting Comment

By definition footnotes have the same force and effect required or allowed by the rule that specifies the useof a table. Footnote 1 contains references to Appendix A. Appendices are not part of the Code and areincluded for information only. A NOTE added to the bottom of the table is more appropriate.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3136


Submitter

Bruce Freimark

Proposed Change


Table 234-4—Electrical component of clearance of buildings, bridges, and other installations

[Add 3% for each 300 m (1000 ft) or portion thereof in excess of 450 m (1500 ft) above mean sea level. See Rules 234H3a and 234H3b.]

Supporting Comment





Accept as modified.


Table 234-4—Electrical component of clearance of buildings, bridges, and other installations

[This clearance shall be increased Add at the rate of 1% per 100 m (330 ft) 3% for each 300 m (1000 ft) in excess of 450 m (1500 ft) above mean sea level. See Rules 234H3a and 234H3b.]



Negative: (0)

Abstention: (0)

New Text

CP3081

Part: 2 Section: 23 235 B1b

Submitter

Mickey Gunter

Proposed Change

Revise Rule 235B1b as follows:

b. Clearance according to sags

The clearance at the supports of line conductors of the same or different circuits of Grade B or C inno case shall be not less than the values given by the following formulas, at a conductortemperature of 15 °C (60 °F), at final unloaded sag, no wind. For the purpose of this rule, the lineconductor clearances are between the surfaces of the conductors only, not including armor rods, tiewires, or other fasteners. and if the clearance at the support is fixed, the resultant calculation of sagshall be rounded down. The requirements of Rule 235B1a apply if they give a greater clearancethan this rule.

Supporting Comment

If the clearance at the support is fixed, the resultant calculation of sag (S) should be rounded down. If it isrounded up, then when using that value to calculate the clearance, the original fixed clearance that was usedto calculate S will become larger. Rounding S down will ensure that the clearance requirement will not belarger than the fixed clearance.



Example: Assume that the horizontal clearance at the support is fixed at 24 in for a conductor larger thanAWG No. 2 at a voltage of 24.94 kV and you need to calculate S. Using the formula in Rule 235B1b(2), S =51.2 = 52 in (rounded up as per Rule 230A4).

If you now use this sag value of 52 in to calculate or to justify the fixed clearance of 24 in, then with a sag of52 in, the “new” clearance will = 24.1 in = 25 in (rounded up as per Rule 232A4). This clearance is nowgreater than the fixed clearance of 24 in, thus violating the Code.

In the same example, if the S is rounded down instead of up, the resultant S = 51 in.

Using the rounded down value of 51 in, the clearance resultant calculation will = 23.97 in = 24 in (roundedup as per Rule 232A4) and there is no code violation.

Rule 230A1 was placed in the Code so that all clearance calculations would be rounded up, because all theformulas and rules that generate a clearance calculation state that the resultant clearance shall be not lessthan that required by the formula and rounding up assures this. However, when calculating sag with a fixedclearance, the sag should be rounded down to ensure that the fixed clearance has not increased.


Accept as modified.



The clearance at the supports of line conductors of the same or different circuits of Grade B or C inno case shall be not less than the values given by the following formulas, at a conductortemperature of 15 °C (60 °F), at final unloaded sag, no wind. For the purpose of this rule, the lineconductor clearances are between the surfaces of the conductors only, not including armor rods, tiewires, or other fasteners. The requirements of Rule 235B1a apply if they give a greater clearancethan this rule.

When using the applicable formula with a fixed conductor clearance to determine maximumallowable sag for that conductor clearance, the resultant maximum sag shall be rounded down.



Negative: (0)

Abstention: (0)

Revised Text

CP3273




Submitter

James T. Collins

Proposed Change



The clearance at the supports of line conductors of the same or different circuits of Grade B or C inno case shall be not less than the values given by the following formulas, at a conductortemperature of 15 °C (60 °F), at final unloaded sag, no wind. For the purpose of this rule, the lineconductor clearances are between the surfaces of the conductors only, not including armor rods, tiewires, or other fasteners. and if the clearance at the support is fixed, the resultant calculation of sagshall be rounded down. The requirements of Rule 235B1a apply if they give a greater clearancethan this rule.

Supporting Comment

If the clearance at the support is fixed, the resultant calculation of sag (S) should be rounded down. If it isrounded up, then when using that value to calculate the clearance, the original fixed clearance that was usedto calculate S will become larger. Rounding S down will ensure that the clearance requirement will not belarger than the fixed clearance.

Example: Assume that the horizontal clearance at the support is fixed at 24 in for a conductor larger thanAWG No. 2 at a voltage of 24.94 kV and you need to calculate S. Using the formula in Rule 235B1b(2), S =51.2 = 52 in (rounded up as per Rule 230A4).

If you now use this sag value of 52 in to calculate or to justify the fixed clearance of 24 in, then with a sag of52 in, the “new” clearance will = 24.1 in = 25 in (rounded up as per Rule 232A4). This clearance is nowgreater than the fixed clearance of 24 in, thus violating the Code. In the same example, if the S is roundeddown instead of up, the resultant S = 51 in.

Using the rounded down value of 51 in, the clearance resultant calculation will = 23.97 in = 24 in (roundedup as per Rule 232A4) and there is no Code violation. Rule 230A1 was placed in the Code so that allclearance calculations would be rounded up, because all the formulas and rules that generate a clearancecalculation state that the resultant clearance shall be not less than that required by the formula and roundingup assures this. However, when calculating sag with a fixed clearance, the sag should be rounded down toensure that the fixed clearance has not increased.




See CP3081.




Affirmative: (17) Amrhyn, Bednarz, Bleakley, Bowmer, Clapp, Crawford, Drzewiecki, Emery, Engdahl,Gunter, Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White

Negative: (0)

Abstention: (0)

New Text

CP3127

Part: 2 Section: 23 235 B1b(4)

Submitter

Bruce Freimark

Proposed Change

Revise the Rule 235B1b(4) (millimeters and inches) as indicated:

Millimeters

(4) The clearance for voltages exceeding 50 kV specified in Rules 235B1b(1) and (2) shall beincreased 3% for each 300 m or portion thereof in excess of 1000 m above mean sea level. Allclearances for lines over 50 kV shall be based on the maximum operating voltage.

EXAMPLES:

(a) At a conductor elevation between 1000.1 m and 1300 m the additional clearance specified inRules 235B1b(1) and (2) are multiplied by 1.03.

(b) At a conductor elevation between 1300.1 m and 1600 m the additional clearance specified inRules 235B1b(1) and (2) are multiplied by 1.06.

Inches

(4) The clearance for voltages exceeding 50 kV specified in Rules 235B1b(1) and (2) shall beincreased 3% for each 1000 ft or portion thereof in excess of 3300 ft above mean sea level. Allclearances for lines over 50 kV shall be based on the maximum operating voltage.

EXAMPLES:

(a) At a conductor elevation between 3301 ft and 4300 ft the additional clearance specified inRules 235B1b(1) and (2) are multiplied by 1.03.

(b) At a conductor elevation between 4301 ft and 5300 ft the additional clearance specified inRules 235B1b(1) and (2) are multiplied by 1.06.



Supporting Comment



Accept as modified.

Revise the Rule 235B1b(4) (millimeters and inches) as indicated:

Millimeters

(4) The clearance for voltages exceeding 50 kV specified in Rules 235B1b(1) and (2) shall beincreased at the rate of 1% per 100 m 3% for each 300 m in excess of 1000 m above mean sea level.All clearances for lines over 50 kV shall be based on the maximum operating voltage.

Inches

(4) The clearance for voltages exceeding 50 kV specified in Rules 235B1b(1) and (2) shall beincreased at the rate of 1% per 330 ft 3% for each 1000 ft in excess of 3300 ft above mean sea level.All clearances for lines over 50 kV shall be based on the maximum operating voltage.


Affirmative: (17) Amrhyn, Bednarz, Bleakley, Bowmer, Clapp, Crawford, Drzewiecki, Emery, Gunter,Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White, Young


Abstention: (0)

Explanation of Vote


New Text

CP3128

Part: 2 Section: 23 235 B3a(2)

Submitter

Bruce Freimark

Proposed Change

Revise the Rule 235B3a(2) as indicated:



(2) The value of D shall be increased 3% for each 300 m (1000 ft) or portion thereof in excess of 450 m(1500 ft) above mean sea level.

EXAMPLES:

(a) At a conductor elevation between 450.1 m and 750 m (1501 ft and 2500 ft) the value of D shallbe multiplied by 1.03.

(b) At a conductor elevation between 750.1 m and 1050 m (2501 ft and 3500 ft) the value of Dshall be multiplied by 1.06.

Supporting Comment



Accept as modified.

Revise the Rule 235B3a(2) as indicated:

(2) The value of D shall be increased at the rate of 1% per 100 m (330 ft) 3% for each 300 m (1000 ft)in excess of 450 m (1500 ft) above mean sea level.




Abstention: (0)

Explanation of Vote

Engdahl: (Negative) See negative comment on 3120.

Revised Text

CP3148

Part: 2 Section: 23 235 C

Submitter

Mickey Gunter



Proposed Change


C. Vertical clearance between line conductors at the support

All line wires, conductors, and cables located at different levels on the same supporting structureshall have vertical clearances not less than the following:

1. Basic clearance for conductors of same or different circuits

a. Between supply lines of the same or different circuits

The clearance requirements given in Table 235-5 shall apply to supply line wires,conductors, or cables of 0 to 50 kV attached to supports. No value is specified forclearances between conductors of the same circuit exceeding 50 kV, between cablesmeeting Rule 230C3 and neutral conductors meeting Rule 230E1 of the same utility, orbetween ungrounded open supply conductors 0 to 50 kV of the same phase and circuit ofthe same utility.

b. Between supply lines and communication lines

The clearance requirements given in Table 235-5 shall apply.

c. Between communication lines located in the communication space

The clearance and spacing requirements of Rule 235H shall apply to communication lineslocated in the communication space.

d. Between communication lines located in the supply space

The clearance requirements of Table 235-5 shall apply to communication lines located inthe supply space.

Supporting Comment

Removing the reference to line conductors will allow Table 235-5 to be used for both line conductors andlateral conductors; presently there is no clearance requirement specified between an open lateral supplyconductor and a communication line conductor. The vertical clearance at the support is basically voltagerelated only; not sag related. Rules 235C2a and b will take care of additional voltage related clearances andsag related clearances for line conductors.


Accept.



Negative: (0)



Abstention: (0)

Revised Text

CP3403


Submitter

Robert Molde

Proposed Change

Revise text to read as follows:

235. Clearance for wires, conductors, or cables carried on the same supporting structure

C. Vertical clearance between line conductors

All line wires, conductors, and cables located at different levels on the same supporting structureshall have vertical clearances not less than the following:

1. Basic clearance for conductors of same or different circuits at the support

(No change)…

2. Additional clearances

Greater clearances than those required (by Rule 235C1) and given in Table 235-5 shall beprovided under the following conditions. The increases are cumulative where more than one isapplicable.

a. Voltage related clearances

(No change) …

b. Sag-related clearances

(1) Line wiresWires, conductors, and cables supported at different levels on the samestructures shall have vertical clearances at the supporting structures so adjusted thatthe clearance at any point in the span shall be not less than any of the following:.When determining vertical clearances between supply conductors at any point alongthe span (not at supports), no distinction between same utility and different utilities isrequired. (The basic value for “same utility” from Table 235-5 may be used regardlessof supply utility ownership.)

(a) For voltages less than 50 kV between conductors, 75% of that required at the supportsby Table 235-5.

EXCEPTION 1: Neutral conductors meeting Rule 230E1, fiber-optic supply cablesmeeting Rule 230F1a or 230F1b, insulated communication cables located in thesupply space and supported by an effectively grounded messenger, and supply cablesmeeting Rule 230C1 (including their support brackets) in the supply space runningabove and parallel to communication cables in the communications space where the



supply neutral or messenger is bonded to the communication messenger at intervalsspecified in Rule 92C, may have a clearance of 300 mm (12 in) at any point in thespan provided that a clearance of 0.75 m (30 in) is maintained between the supplyspace conductors and cables and the communication space cables at the supportingpoles. Bonding is not required for entirely dielectric cables meeting Rule 230F1b.

EXCEPTION 2: When all parties involved are in agreement, for supply conductors ofdifferent utilities, vertical clearance at any point in the span need not exceed 75% ofthe values required at the supports for the same utility by Table 235-5.

(b) For voltages more than 50 kV between conductors, use the value as calculatedclearance determined in by Rule 235C2b(1)(a) shall be increased for that portion ofthe voltage above 50kV in accordance with Rule 235C2a. by the followingappropriate formula:

If the basic value is 0.41 m (16 in): 0.62 m (24.4 in) plus 10 mm (0.4 in) per kV inexcess of 50 kV.

If the basic value is 1.0 m (40 in): 1.08 m (42.4 in) plus 10 mm (0.4 in) per kV inexcess of 50 kV.

NOTE: The 75% clearance reduction does not apply to that portion of the voltageexceeding 50 kV

EXAMPLES:

(Delete the EXAMPLES. Replace the EXAMPLES with the clarifying NOTE above.)

(No changes are requested to the balance of Rule 235C2.)

Supporting Comment

The reasons supporting these changes are as follows.

1. The “basic clearance” described in Rule 235C1 refers to the values in Table 235-5 that are “at support”values. This adds clarity by synchronizing the rule with the table heading. There is no change intended tothis rule.

2. Remove the qualification from EXCEPTION 2 that reads “When all parties involved are in agreement.”This statement is not needed to establish safety since the parties are permitted to use the lesser clearance.Utilities can always mutually agree to provide greater clearance than what is required by the NESC.Furthermore, by placing a condition of mutual agreement, it implies that a record be kept that has nothing todo with the safety of the installation. It does not serve the industry to add record-keeping where no relatedsafety value is provided by virtue of the record.

3. Delete EXCEPTION 2 and make it part of the rule. It is clearer to state how the in-span clearances shouldbe applied to supply conductors within the rule rather than as an EXCEPTION.

4. By including the EXCEPTION as part of the rule, this restores the application of EXCEPTION 2 to Rule2352C2b(1)(b) for voltages exceeding 50 kV. (See also NESC 2002.)

The change in NESC 2007 edition included EXCEPTION 2 in Rule 2352C2b(1)(a), but apparentlyinadvertently omitted the EXCEPTION for the new Rule 2352C2b(1)(b) for voltages >50 kV. In addition,the formulas and examples added in section Rule 2352C2b(1)(b) did not refer back to the clearance valuedetermined in Rule 2352C2b(1)(a), which contained the EXCEPTION 2.



Prior to this edition the EXCEPTION was universally applied to sag-related clearances. Reviewing thereasons for the change in 2007, the intent was to clarify (not change) the clearance associated with voltageabove 50 kV. But, for different ownerships, a change in clearance does occur.

The omission of the EXCEPTION 2 in the new Rule 2352C2b(1)(b) is significant for all non-verticallyintegrated utilities. The ownership of transmission and distribution has changed for many utilities and, forthese utilities, the NESC 2007 clearance requirements increased 18 in with no change in the facilities oroperation. As a result, a distribution utility may not have space to attach or remain attached to a transmissionstructure, or the transmission utility’s capacity may be constrained by the reduced operating temperature ofthe transmission line to maintain clearance, based simply on different ownership of the facilities.

5. Rephrase Rule 2352C2b(1)(b) and add a NOTE to clearly state that the full clearance increase applies forthe incremental voltage above 50 kV. This will resolve the apparent confusion identified by the 2007 changeproposal.

6. Delete the formulas and examples in Rule 235C2b(1)(b).

By adding clarity to the rule and an explanatory NOTE, the formulas and examples are no longer necessary.

The formulas were confusing because they did not reveal all the calculations required to obtain thebeginning value for voltages up to 50kV from Rule 2352C2b(1)(a).

Although the examples add clarity, they do not seem necessary if the rule is described better. If the formulasremain, they would have to be corrected to apply EXCEPTION 2 for supply conductors owned by sameutility.

7. Please note that when EXCEPTION 2 was added in 2002, the NESC committee recognized that theadditional clearance for different utilities is appropriate in the work area at the support and this wasmaintained. Locations along the spans are not within normal work zones and therefore do not require adistinction between ownership of the supply facilities.


Reject.


Different utilities have different work methods and lesser clearance should not be used without concurrenceof effected utilities.



Negative: (0)

Abstention: (0)

Revised Text

CP3394

Part: 2 Section: 23 235 C2a(1)(a)



Submitter

Michael Dyer

Proposed Change

SI units: {0.41 + [(50 – 8.7) × 0.01]} + [(69.7 + 7.2 – 50) × 0.01] = 1.09 m

SI units: 0.41 + [(69.7 + 7.2) – 8.7] × 0.01 = 1.09 m

Customary units: {16.0 + [(50 – 8.7) × 0.4]} + [(69.7 + 7.2 – 50) × 0.4] = 43.3 in. Round up to 44 in.

Customary units: 16 + [(69.7 + 7.2) – 8.7] × 0.4 = 43.3 in. Round up to 44 in because the basic clearance hasno decimal.

Supporting Comment

The example is confusing as it mixes the basic clearance limits 8.7 from Table 235-5 and 50 kV from235C2a(1), the adder, the voltage between conductors, less the limit from 235C2a(1) and the added again.Example can be simplified by taking the basic clearance, determine the voltage between the conductorsinvolved, less the limit given in Table 235-5, determine the added and sum.


Reject.


This example does not add clarity.



Negative: (0)

Abstention: (0)

Revised Text

CP3395

Part: 2 Section: 23 235 C2a(1)(b)

Submitter

Michael Dyer



Proposed Change

SI units: {1.00 + [(50 – 8.7) × 0.01]} + [(69.7 + 7.2 – 50) × 0.01] = 1.68 m

SI units: 1.00 + [(69.7 + 7.2) – 8.7] × 0.01 = 1.68 m

Customary units: {40.0 + [(50 – 8.7) × 0.4]} + [(69.7 + 7.2 – 50) × 0.4] = 67.3 in. Round up to 68 in.

Customary units: 40 + [(69.7 + 7.2) – 8.7] × 0.4 = 67.3 in. Round up to 68 in because the basic clearance hasno decimal.

Supporting Comment

The example is confusing as it mixes the basic clearance limits 8.7 from Table 235-5 and 50 kV from235C2a(1), the adder, the voltage between conductors, less the limit from 235C2a(1) and the added again.Example can be simplified by taking the basic clearance, determine the voltage between the conductorsinvolved, less the limit given in Table 235-5, determine the added and sum.


Reject.


See CP3394.



Negative: (0)

Abstention: (0)

New Text

CP3129

Part: 2 Section: 23 235 C2a(2)

Submitter

Bruce Freimark

Proposed Change

Revise the Rule 235C2a(2) as indicated:



(2) The increase in clearance for voltages in excess of 50 kV specified in Rule 235C2a(1) shall beincreased 3% for each 300 m (1000 ft) or portion thereof in excess of 1000 m (3300 ft) above meansea level.

EXAMPLES:

(a) At a conductor elevation between 1000.1 m and 1300 m (3301 ft and 4300 ft) the additionalclearance specified in Rule 235C2a(1) are multiplied by 1.03.

(a) At a conductor elevation between 1300.1 m and 1600 m (4301 ft and 5300 ft) the additionalclearance specified in Rule 235C2a(1) are multiplied by 1.06.

Supporting Comment



Accept as modified.

Revise the Rule 235C2a(2) as indicated:

(2) The increase in clearance for voltages in excess of 50 kV specified in Rule 235C2a(1) shall be increased at the rate of 1% per 100 m (330 ft) 3% for each 300 m (1000 ft) in excess of 1000 m (3300 ft) above mean sea level.




Abstention: (0)

Explanation of Vote


Revised Text

CP3082

Part: 2 Section: 23 235 C2b(1)

Submitter

Mickey Gunter



Proposed Change

Revise Rule 235C2b(1) as follows:

(1) Line wires, conductors, and cables supported at different levels on the same structures shall havevertical clearances at the supporting structures so adjusted that the clearance at any point in thespan shall be not less than any of the following:

(a) For voltages less than 50 kV between conductors, 75% of that required at the supports by Table235-5.

EXCEPTION 1: Neutral conductors meeting Rule 230E1, fiber-optic supply cables meetingRule 230F1a or 230F1b, insulated communication cables located in the supply space andsupported by an effectively grounded messenger, and supply cables meeting Rule 230C1(including their support brackets) in the supply space running above and parallel tocommunication cables in the communications space where he supply neutral or messenger isbonded to the communication messenger at intervals specified in Rule 92C, may have aclearance of 300 mm (12 in) at any point in the span provided that a clearance of 0.75 m (30 in)is maintained between the supply space conductors and cables and the communication spacecables at the supporting poles. Bonding is not required for entirely dielectric cables meetingRule 230F1b.

EXCEPTION 2: When all parties involved are in agreement, for supply conductors of differentutilities, vertical clearance at any point in the span need not exceed 75% of the values requiredat the supports for the same utility by Table 235-5.

(b) For voltages more than 50 kV between conductors, use the value as calculated by the followingappropriate formula:

If the basic value is 0.41 m (16 in): 0.62 m (24.4 in) plus 10 mm (0.4 in) per kV in excess of50 kV.

If the basic value is 1.0 m (40 in): 1.08 m (42.4 in) plus 10 mm (0.4 in) per kV in excess of50 kV.

EXAMPLES: Calculations of clearances required by Rule 235C2b(1)(b) for a 69.7 kVmaximum operating voltage phase-to-ground conductor above a 7.2 kV phase-to-groundconductor, assuming conductors are 180 degrees out of phase.

Rule 253C2b(1)(b): Clearance required at any point in the span

(i) Same utility [basic clearance = 0.41 m (16 in)]:

SI units: {0.41 + [(50 – 8.7) × 0.01]} × 0.75 + [(69.7 + 7.2 – 50) × 0.01] = 0.89 m. No roundingrequired in this example.

Customary units: {16.0 + [(50 – 8.7) × 0.4]} × 0.75 + [(69.7 + 7.2 – 50) × 0.4] = 35.2 in.Round up to 36 in.

(ii) Different utilities [basic clearance = 1.00 m (40 in)]:




Customary units: {40.0 + [(50 – 8.7) × 0.4]} × 0.75 + [(69.7 + 7.2 – 50) × 0.4] = 53.2 in.Round up to 54 in.

EXCEPTION 1: Neutral conductors meeting Rule 230E1, fiber-optic supply cables meetingRule 230F1a or 230F1b, insulated communication cables located in the supply space andsupported by an effectively grounded messenger, and supply cables meeting Rule 230C1(including their support brackets) in the supply space running above and parallel tocommunication cables in the communications space where the supply neutral or messenger isbonded to the communication messenger at intervals specified in Rule 092C1, may have aclearance of 300 mm (12 in) at any point in the span provided that a clearance of 0.75 m (30 in)is maintained between the supply space conductors and cables and the communication spacecables at the supporting poles. Bonding is not required for entirely dielectric cables meetingRule 230F1b.

EXCEPTION 2: When all parties involved are in agreement, for supply conductors of differentutilities, vertical clearance at any point in the span need not exceed 75% of the values requiredat the support for the same utility by Table 235-5.

Supporting Comment

In the 2002 Code, EXCEPTION 2 was added to apply to Rule 235C2b(1)(a). In that Code, Rule235C2b(1)(b) was a voltage adder to Rule 235C2b(1)(a), so EXCEPTION 2 also applied to voltagesexceeding 50 kV, which was the intent. In the 2007 Code, Rule 235C2b(1)(b) was revised and is now notclear whether or not EXCEPTION 2 also applies to voltages exceeding 50 kV. Deleting EXCEPTIONs 1and 2 from after Rule 235C2b(1)(a) and adding them to the end of Rule 235C2b(1)(b) will clarify thatEXCEPTION 2 applies to both Rule 235C2b(1)(a) and (b).


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3274

Part: 2 Section: 23 235 C2b(1)

Submitter

James T. Collins



Proposed Change

Revise Rule 235C2b(1) as follows:

(1) Line wires, conductors, and cables supported at different levels on the same structures shall havevertical clearances at the supporting structures so adjusted that the clearance at any point in thespan shall be not less than any of the following:

(a) For voltages less than 50 kV between conductors, 75% of that required at the supports by Table235-5.

EXCEPTION 1: Neutral conductors meeting Rule 230E1, fiber-optic supply cables meetingRule 230F1a or 230F1b, insulated communication cables located in the supply space andsupported by an effectively grounded messenger, and supply cables meeting Rule 230C1(including their support brackets) in the supply space running above and parallel tocommunication cables in the communications space where he supply neutral or messenger isbonded to the communication messenger at intervals specified in Rule 92C, may have aclearance of 300 mm (12 in) at any point in the span provided that a clearance of 0.75 m (30 in)is maintained between the supply space conductors and cables and the communication spacecables at the supporting poles. Bonding is not required for entirely dielectric cables meetingRule 230F1b.

EXCEPTION 2: When all parties involved are in agreement, for supply conductors of differentutilities, vertical clearance at any point in the span need not exceed 75% of the values requiredat the supports for the same utility by Table 235-5.


If the basic value is 0.41 m (16 in): 0.62 m (24.4 in) plus 10 mm (0.4 in) per kV in excess of 50 kV.


EXAMPLES: Calculations of clearances required by Rule 235C2b(1)(b) for a 69.7 kV maximumoperating voltage phase-to-ground conductor above a 7.2 kV phase-to-ground conductor, assumingconductors are 180 degrees out of phase.

Rule 253C2b(1)(b): Clearance required at any point in the span

(i) Same utility [basic clearance = 0.41m (16 in)]:


Customary units: {16.0 + [(50 – 8.7) × 0.4]} × 0.75 + [(69.7 + 7.2– 50) × 0.4] = 35.2 in. Round upto 36 in.

(ii) Different utilities [basic clearance = 1.00 m (40 in)]:




Customary units: {40.0 + [(50 – 8.7) × 0.4]} × 0.75 + [(69.7 + 7.2 – 50) × 0.4] = 53.2 in. Round upto 54 in.

EXCEPTION 1: Neutral conductors meeting Rule 230E1, fiber-optic supply cables meeting Rule230F1a or 230F1b, insulated communication cables located in the supply space and supported byan effectively grounded messenger, and supply cables meeting Rule 230C1 (including their supportbrackets) in the supply space running above and parallel to communication cables in thecommunications space where the supply neutral or messenger is bonded to the communicationmessenger at intervals specified in Rule 092C1, may have a clearance of 300 mm (12 in) at anypoint in the span provided that a clearance of 0.75 m (30 in) is maintained between the supply spaceconductors and cables and the communication space cables at the supporting poles. Bonding is notrequired for entirely dielectric cables meeting Rule 230F1b.

EXCEPTION 2: When all parties involved are in agreement, for supply conductors of differentutilities, vertical clearance at any point in the span need not exceed 75% of the values required atthe supports for the same utility by Table 235-5.

Supporting Comment

In the 2002 Code, EXCEPTION 2 was added to apply to Rule 235C2b(1)(a). In that Code, Rule235C2b(1)(b) was a voltage adder to Rule 235C2b(1)(a), so EXCEPTION 2 also applied to voltagesexceeding 50 kV, which was the intent. In the 2007 Code, Rule 235C2b(1)(b) was revised and is now notclear whether or not EXCEPTION 2 also applies to voltages exceeding 50 kV. Deleting EXCEPTIONS 1and 2 from after Rule 235C2b(1)(a) and adding them to the end of Rule 235C2b(1)(b) will clarify thatEXCEPTION 2 applies to both Rule 235C2b(1)(a) and (b).




See CP3082.



Negative: (0)

Abstention: (0)

Revised Text

CP3161

Part: 2 Section: 23 235 C2b(1)(b)



Submitter

David Marne

Proposed Change

Revise Rule 235C2b(1)(b) as follows:




The increase in clearance for voltages in excess of 50 kV specified in Rule 235C2b(1)(b) shall beincreased 3% for each 300 m (1000 ft) in excess of 1000 m (3300 ft) above mean sea level.

All clearances for lines over 50 kV shall be based on the maximum operating voltage.


Supporting Comment

When the rule was reformatted in the 2007 Edition, elevation and maximum operating voltage requirementswere no longer included for “sag-related clearances.” Elevation and maximum operating voltagerequirements are included in Rule 235C2, they are not needed in Rule 235C2b(1)(a), and they are missingand need to be added to Rule 235C2b(1)(b).


Accept as modified.

Revise Rule 235C2b(1)(b) as follows:



If the basic value is 1.0 m (40 in):1.08 m (42.4 in) plus 10 mm (0.4 in) per kV in excess of 50 kV.

The increase in clearance for voltages in excess of 50 kV specified in Rule 235C2b(1)(b) shall beincreased at the rate of 1% per 100 m (330 ft) in excess of 1000 m (3300 ft) above mean sea level.

All clearances for lines over 50 kV shall be based on the maximum operating voltage.






Negative: (0)

Abstention: (0)

Revised Text

CP3396

Part: 2 Section: 23 235 C2b(1)(b)

Submitter

Michael Dyer

Proposed Change

If the basic value is 0.41 m (16 in): 0.62 m (24.4 in) plus 10 mm (0.4 in) per kV in excess of 50kV.

If the basic value is 1.0 m (40 in): 1.08 m (42.4 in) plus 10 mm (0.4 in) per kV in excess of 50kV.

SI units: {Basic clearance + [(kVL1 + kVL2) – 8.7] × 0.01} × 0.75

Customary units: {Basic clearance + [(kVL1 + kVL2) – 8.7] × 0.4} × 0.75

where

kVL1 is the voltage of line 1kVL2 is the voltage of line 2

Supporting Comment

Rule 235C2b(1)(a) establishes a clearance at any point in the span to be 75% of that required at supports.Rule 235C2a(1) establishes the adder for voltages between conductors 50 kV and 814 kV. The aboverecommended change combines these rules.


Reject.


The CP is technically inappropriate and the reduction does not apply to the voltage adder above 55 kV.





Negative: (0)

Abstention: (0)

Revised Text

CP3399

Part: 2 Section: 23 235 C2b(1)(b)(i)

Submitter

Michael Dyer

Proposed Change

SI units: {0.41 + [(50 – 8.7) × 0.01]} × 0.75 + [(69.7 + 7.2 -50) × 0.01] = 0.89 m

SI units: {0.41 + [(69.7 + 7.2) – 8.7] × 0.01} × 0.75 = 0.82 m

Customary units: {16 + [(50 – 8.7) × 0.4]} × 0.75 + [(69.7 + 7.2 – 50) × 0.4] = 35.2 in. Round up to 36 in.

Customary units: {16 + [(69.7 + 7.2) – 8.7] × 0.4} × 0.75 = 32.5 in. Round up to 33 because the basicclearance has no decimal.

Supporting Comment



Reject.


See CP3396.



Negative: (0)



Abstention: (0)

Revised Text

CP3400

Part: 2 Section: 23 235 C2b(1)(b)(ii)

Submitter

Michael Dyer

Proposed Change

SI units: {1.00 + [(50 – 8.7) × 0.01]} × 0.75 + [(69.7 + 7.2 – 50) × 0.01] = 1.33 m

SI units: {1.00 + [(69.7 + 7.2) – 8.7] × 0.01} × 0.75 = 1.26 m

Customary units: {40 + [(50 – 8.7) × 0.4]} × 0.75 + [(69.7 + 7.2 – 50) × 0.4] = 53.2 in. Round up to 54 in.

Customary units: {40 + [(69.7 + 7.2) – 8.7] × 0.4} × 0.75 = 50.5 in. Round up to 51 because the basicclearance has no decimal.

Supporting Comment



Reject.


See CP3396.



Negative: (0)

Abstention: (0)



Revised Text

CP3056

Part: 2 Section: 23 235 C2b(1)(c)

Submitter

Ewell Robeson

Proposed Change

Revise 235C2b(1)(c) as follows:

(c) For purposes of this determination the vertical clearances required in Rule 235C2b(1)(a) and (b)apply to the following conductor temperature and loading conditions whichever produces thegreater vertical clearance at the structure when:

i. The upper conductor is at final sag at 120 °F or the maximum operating temperature for whichthe line is designed to operate and the lower conductor is at final initial sag at the same ambientconditions as the upper conductor without electrical loading, or

ii. The upper conductor is at final sag at 32 °F with the radial thickness of ice, if any, specified inTable 230-1 for the zone concerned and the lower conductor is at final initial sag at the sameambient conditions as the upper conductor without electrical loading, and without ice loading.

EXCEPTION 1: Rule 235C2b(1)(c)i does not apply to conductors of the same utility when theupper and lower conductors are of the same circuit, are the same size and type, installed at the samesag and tension, and will be without electrical loading simultaneously. and are installed at the samesag and tension.

EXCEPTION 2: Rule 235C2b(1)(c)ii does not apply However, where experience in an area hasshown that different ice conditions do not occur between the upper and lower conductors, then Rule235C2b(1)(c)ii shall apply.

If both EXCEPTION 1 and EXCEPTION 2 can be used, then Rule 235C2b does not apply.

Supporting Comment

This CP is an attempt to resolve the issues that have come up in the past several Code cycles with Rule235C2b(1)(c). In i and ii above, final sag was replaced with initial sag for the lower conductors because theintent is to calculate the closest approach between the upper and lower conductors similar to Rules 233A and234A.

The existing EXCEPTION was replaced with two EXCEPTIONs for clarity.

In EXCEPTION 1, if the upper and lower conductors are owned and operated by the same utility, are thesame size and type, are sagged the same, and are of the same circuit and will become de-energized andwithout electrical loading simultaneously, then there would be no sag differentials. Also in EXCEPTION 2,if there are no icing differentials, then there would be no sag differentials due to icing. If both



EXCEPTIONS can be applied, then Rule 235C2b would not be required to be applied because there wouldbe no sag related clearances.


Accept as modified.


Modified EXCEPTION under 235C2b(1)(c) and move under 235C2b(1)(c)ii and add a new EXCEPTIONunder 235C2b(1)(c)i


i. The upper conductor is at final sag at 50 °C (120 °F) or the maximum operating temperaturefor which the line is designed to operate and the lower conductor is at final sag at the sameambient conditions as the upper conductor without electrical loading, or

EXCEPTION: Rule 235C2b(1)(c)i does not apply to conductors of the same utility when theupper and lower conductors are of the same circuit, the same size and type, installed at thesame sag and tension, and will be without electrical loading simultaneously.

ii. The upper conductor is at final sag at 0°C (32 °F) with the radial thickness of ice, if any,specified in Table 230-1 for the zone concerned and the lower conductor is at final sag at thesame ambient conditions as the upper conductor without electrical loading, and without iceloading.

EXCEPTION: Rule 235C2b(1)(c)ii does not apply However, where experience in an area hasshown that different ice conditions do not occur between the upper and lower conductors, thenRule 235C2b(1)(c)ii shall apply.

If both EXCEPTIONs in Rule 235C2b(1)(c) can be used, then Rule 235C2b(1)(c) does notapply. See Rule 012C.



Negative: (0)

Abstention: (0)

Revised Text

CP3275




Submitter

James T. Collins

Proposed Change



i. The upper conductor is at final sag at 120 °F or the maximum operating temperature for whichthe line is designed to operate and the lower conductor is at final sag at the same ambientconditions as the upper conductor without electrical loading, or

ii. The upper conductor is at final sag at 32 °F with the radial thickness of ice, if any, specified inTable 230-1 for the zone concerned and the lower conductor is at final sag at the same ambientconditions as the upper conductor without electrical loading, and without ice loading.

EXCEPTION 1: Rule 235C2b(1)(c)i does not apply to conductors of the same utility when theupper and lower conductors are of the same circuit, are the same size and type, installed at the samesag and tension, and will be without electrical loading simultaneously. and are installed at the samesag and tension.

EXCEPTION 2: Rule 235C2b(1)(c)ii does not apply However, where experience in an area hasshown that different ice conditions do not occur between the upper and lower conductors, then Rule235C2b(1)(c)ii shall apply.

If both EXCEPTION 1 and EXCEPTION 2 can be used, then Rule 235C2b does not apply.

Supporting Comment

This CP is an attempt to resolve the issues that have come up in the past several Code cycles with Rule235C2b(1)(c).

The existing EXCEPTION was replaced with two EXCEPTIONs for clarity. In EXCEPTION 1, if the upperand lower conductors are owned and operated by the same utility, are the same size and type, are sagged thesame, and are of the same circuit and will become de-energized and without electrical loadingsimultaneously, then there would be no sag differentials. Also in EXCEPTION 2, if there are no icingdifferentials, then there would be no sag differentials due to icing. If both EXCEPTIONS can be applied,then Rule 235C2b would not be required to be applied because there would be no sag related clearances.




See CP3056.





Negative: (0)

Abstention: (0)

New Text

CP3401


Submitter

Michael Dyer

Proposed Change

i. The upper conductor is at final sag at 120 °F or the maximum operating temperature for which theline is designed to operate and the lower conductor is: at final sag at the same ambient conditions asthe upper conductor without electrical loading, or

(a) At final sag at the same ambient conditions as the upper conductor without electrical loadingwhen the upper conductor is being built over an existing lower conductor, or

(b) At initial sag at the same ambient conditions as the upper conductor without electrical loadingwhen the lower conductor is being built under an existing upper conductor, or

Supporting Comment

The greater vertical clearance at the structure, as required by Rule 235C2b(1)(c), is dependent on thecondition, initial or final sag, of the lower conductor.


Reject.


The present use of final sag for both upper and lower wire positions in Rule 235C is different from that usedin Rule 233. In the case of Rule 233 line crossings, room must be left above the lower line to be able to putthe line back up with new, unstretched wire if the lower line is knocked down by a falling tree, errantvehicle, etc., while the upper line is at maximum sag in either the winter or summer.

However, in the case of vertical clearances on the same pole line, the situation usually is that (a) the wholepole or line section is knocked down by a tree or errant vehicle or (b) only an upper, outer wire is severed bya falling tree. As a result, little problem is caused by replacing the wire with new unstretched wire.



Usually there is enough clearance between circuits on multiple circuit structures that there is little safetyissue if a lower, outer wire is severed and replaced.

As a result, it is appropriate to use final sag for both the upper and lower wires in Rule 235 and to use finalsag for the upper wire and initial sag for the lower wire in Rule 233.

See CP3056.



Negative: (0)

Abstention: (0)

New Text

CP3383

Part: 2 Section: 23 235 C2b(1)(c) EXCEPTION

Submitter

Nelson Bingel

Proposed Change


i. The upper conductor is at final sag at 120 °F or the maximum operating temperature for whichthe line is designed to operate and the lower conductor is at final sag at the same ambientconditions as the upper conductor without electrical loading, or

ii. The upper conductor is at final sag at 32 °F with the radial thickness of ice, if any, specified inTable 230-1 for the zone concerned and the lower conductor is at final sag at the same ambientconditions as the upper conductor without electrical loading, and without ice loading.

EXCEPTION: Rule 235C2b(1)(c)ii does not apply to conductors of the same utility when theconductors are the same size and type, and are installed at the same sag and tension. However,where experience in an area has shown that different ice conditions do occur between theupper and lower conductors, then Rule 235C2b(1)(c)ii shall apply.

Supporting Comment

Rule 235C2b(1)(c) EXCEPTION needs to be revised to apply only to the icing differential of Rule235C2b(1)(c)ii; the EXCEPTION should never be applied to wire temperature differentials. The originalproposal was meant only to address ice loading differentials. Any time a circuit is configured such that a



lower conductor can have different loading than an upper one, there can be significant temperaturedifferentials and, as a result, sag differentials. Examples are any 3-phase vertical construction where single-phase reclosers or fuses protect individual phases and where a neutral conductor or conductor of another lineis the lower conductor. Sag differentials due to potential conductor thermal differentials should always betaken into account.




See CP3056.



Negative: (0)

Abstention: (0)

Revised Text

CP3162

Part: 2 Section: 23 235 E1

Submitter

David Marne

Proposed Change

Revise NOTE 2 to Rule 235E1 as follows:

NOTE 2: For antennas in the communication space, see Rule 236D1 and Rule 238.

Supporting Comment

Antennas in the communication space are also subject to the clearance requirements of Rule 238. See anadditional change proposal for Rule 238A adding antennas to the list of equipment.


Accept.





Negative: (0)

Abstention: (0)

New Text

CP3130

Part: 2 Section: 23 235 E3b(1)(b)

Submitter

Bruce Freimark

Proposed Change

Revise the Rule 235E3b(1)(b) as indicated:

(b) Atmospheric correction

The value of D shall be increased 3% for each 300 m (1000 ft) or portion thereof in excess of 450 m(1500 ft) above mean sea level.

EXAMPLES:

(1) At a conductor elevation between 450.1 m and 750 m (1501 ft and 2500 ft) the value of D shallbe multiplied by 1.03.

(2) At a conductor elevation between 750.1 m and 1050 m (2501 ft and 3500 ft) the value of Dshall be multiplied by 1.06.

Supporting Comment



Accept as modified.

Revise the Rule 235E3b(1)(b) as indicated:

(b) Atmospheric correction



The value of D shall be increased at the rate of 1% per 100 m (330 ft) 3% for each 300 m (1000 ft)in excess of 450 m (1500 ft) above mean sea level.




Abstention: (0)

Explanation of Vote


Revised Text

CP3473

Part: 2 Section: 23 235 F

Submitter

Subcommittee 4

Proposed Change

Revise to include a voltage range over 50 kV.

F. Clearances between circuits of different voltage classifications located in the supply space on thesame support arm

Circuits of any one voltage classification (0 to 750 V, over 750 V to 8.7 kV, over 8.7 kV to 22 kV,and over 22 kV to 50 kV, and over 50 kV) may be maintained in the supply space on the samesupport arm with supply circuits of the next consecutive voltage classification only under one ormore of the five following conditions. For purposes of these determinations, a neutral conductorshall be considered as having the same voltage classification as the circuit with which it isassociated:

Supporting Comment

Prior to 2007 the title of the rule referenced voltage classifications of voltages as indicated in Table 235-5. In2007 the title was revised to list the voltage ranges covered in Table 235-5, but voltages above 50 kV wereomitted. The clearance values of Table 235-5, with voltage adjustments, also apply for voltages above50 kV, and the title should be revised to include that range of voltages.


Accept.





Negative: (0)

Abstention: (0)

Revised Text

CP3276


Submitter

James T. Collins

Proposed Change

Revise Rule 235G4 and add it to Rule 235G3 as an EXCEPTION as follows:

3. Conductors shall be arranged so that the vertical spacing shall be not less than that specified inTable 235-8 under the conditions specified in Rule 235C2b(1)(c).

EXCEPTION 1: A supporting neutral conductor of a supply cable meeting Rule 230C3 or aneffectively grounded messenger of a supply cable meeting Rule 230C1 or 230C2 may attach to thesame insulator or bracket as a neutral conductor meeting Rule 230E1, so long as the clearances ofTable 235-8 are maintained in mid-span and insulated energized conductors are positioned awayfrom the open supply neutral at the attachment.

EXCEPTION 2: No mid-span clearance is required where supply cables meeting Rule 230C3 orservice drops meeting Rule 234C3a are attached to the neutral conductor meeting Rule 230E1anywhere in the span.

4. A supporting neutral conductor of a supply cable meeting Rule 230C3 or an effectively goundedmessenger of a supply cable meeting Rule 230C1 or 230C2 may attach to the same insulator orbracket as a neutral conductor meeting Rule 230E1, so long as the clearances of Table 235-8 aremaintained in mid-span and the insulated energized conductors are positioned away from the opensupply neutral at the attachment.

Supporting Comment

Rule 235G4 should be an EXCEPTION to Rule 235G3. The deletion of the clearance requirement in presentRule 235G4 will allow a 230C3 cable to be attached to a 230E1 neutral at mid-span. IR 523 dated July 31,2001, did not say that this type installation was a code violation; instead the IR said that it was not specifiedin the Code and that 012C would have to be applied. Since there is no clearance safety issue with this typeinstallation and it is used frequently in the utility industry, EXCEPTION 2 will clarify that this typeinstallation is OK.




Accept as modified.

Revise Rule 235G4 and add it to Rule 235G3 as an EXCEPTION as follows:

3. Conductors shall be arranged so that the vertical spacing shall be not less than that specified inTable 235-8 under the conditions specified in Rule 235C2b(1)(c).

EXCEPTION 1: A supporting neutral conductor of a supply cable meeting Rule 230C3 or aneffectively grounded messenger of a supply cable meeting Rule 230C1 or 230C2 may attach to thesame insulator or bracket as a neutral conductor meeting Rule 230E1, so long as the clearances ofTable 235-8 are maintained in mid-span and insulated energized conductors are positioned awayfrom the open supply neutral at the attachment.

EXCEPTION 2: No mid-span clearance is required where supply cables meeting Rule 230C3 orservice drops meeting Rule 234C3a are attached to the neutral conductor meeting Rule 230E1anywhere in the span.

4. A supporting neutral conductor of a supply cable meeting Rule 230C3 or an effectively goundedmessenger of a supply cable meeting Rule 230C1 or 230C2 may attach to the same insulator orbracket as a neutral conductor meeting Rule 230E1, so long as the clearances of Table 235-8 aremaintained in mid-span and the insulated energized conductors are positioned away from the opensupply neutral at the attachment.



Negative: (0)

Abstention: (0)

New Text

CP3055


Submitter

Ewell Robeson

Proposed Change

Revise Rule 235G4 as follows:

4. A supporting neutral conductor of a supply cable meeting Rule 230C3 or an effectively groundedmessenger of a supply cable meeting Rule 230C1 or 230C2 may attach to the same insulator orbracket as a neutral conductor meeting Rule 230E1, so long as the clearances of Table 235-8 aremaintained in mid-span and the insulated energized conductors are positioned away from the open



supply neutral at the attachment.

EXCEPTION: No mid-span clearance is required where supply cables meeting Rule 230C3 orservice drops meeting Rule 234C3a is attached to the neutral conductor meeting Rule 230E1anywhere in the span.

Supporting Comment

IR 523 dated July 31, 2001, did not say that this type installation was a Code violation; instead the IR saidthat it was not specified in the Code and that 012C would have to be applied. Since there is no clearance safetyissue with this type installation and it is used frequently in the utility industry, this EXCEPTION will clarifythat this type installation is OK.




See CP3276.



Negative: (0)

Abstention: (0)

Revised Text

CP3277

Part: 2 Section: 23 235 H

Submitter

James T. Collins

Proposed Change

Revise Rule 235H1 and delete Rule 235H2 as follows:

H. Vertical clearance and spacing between communication conductors, cables, and equipment

1. The spacing at the supporting structure, between messengers supporting communication cablesshould be not less than 300 mm (12 in). except by agreement between the parties involved.



2. The clearances between the conductors, cables, and equipment of one communication utility tothose of another, anywhere in the span, shall be not less than 100 mm (4 in)., except by agreementbetween the parties involved.

Supporting Comment

The addition of the word “vertical” to the first sentence in this rule will clarify that the clearances stated areto be vertical, not horizontal.

The addition to Rule 235H1 “at the support” will clarify the intent of this spacing is at the support and notanywhere in the span.

Eliminating the term “except by agreement between the parties involved” from 235H1 and 235H2 is neededdue to the confusion generated. Some believe that only the two communication parties need to agree. Somebelieve that the pole owner needs to agree. The 4 in clearance requirement will prevent mechanical damagefrom occurring between the two conductors. The act of agreeing will not prevent the damage, so this needsto be deleted.


Reject.


The 12 in spacing is required to use the lashing machine on one cable without damaging the lashing wire ona second. The “by agreement” permits closer clearances when a single utility has control of all facilities andfor lesser clearance when involved parties agree. Leaves room for repair splice.


Affirmative: (14) Amrhyn, Bednarz, Bowmer, Clapp, Crawford, Drzewiecki, Emery, Engdahl, Hooper,Marne, Neubauer, Slavin, Steiner, Young

Negative: (4) Bleakley, Gunter, Komassa, White

Abstention: (0)

Explanation of Vote

Bleakley: (Negative) The vertical clearance should be specified because 12 in of horizontal clearance willnot be sufficient to prevent the communication conductors from damaging the lashing out in the span. Iagree with the rejection statement that 12 in separation should be maintained throughout the span.

“Except by agreements” should be removed from the rule because the rationale to keep the conductorsseparated is to prevent one from damaging the other. Simply agreeing to keep the communicationconductors closer will not prevent the damage from occurring.

Gunter and Komassa: (Negative) The vertical spacing requirement of 12 in should not be allowed to bereduced even by agreement because hole spacing closer than 12 inch in the communication attachmentsspace on the pole can weaken the pole and make it more susceptible to breakage.



White: (Negative) The minimum clearance of 4 in should be maintained to prevent mechanical damage tothe communication cable lashing wire.

Revised Text

CP3163

Part: 2 Section: 23 235 I

Submitter

David Marne

Proposed Change

Revise Rules 235I2 and 235I3 as follows:

2. Communication antenna

The clearance between a communication antenna, and its associated mounting hardware, operatedat a radio frequency of 3 kHz to 300 GHz and a supply line conductor shall be not less than thevalue given in Table 235-6, row 1b.

NOTE 1: The antenna functions as a rigid, vertical, or lateral open wire communication conductor.

NOTE 2: See Rule 420Q.

3. Equipment case that supports or is in the vicinity of a communication antenna

The clearance between an equipment case that supports or is in the vicinity of a communicationantenna and a supply line conductor shall be not less than the value given in Table 235-6, row 4a.

Supporting Comment

Rule 235I2 needs clarification that the measurement should be made to the antenna and to the antennamounting hardware.

For Rule 235I3, it is possible for an equipment box not to be supporting the antenna but to be in the vicinityof the antenna. Equipment boxes are often mounted near the antenna base but not directly connected or partof the antenna.


Accept as modified.

Revise Rules 235I2 and 235I3 as follows:

2. Communication antenna



The clearance between a communication antenna, and its associated mounting hardware, operatedat a radio frequency of 3 kHz to 300 GHz and a supply line conductor shall be not less than thevalue given in Table 235-6, row 1b.

NOTE 1: The antenna functions as a rigid, vertical, or lateral open wire communication conductor.

NOTE 2: See Rule 420Q.

3. Equipment case that supports or is adjacent to a communication antenna

The clearance between an equipment case that supports or is adjacent to a communication antennaand a supply line conductor shall be not less than the value given in Table 235-6, row 4a.



Negative: (0)

Abstention: (0)

Revised Text

CP3278

Part: 2 Section: 23 235 I2

Submitter

James T. Collins

Proposed Change

Revise the wording in Rule 235I2 as follows:

The clearance between a communication antenna operated at a radio frequency of 3 kHz to 300 GHz and asupply line conductor shall be not less than the value given in Table 235-6, row 1b 1c.

Supporting Comment

Table 235-6 is confusing concerning communication antenna clearances. Communication antennas havebecome common on electric utility power poles and structures.

Adding row 1c in Table 235-6 clarifies the issue of clearance of communication antennas from lineconductors. This wording is needed to make corrections to the proposed new row in the table.


Accept.




See CP3282.



Negative: (0)

Abstention: (0)

Revised Text

CP3279

Part: 2 Section: 23 235 I2 NOTE 2

Submitter

James T. Collins

Proposed Change

Revise the wording of NOTE 2 in Rule 235I2 as follows:

NOTE 2: Clearances shown in Table 235-6 are not intended to apply to personnel working in thevicinity of communication antennas. See Rule 420Q.

Supporting Comment

Changing the wording on this NOTE will clarify the issue that the distances shown in Table 235-6 must notbe interpreted to apply to SAR or MAR rates by workers or people in the area.


Accept.


The subcommittee assumes that the submitter means SAR to indicate Specific Absorption Rate, ameasurement of electromagnetic energy absorbed by a person, but the subcommittee is confused by the termMAR. We think the submitter meant Maximum Permissible Exposure or MPE.





Negative: (0)

Abstention: (0)

Revised Text

CP3054


Submitter

Ewell Robeson

Proposed Change

Revise Table 235-1, row 6, columns 2 and 3 as follows:

725 715 plus 10 per 28.5 29 plus 0.4 per kV over in excess of kV over in excess of 50 kV 50 kV

Supporting Comment

The use of the verbiage “over” was replaced with “in excess of” in the 2007 Code and revising it in this rulewill make it consistent with other rules and tables.

The English value of 28.5 needs to be rounded up to 29 and the metric value of 725 need to be changed to715 as per new rule 230A4.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3137


Also Part: 2 Section: 24 242 Table 242-1



Submitter

Bruce Freimark

Proposed Change

Revise the Table 235-1 and add footnote as indicated:

1 Examples of the elevation adjustment: 1. At a conductor elevation between 1000.1 m and 1300 m (3301 ft and 4300 ft) the additional clearance due to the

voltage adder is multiplied by 1.03.2. At a conductor elevation between 1300.1 m and 1600 m (4301 ft and 5300 ft) the additional clearance due to the

voltage adder is multiplied by 1.06.

Table 235-1—Horizontal clearance between wires, conductors, or cables at supports(All voltages are between conductors involved except for railway feeders, which are to ground.

See also Rules 235A, 235B3b 235B1a, and 235B1a 235B3b.)

Class of circuitClearance

Notes(mm) (in)

Open communication conductors 150 6 Does not apply at conductor transposition points.

75 3 Permitted where pin spacings less than 150 mm (6 in) have been in regular use. Does not apply at conductor transposition points.

Railway feeders:0 to 750 V, AWG No. 4/0 or larger0 to 750 V, smaller than AWG No. 4/0Over 750 V to 8.7 kV

150300300

61212

Where 250 to 300 mm (10 to 12 in) clearance has already been established by practice, it may be continued, subject to the provisions of Rule 235B1b, for conductors having apparent sags not over 900 mm (3 ft) and for voltages not exceeding 8.7 kV.

Supply conductors of the same circuit:0 to 8.7 kVOver 8.7 to 50 kV

Above 50 kV

300300 plus 10 per kV in excess of

8.7 kV

No valuespecified

1212 plus 0.4 per kV

in excess of 8.7 kV

No valuespecified

Supply conductors of different circuits:

0 to 8.7 kVOver 8.7 to 50 kV

Over 50 kV to 814 kV


8.7 kV

725 plus 10 per kV over 50 kV

1212 plus 0.4 per kV

in excess of 8.7 kV

28.5 plus 0.4 per kV over 50 kV

For all voltages above 50 kV, the additional clearance shall be increased 3% for each 300 m (1000 ft) or portion thereof in excess of 1000 m (3300 ft) above mean sea level. All clearances for voltages above 50 kV shall be based on the maximum operating voltage. 1



Supporting Comment



Accept as modified.

Revise the Table 235-1as indicated:

Table 235-1—Horizontal clearance between wires, conductors, or cables at supports(All voltages are between conductors involved except for railway feeders, which are to ground.

See also Rules 235A, 235B3b 235B1a, and 235B1a 235B3b.)

Class of circuitClearance

Notes(mm) (in)

Open communication conductors 150 6 Does not apply at conductortransposition points.

75 3 Permitted where pin spacings less than 150 mm (6 in) have been in regular use. Does not apply at conductor transposition points.

Railway feeders:0 to 750 V, AWG No. 4/0 or larger0 to 750 V, smaller than AWG No. 4/0Over 750 V to 8.7 kV

150300300

61212

Where 250 to 300 mm (10 to 12 in) clearance has already been established by practice, it may be continued, subject to the provisions of Rule 235B1b, for conductors having apparent sags not over 900 mm (3 ft) and for voltages not exceeding 8.7 kV.

Supply conductors of the same circuit:0 to 8.7 kVOver 8.7 to 50 kV

Above 50 kV


8.7 kV

No valuespecified

1212 plus 0.4 per kV in excess of

8.7 kV

No valuespecified

Supply conductors of different circuits:0 to 8.7 kVOver 8.7 to 50 kV

Over 50 kV to 814 kV


8.7 kV

725 plus 10 per kV over 50 kV

1212 plus 0.4 per kV in excess of

8.7 kV

28.5 plus 0.4 perkV over 50 kV

For all voltages above 50 kV, the additional clearance shall be increased at the rate of 1% per 100 m (330 ft) 3% for each 300 m (1000 ft) in excess of 1000 m (3300 ft) above mean sea level. All clearances for voltages above 50 kV shall be based on the maximum operating voltage.





Negative: (0)

Abstention: (0)

Revised Text

CP3280


Submitter

James T. Collins

Proposed Change

Revise Table 235-1, row 6, columns 2 and 3, as follows:

725 715 plus 10 per 28.5 29 plus 0.4 per

kV over in excess of kV over in excess of

50 kV 50 kV

Supporting Comment

The use of the verbiage “over” was replaced with “in excess of” in the 2007 Code and revising it in this rulewill make it consistent with other rules and tables.

The English value of 28.5 needs to be rounded up to 29 and the metric value of 725 need to be rounded up to715 as per new rule 230A4. They were calculated thusly:

English: 12 + 0.4 × (50 – 8.7) = 12 + 16.5 = 28.5 = 29 (rounded up to the nearest whole value)

Metric: 300 + 10 × (50 – 8.7) = 300 + 413 = 713 = 715 (rounded up to the nearest 5 mm)




See CP3054.





Negative: (0)

Abstention: (0)

New Text

CP3138


Submitter

Bruce Freimark

Proposed Change


Table 235-4—Electrical clearances in Rule 235B3a(1)[Add 3% for each 300 m (1000 ft) or portion thereof in excess of 450 m (1500 ft) above mean sea level.

NOTE: See the examples presented under Rule 235B3a(2).]

Supporting Comment



Accept as modified.


Table 235-4—Electrical clearances in Rule 235B3a(1)[This clearance shall be increased Add at the rate of 1% per 100 m (330 ft) 3% for each 300 m (1000 ft) in

excess of 450 m (1500 ft) above mean sea level.]






Abstention: (0)

Explanation of Vote


New Text

CP3115


Submitter

Ewell Robeson

Proposed Change

Revise Footnote 5 of Table 235-5, m and in, as follows:

5May be reduced to 30 in for supply neutrals meeting Rule 230E1, fiber-optic supply cables on aneffectively grounded messenger meeting Rule 230F1a, entirely dielectric fiber-optic supply cables meetingRule 230F1b, insulated communication cables located in the supply space and supported by an effectivelygrounded messenger, and cables meeting Rule 230C1 where the supply neutral or messenger is bonded tothe communication messenger at intervals specified in Rule 092C. Bonding is not required for entirelydielectric cables meeting Rule 230F1b.

Supporting Comment

Adding this language will clarify that bonding between a supply neutral and a communication messenger isnot required at the support. The present language is not clear in this respect and may even imply thatbonding between the supply neutral and communication messenger is required at the support where thereduced clearance is allowed. Similar language is used in Rule 235C2b(1)(a) EXCEPTION 1.


Accept.



Negative: (0)

Abstention: (0)



Revised Text

CP3281


Submitter

James T. Collins

Proposed Change

Revise Footnote 5 of Table 235-5, m and in, as follows:

5May be reduced to 30 in for supply neutrals meeting Rule 230E1, fiber-optic supply cables on aneffectively grounded messenger meeting Rule 230F1a, entirely dielectric fiber-optic supply cables meetingRule 230F1b, insulated communication cables located in the supply space and supported by an effectivelygrounded messenger, and cables meeting Rule 230C1 where the supply neutral or messenger is bonded tothe communication messenger at intervals specified in Rule 092C1. Bonding is not required for entirelydielectric cables meeting Rule 230F1b.

Supporting Comment

Adding this language will clarify that bonding between a supply neutral and a communication messenger isnot required at the support. The present language is not clear in this respect and may even imply thatbonding between the supply neutral and communication messenger is required at the support where thereduced clearance is allowed. Similar language is used in Rule 235C2b(1)(a) EXCEPTION 1.




See CP3115.



Negative: (0)

Abstention: (0)



New Text

CP3080


Submitter

Mickey Gunter

Proposed Change

Add new Footnote 8 (currently not used) to Table 235-5, row 2a, column 2, m and in as follows:

0.41 9, 8 16 9, 8

8 No clearance is specified between supply cables meeting Rule 230C3 and neutral conductors meeting Rule230E1.

Supporting Comment

Adding this language will be consistent with Rule 235C1a language that was added in the 2007 Code andeliminate a contradiction between Rule 235C1a and Table 235-5.


Accept.


Affirmative: (17) Amrhyn, Bednarz, Bleakley, Bowmer, Crawford, Drzewiecki, Emery, Engdahl, Gunter,Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White, Young

Negative: (1) Clapp

Abstention: (0)

Explanation of Vote

Clapp: (Negative) I agree with adding the footnote, but believe that “See Rule 235G4” should be added tothe newer footnote.

New Text




CP3292

Submitter

James T. Collins

Proposed Change

Add new Footnote 8 (currently not used) to Table 235-5, row 2a, column 2, m and in as follows:

16 9, 8 41 9, 8

8 No clearance is specified between supply cables meeting Rule 230C3 and neutral conductors meeting Rule230E1.

Supporting Comment

Adding this language will be consistent with Rule 235C1a language that was added in the 2007 Code andeliminate a contradiction between Rule 235C1a and Table 235-5.




See CP3080.


Affirmative: (17) Amrhyn, Bednarz, Bleakley, Bowmer, Crawford, Drzewiecki, Emery, Engdahl, Gunter,Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White, Young

Negative: (1) Clapp

Abstention: (0)

Explanation of Vote


New Text

Part: 2 Section: 23 235 Table 235-5 Footnotes 9 and 10



CP3375

Submitter

Nelson Bingel

Proposed Change

Revise the two footnotes in Table 235-5 by adding the following text:

9 No clearance is specified between neutral conductors meeting Rule 230E1 and insulated communicationcables located in the supply space and supported by an effectively grounded messenger. The cablemessenger may be attached to the neutral at the pole or in the span, providing that the cable is positionedaway from the neutral to prevent abrasion damage. If the cable messenger is not attached to the neutral in thespan, clearances not less than those specified in Rule 235G shall be used to limit the opportunity for mid-span contact during storm loadings.

10 No clearance is specified between fiber-optic supply cables (FOSC) meeting Rule 230F1b and supplycables and conductors. The FOSC may be attached to a supply conductor or cable at the pole or in the span,providing that the FOSC is positioned away from the supply conductor or cable to prevent abrasion damage.If the FOSC is not attached to the supply cable or conductor in the span, clearances not less than thosespecified in Rule 235G shall be used to limit the opportunity for mid-span contact during storm loadings.

Supporting Comment

Since the following is true:

(a) Rule 012C requires accepted good practice where particulars are not specified in the Code,

(b) Footnotes 9 and 10 of Table 235-5 do not specify a mid-span clearance between the covered items, and

(c) It is good practice to limit the opportunity for cables and conductors to touch in mid-span during stormloadings,

Then Footnotes 9 and 10 to Table 235-5 should be revised as shown. These revisions specifically allow thecovered items to be attached to the related items, which was the original purpose of the notes.


Reject.


The additional language contradicts the existing footnote language.


Affirmative: (15) Amrhyn, Bednarz, Bleakley, Bowmer, Crawford, Drzewiecki, Emery, Engdahl, Gunter,Komassa, Marne, Slavin, Steiner, White, Young

Negative: (3) Clapp, Hooper, Neubauer



Abstention: (0)

Explanation of Vote

Clapp: (Negative) The present Code specifically states that no clearance is specified between the itemscovered in Footnotes 9 and 10 to Table 235-5. As a result, Rule 012C applies and good practice is requiredfor the given local conditions.

The intention of the rule is to allow these items to be attached to one another. However, when they are notattached to each other, good practice requires that the items covered by these footnotes do not contact eachother during storm loadings (so that the opportunity for damage is limited).

Rule 235G has been used by the NESC for decades to limit conflict between open-wire secondaryconductors. The required clearances are based upon span lengths and are shown in Table 235-8. Theseclearances are good practice for clearances less than those required by the main rule.

Even though Rule 235G essentially only applies to secondary conductors and cables meeting Rule 230C1(that have limited voltage-related issues), these clearances also provide good practice for the items coveredby Footnotes 9 and 10 to keep them apart out in the span. There is no better guidance in the NESC or in anyother document of which I am aware.

I have received literally dozens of questions about appropriate clearances between fiber-optic cables in thesupply space. This question will not go away until the NESC gives some reasonable guidance to users thatthey can use and be comfortable that they are, in fact, meeting the intent of the NESC. In the absence ofmore detailed requirements, Rule 235G can serve this purpose and should be referenced in these footnotes.

After the discussions of this CP, I believe that the proposed changes should be changed to the following. It ismore succinct and more clear.

9 No clearance is specified between neutral conductors meeting Rule 230E1 and an insulatedcommunication cables located in the supply space and supported by an effectively grounded messenger. Thecable may be attached to the neutral at the pole or in the span. If the cable messenger is not attached to theneutral in the span, clearances not less than those specified in Rule 235G shall be met at mid-span.

10 No clearance is specified between fiber-optic supply cables (FOSC) meeting Rule 230F1b and a supplycables and or conductors. The FOSC may be attached to a supply conductor or cable at the pole or in thespan. If the FOSC is not attached to the supply cable or conductor in the span, clearances not less than thosespecified in Rule 235G shall be met at mid-span.

Hooper: (Negative) I support the basic concept of the change proposal and believe that it, or a suitablemodification, should be approved.

Neubauer: (Negative) I agree with Mr. Clapp’s supporting statement and in principle with both CPs. Duringthe discussion it was brought up that with the increased use of fiber-optic supply cables, the Code should atleast give guidance. These CPs did that and I supported them.

Revised Text

CP3438

Part: 2 Section: 23 235 Table 235-5 Footnotes 9 and 10



Submitter

Allen Clapp

Proposed Change

Revise Footnotes 9 and 10 to Table 235-5 as shown below.

9 No clearance is specified between neutral conductors meeting Rule 230E1 and insulated communicationcables located in the supply space and supported by an effectively grounded messenger. The cablemessenger may be attached to the neutral at the pole or in the span, providing that the cable is positionedaway from the neutral to prevent abrasion damage. If the cable messenger is not attached to the neutral in thespan, clearances not less than those specified in Rule 235G shall be used to limit the opportunity for mid-span contact during storm loadings.

10 No clearance is specified between fiber-optic supply cables (FOSC) meeting Rule 230F1b and supplycables and conductors. The FOSC may be attached to a supply conductor or cable at the pole or in the span,providing that the FOSC is positioned away from the supply conductor or cable to prevent abrasion damage.If the FOSC is not attached to the supply cable or conductor in the span, clearances not less than thosespecified in Rule 235G shall be used to limit the opportunity for mid-span contact during storm loadings.

Supporting Comment

Since (a) Rule 012C requires accepted good practice where particulars are not specified in the Code, (b)Footnotes 9 and 10 of Table 235-5 do not specify a mid-span clearance between the covered items, and (c) itis good practice to limit the opportunity for cables and conductors to touch in mid-span during stormloadings, Footnotes 9 and 10 to Table 235-5 should be revised as shown above. These revisions specificallyallow the covered items to be attached to the related items, which was the original purpose of the notes.


Reject.


See CP3375.


Affirmative: (15) Amrhyn, Bednarz, Bleakley, Bowmer, Crawford, Drzewiecki, Emery, Engdahl, Gunter,Komassa, Marne, Slavin, Steiner, White, Young

Negative: (3) Clapp, Hooper, Neubauer

Abstention: (0)

Explanation of Vote


Hooper: (Negative) See comment on CP3375.



Neubauer: (Negative) See comment on CP3375.

Revised Text

CP3085


Submitter

Mickey Gunter

Proposed Change

Revise Table 235-6, m and in, row 2a and 2b categories, column 1, as follows:

a. When installed alongside and in the same general direction as the line conductors parallel to line

b. Anchor guys When installed at an angle to the general direction of the line conductors

Supporting Comment

The intent of the word “parallel” is not well defined in this table and could have different meanings todifferent personnel. This change better reflects the intention of the clearance of span guys, anchor guys, andspan wires from line conductors. For example, an anchor guy installed alongside and in the same generaldirection as the energized line conductors needs a greater clearance than an anchor guy installed at an angleto the line with line conductors, because of the movement of the line conductors toward the anchor guy.


Accept as modified.

Revise Table 235-6, m and in row 2a and delete entire row 2b, and renumber 2c as 2b:

a. When installed in the same general longitudinal direction as the adjacent line conductors parallel to line

unchanged unchanged unchanged unchanged unchanged

b. Anchor guys 3 7 6 1, 7 6 7 6 plus 0.25per kV

in excess of8.7 kV

16 plus 0.25per kV

in excess of50 kV

c. b. All other 3 7 6 1, 7 6 6 plus 0.4per kV

in excess of8.7 kV

23 plus 0.4per kV

in excess of50 kV




Affirmative: (17) Amrhyn, Bednarz, Bleakley, Bowmer, Clapp, Crawford, Drzewiecki, Emery, Engdahl,Gunter, Hooper, Komassa, Neubauer, Slavin, Steiner, White, Young

Negative: (1) Marne

Abstention: (0)

Explanation of Vote

Marne: (Negative) I would like more time to review the impact of the proposed changes. I also believe areview of the guy insulator reduction is needed (Footnote 11).

New Text

CP3140


Submitter

Bruce Freimark

Proposed Change

Revise Table 235-6, m and in, row 2a and 2b in column 1, as follows:(m and in)

Table 235-6—Clearance in any direction from line conductors to supports and to vertical or

lateral conductors, span, or guy wires attached to the same support[See also Rules 235E1, 235E3b(2), and 235I.]

Clearance of lineconductors from

Supply lines over 50 kV

Base clearance @ 50 kV Clearance adder

2. Span or guy wires, 11 or messengers attached to same structure:

a. When parallel to line (generally horizontal, alongside and in-line with line conductors)

29 in 0.4 in per kV

b. Anchor guys (installed between the structure and an anchor point in the ground or on a stub pole; anchor guys are positioned such that they are directed away from energized facilities)

16 in 0.25 in per kV

c. All other 23 in 0.4 in per kV



Supporting Comment

I recently fielded a question from an experienced engineer (almost 30 years) asking for definitions of thevarious types of guys described in Table 235-6, which I was not able to locate either in Rule 235, Table 235-6, nor the Definitions section of the NESC.

Definitions, as defined above, should be added either to Table 235-6 or to the Definitions section of theNESC.

Additional comments

I wish to point out to the members of NESC Subcommittee 4 that they need to be very careful in developingdefinitions for “Span or guy wires, etc.”

In reviewing this proposal with others in the utility industry, I discovered various interpretations of what isintended by this table. As SC4 reviews this and other change proposals that attempt to define the intent ofthis rule, I wish to point out to the members of NESC Subcommittee 4 the following:

There is no electrical basis for the clearance adders to increase at different rates as indicated above sincethey are all phase-to-ground situations.

Below is a portion of a spreadsheet that extrapolates the clearances in Table 235-6 for various voltages over50 kV.

Nominal Voltage 138 161 230 500 765

Maximum Voltage 144.9 169.05 241.5 550 803.25

Base @ 50kV Per kV Adder Delta Over 50kV 94.9 119.1 191.5 500.0 753.3

a. Of the same Circuit

b. Of other circuits 3 0.25 2.23 2.73 4.24 10.67 15.94

a. When parallel to line 29 0.4 5.58 6.39 8.80 19.08 27.53

b. Anchor guys 16 0.25 3.31 3.81 5.32 11.75 17.03

c. All other 23 0.4 5.08 5.89 8.30 18.58 27.03

11 0.2 2.50 2.90 4.11 9.25 13.47

a. On jointly used

structures

13 0.2 2.67 3.07 4.28 9.42 13.64

b. All other 11 0.2 2.50 2.90 4.11 9.25 13.47

NESC Table 235-6

Clearance in any direction from Line Conductors to Supports

and to Vertical or Lateral Conductors, span, or guy wires

attached to the same structure.

Not Specified

Calculations for Supply Lines Over 50 kV

2. Span or guy wires, or

messengers attached to same:

3. Surface of support arms

4. Surface of structure:

1. Vertical and Lateral

Conductors:



Please note the following examples:

The above examples demonstrate that the clearances to guys “when parallel to line” are increasing at anexcessive rate compared to clearances to structures and anchor guys, resulting in clearances for transmissionlines, especially EHV, that were probably were not intended by SC4.

While there is justification to have different clearances (starting at 8.7 kV) due to the possible motion of 1wire (the conductor) to the fixed structure, versus two wires (the conductor and a guy) to each other, theextra clearance margins desired should probably be based on the “mechanical” parameters such as the lengthof the guys and spans, where in these lengths the clearance “conflict” might occur and the relative directionsof the conductors and guys.

This CP does not address changing the electrical voltage adders or adding mechanical adders as I do nothave a recommendation regarding what is appropriate.

I mainly desire that the definitions selected by SC4 for “Span or guy wires, etc.” do not arbitrarily cause theclearances for “anchor guys” (guys going from the structure directly towards an earth anchorage) to increaseabove their present values at higher voltages.




See CP3085.

Nominal voltage Clearance category Clearance Increased clearance over

“structure” clearance

50 kV Structure 11 in(1.0 ft)

Anchor guys 16 in(1.4 ft)

5 in (0.5 ft)

When parallel to line (span guys)

29 in (2.5 ft)

18 in (1.5 ft)

138 kV Structure 2.5 ft

Anchor guys 3.2 ft 0.7 ft

When parallel to line 5.6 ft 3.1 ft

765 kV Structure 13.5 ft

Anchor guys 17.1 ft 3.6 ft

When parallel to line 27.6 ft 14.1 ft




Affirmative: (16) Amrhyn, Bednarz, Bleakley, Bowmer, Clapp, Crawford, Drzewiecki, Emery, Engdahl,Gunter, Hooper, Komassa, Neubauer, Slavin, Steiner, White

Negative: (1) Marne

Abstention: (0)

Explanation of Vote

Marne: (Negative) See comment on CP3085.

Revised Text

CP3282


Submitter

James T. Collins

Proposed Change

Add “communication antennas” to the table titles and add row 1c to Tables 235-6 m and in as follows:

m

Table 235-6—Clearance in any direction from line conductors to supports, and to vertical or lateral conductors, span, or guy wires, and to communication antennas

attached to the same support[See also Rules 235E1, 235E3b(2), and 235I.]

Clearance of line conductors from

Communi-cation linesin general

(mm)

Communi-cation

lines on jointlyused

structures;neutral

conductorsmeeting

Rule 230E1(mm)

Supply linesCircuit phase-to-phase voltage

0 to8.7 kV 14

(mm)

Over 8.7to 50 kV

(mm)

Over 50 to 814 kV 4, 9

(mm)

1. Vertical and lateral conductors:

a. Of the same circuit

75 75 75 75 plus 6.5per kV

in excess of8.7 kV

No valuespecified



NOTE: Remainder of Table 235-6 and footnotes remain unchanged.

in

b. Of other circuits 12 13

75 75 150 5 150 plus 10per kV

in excess of8.7 kV

580 plus 10per kV

in excess of50 kV

c. Communication13

antennas75 75 150 5

150 plus 10per kV

in excess of8.7 kV

580 plus 10per kV

in excess of50 kV





(in)

Communi-cation


structures;neutral

conductorsmeeting

Rule 230E1(in)


0 to8.7 kV 14

(in)

Over 8.7to 50 kV

(in)

Over 50to 814 kV 4, 9

(in)

1. Vertical and lateralconductors:


3 3 3 3 plus 0.25per kV

in excess of8.7 kV

No valuespecified


attached to the same support[See also Rules 235E1, 235E3b(2), and 235I.] (continued)

Clearance of line conductors from


(mm)

Communi-cation


structures;neutral

conductorsmeeting

Rule 230E1(mm)


0 to8.7 kV 14

(mm)

Over 8.7to 50 kV

(mm)

Over 50 to 814 kV 4, 9

(mm)




Supporting Comment

Communication antennas are becoming common on electric utility power poles and structures. The tableshould reflect this growing trend of installing communication antennas on these poles and structures byadding row 1c in Table 235-6. This will reduce confusion and help eliminate misinterpretation of this rule.


Accept as modified.

Add “communication antennas” to the table titles and add row 1c to Tables 235-6 m and in as follows:


3 3 6 5 6 plus 0.4per kV

in excess of8.7 kV

23 plus 0.4per kV

in excess of50 kV

c.Communication13

antennas

3 3 6 5 6 plus 0.4per kV

in excess of8.7 kV

23 plus 0.4per kV

in excess of50 kV


attached to the same support[See also Rules 235E1, 235E3b(2), and 235I.] (continued)



(in)

Communi-cation


structures;neutral

conductorsmeeting

Rule 230E1(in)


0 to8.7 kV 14

(in)

Over 8.7to 50 kV

(in)

Over 50to 814 kV 4, 9

(in)



m






(mm)

Communi-cation


structures;neutral

conductorsmeeting

Rule 230E1(mm)


0 to8.7 kV 14

(mm)

Over 8.7to 50 kV

(mm)

Over 50 to 814 kV 4 9

(mm)



75 75 75 75 plus 6.5per kV

in excess of8.7 kV

No valuespecified


75 75 150 5 150 plus10per kV

in excess of8.7 kV

580 plus 10per kV

in excess of50 kV

c. Communication13

antennas

75 75 150 5 150 plus 10per kV

in excess of8.7 kV

580 plus 10per kV

in excess of50 kV



in


Revise Footnote 13 in both metric and English Tables 235-6:

13 These clearances apply to communication antennas operated at a radio frequency of 3 kHz to 300 GHz.Also see Rules 235I4, 238, and 239.



Negative: (0)

Abstention: (0)





(in)

Communi-cation


structures;neutral

conductorsmeeting

Rule 230E1(in)


0 to8.7 kV 14

(in)

Over 8.7to 50 kV

(in)

Over 50to 814 kV4, 9

(in)



3 3 3 3 plus 0.25per kV

in excess of8.7 kV

No valuespecified


3 3 6 5 6 plus 0.4per kV

in excess of8.7 kV

23 plus 0.4per kV

in excess of50 kV

c. Communication13

antennas

3 3 6 5 6 plus 0.4per kV

in excess of8.7 kV

23 plus 0.4per kV

in excess of50 kV



Revised Text

CP3283


Submitter

James T. Collins

Proposed Change

Revise Table 235-6, m and in, row 2a and 2b categories, column 1, as follows:

a. When parallel to line Span wires, guy wires, or messengers alongside and in line with lineconductors

b. Anchor guys passing by, but not alongside and in line with line conductors

Supporting Comment

The intent of the word “parallel” is not well defined in this table and could have different meanings todifferent personnel. This change better reflects the intention of the clearance of span guys, anchor guys, andspan wires from line conductors. For example, an anchor installed alongside and in line with energized lineconductors needs a greater clearance than an anchor guy installed passing by but not in line with lineconductors, because of the movement of the line conductors toward the anchor guy. By placing anchor guysthat are installed alongside and in line with line conductors in category 2a, a greater clearance is achieved.




See CP3085.


Affirmative: (16) Amrhyn, Bednarz, Bleakley, Bowmer, Clapp, Crawford, Drzewiecki, Emery, Engdahl,Gunter, Hooper, Komassa, Neubauer, Slavin, Steiner, White

Negative: (1) Marne

Abstention: (0)

Explanation of Vote

Marne: (Negative) See comment on CP3085.



Revised Text

CP3298


Submitter

James T. Collins

Proposed Change

Make editorial corrections to Table 235-6. Revise footnote reference format to place the reference inside ofassociated punctuation.

Table 235-6 (m) and (ft)

Column 1, row 2 title. Reference to Footnote 11 associated with span of guy wires.

Supporting Comment

Placements of footnote references in several Code tables are incorrect in that they are placed after associatedpunctuation. For examples of proper placement of similar references, see Tables 234-1, 234-2, and 234-3.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3346


Submitter

Mickey Gunter

Proposed Change



Add new row 2 and renumber existing rows as follows:

Add Footnotes 15 and 16 as follows:

15 For service drops meeting rule 234C3a(2), this clearance value may be reduced to 30 in.

16 This clearance value may be reduced to the following:

communication neutral conductors cables meeting rule 230E1

(a) Service drops meeting 30 in not specified

Rule 230C1

(b) Service drops meeting not specified Rule 230C3

(c) Service drops meeting 3 in Rule 230D

Supporting Comment

Service drops are neither line conductors nor lateral conductors and are not covered by this table. Adding thisnew row 2 will allow proper clearances for supply service drops passing by a communication conductor.Many utilities are providing service to traffic cameras, etc., to a service pole located under the line. The supplyserviced drop usually has to pass by communication line conductors to the traffic service pole. This additionwill provide appropriate clearances from the communication conductors in any direction. New Footnotes 15and 16 will allow reduced clearances to communication cables and neutral conductors meeting Rule 230E1.


Accept as modified.

Change title to Rule 235E, Table 235-6, and add new row 5 to Table 235-6 as follows:

E. Clearances in any direction from line conductors to supports, and to vertical or lateralconductors, service drops, span, or guy wires attached to the same support

2. Supply service drop conductors

40 15 40 16 6 6 plus 0.4per kV

in excess of8.7 kV

23 plus 0.4per kV

in excess of50 kV



Table 235-6—Clearance in any direction from line conductors to supports and to vertical or lateral

conductors, service drops, span, or guy wires attached to the same support[See also Rules 235E1, 235E3b(2), and 235I.]



Negative: (0)

Abstention: (0)

Deleted Text

CP3084


Submitter

Mickey Gunter

Proposed Change

Delete Footnote 6, m and in, rows 3 and 4b, column 2, in Table 235-6 as follows:

3 2 6

Also, as an editorial comment, Table 235-6, m heading should be mm.

Supporting Comment

Table 235-6 column 2 category is for communication lines in general and does not include neutral conductors.Footnote 6 applies to a neutral conductor meeting Rule 230E1 and applies only to column 3 where thecategory for neutral conductors meeting Rule 230E1 is found. Table 235-6 heading should be mm since allthe values in the table are in mm values.

5. Service drops

a. Communication 12 12 30 30 plus 0.4per kV

in excess of8.7 kV

47 plus 0.4per kV

in excess of50 kV

b. Supply N/A 30 16 16 plus 0.4per kV

in excess of8.7 kV

33 plus 0.4per kV

in excess of50 kV




Accept.



Negative: (0)

Abstention: (0)

Deleted Text

CP3284


Submitter

James T. Collins

Proposed Change

Delete Footnote 6, m and in, rows 3 and 4b, column 2 in Table 235-6 as follows:

3 2 6

Also, as an editorial comment, Table 235-6, m heading should be mm.

Supporting Comment

Table 235-6 column 2 category is for communication lines in general and does not include neutralconductors. Footnote 6 applies to a neutral conductor meeting Rule 230E1 and applies only to column 3where the category for neutral conductors meeting Rule 230E1 is found. Table 235-6 heading should be mmsince all the values in the table are in mm values.




See CP3084.





Negative: (0)

Abstention: (0)

New Text

CP3139


Submitter

Bruce Freimark

Proposed Change

Revise the Footnote 9 of Table 235-6 (m and in) as indicated:

m—Footnote 9

9 The additional clearance for voltages in excess of 50 kV specified in Table 235-6 shall be increased 3% foreach 300 m or portion thereof in excess of 1000 m above mean sea level.

Examples of the elevation adjustment:

1. At a conductor elevation between 1000.1 m and 1300 m the additional clearance in Table 235-6 dueto the voltage adder is multiplied by 1.03.

2. At a conductor elevation between 1300.1 m and 1600 m the additional clearance in Table 235-6 dueto the voltage adder is multiplied 1.06.

in—Footnote 9

9 The additional clearance for voltages in excess of 50 kV specified in Table 235-6 shall be increased 3% foreach 1000 ft or portion thereof in excess of 3300 ft above mean sea level.


1. At a conductor elevation between 3301 ft and 4300 ft the additional clearance in Table 235-6 due tothe voltage adder is multiplied by 1.03.


Supporting Comment





Accept as modified.

Revise the footnote 9 of Table 235-6 (m and in) as indicated:

m—Footnote 9

9 The additional clearance for voltages in excess of 50 kV specified in Table 235-6 shall be increased at therate of 1% per 100 m 3% for each 300 m in excess of 1000 m above mean sea level.

in—Footnote 9

9 The additional clearance for voltages in excess of 50 kV specified in Table 235-6 shall be increased at therate of 1% per 330 ft 3% for each 1000 ft in excess of 3300 ft above mean sea level.


Affirmative: (16) Amrhyn, Bednarz, Bleakley, Bowmer, Clapp, Crawford, Drzewiecki, Emery, Gunter,Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White


Abstention: (0)

Explanation of Vote


Revised Text

CP3164


Submitter

David Marne

Proposed Change

Revise Footnote 1 to Table 235-7 as follows:

1 Limited by Rule 235E3(b)(2). Increase clearance due to elevation as specified in Footnote 9 of Table 235-6.

Supporting Comment

Table 235-7 [and Rule 235E3b(1)(b)] increase clearance for elevations greater than 1500 ft. When limited byRule 235E3b(2), which references Table 235-6, it is appropriate to use an increase in clearance for elevations



greater than 3300 ft as specified in Footnote 9 of Table 235-6. This change to the footnote removes confusionas to which elevation should be used when the clearance is limited by Rule 235E3b(2).


Accept as modified.

Modify Footnote 9 in Table 235-6 and revise Footnote 1 to Table 235-7 as follows:

9 The additional clearance for voltages in excess of 50 kV specified in Table 235-6 shall be increased at arate of 1% per 100m (330ft) 3% for each 1000 ft in excess of 3300 ft above mean sea level.

1 Shall be not less than that required Limited by Rule 235E3(b)(2), including the altitude correction for linesas specified in Footnote 9 of Table 235-6.



Negative: (0)

Abstention: (0)

New Text

CP3285


Submitter

James T. Collins

Proposed Change

Add Footnote 3 reference to Table 236-1, row 4 category (Exceeding 73 kV), column 2, as follows:

Exceeding 73 kV3

Supporting Comment

The horizontal clearances above 73 kV are related to the work rules. Rule 441A4 addresses the requirementsfor working on voltages exceeding 73 kV.


Reject.




The footnote applies to every heading in the table.



Negative: (0)

Abstention: (0)

Revised Text

CP3165

Part: 2 Section: 23 238 A

Submitter

David Marne

Proposed Change


A. Equipment

For the purpose of measuring clearances under this rule, equipment shall be taken to meannoncurrent-carrying metal parts of equipment, including metal supports for cables or conductors,and metal support braces that are attached to metal supports or are less than 25 mm (1 in) fromtransformer cases or hangers that are not effectively grounded, and metal or nonmetallic supports orbraces associated with communication cables or conductors.

Supporting Comment

Clarification is necessary to indicate that communication supports or braces of any type are consideredequipment, whether metal or nonmetallic. This change enforces official interpretation requests such as IR 268and IR 388 in ensuring that even non-conductive wood or fiberglass braces and supports for communicationconductors are not allowed to be installed in the communication worker safety zone.


Accept.





Negative: (0)

Abstention: (0)

Revised Text

CP3166


Submitter

David Marne

Proposed Change


A. Equipment

For the purpose of measuring clearances under this rule, equipment shall be taken to meannoncurrent-carrying metal parts of equipment, including metal supports for cables or conductors,and metal support braces that are attached to metal supports or are less than 25 mm (1 in) fromtransformer cases or hangers that are not effectively grounded. Antennas shall be consideredequipment for the purpose of measuring clearances under this rule.

Supporting Comment

A communication antenna in the communication space must be considered equipment to solidify theclearance measurements for the communication worker safety zone. Antennas were not specificallyaddressed in the list of equipment. This change removes confusion as to how they should be addressed.


Accept.



Negative: (0)

Abstention: (0)



Revised Text

CP3167

Part: 2 Section: 23 238 B

Submitter

David Marne

Proposed Change


B. Clearances in general

Vertical clearances between supply conductors and communications equipment, betweencommunication conductors and supply equipment, and between supply and communicationsequipment shall be as specified in Table 238-1, except as provided in Rules 238C and 238D.

Supporting Comment

Rule 238D clearances are less than Table 238-1 clearances and need to be recognized in this rule.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3168

Part: 2 Section: 23 238 D

Submitter

David Marne



Proposed Change

Revise Rule 238D as follows:

D. Clearance of drip loops of luminaire or traffic signal brackets

If a drip loop of conductors entering a luminaire bracket or traffic signal bracket from the surface ofthe structure is above a communication cable, the lowest point of the loop shall be at least 300 mm(12 in) above the highest communication cable or through bolt equipment.

EXCEPTION: The above clearance may be reduced to 75 mm (3 in) if the loop is covered by asuitable nonmetallic covering that extends at least 50 mm (2 in) beyond the loop.

Supporting Comment

Rule 238 uses the word “equipment” throughout the rule except in this one location where the term “throughbolt” is used. The proposed changed adds consistency to the rule and changes the measuring point to the topof the communication cable attachment hardware rather than the communication through bolt, which isusually centered on the attachment hardware.


Accept as modified.



If a drip loop of conductors entering a luminaire bracket or traffic signal bracket from the surface ofthe structure is above a communication cable, the lowest point of the loop shall be at least 300 mm(12 in) above the highest communication cable or through bolt or other exposed metal objects.




Negative: (0)

Abstention: (0)

Revised Text

CP3342




Submitter

James T. Collins

Proposed Change

Revise NESC Rule 238D to clarify intent.


If a drip loop of conductors entering a luminaire, a luminaire bracket, or a traffic signal bracketfrom the surface of the structure is above a communication cable, the lowest point of the loop shallbe at least 300 mm (12 in) above communication cable or through bolt.


Supporting Comment

NESC Rule 238D states the 12 in clearance exception for luminaires only applies when the street light driploop enters the luminaire bracket from the surface of the structure. Some utilities install floodlight drip loopsto the luminaire directly from the secondary. For this reason, some NESC users will not apply the 12 inexception at floodlight installations.




Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3390


Submitter

Nelson Bingel

Proposed Change

Revise Table 238-2 to show 40 in clearance requirements from ungrounded luminaire and traffic brackets andtrolley car conductor brackets.



Supporting Comment

Table 238-2 should be revised to prohibit ungrounded luminaire and traffic signal brackets in thecommunication worker safety zone (i.e., make the clearance be 40 in). Many power utilities ground allluminaire and traffic signal brackets on their poles. Other utilities have a practice of intentionally notgrounding such brackets, primarily due to a desire not to have grounded brackets up in the supply space,particularly the primary space. Such decisions were made long before Rule 441A3a was added to requirecovering of all grounded items in the work area when working above 300 V. However, since Rule 420Drequires items not positively known to be de-energized to be treated as energized, and since Rule 441A3b(2)requires all parts in the work area other than those being worked to be covered with insulating materials, theCode essentially requires luminaire brackets and traffic signal brackets to be covered if they are located in awork area that includes lines above 300 V. In essence, since the neutral is grounded, there is little reason toallow ungrounded luminaire and traffic signal brackets to be located below a distribution neutral level.


Reject.


The change was submitted last cycle and SC4 believes the present wording is adequate; it has been thepractice of communication workers to test metallic fixtures and brackets in the safety work zone prior toworking. Communication workers experience does not support the change.

40 40

40

40

40

40

40

40

40

40

100

100

100

100

100

100

100

100

100

100




Affirmative: (15) Amrhyn, Bednarz, Bleakley, Bowmer, Crawford, Drzewiecki, Emery, Engdahl, Gunter,Hooper, Komassa, Marne, Neubauer, Steiner, White

Negative: (1) Clapp

Abstention: (0) Slavin

Explanation of Vote

Clapp: (Negative) In the older days when telephone was open wire dc voltage only, there was no directconnection to the supply circuit feeding the luminaires. As a result, there was little probability of death ifsimultaneous contact with an energized luminaire bracket and a telephone wire occurred. Now there aregrounded messengers throughout the communications space. As a result, simultaneous contact between acommunication line worker with a grounded messenger and a luminaire that is energized due to a fault cankill the line worker.

In addition, I had the opportunity to discuss this issue with employees of several communication utilitiesbetween the time of the Fall subcommittee meeting and the time of the final subcommittee voting on theactions on proposed changes. None of those communication utility personnel were allowed to contact aluminaire bracket to test it for voltage. It appears that the information supplied to the subcommittee uponwhich the subcommittee based its rejection applies to some communication utilities but not to others. As aresult, I believe even more strongly that the action for rejection should be reversed and that the Code shouldbe changed to remove ungrounded luminaire or traffic signal brackets from the communication worker safetyzone.

In addition, during the same period, I talked with employees of several different electrical utilities during thesame time frame. Given that the NESC work rules now (they did not earlier) require grounded luminaire orsignal brackets in work areas involving voltages in excess of 300V (Rule 441A3a) to be covered withinsulating materials during work, and given that Rule 420D requires such ungrounded luminaire or signalbrackets to be considered as energized (and thus be covered with suitable insulating materials), there is nolonger any apparent advantage that could be identified by any of the individual employees of electric utilitiesfor not grounding those brackets. I find many electric utility employees whose employer policy for manydecades has been to keep all luminaire brackets ungrounded. However, I have so far been unable to findanyone who sees any advantage to doing so, given the current work rules. While there may be some validreason of which I am unaware, it appears that this policy is a holdover from an earlier era and no longer hasa valid basis for continuance.

There are no inspection procedures in use in the electric utility industry that allow utilities to identifyluminaires or traffic signals that are about to have a short circuit to the case or bracket. As a result, there is nopractical way for utilities to change out luminaires before they short out. The general practice is to changethem out only after they have faulted.

For the protection of communication workers in contact with their grounded neutrals, no ungroundedluminaire bracket or traffic signal bracket should be allowed in the communication worker safety zone. Evenif there is some advantage to not grounding luminaire or traffic signal brackets located in the primary zone,it does not make sense to have ungrounded brackets located below the grounded power neutral.

Slavin: (Abstention) This is an apparent safety issue for communication workers, and should be discussed, orpossibly investigated, further.



Revised Text

CP3287

Part: 2 Section: 23 239 A2b

Submitter

James T. Collins

Proposed Change

Revise Rule 239A2b as follows:

b. Supply cables exceeding 600 V meeting Rule 230C1 or 350B may be installed together in the sameduct or U-guard if all of the cables are operated and maintained by the same utility.

Supporting Comment

Underground cables meeting Rule 350B are typically installed on the surface of structures and need to beincluded in this rule.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3288

Part: 2 Section: 23 239 A2c

Submitter

James T. Collins

Proposed Change




c. Supply cables 0 to 600 V and supply cables exceeding 600 V meeting Rule 230C1 or 350B may beinstalled together in the same duct or U-guard if all of the cables are operated and maintained by thesame utility.

Supporting Comment

Underground cables meeting Rule 350B are typically installed on the surface of structures and need to beincluded in this rule.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3289

Part: 2 Section: 23 239 D2

Submitter

James T. Collins

Proposed Change

Revise Rule 239D2 as follows:

2. Where guarding is required by Rule 239D1, either conduit or U-guards may be used. A backingplate shall be used with a U-guard unless the U-guard fits tightly to the supporting structuresurface.

Supporting Comment

Adding this reference makes clear that the backing plate is required to be used with a U-guard only whenguarding is required within 8 ft of the ground.


Accept.





Negative: (0)

Abstention: (0)

Revised Text

CP3169

Part: 2 Section: 23 239 H1

Submitter

David Marne

Proposed Change

Add a new EXCEPTION 3 to Rule 239H1 as follows:

EXCEPTION 3: The nonmetallic covering may extend less than 40 in above the highest trolley feedersor other supply conductors where the communication cables connect to a communication antenna in thesupply space and the clearances specified in Rule 235I are maintained.

Supporting Comment

Rule 235I allows communication antennas in the supply space to be installed as little as 8 in from supplyconductors. Rule 239H should be updated to recognize antenna clearances less than 40 in above supplyconductors.


Accept as modified.

Add a new EXCEPTION 3 to Rule 239H1 as follows:

EXCEPTION 3: Where the cable terminates at an antenna in the supply space meeting Rule 235I, thenonmetallic covering need only extend to the antenna.



Negative: (0)

Abstention: (0)



New Text

CP3066


Submitter

Ewell Robeson

Proposed Change

Add new Footnote 6 to Table 239-1, row 2, column 3 value, m and in, and change table heading from m tomm as follows:

3 plus 0.2 per kV 75 plus 5 per kV

in excess of 8.7 kV 6 in excess of 8.7 kV 6

6 Where the circuit is effectively grounded and the neutral conductor meets Rule 230E1, phase-to-neutralvoltage shall be used to determine the clearance from the surface of support arms and structures.

Supporting Comment

Footnote 10 in Table 235-6 allows the phase-to-ground voltage to be used in calculating the voltage adder foreffectively grounded circuits when the phase-to-phase voltage is over 8.7 kV to 50 kV when calculating theclearance of line conductors from the surface of supports. A similar footnote needs to be added to Table 239-1 to allow this voltage reduction when calculating the clearance of lateral or vertical conductors from thesurface of supports.

Also since all the metric values are in mm, then the Table heading needs to be in mm.


Accept as modified.

Add new footnote 6 to Table 239-1, row 2, column 3 value, m and in, and change table heading from m tomm as follows:

3 plus 0.2 per kV 75 plus 5 per kV

in excess of 8.7 kV 6 in excess of 8.7 kV 6

6 Where the circuit neutral is effectively grounded and the neutral conductor meets Rule 230E1, phase-to-neutral voltage shall be used to determine the clearance from the surface of support arms and structures.



Negative: (0)



Abstention: (0)

Revised Text

CP3119


Submitter

Bruce Freimark

Proposed Change

Revise the Footnote 4 of Table 239-1 (m and in) as indicated:

m—Footnote 4

4 The additional clearance for voltages in excess of 50 kV specified in Table 239-1 shall be increased 3% foreach 300 m or portion thereof in excess of 1000 m above mean sea level.


1. At a conductor elevation between 1000.1 m and 1300 m the additional clearance in Table 239-1 dueto the voltage adder is multiplied by 1.03.

2. At a conductor elevation between 1300.1 m and 1600 m the additional clearance in Table 239-1 dueto the voltage adder is multiplied 1.06

in—Footnote 4

4 The additional clearance for voltages in excess of 50 kV specified in Table 239-1 shall be increased 3% foreach 1000 ft or portion thereof in excess of 3300 ft above mean sea level.




Supporting Comment





Accept as modified.

Revise the footnote 4 of Table 239-1 (m and in) as indicated:

m—Footnote 4

4 The additional clearance for voltages in excess of 50 kV specified in Table 239-1 shall be increased at therate of 1% per 100 m 3% for each 300 m in excess of 1000 m above mean sea level.

in—Footnote 4

4 The additional clearance for voltages in excess of 50 kV specified in Table 239-1 shall be increased at therate of 1% per 330 ft 3% for each 1000 ft excess of 3300 ft above mean sea level.


Affirmative: (16) Amrhyn, Bednarz, Bleakley, Bowmer, Clapp, Crawford, Drzewiecki, Emery, Gunter,Hooper, Komassa, Marne, Neubauer, Slavin, Steiner, White


Abstention: (0)

Explanation of Vote


Revised Text

CP3291


Submitter

James T. Collins

Proposed Change

Revise Table 239-1 as follows:

Add a new column between the first and second columns, rows 2 and 3, as follows:

Neutral conductors

meeting Rule 230E1

in mm

Row 2 3 1 75 1



Row 3 3 75

Add new Footnote 6 to row 1, second column heading, as follows:

0 to 8.7 kV 6

6 Does not include neutral conductors meeting Rule 230E1.

Delete Footnote 1 from the second column and row value as follows:

31 2

Supporting Comment

Since this table does not include a neutral conductor meeting Rule 230E1 category, one needed to be added.A clearance of 3 in for a neutral lateral conductor meeting Rule 230E1 from a support surface to limit abrasionshould be adequate since a lateral conductor is considered to be rigid with no sag variation.

New Footnote 6 is added to be consistent with similar footnotes added in the 2007 Code to make sure usersdo not confuse a 0 supply voltage with a neutral conductor meeting Rule 230E1. Footnote 1 was deleted fromthe second row column 2 and added to the new column where it is now appropriate.


Accept as modified.

Revise Table 239-1 as follows:

Add a new column between the first and second columns, rows 2 and 3, as follows:

Neutral conductors

meeting Rule 230E1

in mm

Row 2 Not specified 1 Not specified 1

Row 3 3 75

Add new Footnote 6 to row 1, second column heading, as follows:

0 to 8.7 kV 6

6 Does not include neutral conductors meeting Rule 230E1.

Delete Footnote 1 from the second column and row value as follows:

31 2

Revise Footnote 4:

4 The additional clearance for voltages in excess of 50 kV specified in Table 239-1 shall be increased at arate of 1% per 100 m (330 ft) 3% for each 300 m in excess of 1000 m (3300 ft) above mean sea level.





Negative: (0)

Abstention: (0)

New Text

CP3290


Submitter

James T. Collins

Proposed Change

Add new Footnote 6 to Table 239-1, row 2 category, column 3, m and in, and change table heading from mto mm as follows:

3 plus 0.2 per kV 75 plus 5 per kVin excess of 8.7 kV 6 in excess of 8.7 kV 6

6 Where the circuit is effectively grounded and the neutral conductor meets Rule 230E1, phase-to-neutralvoltage shall be used to determine the clearance from the surface of support arms and structures.

Supporting Comment

Footnote 10 in Table 235-6 (page 156) allows the phase to ground voltage to be used in calculating the voltageadder for effectively grounded circuits when the phase to phase voltage is over 8.7 kV to 50 kV whencalculating the clearance of line conductors from the surface of supports. A similar footnote needs to be addedto Table 239-1 to allow this voltage reduction when calculating the clearance of lateral or vertical conductorsfrom the surface of supports.

Also since all the metric values are in mm, then the table heading needs to be in mm.




See CP3066.





Negative: (0)

Abstention: (0)

Revised Text

CP3177


Submitter

Grant Glaus

Proposed Change


C. Communication circuit conductors located in the supply space

Communication circuit conductors located in the supply space shall have their grade ofconstruction determined as follows:

1. Circuits meeting the requirements of Rule 224A3 may have the same grade of construction asordinary communication circuits.

2. Circuits not meeting the requirements of Rule 224A3 shall have the same grade of constructionas the supply circuits above which they are located.

Supporting Comment

The reference to Rule 224A3 is outdated or incorrect. Simplification of the rule is appropriate. Table 242-1(last column) uses the wording “B, C, or N; see Rule 242C.” The proposed revision to Rule 242C coordinateswith the Table.


Reject.


Open wire communication is treated as secondary and it may be located above communication cables in thecommunication space and not above supply conductors.




Affirmative: (27) Bingel, Bullinger, Busel, Byrne, Clapp, Clem, Corzine, Denbrock, Erdle, Freimark,Fuller, Glaus, Guerry, Haire, Harrel, Heald, Jones, Kempner, Kluge, Lynch, Ng, Peters, Schwalm, Shultz,Soderberg, Jr., Standford, Wong

Negative: (0)


Revised Text

CP3299


Submitter

James T. Collins

Proposed Change

Revise Footnotes 3 and 7 to read as follows:

3Supply conductors shall meet the requirements of Grade B construction shall be used if the supply circuitswill not be promptly de-energized, both initially and following subsequent breaker operations, in the eventof a contact with lower supply conductors or other grounded objects.

7The supply conductors need only meet the requirements of Grade C construction may be used if both of thefollowing conditions are fulfilled:

Supporting Comment

The title of the Table 242-1 has already made it clear that the grades of construction shown in the table arefor supply conductors. It is inconsistent to mention it in Footnotes 3 and 7 while not mentioning it inFootnotes 5, 6, and 8. The proposed changes help improve the consistency and clarity of the entire footnotesection.


Accept.


Affirmative: (31) Berlinger, Bingel, Bullinger, Burley, Busel, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Fuller, Glaus, Guerry, Haire, Harrel, Heald, Jones, Kempner, Kluge, Lynch,Peters, Schwalm, Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (0)



Abstention: (0)

Deleted Text

CP3176


Submitter

Grant Glaus

Proposed Change

Revise the title of Table 242-1 as follows:

Grades of construction for supply conductors alone, at crossing, or on the same structure with other conductors

Revise the title over the grade of construction columns of Table 242-1:

Supply cConductors at higher levels

Delete the title over the first group of columns of Table 242-1:

Constant-potential supply conductors

Revise the title of the first grade-of-construction column of Table 242-1 as follows:

0–750 V and communication conductors located in the communication space

Delete Table 242-2 on page 175.

Supporting Comment

Communication cables in the supply space are currently covered in both Table 242-1 (last column) and Table242-2 and each gives different requirements. For example, a communication cable in the supply space abovea 7.2 kV phase-to-ground line is required by Table 242-1 to be “B, C, or N; see Rule 242C” but is requiredto be grade “B” in Table 242-2. Also, Table 242-1 uses an 8.7 kV and Table 242-2 uses a 2.9 kV voltage limit.

The proposed change eliminates the discrepancies between the tables and keeps the intended grades ofconstruction relatively unchanged.


Accept as modified.

Revise to Rule 242 and Tables 242-1 and 242-2



242. Grades of construction for conductors

The grades of construction required for conductors and cables are given in Tables 242-1 and 242-2. Forthe purpose of these tables certain classes of circuits are treated as follows:

A. Constant-current circuit conductors

The grade of construction for conductors of a constant-current supply circuit involved with acommunication circuit and not in Type 1 cable shall be based on either its current rating or on theopen-circuit voltage rating of the transformer supplying such circuit., as set forth in Tables 242-1and242-2. When the constant current supply circuit is in Type 1 cable, the grade of constructionshall be based on its nominal full-load voltage. The grade of construction shall be not less than thatrequired in Table 242-1 for a supply conductor of the same voltage.

C. Communication circuit conductors and cables located in the supply space

Communication circuit conductors and cables shall have a grade of construction not less than (a)that required by Table 242-1 or (b) the highest grade of construction required for any conductors orcables located below. located in the supply space shall have their grade of construction determinedas follows:

1. Circuits meeting the requirements of Rule 224A3 may have the same grade of construction asordinary communication circuits.

2. Circuits not meeting the requirements of Rule 224A3 shall have the same grade of constructionas the supply circuits above which they are located.

Table 242-1—Grades of construction for supply conductors and cables alone, at crossing, or on the same structures with other conductors and cables

(The voltages listed in this table are phase-to-ground values for: effectively grounded ac circuits, two-wire grounded circuits, or center-grounded dc circuits; otherwise phase-to-phase values shall be used. The grade of construction for supply conductors and cables, as indicated across the top of the table, shall also meet the requirements for any lines at lower levels except when otherwise noted. Placing of communication conductors

and cables at higher levels at crossings or on jointly used poles in a communication space above supply conductors or cables should generally be avoided, unless the supply conductors are trolley-contact conductors

and their associated feeders.)

Conductors, tracks, and rights-of-way at

lower levels

Supply cConductors and cables at higher levels 1

Constant-potential sSupply conductors

Constant current supply

conductors

Communication

conductors and cables

located in the supply space

0 to 750 V

751 V to8.7 22 kV

Exceeding 8.7 22 kV

Open or cable Open Cable Open Cable Open Cable Open or

cable

Exclusive private rights-of-way

N N2 N N2 N2 B, C, or N;see Rule 242A

C, or N;see Rule 242C

Common or public rights-of-way

N C N C3 C C, or N;see Rule 242C



Revise Footnote 8.

8 Grade C construction may be used if the current cannot exceed 7.5 A or the open-circuit voltage of thetransformer supplying the circuit does not exceed 2.9 kV. Not used in this edition.

Delete Table 242-2 and all footnotes.

Railroad tracks and limited-access high-ways 10

B B B B B B B B

Constant-potential sSupply conductors,0 to 750 V, open or cable

N C N C B, C, or N;see Rule 242A

B, C, or N;see Rule 242C

750 V to 8.7 22 kV Open

C5 C C C3 C

Cable N C N C3 C

Exceeding 8.7 22 kVOpen

B4 B B C3 C

Cable C5 C N C3 C

Constant current supply conductors: open or cable

B, C, or N; see Rule 242A B, C, or N;see Rule 242A

B, C, or N; see Rules 242A and 242C

Communication conductors: Open or cable, located in the supply space 9

B, C, or N; see Rule 242C B, C, or N; see Rules 242A and 242C


Communication conductor: open or cable 5

N B 6, 7 C B7 C B 7, 8 C or N;see Rule 242A


Table 242-1—Grades of construction for supply conductors and cables alone, at crossing, or on the same structures with other conductors and cables

(The voltages listed in this table are phase-to-ground values for: effectively grounded ac circuits, two-wire grounded circuits, or center-grounded dc circuits; otherwise phase-to-phase values shall be used. The grade of construction for supply conductors and cables, as indicated across the top of the table, shall also meet the requirements for any lines at lower levels except when otherwise noted. Placing of communication conductors

and cables at higher levels at crossings or on jointly used poles in a communication space above supply conductors or cables should generally be avoided, unless the supply conductors are trolley-contact conductors

and their associated feeders.) (continued)

Conductors, tracks, and rights-of-way at

lower levels

Supply cConductors and cables at higher levels 1

Constant-potential sSupply conductors

Constant current supply

conductors

Communication

conductors and cables

located in the supply space

0 to 750 V

751 V to8.7 22 kV

Exceeding 8.7 22 kV

Open or cable Open Cable Open Cable Open Cable Open or

cable




Affirmative: (29) Berlinger, Bingel, Bullinger, Burley, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Glaus, Haire, Harrel, Heald, Jones, Joplin, Kempner, Kluge, Lacoursiere,Lynch, Peters, Schwalm, Shultz, Soderberg, Jr., Standford, Wong

Negative: (0)

Abstention: (2) Fuller, Slavin

Explanation of Vote

Fuller: (Abstain) I would also like to understand the change of the 8.7 kV limits, as noted by Mr. Slavin inhis abstention.

Slavin: (Abstain) I fully support the attempt to simplify and consolidate Tables 242-1 and 242-2 fordetermining the grade of construction. However, I am confused by the change of the “8.7 kV” limits in thecorresponding columns and rows to “22 kV” limits. As a result, in several cases, the grades of constructionwould change. For example, an 8.7 kV (or lower) cable above a 15 kV open wire was originally Grade B, butwould now be downgraded to Grade C. As another example, a 15 kV cable above common or public rights-of-way was originally Grade C, but would now be downgraded to Grade N. It is not apparent that suchdowngrades are appropriate, and I suggest that either the original 8.7 kV limits be retained to avoid this issue,or that the higher grade of construction be retained in such cases. In any case, it is not my intention to inhibitthe simplification of these tables.

Revised Text

CP3300

Part: 2 Section: 24 242 Tables 242-1, 242-2

Submitter

James T. Collins

Proposed Change

Make editorial corrections to tables. Revise footnote reference format to place the reference inside ofassociated punctuation.

Table 242-1

Column 1, row 3. Reference to Footnote 10 associated with limited-access highways.

Table 242-2

Column 1, row 3. Reference to Footnote 5 associated with limited-access highways.

Supporting Comment

Placements of footnote references in several Code tables are incorrect in that they are placed after associated



punctuation. For examples of proper placement of similar references, see Tables 234-1, 234-2, and 234-3.


Accept.


Affirmative: (28) Berlinger, Bingel, Bullinger, Busel, Byrne, Clapp, Clem, Corzine, Denbrock, Erdle,Freimark, Fuller, Glaus, Guerry, Haire, Harrel, Heald, Jones, Kempner, Kluge, Lynch, Ng, Peters, Schwalm,Shultz, Soderberg, Jr., Standford, Wong

Negative: (0)

Abstention: (0)

Revised Text

CP3372

Part: 2 Section: 25 250 B Figure 250-1

Submitter

Nelson Bingel

This change proposal was discussed within the IEEE WG-7 and it was decided to put the CP forward togenerate full and open discussion that would more completely evaluate the implications.

Proposed Change

Revise Figure 250-1 as shown below. (Red lines indicate new district boundaries. Dashed blue linesindicated boundaries to be removed. Solid blue indicates no change.) The text for the rule does not change.

250. General loading requirements and maps


Three general degrees of district loading due to weather conditions are recognized and aredesignated as heavy, medium, and light loading. Figure 250-1 shows the districts where theseloadings apply.

NOTE: The localities are classified in the different loading districts according to the relativesimultaneous prevalence of the wind velocity and thickness of ice that accumulates on wires. Lightloading is for places where little, if any, ice accumulates on wires.

Table 250-1 shows the radial thickness of ice and the wind pressures to be used in calculating loads.Ice is assumed to weigh 913 kg/m3 (57 lb/ft3).



Supporting Comment

Historical: When the ice map was originally published in 1916, the Heavy Loading region in the eastern U.S.extended further south and the Light Loading district extended north further along the Atlantic coast. Laterthe Heavy/Medium boundary was revised and moved northward during several revisions and the LightLoading was truncated in South Carolina. These changes to the District map are not substantiated by recentresearch of icing records and weather conditions that produce ice.

ASCE-7, 2005: Combined Ice and Wind map shows the 0.5 and 0.75 in ice boundaries south of the currentNESC Heavy Loading boundary. Note ASCE-7 2005 correlates more closely with the old 1916 NESCDistrict Ice Map.

From Texas to the Carolinas, the ASCE-7 transition zone between the 0.5 and 0.75 in icing regions isrelatively narrow. Also NESC Extreme wind map shows the 100 mph wind speed boundary overlapping the0.75 in ice boundary on the icing map for much of the southeastern region. Comparing these two loading mapssuggest a Medium loading district does not really exist in the southeast region of U.S. and that it would beadvisable to simply transition from “Heavy” directly to “Light” loading.

Along the East Coast, the proposed Light loading district has been extended north of Washington DC becausethe coastal region is more likely to experience extreme winds than ice, according to ASCE-7. This is alsocloser to where the old 1916 NESC District Ice Map showed the boundary for Light Loading. This is notintended to prescribe a hurricane loading, but to recognize the greater wind loading expected along the easterncoast, similar to the Gulf and Florida coasts.

Furthermore, the present Medium Loading district does not provide adequate structures strength for lines withlarge diameter conductor and cables when exposed to winds that could approach hurricane velocities. Forconductors larger than 0.05 in diameter, the transverse loads in the Light Loading district are greater than theMedium Loading district as can be seen in the following table. The transverse loading difference wouldbecome even greater as the diameters get larger.


http://www.nhc.noaa.gov/1995luis.html

http://www.nhc.noaa.gov/1995felix.h

http://www.nhc.noaa.gov/1995opal.html

http://www.nhc.noaa.gov/1995opal.html

http://www.nhc.noaa.gov/1998mitch.html

http://www.nhc.noaa.gov/1988gilbert.html

http://www.nhc.noaa.gov/1988gilbert.html


This deficiency in the Medium Loading district has been exemplified by recent NESC change proposals toincrease the wind load on structures less than 60 ft in height where comments in the proposal reported failuresof structures supporting larger conductors or over-lashed cables. Often these change proposals haveoriginated in the Southeast where several states have regions exposed to heavy ice loads and hurricane loadsand these states, such as North Carolina, are currently in the Medium Loading district, which is inadequate.Heavy and Light Loading better describes the ice and wind exposure for this region.

No change is proposed for the greater western U.S. According to the ASCE-7 loading maps, this region ingeneral shows both lighter wind and ice loading, which substantiates the current NESC Medium district loads.

In the Northwest, a Heavy district is identified along the Columbia River Gorge. Otherwise it remains aMedium Loading district. ASCE-7 shows this region to experience heavy ice loading between 0.5 and 1.5 in,therefore a heavier loading assignment is appropriate.

NESC District

Conductordiameter (in)

Radial Ice(in)

Total diameter

District wind

Transverse load factor

Transverse load (lb/ft)

Heavy 0.5 0.5 1.5 4 2.5 15

Medium 0.5 0.25 1 4 2.5 10

Light 0.5 0 0.5 9 2.5 11.25



NESC 2nd ed., 1916 and 3rd ed., 1920

NESC 4th ed., 1926

NESC 5th ed. Part II, 1941



NESC 7th ed. Part II, 1977 to present



NESC Rule 250 D, Extreme Ice & Concurrent Wind utilizes the ASCE 7-05 map 7


Reject.


Proposal lacks sufficient data to make a decision.




Affirmative: (26) Bingel, Bullinger, Busel, Byrne, Clapp, Clem, Corzine, Denbrock, Erdle, Freimark,Fuller, Glaus, Guerry, Haire, Harrel, Heald, Jones, Kempner, Lynch, Ng, Peters, Schwalm, Shultz,Soderberg, Jr., Standford, Wong

Negative: (1) Kluge


Explanation of Vote

Fuller: (Affirmative) Such a substantial change needs substantial supporting data and discussion beforeadoption.

Kluge: (Negative) Negative as proposed, but supportable with proper modification.

I disagree with the subcommittee’s basis for rejecting this proposal because of “lacking sufficient data.”

The proposed map actually aligns better with current meteorological records of concurrent ice and wind thandoes the existing District Load map. Clearly, the NESC District Load map is flawed as was illustrated by theNESC Subcommittee 5 Task Force comparison to ASCE 7 concurrent wind and ice maps in the 2007 NESCPreprint. (See NESC 2005 Preprint, Appendix.)

My reason for voting to reject is that certain boundaries apparently do not match experience or local data.Discussions at both IEEE and NESC meetings highlighted several local areas where boundaries in this changeproposal are not drawn properly.

For example, one correction suggested during NESC subcommittee discussions would be to keep a mediumloading district in northern Alabama. This is supported by both local utility experience and the weather datasupporting the ASCE ice and wind map. This modification should be made.

A second location of debate was the Washington DC area. Should the heavy loading extend further south?Yet, no one argued that the present medium load district was correct for DC. Therefore, further improvementsor adjustments may be in order.

The proposal needs modification by those familiar with the ice and wind occurrences in the change affectedareas. Adjustments to the proposed boundaries are welcome. It is through contributions from utilities, ASCEor IEEE, and this Preprint review process that such specific data could be obtained and considered.

Revised Text

CP3131


Submitter

Bruce Freimark



Proposed Change

Revise the wind formula definitions in Rule 250C to as follows:

Cf Force coefficient (shape factor). As defined in Rules 251A2 and 252B.

Supporting Comment

The definition of Cf, force coefficient (shape factor) needs to also direct the reader to Rule 251A2.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3302


Submitter

James T. Collins

Proposed Change

Part 1: Add new NOTEs to Rule 250C and Figures 250-2(a) through 250-2(e) as follows:

C. Extreme wind loading

If no portion of a structure or its supported facilities exceeds 18 m (60 ft) above ground or waterlevel, the provisions of this rule are not required, except as specified in Rule 261A1c or 261A2e.Where a structure or its supported facilities exceeds 18 m (60 ft) above ground or water level thestructure and its supported facilities shall be designed to withstand the extreme wind loadassociated with the Basic Wind Speed, as specified by Figure 250-2.

NOTE: Special wind regions—Although the wind speed map is valid for most regions of thecountry, there are special regions in which wind speed anomalies are known to exist. Windsblowing over mountain ranges or through gorges or river valleys in these special regions candevelop speeds that are substantially higher than the values indicated on the map. When selecting



basic wind speeds in these special regions, use of regional climatic data and consultation with awind engineer or meteorologist is advised.

The wind pressures calculated shall be applied to the entire structure and supported facilitieswithout ice. The following formula shall be used to calculate wind load.

Part 2: Change existing “NOTE” to “NOTE 1” and add new “NOTE 2” in captions of each of Figures 250-2(a) through 250-2(e) as follows:

Figure 250-2(a)

NOTE 1: Figure 250-2(a) reprinted with the permission of ASCE Publications, 1801 Alexander BellDr., Reston, VA 20191 from ASCE 7-05, Minimum Design Loads for Buildings and Other Structures.Copyright © 2005.

NOTE 2: For determination of wind velocities in special wind regions see NOTE following firstparagraph of Rule 250C.

Figure 250-2(b)

NOTE 1: Figure 250-2(b) reprinted with the permission of ASCE Publications, 1801 Alexander BellDr., Reston, VA 20191 from ASCE 7-05, Minimum Design Loads for Buildings and Other Structures.Copyright © 2005.


Figure 250-2(c)

NOTE 1: Figure 250-2(c) reprinted with the permission of ASCE Publications, 1801 Alexander BellDr., Reston, VA 20191 from ASCE 7-05, Minimum Design Loads for Buildings and Other Structures.Copyright © 2005.


Figure 250-2(d)

NOTE 1: Figure 250-2(d) reprinted with the permission of ASCE Publications, 1801 Alexander BellDr., Reston, VA 20191 from ASCE 7-05, Minimum Design Loads for Buildings and Other Structures.Copyright © 2005.


Figure 250-2(e)

NOTE 1: Figure 250-2(e) reprinted with the permission of ASCE Publications, 1801 Alexander BellDr., Reston, VA 20191 from ASCE 7-05, Minimum Design Loads for Buildings and Other Structures.Copyright © 2005.




Supporting Comment

In each of Figures 250-2(a) through 250-2(e) a “Special Wind Region” is indicated. There is nothing in theCode that explains what these special wind regions are or how to determine the appropriate speeds. Theproposed revisions and additions, based on ASCE 7-2005, will aid the NESC user in deciding the appropriatewind velocities for such regions.


Accept as modified.

Add a new NOTE just before Rule 250C1.

NOTE: Special wind regions are regions in which wind speed anomalies are known to exist.


Affirmative: (25) Berlinger, Bingel, Bullinger, Busel, Byrne, Clapp, Clem, Cooke, Denbrock, Erdle,Freimark, Glaus, Guerry, Haire, Harrel, Heald, Jones, Kempner, Kluge, Lynch, Peters, Slavin, Soderberg,Jr., Standford, Wong

Negative: (5) Burley, Corzine, Cotant, Fuller, Shultz

Abstention: (1) Schwalm

Explanation of Vote

Burley: (Negative): The special wind definition is vague and does not add any value.

Corzine: (Negative) As was modified by SC5, the resulting proposal gave no guidance to the Code user forwhat action is needed in special wind regions. Also, the reference was removed from Figure 250-2 asoriginally proposed.

Cotant: (Negative) The proposed NOTE as changed duplicates information that is already contained inNOTE 4 on each of the Figures 250-2(a) through 250-2 (e). Adding essentially the same information as aNOTE in the rule itself is unnecessary.

Fuller: (Negative) The proposed change in RC3302 does not aid in understanding what is meant by the termspecial wind region. Original wording in CP3302 seems better.

Kluge: (Affirmative) The simpler proposal of the subcommittee is preferred but it does not provide anyguidance on what to do. Although we are restricted on providing specific direction in a NOTE, the followinggeneral reference seems appropriate and should be added to this NOTE.

Sources of information regarding special wind region can be found in ASCE 7 from local meteorologicalstudies.

The proposed note as changed provides no guidance to the user as how to determine wind speeds in specialwind regions. Somewhere the user needs to receive guidance to appropriately account for the wind speedanomalies in the special wind regions.

Shultz: (Negative) The purpose of this change proposal was to provide guidance to the Code user on how to



determine wind speeds for loading requirements for those areas designated on the maps in Figures 250-2 (a)through (e) as “special wind regions.” The modifications made by Subcommittee 5 to the original proposalstrip any useful guidance from it, and the resulting NOTE still leaves the Code user wondering how to decidewhat are appropriate wind speeds for those regions. As a result, the revision serves no purpose

New Text

CP3303

Part: 2 Section: 25 250 C NOTE

Submitter

James T. Collins

Proposed Change

Add new NOTE following Rule 250C2 as follows:


1. Velocity pressure exposure coefficient, kz

2. Gust response factor, GRF

NOTE: Where structure heights are 50 m (165 ft) or less and spans are 600 m (2000 ft) or less,the combined product of kz and GRF may be conservatively taken as 1.15.

D. Extreme wind with concurrent ice loading

Supporting Comment

The rule as it currently stands is often criticized as being unnecessarily complex. The attached evaluation ofthe kz and GRF values contained in Tables 250-2 and 250-3 does show the combined impact of kz and GRF tobe fairly small for most normal combinations of height and span.

The existing rule is particularly problematic with respect to wire tensions, greatly complicating pole spotting,which is already an iterative solution. Iteration for changing structure locations and ruling spans becomesexceedingly complicated when additional iterations are also required to adjust kz and GRF and recalculatewind pressures for the changes in structure heights and spans.

Given the marginal impact of kz and GRF, a less complex approach is warranted, particularly with respect towind pressures used for calculating wire tensions. Adding the proposed NOTE offers a simpler option, butstill keeps the existing methodology intact for those wishing to iterate for a slightly more cost effectivesolution.




Accept as modified.

Add new NOTE following Rule 250C2 as follows:


1. Velocity pressure exposure coefficient, kz


NOTE: Where structure heights are 50 m (165 ft) or less and spans are 600 m (2000 ft) or less,the combined product of kz and GRF may be conservatively taken as 1.15 if it is desired tosimplify calculations.


Affirmative: (27) Berlinger, Bingel, Bullinger, Busel, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Glaus, Guerry, Haire, Harrel, Jones, Kempner, Kluge, Lynch, Schwalm, Shultz,Slavin, Soderberg, Jr., Standford, Wong

Negative: (4) Burley, Fuller, Heald, Peters

Abstention: (0)



Explanation of Vote

Burley and Heald: (Negative) The NESC can always be used conservatively. We do not need to repeat thesestatements for specific situations.

Fuller: (Negative) I agree with Mr. Kluge’s point about being sure the conservative value is reallyconservative for all applicable ranges of height.

Kluge: (Affirmative) I support in principal a proposal to simplify a rule that is an overly complex for manylower voltage applications. James T. Collins, author of CP3303, offers a third alternate means to convert windspeed to pressure. However, NESC does not need three (3) methods to calculate a these factors. NESCintended the tables to be the simpler method. The tables should be further simplified instead of offering a thirdmethod.

The shortcomings of Collins’ proposal are:

1. This cannot be a NOTE. It must be a rule if NESC is sanctioning the use of this single factor for kz and GRFfor certain applications.

2. Three alternate methods to obtain kz and GRF seem excessive (formulas, table values, and the single factorproposed by Collins).

3. The single factor Collins proposes is highly conservative. For example, the table’s values are alreadyconservative to the point of discouraging their use entirely.

Please consider the following modified proposal.

Modified change proposal 3303 Rule 250C

Replace Rule 250C with the following except Figures 250-2 do not change.


If no portion of a structure or its support facilities exceed 18 m (60 ft) above ground or water level,the provisions of this rule are not required, except as specified by the addition in Rule 261A1c,261A2e, or 261A3d. Where a structure or its supported facilities exceed 18 m (60 ft) above groundor water level, the structure and its supported facilities shall be designed to withstand the extremewind load associated with the Basic Wind Speed, as specified by Figure 250-2. The wind pressurescalculated shall be applied to the entire structure and supporting facilities without ice. The followingformula shall be used to calculate wind load.

where

0.613 0.00256 = Velocity-pressure numerical coefficient reflects the mass density of air for the standard

atmosphere, i.e., temperature of 15 °C (59 °F) and sea level pressure of 760 mm (29.92 in) ofmercury. The numerical coefficient 0.613 metric (0.00256 customary) shall be used except

LoadNewtons 0.613 Vm s⁄( )2 kz GRF I Cf A m2( )⋅ ⋅ ⋅ ⋅ ⋅ ⋅=

Loadpounds 0.00256 V mi( ) h⁄( )2 kz GRF I Cf A ft2( )⋅ ⋅ ⋅ ⋅ ⋅ ⋅=



where sufficient climatic data are available to justify the selection of a different value of thisfactor for a design application.

V = Basic wind speed, 3-s gust wind speed in m/s at 10-m (mph at 33-ft) above ground, Figure250-2

kz = Velocity-pressure exposure coefficient, as defined in Rule 250C1, Table 250-2

GRF = Gust response factor, as defined in Rule 250C2

I = Importance factor, 1.0 for utility structures and their supported facilitiesCf = Force coefficient (shape factor), as defined in Rule 252B

A = Projected wind area, m2 (ft2)

The wind pressure parameters (kz, V, and GRF) are based on open terrain with scatteredobstructions (Exposure Category C as defined in ASCE 7-05). Exposure Category C is the basis ofthe NESC extreme wind criteria. Topographical features such as ridges, hills, and escarpments mayincrease the wind loads on site-specific structures. A Topographic Factor, Kzt, from ASCE 7-05,may be used to account for these special cases. Wire attachment points that are 18 m (60 ft) or lessabove ground or water level must be considered if the total structure height is greater than 18 m(60 ft) above ground or water.

Wind pressure parameters (kz and GRF) shall be determined using the following formulas or fromTables 250-2 and 250-3, if applicable. Tables 250-3 and 250-3 may only be used for structure andwire parameters (kz, and GRF) within the designated height and span limits.

1. Velocity pressure exposure coefficient, kz, for h ≤ 275 ft (metric)

for structure for wire, structure location and component:

Velocity pressure exposure coefficient, kz, for h ≤ 900 ft (customary)


Velocity pressure exposure coefficient, kz, for h > 275 ft (h > 900ft)


kz = 1.85 kz = 2.01

where

h = Height, m (ft), as defined in Rule 250C4

Minimum, kz:

kz 2.01 0.67 h 275⁄⋅( )2 9.5⁄⋅= kz 2.01 0.67 h 900⁄⋅( )2 9.5⁄⋅=

kz 2.01 h 275⁄( )2 9.5⁄⋅= kz 2.01 h 900⁄( )2 9.5⁄⋅=

kz 0.85≥



2. Gust response factor, GRF, for structure, structure location and component:

Metric Customary

Gust response factor, GRF, for wire:

Customary Metric

where

Es= Structure exposure factorEw = Wire exposure factorBs = Dimensionless response term corresponding to the quasi-static background wind loads on the

structure.kv = 1.430h = Height, m (ft), as defined in Rule 250C4L = Design wind span, (ft).

The gust response factor, GRF, to be used on components, such as antennas, transformers, etc., shallbe the structure gust response factor.

3. Alternatively, values for the product (kz × GRF × I) may be used from Tables 250-2 and 250-3 forstructures and wires, respectively. Use of these tables the general equations is only applicable forstructure heights up to 165 ft and wire spans up to 1500 ft. The tables are not applicable whencalculating a wind load at a specific structure location or component such as antennas,transformers, etc. where h used to determine kz is the height to the component and h used todetermine GFR is the height of the structure.

where

h = Height of structure or wire as defined in Rule 250C4L = Design wind-span lengthI = 1.0 as previously defined for utility applications

GRF1 2.7 ES Bs⋅ ⋅+

kv2

-----------------------------------------=

Es 0.346 10 0.67⁄ h⋅( )1 7⁄⋅= Es 0.346 33 0.67⁄ h⋅( )1 7⁄⋅=

Bs1

1 0.375 h 67⁄⋅+----------------------------------------= Bs

11 0.375 h 220⁄⋅+-------------------------------------------=

GRF1 2.7 Ew Bw⋅ ⋅+

kv2

-------------------------------------------=

Ew 0.346 10 h⁄( )1 7⁄⋅= Ew 0.346 33 h⁄( )1 7⁄⋅=

Bw1

1 0.8 L 67⁄⋅( )+---------------------------------------= Bw

11 0.8 L 220⁄⋅( )+------------------------------------------=



1 Structures with a total height of 18 m (60 ft) or less above ground or water level are exempt from Rule 250C.

1 When wires are attached at multiple heights on a single structure, the attachment height associated with each wiremay be used for that respective wire, or, the average attachment height for all wires on that structure may be usedto determine a single (I × kz × GRF) factor for use with all wires.

2 Wire attachment points that are 18 m (60 ft) or less above ground or water level must be considered if the total struc-ture height is greater than 18 m (60 ft) above ground or water level.

3 Wire attachment 3.

4. Effective height, h, of structure, wire or significant component or attachment

The height, h, to the center-of-pressure of the wind area as used to determine the velocity pressureexposure coefficient, kz, and the structure and wire gust response factor, GRF, or for use in Tables250-2 and 250-3 is based on the following load applications:

a. Structure: h = height of the structure above ground line

Table 250-2Product of kz, GRF, and I

for structure

Height For structure

(m) (ft) kz · GRF · I

10 33 0.881

>10 to 15 >33 to 50 0.931

>15 to 25 >50 to 80 0.99

>25 to 35 >80 to 115 1.03

>35 to 50 >115 to 165 1.07

>50 >165 Use formulas

Table 250-3For wires: Product of kz, GRF, and I

Product of (kz · GRF · I) for respective span length (L) 3

Height1 m L75 75<L150 150<L225 225<L300 300<L450 450<L600 L>600

m ft ft L100 100<L250 250<L500 500<L750 750<L1000

1000<L1500 L>1500

10 33 0.962 0.932 0862 0.792 0.752 0.732 Useformulas

>10 to 15 >33 to 50 1.002 0.962 0.902 0.832 0.802 0.772

>15 to 25 >50 to 80 1.06 1.03 0.96 0.90 0.85 0.83 —

>25 to 35 >80 to 115

1.12 1.08 1.01 0.95 0.91 0.88 —

>35 to 50 >115 to 165

1.18 1.14 1.07 1.00 0.96 0.93 —

>50 >165 Use formulas



NOTE: In Table 250-2, for h 75 m (250 ft), the structure kz values are adjusted for the wind load tobe determined at the center-of-pressure of the structure assumed to be at 0.67 h. The wind pressureis assumed uniformly distributed over the structure face normal to the wind.

b. Wire: h = height of the wire at the structure.

(1) The height of the wire at mid-span should be considered, if greater than at the attachmentpoint.

(2) Wire attachment points that are 18 m (60 ft) or less above ground or water level must beconsidered if the total structure height is greater than 18 m (60 ft) above ground or waterlevel.

NOTE: In special terrain conditions (i.e., mountainous terrain and canyon) where theheight of the wire above ground at mid-span may be substantially higher than at thestructure, engineering judgment may be used in determining an appropriate value for theheight of the wire.

c. Structure location and component:

When calculating a wind load at a specific structure location, the structure gust responsefactor, GRF, determined using the total structure height, h, shall be used.

For kz: h = height to the center-of-pressure of the wind area being considered

For GRF: h = height of the structure above ground line

d. Units of measure for (h) is meters for metric and feet for customary.

Additional comments

— There appears to be an error in the NESC Table 250-3 (metric and customary) for the structure gustresponse factors. The values appear to be off by one row relative to the height.

— The information is arranged with formulas (being the primary means to calculate the wind pressureparameters) first followed by the tables as an alternate method. The factors for “structures” arepresented in one table and factors for “wires” in another table. We believe this arrangement is moreconvenient. Velocity pressure exposure coefficient, gust response factor and importance factor arecombined into a single coefficient.

— See also CP3459.

Besides simplifying the tables, this modification also moves the formulas for GRF and kz into the rule ratherthan as footnotes in the tables. Tables follow as an alternate method. Collins’ proposed factor could followthat as an additional alternate but I do not believe that will be necessary if these changes are made.

Peters: (Negative) No need to simplify calculations.

Revised Text

CP3448

Part: 2 Section: 25 250 C, Figures 250-2

Submitter

Subcommittee 5



Proposed Change

Replace Figures 250-2 with the latest corresponding “Basic Wind Speed” maps of ASCE 7-10, MinimumDesign Loads for Buildings and Other Structures.

Supporting Comment

The upcoming (2010) edition of the ASCE 7 standard may include revised maps, reflecting more recent basicwind speed data. The 2012 edition of the NESC should reflect the latest information, by adopting the ASCE7-10 maps.


Accept.


Affirmative: (31) Berlinger, Bingel, Bullinger, Burley, Busel, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Fuller, Glaus, Guerry, Haire, Heald, Jones, Kempner, Kluge, Lynch, Pehosh,Peters, Schwalm, Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (0)

Abstention: (0)

Revised Text

CP3459

Part: 2 Section: 25 250 C1, Table 250-2

Submitter

Subcommittee 5

Rule 250C1

The selected values of kz are tabulated in Table 250-2. When h > 75 m (250 ft), the formulas shall be used todetermine a kz value.

Table 250-2 (title)

Velocity pressure exposure coefficient kz, structure, structure location, component, and wire

and

Any where the phase “structure location” is used.



Proposed Change

Rule 250C1

The formulas shown in Table 250-2 shall be used to determine all values of kz.

EXCEPTION: The selected values of kz are tabulated in Table 250-2 may be used instead of calculatingthe values. When h is > 75 m (250ft), the formulas shall be used to determine a kz value.

Table 250-2 (title)

Table 250-2—Velocity pressure exposure coefficient kz, structure, structure location specified height on the structure, component, and wire

All locations (4 places) in Table 250-2, “structure location” change to “specified height on the structure.”

Supporting Comment

These changes are based on comments received from an NESC user. They are provided for clarification.


Accept.


Affirmative: (27) Berlinger, Bingel, Bullinger, Burley, Clapp, Clem, Corzine, Cotant, Denbrock, Erdle,Freimark, Fuller, Glaus, Haire, Heald, Jones, Joplin, Kempner, Kluge, Lynch, Ng, Peters, Schwalm, Shultz,Slavin, Soderberg, Jr., Wong

Negative: (0)

Abstention: (0)

Revised Text

CP3301

Part: 2 Section: 25 250 C2

Submitter

James T. Collins

Proposed Change

Reformat Rule 250C2 as shown and demote special terrain statement to a note as in Rule 250C1b. (There areno other changes of substance in the rule; all existing verbiage is still included, only rearranged.)




Selected values of the structure and wire gust response factors are tabulated in Table 250-3. Thestructure gust response factor, GRF, is determined using the total structure height, h. The wire gustresponse factor is determined using the height of the wire at the structure, h, and the design windspan, L. The structure and wire gust response factors may also be determined using the formulas inTable 250-3. For values of h > 75 m (250 ft) and L > 600 m (2000 ft) the GRF shall be determinedusing the formulas in Table 250-3. In special terrain conditions (i.e., mountainous terrain andcanyon) where the height of the conductor aboveground at mid-span may be substantially higherthan at the attachment point, engineering judgment may be used in determining an appropriatevalue for the wire GRF. Wire attachment points that are 18 m (60 ft) or less above ground or waterlevel must be considered if the total structure height is greater than 18 m (60 ft) above ground orwater.

When calculating a wind load at a specific structure location, the structure gust response factor,GRF, determined using the total structure height, h, shall be used. The gust response factor, GRF, tobe used on components, such as antennas, transformers, etc., shall be the structure gust responsefactor.

a. The structure gust response factor, GRF, is determined using the total structure height, h. Whencalculating a wind load at a specific structure location, the structure gust response factor, GRF,determined using the total structure height, h, shall be used.

b. The wire gust response factor is determined using the height of the wire at the structure, h, andthe design wind span, L. Wire attachment points that are 18 m (60 ft) or less above ground orwater level must be considered if the total structure height is greater than 18 m (60 ft) aboveground or water.

NOTE: In special terrain conditions (i.e., mountainous terrain and canyon) where the height ofthe conductor aboveground at mid-span may be substantially higher than at the attachmentpoint, engineering judgment may be used in determining an appropriate value for the wireGRF.

c. The gust response factor, GRF, to be used on components, such as antennas, transformers, etc.,shall be the structure gust response factor.

Selected values of the structure and wire gust response factors are tabulated in Table 250-3. Thestructure and wire gust response factors may also be determined using the formulas in Table 250-3.For values of h > 75 m (250 ft) and L > 600 m (2000 ft), the GRF shall be determined using theformulas in Table 250-3.

Supporting Comment

This CP proposes to reformat Rule 250C2 for consistency with Rule 250C1. In addition it is proposed toreduce the terrain statement for the gust response factor to a NOTE in Rule 250C2 as the velocity coefficientfactor is treated in Rule 250C1.

Other than the proposed NOTE above, no changes in requirements of the rule are proposed. All of therequirements are retained, except in a reformatted presentation similar to the velocity coefficient factor rule.

The two wind variables in the velocity-to-force equation, kz and GRF, are of equal significance in determiningthe required wind pressures. As such, they should be presented similarly for consistency. Reformatting thegust response factor rule as proposed will accomplish this.




Accept as modified.

Revise wording of Rules 250C1b and 250C1c as shown. Reformat Rule 250C2 as shown and demote specialterrain statement to a NOTE as in Rule 250C1b. (There are no other changes of substance in the rule; allexisting verbiage is still included, only rearranged.)

1. Velocity pressure exposure coefficient, kz.

The velocity pressure coefficient, kz, is based on the height, h, to the center-of- pressure of the windarea for the following load applications:

a. …

b. kz for the wire is based on the height, h, of the wire at the structure.

NOTE: In special terrain conditions (i.e., mountainous terrain and canyon) where the height ofthe wire aboveground at mid-span may be substantially higher than at the structure,engineering judgment may be used in determining an appropriate value for the wire kz.

c. kz for a specific height on a structure location or component is based on the height, h, to thecenter-of-pressure of the wind areas being considered.



When calculating a wind load at a specific structure location, the structure gust response factor,GRF, determined using the total structure height, h, shall be used. The gust response factor, GRF, tobe used on components, such as antennas, transformers, etc., shall be the structure gust responsefactor.

a. The structure gust response factor, GRF, is determined using the total structure height, h. Whencalculating a wind load at a specific height on a structure, the structure gust response factor,GRF, determined using the total structure height, h, shall be used.

b. The wire gust response factor is determined using the height of the wire at the structure, h, andthe design wind span, L. Wire attachment points that are 18 m (60 ft) or less above ground orwater level must be considered if the total structure height is greater than 18 m (60 ft) aboveground or water.



In special terrain conditions (i.e., mountainous terrain and canyon) where the height of the wireaboveground at mid-span may be substantially higher than at the attachment point, engineeringjudgment may be used in determining an appropriate value for the wire GRF.

c. The gust response factor, GRF, to be used on components, such as antennas, transformers, etc.,shall be the structure gust response factor determined in Rule 250C2a.

Selected values of the structure and wire gust response factors are tabulated in Table 250-3. Thestructure and wire gust response factors may also be determined using the formulas in Table 250-3.For values of h > 75 m (250 ft) and L > 600 m (2000 ft), the GRF shall be determined using theformulas in Table 250-3.

Supporting Comment

This CP proposes to reword the note to Rule 250C1b to language suitable for an NESC note (i.e., to clarifythat no requirement is imposed, and to only provide information).

This CP also proposes to reword Rule 250C1c to language that makes clear that the intent of this rule is todescribe a location on a structure at a height, h, aboveground, and not a geographical location in an overheadline.

This CP proposes to reformat Rule 250C2 for consistency with Rule 250C1. In addition it is proposed toreduce the terrain statement for the gust response factor to a NOTE in Rule 250C2 as the velocity coefficientfactor is treated in Rule 250C1.

The wording of 250C2a is revised to make clear that gust response factor is intended to apply to a point at aspecific height on a structure, and not to a survey location of a structure in an overhead line. The wording inthe NOTE to Rule 250C2b is revised to language suitable for an NESC NOTE (i.e., to clarify that norequirement is imposed, and to only provide information). The wording of Rule 250C2c is revised to makeclear that the intended gust response factor is per Rule 250C2a.

All other requirements are retained, except in a reformatted presentation similar to the velocity coefficientfactor rule.

The two wind variables in the velocity-to-force equation, kz and GRF, are of equal significance indetermining the required wind pressures. As such, they should be presented similarly for consistency.Reformatting the gust response factor rule as proposed will accomplish this.


Affirmative: (28) Berlinger, Bingel, Bullinger, Burley, Byrne, Clapp, Clem, Corzine, Cotant, Denbrock,Erdle, Freimark, Fuller, Glaus, Haire, Heald, Jones, Joplin, Kempner, Kluge, Lacoursiere, Lynch, Schwalm,Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (0)

Abstention: (0)



Deleted Text

CP3423


Submitter

Nelson Bingel

This change proposal was discussed within the IEEE WG-7 and it was decided to put the CP forward togenerate full and open discussion that would evaluate the implications completely.

Proposed Change

Revise Rules 250C and 250D to eliminate the 60 ft exclusion for applying these loads.


If no portion of a structure or its supported facilities exceeds 18 m (60 ft) above ground or waterlevel, the provisions of this rule are not required, except as specified in Rule 261A1c, 261A2e, or261A3d. Where a structure or its supported facilities exceeds 18 m (60 ft) above ground or waterlevel the structure Structures and its supported facilities shall be designed to withstand the extremewind load associated with the Basic Wind Speed, as specified by Figure 250-2. The wind pressurescalculated shall be applied to the entire structure and supported facilities without ice. The followingformula shall be used to calculate wind load.


If no portion of a structure or its supported facilities exceeds 18 m (60 ft) above ground or waterlevel, the provisions of this rule are not required. Where a structure or its supported facilitiesexceeds 18 m (60 ft) above ground or water level, the structure Structures and its supportedfacilities shall be designed to withstand the ice and wind load associated with the Uniform IceThickness and Concurrent Wind Speed, as specified by Figure 250-3. The wind pressures for theconcurrent wind speed shall be as indicated in Table 250-4. The wind pressures calculated shall beapplied to the entire structure and supported facilities without ice and to the iced wire diameterdetermined in accordance with Rule 251.

Also eliminate the Kz and GRF.

Supporting Comment

KEMA was commissioned to evaluate the forensic data following the devastation of Hurricane Wilma inFlorida in 2005. This report states that during Hurricane Wilma, the pole failure rates were highest due tobreakages caused by wind only.

During the last Code cycle, proposals to eliminate the 60 ft exclusion limit were rejected in large part becauseit was felt that trees and debris blown into lines were the biggest cause of pole failures. The KEMA reportsuggests this is not true and it is the first report based on documented forensic evaluation.

The maps for Rules 250C and 250D are modern, scientifically developed maps that more accurately calculate



the statistical 50 year weather events than any previous maps in the NESC. The wind speeds were measuredat 33 ft and thereby should be applied to structures that extend less than 60 aboveground.

Applying all three load cases to all structures will make designs nationwide more consistent and will help toprovide the improved reliability that state regulators are seeking.

Structures less than 60 ft are affected very little by the constants Kz and GRF. Therefore we should justeliminate them to make equations simpler for distribution. Most transmission lines are designed for higherloads anyway.


Reject.


The proposal does not increase safety.


Affirmative: (24) Bingel, Bullinger, Byrne, Clem, Cooke, Corzine, Cotant, Denbrock, Erdle, Freimark,Haire, Harrel, Heald, Jones, Joplin, Kempner, Kluge, Peters, Schwalm, Shultz, Slavin, Soderberg, Jr.,Standford, Wong

Negative: (3) Burley, Clapp, Lynch

Abstention: (3) Berlinger, Fuller, Glaus

Explanation of Vote

Burley: (Negative) It will increase safety.

Clapp: (Negative) We have problems with distribution lines coming down due to wind loads only. Extremewind loads should apply to all structures, regardless of pole height.

Now that distribution pole heights have increased to the 40 ft to 50 ft range, rather than the 35 ft poles thatwere in use when the decision was made to exempt distribution poles from extreme wind loading. The wiresand cables are at elevated levels and experience the full wind loading. In addition, my experience is thatdistribution lines are generally loaded to a higher percentage of allowed loading than in earlier years, and thegreater diameters of conductors and cables located at higher levels are causing loads from storm winds onbase conductors and cables to exceed the old Rule 250B loading.

Every distribution line section’s failure I have investigated met Rule 250B loading but was either near to orfailed to meet Rule 250C extreme wind requirements.

Fuller: (Abstention) It seems that we are gathering compelling evidence that the 60 ft exclusion is notwarranted. This at least merits further discussion at future meetings.

Glaus: (Abstention) Further consideration is necessary regarding eliminating the 60 ft exclusion, Kz, andGRF.

Joplin: (Affirmative) Within the last ten years, NCMEC has not experienced significant failures due to wind



only. The majority of pole failures were contributed to debris blown on the lines. Based on our experience,this change proposal would not make a significant impact to improve reliability on distribution lines.

Lynch: (Negative) It is time that we bring all overhead line facilities up to modern day standards. Theexemption of facilities less than 60 ft from the scientifically based 50 year return period Extreme Wind andCombined Ice and Wind loadings that facilities above 60 ft are required to follow. The argument that allstructures that are less than 60 ft that have failed due to wind or ice events were due to flying and falling debrishitting them has been disputed many times, including the report submitted to the Florida PSC regardingHurricane Wilma and the fact that some 75% of those poles that failed under wind load alone that was underthe Rule 250C winds for that region. Further, the concept that a structure will only fail with flying debris andtherefore does not need to be designed for an extreme wind condition is flawed; what about structures that arenot exposed to flying debris and where right-of-ways have been properly maintained to guard against fallingdebris? Should they not be designed adequately and in the interest of public safety? Not designing allaboveground facilities for these extreme wind and combined ice and wind events because they will fail dueto external debris is like saying that we should not eat right or exercise because we will all die anyway.

It also does not make sense that we do not require loadings consistent with their expected lifetime; we expectthese structures to last for 50 years (or more), yet we only require structures less than 60 ft to be designed for20 year (more or less) wind and ice events.

It is time that we as professional engineers and leaders in our industry accept this responsibility and beginrequiring that shorter structures and lines be designed for these same 50 year events that taller facilities aredesigned for before public service commissions or other outside organizations mandate that we do properengineering.

New Text

CP3446

Part: 2 Section: 25 250 D, Figures 250-3

Submitter

Subcommittee 5

Proposed Change

Replace Figures 250-3, with the latest corresponding “Uniform ice thickness with concurrent wind” maps ofASCE 7-10, Minimum Design Loads for Buildings and Other Structures.

Supporting Comment

The upcoming (2010) edition of the ASCE 7 standard includes revised maps, reflecting more recent stormdata, for the 50-year ice storms for use in Rule 250D, Extreme ice with concurrent wind loading. The 2012edition of the NESC should reflect the latest information, by adopting the ASCE 7-10 maps.


Accept.




Affirmative: (31) Berlinger, Bingel, Bullinger, Burley, Busel, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Fuller, Glaus, Guerry, Haire, Heald, Jones, Kempner, Kluge, Lynch, Pehosh,Peters, Schwalm, Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (0)

Abstention: (0)

New Text

CP3133

Part: 2 Section: 25 251 A2

Submitter

Bruce Freimark

Proposed Change


2. In determining wind loads on a conductor or cable without ice covering, the assumed projected areashall be that of a smooth cylinder whose outside diameter is the same as that of the conductor orcable. The force coefficient (shape factor) for cylindrical surfaces is assumed to be 1.0.

EXCEPTION: The force coefficient (shape factor) of 1.0 may be reduced for the bare conductor(without radial ice) if wind tunnel tests or a qualified engineering study justifies a reduction.

NOTE: Experience has shown that as the size of multi-conductor cable decreases, the actualprojected area decreases, but the roughness factor increases and offsets the reduction in projectedarea.

Supporting Comment

Rule 252B contains the EXCEPTION permitting a reduction in the force coefficient (shape factor) forcalculating wind pressures on the structures supporting the line “if wind tunnel tests or a qualified engineeringstudy justifies a reduction.”

A similar EXCEPTION permitting a reduction in the force coefficient (shape factor) for the conductor shouldbe permitted here.


Accept.




Affirmative: (29) Berlinger, Bingel, Bullinger, Burley, Busel, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Fuller, Glaus, Guerry, Haire, Harrel, Heald, Jones, Kempner, Kluge, Lynch,Peters, Shultz, Slavin, Soderberg, Jr., Standford

Negative: (1) Wong

Abstention: (1) Schwalm

Explanation of Vote

Clapp: (Affirmative) I recommend adding the following to the existing NOTE: However, special low-dragconstruction can reduce the effective force coefficient.

Kluge (Affirmative) There are additional issues with this rule. The present NOTE is vague. I am not sure Iunderstand what useful information it is providing. Secondly, the NOTE contains a different term “roughnessfactor” not used in the rule. Is this the same as “force coefficient (shape factor)”?

Rule 013 allows for the regulatory authority to waive or modify a rule, therefore, possibly the proposedEXCEPTION and the NOTE could be combined with a clearer message.

Wong: (Negative) This CP duplicated statement already exists in the Code. It also only addresses thereduction of force coefficient. There are many cases where the force coefficient can be higher than 1.0.Adding this EXCEPTION gives the wrong impression that bare wire force coefficient will always be less thanone, which would not be correct.

New Text

CP3304

Part: 2 Section: 25 251 B2

Submitter

James T. Collins

Proposed Change

Add NOTE to rule as follows:


The horizontal load shall be the horizontal wind pressure determined under Rule 250 applied atright angles to the direction of the line using the projected area of the conductor or messenger andconductors, spacers, or equipment that it supports, ice covered where required by Rule 250.

NOTE: The projected area of the conductor or messenger upon which the wind load is based is therectangle defined by a width equal to the diameter of the conductor or messenger, plus ice ifappropriate, multiplied by the length of the conductor or messenger upon which the wind blows.See Rule 252B2 for force coefficient values of different surface shapes.



Supporting Comment

This proposal will explain the model for calculating horizontal wind loads on the “projected area” of aconductor. On occasion, infrequent or non-technical Code users have questioned the terms “projected area”and “force coefficient (shape factor).”


Accept as modified.

Add NOTE to rule as follows:


The horizontal load shall be the horizontal wind pressure determined under Rule 250 applied atright angles to the direction of the line using the projected area of the conductor or messenger andconductors, spacers, or equipment that it supports, ice covered where required by Rule 250.

NOTE: The projected area of the conductor or messenger is equal to the diameter of the conductoror messenger, plus ice if appropriate, multiplied by the span length (see Rule 252B4). See Rule251A2 for force coefficient values of different surface shapes.


Affirmative: (30) Berlinger, Bingel, Bullinger, Burley, Busel, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Fuller, Glaus, Guerry, Haire, Harrel, Heald, Jones, Kempner, Kluge, Lynch,Peters, Schwalm, Shultz, Slavin, Soderberg, Jr., Wong

Negative: (1) Standford

Abstention: (0)

Explanation of Vote

Erdle: (Affirmative) I voted yes, because I believe this is technically correct. However, I do not believe thisneeds to be added to the Code. Users of the Code should know how to calculate projected area. We are movinginto the direction of creating a design/instruction manual.

Kluge: (Affirmative) Is this truly necessary? This belongs in an NESC commentary. As an alternative, maybeClapp could add this to his handbook.

Standford: (Negative) The need to add a clarification of “projected area” is not needed. A person holding atechnical position certainly should know a basic concept like projected area and how to determine it.

If a definition of “projected area” is needed, then it should be in the definitions Section 2. There are four otherplaces in Section 25 where this term is used in relation to wind loading. These sections are 250C (definesfactor A used in calculations), 250D3, 251A2, and 252B2c. The term should be in the definitions to cover allinstances, including conductors, spacers, cables, equipment, and structures.



New Text

CP3145


Submitter

Bruce Freimark

Proposed Change

Add Footnote 1 as indicated:


1For multiple-conductor cable arrangements supported by a messenger using spacers and where each conductor is sep-arately loaded with ice and wind as described in Rule 251A3b (as opposed to being analyzed with the ice and windapplied to a hollow cylinder touching the outer strands of the conductors as described in Rule 251A3a), the factorspecified here shall be added to the resultant load of each component conductor and the messenger.

Supporting Comment

There is apparently some confusion regarding the inclusion of the K factor when performing sag and tensioncalculations on certain types of multiplex cables such as Hendrix. Southwire’s manual for the Sag 10 programstates on page 42:

The NESC K factor can be applied in two ways: Only to messenger or to each cable and messenger. The NESCmanual does not clearly define whether the K factor should be applied to the messenger only, or to each ofthe cables and the messenger, so both options have been offered to allow for the users discretion.

If the old NESC district loads, i.e., 0 °F, 0.5 in ice, 8 PSF wind for the Heavy District were still in use, all ofthe conductor components supported by the messenger would be loaded with the equivalent of the K factor.This CP is intended to clarify the intentions of the NESC.

Loading districts (for use with Rule 250B) Extreme windloading (for

use with Rule 250C

Extreme iceloading withconcurrent

wind(For use with Rule 250D)

Heavy Medium Light

Temperature (°C) –20 –10 –1 +15 –10

(°F) 0 +15 +30 +60 +15

Constant to be added to the resultant (all conductors) 1

(N/m) 4.4 2.9 0.73 0.0 0.0

(lb/ft) 0.30 0.20 0.05 0.0 0.0




Accept as modified.

Add Footnote 1 as indicated:

1For cable arrangements supported by a messenger using spacers and where each conductor is separately loaded withice and wind as described in Rule 251A3b (as opposed to being analyzed with the ice and wind applied to a hollowcylinder touching the outer strands of the conductors as described in Rule 251A3a), the factor specified here shallbe added to the resultant load of each component conductor and the messenger.


Affirmative: (24) Bingel, Bullinger, Busel, Byrne, Clapp, Clem, Cooke, Corzine, Cotant, Denbrock, Erdle,Freimark, Guerry, Haire, Harrel, Jones, Kempner, Kluge, Lynch, Peters, Shultz, Slavin, Standford, Wong

Negative: (5) Burley, Fuller, Glaus, Heald, Soderberg, Jr.

Abstention: (2) Berlinger, Schwalm

Explanation of Vote

Burley and Heald: (Negative) The K constant is only applied to the wires carrying the tension. It is not appliedto dead loads (equipment, other wires, aerial marker balls, etc.) that are supported by the wire.

Fuller: (Negative) It appears that more discussion is needed about the proper application of the K factor.

Glaus: (Negative) Adequate justification was not provided for applying the K factor as specified in theproposed new footnote.

Soderberg: (Negative) This is not the proper application of the K factor.


Loading districts (for use with Rule 250B) Extreme windloading (for

use with Rule 250C)

Extreme iceloading withconcurrent

wind(For use with Rule 250D)

Heavy Medium Light

Temperature (°C) –20 –10 –1 +15 –10

(°F) 0 +15 +30 +60 +15

Constant to be added to the resultant (all conductors) 1

(N/m)

4.4 2.9 0.73 0.0 0.0

(lb/ft) 0.30 0.20 0.05 0.0 0.0



Revised Text

CP3305

Part: 2 Section: 25 252 B2a

Submitter

James T. Collins

Proposed Change

Editorial correction. Change “shape factors” to “force coefficients (shape factors).”

2. Wind loads on structures

The transverse load on structures and equipment shall be computed by applying, at right angles tothe direction of the line, the appropriate horizontal wind pressure determined under Rule 250. Thisload shall be calculated using the projected surfaces of the structures and equipment supportedthereon, without ice covering. The following force coefficients (shape factors) shall be used.

a. Cylindrical structures and components

Wind loads on straight or tapered cylindrical structures or structures composed of numerousnarrow relatively flat panels that combine to form a total cross section that is circular orelliptical in shape shall be computed using a force coefficient (shape factor) of 1.0.

Supporting Comment

Editorial correction. In 2007 the term “shape factor” was to have been replaced with “force coefficient (shapefactor).” This revision was not made in Rule 252B2.


Accept.



Negative: (0)

Abstention: (0)



New Text

CP3306


Submitter

James T. Collins

Proposed Change

Add EXCEPTION.

C. Assumed longitudinal loading

1. Change in grade of construction

The longitudinal loads on supporting structures, including poles, towers, and guys at the endsof sections required to be of Grade B construction, when located in lines of lower than Grade Bconstruction, shall be taken as an unbalanced pull in the direction of the higher grade sectionequal to the larger of the following values:

a. Conductors with rated breaking strength of 13.3 kN (3000 lb) or less

The pull of two-thirds, but not less than two, of the conductors having a rated breakingstrength of 13.3 kN (3000 lb) or less. The conductors selected shall produce the maximumstress in the support.

EXCEPTION: Where there are one or two conductors having rated breaking strength of13.3 kN (3000 lb) or less, the load shall be that of one conductor.

b. Conductors with rated breaking strength of more than 13.3 kN (3000 lb)

The pull resulting from one conductor when there are eight or less conductors (includingoverhead ground wires) having rated breaking strength of more than 13.3 kN (3000 lb),and the pull of two conductors when there are more than eight conductors. The conductorsselected shall produce the maximum stress in the support.

Supporting Comment

Where structures support circuits of mixed conductor strengths, parts a and b are sufficient except where oneor two conductors are less than 3000 lb rated breaking strength, such as in the case of a distribution neutral,transmission shield wire, communication wire, or single-phase distribution primary with neutral. The intentof adding the EXCEPTION to part a is to clarify the procedure for these cases.


Accept as modified.

Add EXCEPTION.



C. Assumed longitudinal loading

1. Change in grade of construction

The longitudinal loads on supporting structures, including poles, towers, and guys at the endsof sections required to be of Grade B construction, when located in lines of lower than Grade Bconstruction, shall be taken as an unbalanced tension pull in the direction of the higher gradesection equal to the larger of the following values:

a. Conductors with rated breaking strength of 13.3 kN (3000 lb) or less

The unbalanced tension shall be the tension pull of two-thirds, but not less than two, of theconductors having a rated breaking strength of 13.3 kN (3000 lb) or less. The conductorsselected shall produce the maximum stress in the support.

EXCEPTION: Where there are one or two conductors having rated breaking strength of13.3 kN (3000 lb) or less, the load shall be that of one conductor.

b. Conductors with rated breaking strength of more than 13.3 kN (3000 lb)

The unbalanced tension shall be the tension pull resulting from one conductor when thereare eight or less conductors (including overhead ground wires) having rated breakingstrength of more than 13.3 kN (3000 lb), and the pull of two conductors when there aremore than eight conductors. The conductors selected shall produce the maximum stress inthe support.



Negative: (0)

Abstention: (0)

Revised Text

CP3455

Part: 2 Section: 25 253





Part: 2 Section: 26 261 Table 261-1A, 1B



Submitter

Subcommittee 5

Proposed Change

1) Revise Rule 253 as indicated:

253. Load factors for structures, crossarms, support hardware, guys, foundations, andanchors

Loads due to the district loads in Rule 250B, the extreme wind loading condition in Rule 250C, and theextreme ice with concurrent wind condition in Rule 250D shall be multiplied by the load factors inTable 253-1 or the alternate load factors in Table 253-2. Table 253-1 shall be used with Table 261-1A.Table 253-2 shall be used with Table 261-1B. The alternate method, including alternate load factors ofTable 253-2 and strength factors of Table 261-1B, shall not be used after July 31, 2010.

2) Delete Table 253-2 along with all associated footnotes.

3) Revise Rule 261A1 as follows:

1. Metal, prestressed-, and reinforced-concrete structures

a. These structures shall be designed to withstand the loads in Rule 252 multiplied by theappropriate load factors in Table 253-1 or 253-2 without exceeding the permitted stress.

b. The permitted stress shall be the strength multiplied by the strength factors in Table 261-1A or261-1B (where guys are used, see Rule 261C).

c. All structures including those below 18 m (60 ft) shall be designed to withstand, withoutconductors, the extreme wind load in Rule 250C applied in any direction on the structure.

d. Spliced and reinforced structures

Reinforcements or permanent splices to a supporting structure are permitted provided theydevelop the required strength of the structure.

e. The alternate method, including alternate load factors of Table 253-2 and strength factors ofTable 261-1B, shall not be used after July 31, 2010.

4) Revise Rule 261A2a and 261A2b as follows:

2. Wood structures

Wood structures shall be of material and dimensions to meet the following requirements:

a. Wood structures shall be designed to withstand the loads in Rule 252 multiplied by theappropriate load factors in Table 253-1 or 253-2, without exceeding the permitted stress level.The alternate method, including alternate load factors of Table 253-2 and strength factors ofTable 261-1B, shall not be used after July 31, 2010.

NOTE: When determining a fiber stress for column loads, buckling needs to be considered.



EXCEPTION 1: When installed, naturally grown wood poles, acting as single-based structuresor unbraced multiple-pole structures, shall meet the requirements of Rule 261A2a withoutexceeding the permitted stress level at the ground line for unguyed poles or at the points ofattachment for guyed poles.

EXCEPTION 2: At a Grade B crossing, in a straight section of line, wood structures complyingwith the transverse strength requirements of Rule 261A2a, without the use of transverse guys,shall be considered as having the required longitudinal strength, providing the longitudinalstrength is comparable to the transverse strength of the structure. This EXCEPTION does notmodify the requirements of this rule for deadends.

EXCEPTION 3: At a Grade B crossing of a supply line over a highway or a communicationline where there is an angle in the supply line, wood structures shall be considered as havingthe required longitudinal strength if all of the following conditions are met:

(a) The angle is not over 20 degrees.

(b) The angle structure is guyed in the plane of the resultant of the conductor tensions. Thetension in this guy under the loading in Rule 252 multiplied by a load factor of 2.0 shallnot exceed the rated breaking strength multiplied by the strength factor in Table 261-1A.

(c) The angle structure has sufficient strength to withstand, without guys, the transverseloading of Rule 252 multiplied by the appropriate load factors in Table 253-1 or 253-2,which would exist if there were no angle at that structure without exceeding the permittedstress level.

b. Permitted stress level

(1) Natural wood pole

The permitted stress level of natural wood poles of various species meeting therequirements of ANSI O5.1-1992 shall be determined by multiplying the designated fiberstress set forth in that standard by the appropriate strength factors in Table 261-1A or 261-1B.

(2) Sawn or laminated wood structural members, crossarms, and braces

The permitted stress level of sawn or laminated wood structural members, crossarms, andbraces meeting the requirements of ANSI O5.2-1996 [B15] or ANSI O5.3-2002 [B16]shall be determined by multiplying the appropriate designated fiber stress set forth in therespective standard, by the appropriate strength factors in Table 261-1A or 261-1B.

(3) The alternate method, including alternate load factors of Table 253-2 and strength factorsof Table 261-1B, shall not be used after July 31, 2010.

5) Revise Rule 261A3b as follows:

b. The permitted load shall be the 5th percentile strength (i.e., “5% lower exclusion limit”) or less,multiplied by the strength factors in Table 261-1A (where guys are used, see Rule 261C).

6) Revise Rule 261B as follows:

B. Strength of foundations, settings, and guy anchors



Foundations, settings, and guy anchors shall be designed or be determined by experience towithstand the loads in Rule 252 multiplied by the load factors in Table 253-1 without exceeding thepermitted load. The permitted load shall be equal to the strength multiplied by the strength factorsin Table 261-1A.

7) Revise Rules 261D1, 261D2 and 261D3 as follows:

D. Crossarms and braces

1. Concrete and metal crossarms and braces

Crossarms and braces shall be designed to withstand the loads in Rule 252 multiplied by theload factors in Table 253-1 without exceeding the permitted load. The permitted load shall beequal to the strength multiplied by the strength factors in Table 261-1A.

2. Wood crossarms and braces

a. Strength

(1) Crossarms and braces shall be designed to withstand the loads in Rule 252 multipliedby the load factors in Table 253-1 without exceeding their permitted stress.

(2) The permitted stress level of solid sawn or laminated wood crossarms and bracesshall be determined by multiplying their ultimate fiber stress by the strength factors inTable 261-1A or 261-1B.

b. Material and size

Wood crossarms and braces of select Southern pine or Douglas fir shall have a crosssection of not less than those in Table 261-2. Crossarms of other species may be usedprovided they have equal strength.

3. Fiber-reinforced polymer crossarms and braces

Crossarms and braces shall be designed to withstand the loads in Rule 252 multiplied by theload factors in Table 253-1 without exceeding the permitted load. The permitted load shall bethe 5th percentile strength (i.e., “5% lower exclusion limit”) or less, multiplied by the strengthfactors in Table 261-1A.

8) Rename Table 261-1A as follows:

Table 261-1A—Strength factors for structures,1 crossarms, braces, support hardware, guys, foundations, and anchors for use with load factors of Table 253-1

9) Revise Table 261-1A Footnotes 2 and 3 as follows:

2Wood and reinforced concrete structures shall be replaced or rehabilitated when deterioration reduces thestructure strength to 2/3 of that required when installed. If a structure or component is replaced, it shall meetthe strength required by Table 261-1A. Rehabilitated portions of structures shall have strength greater than2/3 of that required when installed.

3Wood and reinforced concrete structures shall be replaced or rehabilitated when deterioration reduces thestructure strength to 3/4 of that required when installed. If a structure or component is replaced, it shall meet



the strength required by Table 261-1A. Rehabilitated portions of structures shall have strength greater than3/4 of that required when installed.

10) Delete Table 261-1B along with all associated footnotes.

Supporting Comment

For the 2007 NESC, CP2717, which was approved by SC5, no longer permits the use of the “AlternateMethod” for calculating loads and stresses on wood structures and components after July 31, 2010.

This CP will formally delete from the 2012 NESC the tables and reference that are no longer part of the NESCbeginning August 1, 2010.


Accept.


Affirmative: (28) Berlinger, Bingel, Bullinger, Burley, Byrne, Clapp, Clem, Corzine, Cotant, Denbrock,Erdle, Freimark, Fuller, Glaus, Haire, Heald, Jones, Joplin, Kempner, Kluge, Lynch, Ng, Peters, Schwalm,Shultz, Slavin, Soderberg, Jr., Wong

Negative: (0)

Abstention: (0)

Revised Text

CP3307


Submitter

James T. Collins

Proposed Change

Add new Footnote 8. Add load case descriptions under rule numbers in Column 1. Correct placement ofcomma following reference to Footnote 1 in table title.



(Footnotes 1-7 omitted, no change.)

8Support hardware does not include insulators. See Section 27 for insulator strength and loadingrequirements.

Supporting Comment

The fact that insulator strength is not covered in Section 25 and that Table 253-1 load factors do not coverinsulator loading is frequently overlooked by Code users. In some instances, users have assumed that supporthardware includes insulators and have applied incorrect load factors to insulator loads. Adding a newFootnote 8 will help distinguish insulator loading requirements from loading requirements for other linecomponents.

Identifying loading cases in the table only by reference to the governing NESC rules (i.e., Rules 250B, 250C,and 250D) has led to confusion on the part of some infrequent Code users as to which load case load factorsare being specified. Adding the description below the rule reference will make the appropriate load cases andload factors more easily identifiable.

Editorial: The reference to Footnote 1 in the table title should precede the comma as is the format in mostother tables. See column headings in Table 232-1 as examples of proper reference placement.


Accept as modified.

Table 253-1—Load factors for structures 1, 1 crossarms, support hardware 8, guys, foundations, and anchors to be used with the strength factors of Table 261-1A

Load factors

Grade BGrade C

At crossings 6 Elsewhere

Rule 250B loads(Combined ice and wind)

Vertical loads 3 1.50 1.90 5 1.90 5

Transverse loadsWindWire tensions

2.501.65 2

2.201.30 4

1.751.30 4

Longitudinal loadsIn generalAt deadends

1.101.65 2

No requirement1.30 4


Rule 250C loads(Extreme wind)

Transverse loadWind All other loads

1.001.00

0.87 71.00

0.87 71.00

Rule 250D loads(Extreme ice with concurrent wind)

1.00 1.00 1.00




Add new Footnote 8. Add load case descriptions under rule numbers in Column 1. Correct placement ofcomma following reference to Footnote 1 in table title.

(Footnotes 1–7 omitted, no change.)

8Support hardware does not include insulators. See Section 27 for insulator strength and loadingrequirements.



Negative: (0)

Abstention: (0)

Table 253-1—Load factors for structures 1, 1 crossarms, support hardware 8, guys, foundations, and anchors to be used with the strength factors of Table 261-1A

Load factors

Grade BGrade C

At crossings 6 Elsewhere

Rule 250B loads(Combined ice and wind district loading)

Vertical loads 3 1.50 1.90 5 1.90 5


2.501.65 2

2.201.30 4

1.751.30 4


1.101.65 2



Rule 250C loads(Extreme wind)

Transverse loadWind All other loads

1.001.00

0.87 71.00

0.87 71.00

Rule 250D loads(Extreme ice with concurrent wind) 1.00 1.00 1.00



Revised Text

CP3460


Submitter

Subcommittee 5

Proposed Change

Revise Table 253-1 as indicated.

Supporting Comment

As approved in TIA 2007-2, approved on August 3, 2007, NESC SC5 did not intend to reduce the load factorfrom 1.00 to 0.87 for all Rule 250C loads including weight or wire tension. The intention of SC5 was to applythe 0.87 factor only to the wind component. The same intent also applies to the 0.75 factor allowed byFootnote 7 in Table 253-1 and Footnote 8 in Table 253-2.

The intent is to fully incorporate the changes of NESC TIA-2.


Accept.

Table 253-1—Load factors for structures,1 crossarms, support hardware, guys,foundations, and anchors to be used with the strength factors of Table 261-1A

Load factors

Grade BGrade C

At crossings6 Elsewhere

Rule 250B loadsVertical Loads 3 1.50 1.905 1.905


2.501.652

2.201.30 4

1.751.30 4


1.101.65 2



Rule 250C loadsWind loadsAll other loads

1.001.00

0.87 71.00

0.87 71.00

Rule 250D loads 1.00 1.00 1.00




Affirmative: (30) Berlinger, Bingel, Bullinger, Burley, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Fuller, Glaus, Guerry, Haire, Jones, Joplin, Kempner, Kluge, Lacoursiere,Lynch, Ng, Schwalm, Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (0)

Abstention: (1) Heald

Explanation of Vote

Heald: (Abstention) I agree with making any necessary clarifications to the Code. Rule 250C relates to windloads only and the 0.87 is to be applied to the wind pressure calculated from Rule 250C.

Revised Text

CP3035


Submitter

Ewell Robeson

Proposed Change

Modify Rule 260B as follows:

B. Application of strength factors

1. Supporting Sstructures and structural components shall be designed to withstand theappropriate loads multiplied by the load factors in Section 25 without exceeding their strengthmultiplied by the strength factors in Section 26Table 261-1A.

NOTE 1: The latest edition of the following document may be used for providing informationfor determining the 5% lower exclusion limit strength of a FRP structure or component for usewith an appropriate strength factor (Table 261-1A) and the specified NESC loads and loadfactors (Table 253-1): ASCE-111, Reliability-Based Design of Utility Pole Structures.

NOTE 2: The latest edition (unless a specific edition is referenced) of the following documentsare among those available for determining structure design capacity with the specified NESCloads, load factors, and strength factors:

ANSI/ASCE-10, Design of Latticed Steel Transmission Structures

ASCE-91, Design of Guyed Electrical Transmission Structure

ASCE-PCI, Guide for the Design of Prestressed Concrete Poles

ASCE-72, Design of Steel Transmission Pole Structures



ASCE-104, Recommended Practice For Fiber-Reinforced Polymer Products For OverheadUtility Line Structures

PCI, Design Handbook-Precast and Prestressed Concrete

ACI-318, Building Code Requirements for Structural Concrete (for reinforced concretedesigns)

ACI-318, 1983, Building Code Requirements for Structural Concrete (for anchor bolt bondstrength)

IEEE Std 751™-1990, IEEE Trial-Use Design Guide for Wood Transmission Structures [B38]

AISI, Specification for the Design of Cold-Formed Steel Structural Members

The Aluminum Association, Aluminum Design Manual

2. Unless otherwise specified Where strength factors are not defined in Table 261-1A orelsewhere in Section 26, a strength factor of 0.80 shall be used for the extreme wind loadingconditions specified in Rule 250C and for the extreme ice with concurrent wind specified inRule 250D for all supported facilities.

NOTE: The latest edition (unless a specific edition is referenced) of the following documentsare among those available for determining structure design capacity with the specified NESCloads, load factors, and strength factors:














Supporting Comment

IR 549 stated: The strength factor used for weathering steel poles subject to the extreme wind considerationshas been 0.80, as mentioned in 260B2. However, since this is for materials not otherwise specified, and Rule261A1b addresses metal structures, this doesn’t apply to the steel poles, and the 1.0 strength factor for Rule250C loads given in Table 261-1A for both Grades B & C applies. Is this the correct interpretation?

The change proposed above should help clarify the intent of Rule 260B2.


Accept as modified.

Modify Rule 260B as follows:

B. Application of strength factors

1. Supporting Sstructures and structural components shall be designed to withstand theappropriate loads multiplied by the load factors in Section 25 without exceeding their strengthmultiplied by the strength factors in Section 26Table 261-1A.

EXCEPTION: For insulators, see Section 27 for strength and loading requirements.

NOTE 1: The latest edition of the following document may be used for providing informationfor determining the 5% lower exclusion limit strength of a FRP structure or component for usewith an appropriate strength factor (Table 261-1A) and the specified NESC loads and loadfactors (Table 253-1): ASCE-111, Reliability-Based Design of Utility Pole Structures.

NOTE 2: The latest edition (unless a specific edition is referenced) of the following documentsare among those available for determining structure design capacity with the specified NESCloads, load factors, and strength factors:







ASCE-113, Substation Structure Design Guide


ACI-318, 1983, Building Code Requirements for Structural Concrete (for anchor bolt bondstrength and design)






2. Unless otherwise specified Where strength factors are not defined in Rule 261, a strengthfactor of 0.80 shall be used for the extreme wind loading conditions specified in Rule 250Cand for the extreme ice with concurrent wind specified in Rule 250D for all supportedfacilities.

NOTE: The latest edition (unless a specific edition is referenced) of the following documentsare among those available for determining structure design capacity with the specified NESCloads, load factors, and strength factors:














Negative: (0)

Abstention: (0)



Revised Text

CP3034


Submitter

Ewell Robeson

Proposed Change


2. Unless otherwise specified, a strength factor of 0.80 shall be used for the extreme wind loadingconditions specified in Rule 250C and for the extreme ice with concurrent wind specified in Rule250D for all supported facilities.

NOTE 1: Examples of supported facilities include components such as line hardware, equipmenthanger brackets, and switches.

NOTE 2: The latest…….

Supporting Comment

This change will clarify that supported facilities are not supporting structures.




Recommend SC1 accept CP3212.


Affirmative: (29) Berlinger, Bingel, Bullinger, Burley, Busel, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Fuller, Glaus, Haire, Harrel, Jones, Kempner, Kluge, Lynch, Peters, Schwalm,Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (1) Heald

Abstention: (0)

Explanation of Vote

Heald: (Negative) I voted no since 3312 includes conductor in the definition of supported facilities. Theintention of the Code is that the strength criteria for conductors and insulators be covered under theirrespective sections and supported facilities referred to components such as line hardware equipment, hangers,



switches, and other facilities supported by the structure.

New Text

CP3308

Part: 2 Section: 26 261 A1a NOTE

Submitter

James T. Collins

Proposed Change

Add NOTE to consider need for buckling analysis.



NOTE: When determining required strength for column loads, buckling needs to beconsidered.

b. ….

Supporting Comment

The buckling NOTE has been included for wood structure strength since the 1997 revision. Buckling is alsoan issue for other types of materials, particularly tubular metal components, and the NOTE should be addedfor them also.


Accept as modified.




NOTE: When determining required strength for axial loads, buckling needs to be considered.

b. ….




Affirmative: (30) Berlinger, Bingel, Bullinger, Burley, Busel, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Fuller, Glaus, Haire, Harrel, Heald, Jones, Kempner, Kluge, Lynch, Peters,Schwalm, Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (0)

Abstention: (0)

Explanation of Vote

Clapp and Kluge: (Affirmative) The language of the NOTE can be read to require consideration of buckling.Such requirements must be a part of the Code rule, not in a NOTE. I suggest the language of the NOTE bechanged to “buckling stresses may control.”

Revised Text

CP3309

Part: 2 Section: 26 261 A1c

Submitter

James T. Collins

Proposed Change

Add provision to require that strength is required for extreme wind on supported facilities and equipmentinstalled prior to conductors.


The strength requirements for supporting structures may be met by the structures alone or with theaid of guys or braces or both.


a. ...

b. ...

c. All structures including those below 18 m (60 ft) shall be designed to withstand, withoutconductors, the extreme wind load in Rule 250C applied in any direction on the structureand any supported facilities which may be in place prior to installation of conductors.

Supporting Comment

The rule is intended to require strength of the structure to support any applied wind loads prior to installationof conductors. This is to assure that the absence of strength provided by the conductors does not cause astructure failure prior to wires being strung. It is unstated, but can be inferred, that any facilities or equipment



(such as transformers, switches, cut-outs, line traps, etc.) that may be in place prior to installation ofconductors should be considered in determining the required strength of the structure for extreme wind loads.This revision would clarify that the loading effect of such facilities and equipment is to be considered.


Accept as modified.





a. ...

b. ...

c. All structures including those below 18 m (60 ft) shall be designed to withstand, withoutconductors, the extreme wind load in Rule 250C applied in any direction on the structureand any supported facilities and equipment that may be in place prior to installation ofconductors.


Affirmative: (29) Berlinger, Bingel, Bullinger, Burley, Busel, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Fuller, Glaus, Haire, Harrel, Heald, Jones, Kempner, Lynch, Peters, Schwalm,Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (0)

Abstention: (1) Kluge

Explanation of Vote

Kluge: (Abstention) The wording adds no additional information. Another example of the NESC becominga design guide.

Revised Text

CP3458

Part: 2 Section: 26 261 A2a

Submitter

Subcommittee 5



Proposed Change

Revise text to read as follows:

Add NOTE 2 under Rule 261A2a.

Making existing NOTE “NOTE 1.”

NOTE 2: Sustained loads (examples gravity, tension loads) are known to reduce the permitted stresslevel of wood (round, solid-sawn, and laminated) members and poles. This may be of significancewhere gravity or tension loads are supported by the wood member in cantilever, without appropriatebracing or guy support. Wind loading is not considered a “sustained” load in this regard. IEEE Std 751-1990 [B38] may be useful in considering the effects of load duration.

Add NOTE under Rule 261A3a as follows:

NOTE: Sustained loads (examples gravity, tension loads) are known to reduce the permitted stress levelof fiber reinforced polymer members and poles. This may be of significance where gravity or tensionloads are supported by the fiber reinforced polymer members or poles in cantilever, without appropriatebracing or guy support. Wind loading is not considered a “sustained” load in this regard.

Supporting Comment

The strength of all materials will vary with the duration of a load. In some materials, this effect isinsignificant. In other materials such as wood and fiber-reinforced polymers, the strength variation withduration is significant and should be addressed.

IEEE Std 751, IEEE Trial-Use Design Guide for Wood Transmission Structures, provides adjustments thathave been calibrated for use with the load-resistance factors used in the NESC. See recommendations fromTable 5.2 below. Other sources on this subject may be found in National Design Standard and Wood DesignHandbooks.

IEEE Std 751-1991: Regarding fiber-reinforced composite components, the supporting information comesfrom test data of composite suspension insulator tests. Those data of composite (fiber-reinforced) insulatorsdemonstrated that significant strength reduction occurs similar to that for wood. No reference is providedbecause the manufactures of structural fiber-reinforced products have not provided sufficient data for thoseproducts.


Accept.




Affirmative: (28) Berlinger, Bingel, Bullinger, Burley, Clapp, Clem, Corzine, Cotant, Denbrock, Erdle,Freimark, Fuller, Glaus, Haire, Heald, Jones, Joplin, Kempner, Kluge, Lacoursiere, Lynch, Ng, Peters,Schwalm, Shultz, Slavin, Soderberg, Jr., Wong

Negative: (0)

Abstention: (0)

Revised Text

CP3373

Part: 2 Section: 26 261 A2b(1)

Also Part: 2 Section: 26 261 A2a EXCEPTION 1

Submitter

Nelson Bingel

Proposed Change

Revise this rule to adopt the 2008 Edition of ANSI O5.1.



The permitted stress level of natural wood poles of various species meeting the requirementsof ANSI O5.1-1992 2008 shall be determined by multiplying the designated fiber stress(recognizing the “fiber stress height effect” as appropriate) set forth in that standard by theappropriate strength factors in Table 261-1A or 261-1B.

Delete the following EXCEPTION in 261A2a that no longer applies:

EXCEPTION 1: When installed, naturally grown wood poles, acting as single-based structures orunbraced multiple-pole structures, shall meet the requirements of Rule 261A2a without exceeding thepermitted stress level at the ground line for unguyed poles or at the points of attachment for guyedpoles.

Supporting Comment

The 2008 Edition of ANSI O5.1 has been balloted twice in 2008 and will be published this year. The NESCwill be current with the improvements in the O5.1 standard.


Accept as modified.



Revise this rule to adopt the 2008 edition of ANSI O5.1.



The permitted stress level of natural wood poles of various species meeting the requirementsof ANSI O5.1-1992 2008 shall be determined by multiplying the designated fiber stressstrength set forth in that standard by the appropriate strength factors in Table 261-1A or 261-1B.

Revise the following NOTE and EXCEPTION in 261A2a:

NOTE: When determining a fiber stress for column axial loads, buckling needs to be considered.

EXCEPTION 1: When installed, naturally grown wood poles 55 ft in length or shorter, acting as single-based structures or unbraced multiple-pole structures, shall meet the requirements of Rule 261A2awithout exceeding the permitted stress level at the ground line for unguyed poles or at the points ofattachment for guyed poles. However, all guyed poles, regardless of length, shall meet the requirementsof Rule 261A2a without exceeding the permitted stress level at points of attachment for guys and guystruts.


Affirmative: (26) Berlinger, Bingel, Bullinger, Burley, Byrne, Clem, Cooke, Corzine, Cotant, Denbrock,Erdle, Glaus, Harrel, Jones, Joplin, Kempner, Kluge, Lacoursiere, Lynch, Peters, Schwalm, Shultz, Slavin,Soderberg, Jr., Standford, Wong

Negative: (4) Clapp, Freimark, Haire, Heald

Abstention: (1) Fuller

Explanation of Vote

Clapp: (Negative) It should include the 55 ft adjustment and recognizing conflict over the testingmethodology.

Freimark: (Negative) For wood poles, the reduction of the allowable fiber stress with height is a realphenomena. Unfortunately the majority opinion of the members of the ANSI-O5.1 committee was to placethis information in an annex for the 2008 revision. It is noted that an annex is for information only and istechnically not a part of the approved standard. On that basis, i.e., that the information on the “fiber stressheight effect” is not an official part of the ANSI-O5.1, the majority of SC5 has voted to not mention this effectin the rule, nor to include mention in a NOTE. I feel that the action of ANSI-O5.1 to relegate the informationto an Annex was wrong and that the SC5’s proposed action to ignore the effect is also wrong. At the veryleast, a reference to the “fiber stress height effect” information in the annex to ANSI-O5.1 should be includedin a NOTE in NESC Rule 261A2b(1).

Fuller: (Abstention) The comments made pertaining to the “fiber stress height effect” are of interest. I wouldrather first hear the opposing view before voting for or against.

Haire: (Negative) Based on the discussion of SC 5, ANSI O5.1 2008 Annex A contains data suggesting fiberstress height effect is negated due to manufacturers oversize of poles to meet minimum requirements. Thisnegation is acceptable for poles up to and including 55 ft poles. However, annexes and appendixes are not



normative parts of codes and standards, only informative. To remove ambiguity, the Rule 261 A2b(1) shouldincluded an exemption for poles 55 ft and shorter, or at least, a NOTE identifying the existence of the findingsin Annex A of ANSI O5.1.

Additional discussion of the methods used to determine the data supporting the findings of ANSI O5.1provided significant questions. Rule 261 A2b(1) should not include data or cite requirements from a standarduntil the methods can be properly defended.

Heald: (Negative) I am basically in agreement with the CP as modified. My negative vote is based on the factthat this change in philosophy was not provided. The philosophy since September 21, 1928 “Discussion ofthe NESC” to accompany the Fourth Edition of the Code follows: “The strength of a pole is based on ground-line circumferences. This is because of the fact that the ground line, if not originally so, soon becomes throughdecay, the weakest section of the pole or the point where failure is most likely to occur. In species of poleshaving slight tapers or flaring butts the weakest section is initially at some distance above the ground line.However, even in these poles the ground line will generally become the section of least resistance (inproportion to bending moment of load) before they deteriorate to the point of removal.”

Revised Text

CP3374

Part: 2 Section: 26 261 A2b(2)

Submitter

Nelson Bingel

Proposed Change

Revise this rule to adopt the 2008 edition of ANSI O5.3 and the 2006 Edition of ANSI O5.2.


The permitted stress level of sawn or laminated wood structural members, crossarms, and bracesmeeting the requirements of ANSI O5.2-1996 2006 [B15] or ANSI O5.3-2002 2008 [B16] shall bedetermined by multiplying the appropriate designated fiber stress set forth in the respectivestandard, by the appropriate strength factors in Table 261-1A or 261-1B.

Supporting Comment

The 2008 Edition of ANSI O5.3 has been balloted in 2008 and will be published this year. The 2006 Editionof ANSI O5.2 is already published. The NESC will be current with the improvements in these standards.


Accept as modified.

Revise this rule to adopt the 2008 Edition of ANSI O5.3 and the 2006 edition of ANSI O5.2.




The permitted stress level of sawn or laminated wood structural members, crossarms, and bracesmeeting the requirements of ANSI O5.2-1996 2006 [B15] or ANSI O5.3-2002 2008 [B16] shall bedetermined by multiplying the appropriate designated fiber stress set forth in the respectivestandard, by the appropriate strength factors in Table 261-1 A or 261-1B.


Affirmative: (31) Berlinger, Bingel, Bullinger, Burley, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Fuller, Glaus, Haire, Harrel, Heald, Jones, Joplin, Kempner, Kluge, Lacoursiere,Lynch, Peters, Schwalm, Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (0)

Abstention: (0)

Revised Text

CP3371

Part: 2 Section: 26 261 A2c, e

Also Part: 2 Section: 25 250 A, C

Submitter

Nelson Bingel

Proposed Change

Revise Rules 250A and C to apply reduced extreme winds to structures 60 ft or shorter and show conductorsizes boundaries where such winds would not control design.

250. General loading requirements and maps

A. General

1. It is necessary to assume the wind and ice loads that may occur on a line. Three weatherloadings are specified in Rules 250B, 250C and 250D. Where all three rules apply, Therequired loading shall be the one that has the greater effect.

2. Where construction or maintenance loads exceed those imposed by Rule 250A1, which mayoccur more frequently in light loading areas, the assumed loadings shall be increasedaccordingly.

3. It is recognized that loadings actually experienced in certain areas in each of the loadingdistricts may be greater, or in some cases, may be less than those specified in these rules. In theabsence of a detailed loading analysis, no reduction in the loadings specified therein shall bemade without the approval of the administrative authority.

4. The structural capacity provided by meeting the loading and strength requirements of Sections25 and 26 provides sufficient capability to resist earthquake ground motions.



B. Combined ice and wind loading

Three general degrees of loading due to weather conditions are recognized and are designated asheavy, medium, and light loading. Figure 250-1 shows the districts where these loadings apply.

NOTE: The localities are classified in the different loading districts according to the relativesimultaneous prevalence of the wind velocity and thickness of ice that accumulates on wires. Lightloading is for places where little, if any, ice accumulates on wires.



If no portion of a structure or its supported facilities exceeds 18 m (60 ft) above ground or waterlevel, the provisions of this rule are not required, except as specified in Rule 261A1c, 261A2e, orRule 261A3d. Where a structure or its supported facilities exceeds 18 m (60 ft) above ground orwater level the structure Structures and its supported facilities shall be designed to withstand theextreme wind load associated with the Basic Wind Speed, as specified by Figure 250-2. The windpressures calculated shall be applied to the entire structure and supported facilities without ice.

EXCEPTION: If no portion of a structure or its supported facilities exceeds 18 m (60 ft) aboveground or water level, the wind load need not exceed = (18.0psf) · A(ft2) in pounds.

NOTE: The provisions of Rule 250C do not control if no portion of a structure or its supportedfacilities exceeds 18 m (60 ft) above ground or water level and the structure is located in either

Light loading district,Medium load district and no supported conductor has a diameter greater than 15.9 mm0.625 in), orHeavy load district and no supported conductor has a diameter greater than 31.7 mm (1.25 in).

The following formula shall be used to calculate wind load.

Formulas and definitions of variables remain unchanged.

Delete the last sentence of the first paragraph of Rule 250C2:



Reformat Table 253 and correct numbering since there is only one Table 253:



Change Rule 261A1c to read:

All structures including those below 18 m (60 ft) shall be designed to withstand, without conductors, theextreme wind load in Rule 250C applied in any direction on the structure.

Change Rule 261A2e to read:

All structures including those below 18 m (60 ft) shall be designed to withstand, without conductors, theextreme wind load in Rule 250C applied in any direction on the structure.

Supporting Comment

NESC Subcommittee 5 Task Group identified 74 mph wind speed (fastest mile) or 82 mph wind speed (3-second gust) from ASCE-7 Table C6-2 “Approximate Relationship between Wind Speeds in ASCE 7 and theSaffir-Simpson Hurricane Scale, Category 1” as the threshold wind speed above which large debris and treebranches would likely blow into or fall onto lines. At or above this wind speed (according to Saffir-SimpsonHurricane Scale), “primary damage (occurs) to unanchored mobile homes, shrubbery, and trees.” Inconcurrence, utilities have observed collateral damage from sheet metal cladding, trees and other debrisimpacting lines at wind speed approximately 74 mph (one-minute average). Therefore, 82 mph wind speed(3-second gust) was used in this analysis.

Using NESC-2007 Extreme wind pressure formula and 82 mph wind speed, the following wind pressures arecalculated for the respective structure heights and an assumed span length of 264 ft.

Table 253-1 Load factors for structures,1 crossarms, support hardware, guys, foundations, and anchors to be used with the strength factors of Table 261-1A

Load factors

Grade BGrade C

At crossing 6 Elsewhere

Rule 250B loads

Vertical loads3 1.50 1.905 1.905

Transverse loads Wind Wire tension

2.50 1.652

2.20 1.304

1.75 1.304

Longitudinal loads In general At deadends

1.10 1.652

No requirement 1.304

No requirement1.304

Rule 250C loads

Transverse loads Wind 1.00 0.877 0.877

All other loads 1.00 1.00 1.00

Rule 250D loads 1.00 1.00 1.00



Note all of the wind pressures for wires listed in the above table are less than 18 psf.

Based on a threshold 3-second wind speed of 82 mph, the not-to-exceed values for medium and heavy loaddistricts should be established as follows:

“Not to exceed” Basis

Grade C 16.0 psf (82 mph threshold wind speed)

Grade B 18.0 psf (15.7 psf ÷ 0.87)

Evaluate at what wire diameters the District Loads control and extreme wind loads need not be considered.

The following analysis illustrates that district loads generally provide adequate security without an extremewind load requirements for short structures. For any conductor diameters smaller than the diameterscalculated below, the district loads, not 82 mph wind, will govern the required strength of structures lessthan 61 ft tall.

Wind load on wire with ice based on NESC district load:

Wind load (lb/ft) = [Dc + (2 · I)] · OLFD · PD/12

Wind load on bare wire based on extreme wind pressure:

Wind load (lb/ft) = [Dc] · OLFE · PE /12

Solving for conductor diameter where NESC district load equals extreme wind load.

Dc = [2 · I · (OLFD · PD)] / [(OLFE · PE) – (OLFD · PD)]

Where

OLFD = 2.5 (overload factor for Rule 250B loads, Grade B, Table 253-1)= 2.2 (overload factor for Rule 250B loads, Grade C, Table 253-1)

OLFE = 1.0 (overload factor for Rule 250C loads, Grade B, Table 253-1)= 0.87 (overload factor for Rule 250C loads, Grade C, Table 253-1)

Dc = Diameter on conductor or cable (in)I = Radial ice thickness (in) (0.5 for heavy distr.; 0.25 for medium distr.)

Wind pressure

Pole length (ft) Struc. height (ft)

Attachment height (ft)

On wire (psf)

On pole (psf)

70 61.0 61.0 15.5 16.4

55 47.5 47.5 14.9 15.9

40 34.0 34.0 14.1 15.3

Neutral 26.0 13.6

Comm. cable 22.5 13.3



PD = 4.0 psf, Wind pressure for district load, medium and heavy= 9.0 psf, Wind pressure for district load, light

PE = 18 psf, Wind pressure associated with 82 mph wind speed / 0.87

Conclusion

For structures shorter than 61 ft tall,

Light loading district:

Grade B: District loads are adequate for all conductor sizes.

Grade C: 18 pfs wind must be considered for all wire sizes.

Medium loading district: District loads are adequate for conductors <0.625 in diameter.

Heavy loading district: District loads are adequate for conductors <1.25 in diameter.

The calculations show that considering extreme wind loading (Rule 250C) only controls for certaininstallations for structures 60 ft or less in height. Therefore, an exclusion and a note should denote underwhat circumstances extreme wind loads would apply.


Reject.


The proposal does not increase safety.


Affirmative: (23) Bingel, Bullinger, Burley, Byrne, Clem, Corzine, Cotant, Denbrock, Erdle, Freimark,Haire, Heald, Jones, Joplin, Kluge, Lynch, Ng, Schwalm, Shultz, Slavin, Soderberg, Jr., Standford, Wong

Table Threshold conductor diameter (in)Only conductors larger than diameters shown below would be affected by 74 mph wind speeds

(for structures < 61 ft and an assumed 264 ft span length)

Grade B Grade C

82 mph wind speed, pressure = OLFE · PE = 18 psf OLFE · PE = 18 psf

District wind load × LF =(for heavy and medium)

OLFD · PD = 10 psf OLFD · PD = 8.8 psf

Heavy >1.25 in >1.4 in

Medium >0.625 in >0.7 in

Loading district (light) OLFD · PD = 22.5 psf OLFD · PD = 15 psf

Light District load governs District load governs



Negative: (3) Clapp, Fuller, Kempner


Explanation of Vote

Bingel: (Affirmative) I voted to reject because more consideration should be given to understanding theimpact of this and other proposals addressing loading and the extreme wind 60 ft exclusion. I wouldreconsider if the following proposals should also be included in further evaluation.

If 250C wind speed is 100 mph or less, then 250C does not apply (250C will only apply to coastal areas).

Proposed Change

Revise Rule 250C as indicated.


Except as provided below, If no portion of a structure or its supported facilities exceeds 18 m (60 ft)above ground or water level, the provisions of this rule are not required, except as specified in Rule261A1c, 261A2e, or 261A3d. Where a structure or its supported facilities exceeds 18 m (60 ft)above ground or water level the sStructure and its their supported facilities shall be designed towithstand the extreme wind load associated with the Basic Wind Speed, as specified by Figure 250-2. The wind pressures calculated shall be applied to the entire structure and supported facilitieswithout ice. The following formula shall be used to calculate wind load.

EXCEPTION: If no portion of a structure or its supported facilities exceeds 18 m (60 ft) aboveground or water level, and the Basic Wind Speed, as specified by Figure 250-2 is 100 mph or less,then the provisions of this rule are not required, except as specified in Rule 261A1c, 261A2e, or261A3d.

Supporting Comment

This CP acknowledges that the wind does blow at heights that are less than 60 feet above ground level, butonly in coastal (hurricane) regions.

Cap wind pressure at 15 psf and 22 psf, Grade B and C (equates to applying light loading criteriaeverywhere).

Proposed Change

NOTE: Adapted from CP2766 (developed by WG 5.1.2, chaired by Don Heald) for the 2007 NESC RevisionCycle

Remove the 60 ft exclusion from Grade B and Grade C construction and provide a maximum wind load forGrade B and Grade C construction under 60 ft that is no greater than the current loads for the light loadingdistrict. This change proposal is based a previously submitted change proposal which provides appropriateload factors for Grade C construction from Grade B construction under 250C wind loads (extreme wind). Theproposed changes are shown below:



8If no portion of the structure or its supported facilities exceeds 18 m (60 ft) above ground or water level, the windpressure defined by 0.00256 V2 kz GRF times the overload factor need not exceed 22.5 psf.

9If no portion of the structure or its supported facilities exceeds 18 m (60 ft) above ground or water level, the windpressure defined by 0.00256 V2 kz GRF times the overload factor need not exceed 15psf.

Additional changes

The following additional rules need to be changed to accommodate the above change:

Rule 250C Extreme wind loading

If no portion of a structure or its supported facilities exceeds 18 m (60 ft) above ground or water level,the provisions of this rule are not required, except as specified in Rule 261A1c, 261A2e, or 261A3d.Where a structure or its supported facilities exceeds 18 m (60 ft) above ground or water level thesStructures and itstheir supported facilities shall be designed to withstand the extreme wind loadassociated with the Basic Wind Speed, as specified by Figure 250-2. The wind pressures calculatedshall be applied to the entire structure and supported facilities without ice. The following formula shallbe used to calculate wind load.

Rule 250C2


Selected values of the structure and wire gust response factors are tabulated in Table 250-3. Thestructure gust response factor, GRF, is determined using the total structure height, h. The wire gustresponse factor is determined using the height of the wire at the structure, h, and the design windspan, L. The structure and wire gust response factors may also be determined using the formulas inTable 250-3. For values of h > 75 m (250 ft) and L > 600 m (2000 ft) the GRF shall be determinedusing the formulas in Table 250-3. In special terrain conditions (i.e., mountainous terrain and

Table 253-1—Load factors for structures,1 crossarms, support hardware, guys,foundations, and anchors to be used with the strength factors of Table 261-1A

Load factors

Grade BGrade C


Rule 250B loadsVertical loads 3 1.50 1.905 1.905


2.501.652

2.201.30 4

1.751.30 4


1.101.65 2



Rule 250C loadsTransverse loadWindAll other loads

1.00 81.00

0.87 7, 9

1.000.87 7, 9

1.00

Rule 250D loads 1.00 1.00 1.00



canyon) where the height of the conductor aboveground at mid-span may be substantially higherthan at the attachment point, engineering judgment may be used in determining an appropriatevalue for the wire GRF. Wire attachment points that are 18 m (60 ft) or less above ground or waterlevel must be considered if the total structure height is greater than 18 m (60 ft) above ground orwater.

Rule 261A1c

c. All structures including those below 18 m (60 ft) shall be designed to withstand, withoutconductors, the extreme wind load in Rule 250C applied in any direction on the structure.

Rule 261A1e

e. All structures including those below 18 m (60 ft) shall be designed to withstand, withoutconductors, the extreme wind load in Rule 250C applied in any direction on the structure.

Supporting Comment

NOTE: Adapted from CP2766 for the 2007 NESC Revision Cycle

Define the problem: For the 2007 NESC revision cycle, Subcommittee 5 established Task Force 5.1.2 ofWorking Group 5.1 to revisit the 60 ft height limit for extreme winds in the 2002 NESC. Rule 250C, Extremewind loading, states:

“If no portion of a structure or its supported facilities exceeds 60 ft. above ground or water level, theprovisions of this rule are not required, except as specified in Rule 261A1c or Rule 261A2e.”

Subcommittee 5 established the working group to make a recommendation concerning the disposition of the60 ft exclusion limit.

History: The “60 ft exclusion” was added in the 1977 Edition of the NESC at the same time when the extremewinds (50 year) were added. Extreme winds were added primarily for instances of conductors over 0.9 inchin diameter used on transmission. Thus, whenever the conductor diameter exceeded 0.9 in, the extreme windcase could possibly dictate the governing transverse load within the heavy loading district. This additionalloading case enhanced the structure safety under transverse loads, particularly on EHV lines where largediameter conductors are being employed. The 60 ft exclusion limit was added primarily so distribution linesneed only meet Light, Medium, and Heavy District loads requirements and to keep line design simple butsafe.

Summary of comments to CP2151 for the 1997 NESC: This change proposal was to remove the 60 ftexclusion from Rule 250C. Comments from the public and from members of Subcommittee 5 seemed toindicate that removal of the 60 ft exemption would not necessarily increase safety and reliability. Duringextreme wind events, debris is blown into overhead line facilities (especially those under 60 ft), which has amore dramatic affect on the line than does the extreme wind event. Removal of this exemption ignores thisproblem while imposing a possible costly solution. Darr of Virginia Power, further explained “….howunnecessary it is to require extreme wind load calculations for structures of low height that are typicallyshielded by buildings and trees. Multi-pole structures and structures above 60 ft in height are much morelikely to be affected by high wind loads and should be covered by this Rule. The combined ice and wind loadsfor each conductor plus the required overload factors provide the protection required to the public and utilityworkers.” The change proposal to remove the 60 exclusion was eventually voted down.

Task Force 5.1.2: The task force discussed two options: 1) do not require high wind for structures below60 ft and Grade C construction, or 2) to require high wind but at a reduced amount for structures below 60 ftand Grade C construction. The task force decided on option 2.



The task force debated as to what this designated maximum wind load should be for structures under 60 ft.The Saffir-Simpson Hurricane Scale and the Fujita Tornado Damage scale were reviewed to help determinea designated wind load at which point debris and objects are blown into the line. The task force realizes thatthis is only a rough estimate.

These two scales seem to indicate that the wind speed that debris and trees would blow into the line or fall onthe line happens between 75 mph and 110 mph for hurricane loads and 73 mph to 112 mph for tornado loads.If one considers that the hurricane scale closely approximates the fastest mile wind, the wind load (fastestmile) would be between 13.7 psf and 32 psf.

Because the range of the wind load is considerable, the task force decided to calibrate the maximum loadusing existing requirements associated with the Light Loading District. Existing Light Loading District Loadsfor Grade C is the product of the load factor of 1.75 load factor and 9 psf (2002 NESC, Table 253-1) and theload factor of 2 and 9 psf (2002 NESC, Table 253-2). The load in the Light Loading district is between 15.8for Table 253-1 and 18 psf for Table 253-2.

The task force decided to designate 15 psf as the maximum load as defined by 0.00256 V2 kz GRF forstructures and facilities under 60 ft that need to be taken into account. This 15 psf wind becomes 16.1 psf and17.4 psf when considering the kzGRF factor for spans less than 250 ft and between 250 and 500 ft, typicalspans one might find for lines under 60 ft in height. The wind velocity for these loads is approximately 80mph, within the range of 73 mph and 110 mph.

The task force considered maximum load limits for Grade B construction under 60 feet. For Grade Bconstruction, the task force decided to designate 22.5 psf as the maximum load as defined by 0.00256 V2 kzGRF for structures and facilities under 60 ft that need to be taken into account. This maximum loadapproximately corresponds to a Category 2 hurricane. The task force recognizes that there exists aninconsistency in relative strengths between Grade B and Grade C for structures under 60 ft when consideringextreme winds.

The Saffir-Simpson Hurricane Scalehttp://www.nhc.noaa.gov/aboutsshs.shtml

The Saffir-Simpson Hurricane Scale is a 1–5 rating based on the hurricane's present intensity. This is used togive an estimate of the potential property damage and flooding expected along the coast from a hurricanelandfall. Wind speed is the determining factor in the scale, as storm surge values are highly dependent on theslope of the continental shelf in the landfall region. Note that all winds are using the U.S. 1 min average.

Category One Hurricane

Winds 74–95 mph (64–82 kt or 119–153 km/h). Storm surge generally 4–5 ft above normal. No real damageto building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Some damageto poorly constructed signs. Also, some coastal road flooding and minor pier damage. Hurricanes Allison of1995 and Danny of 1997 were Category One hurricanes at peak intensity.

Category Two Hurricane

Winds 96–110 mph (83–95 kt or 154–177 km/hr). Storm surge generally 6–8 ft above normal. Some roofingmaterial, door, and window damage of buildings. Considerable damage to shrubbery and trees with sometrees blown down. Considerable damage to mobile homes, poorly constructed signs, and piers. Coastal andlow-lying escape routes flood 2–4 h before arrival of the hurricane center. Small craft in unprotectedanchorages break moorings. Hurricane Bonnie of 1998 was a Category Two hurricane when it hit the NorthCarolina coast, while Hurricane George of 1998 was a Category Two Hurricane when it hit the Florida Keysand the Mississippi Gulf Coast.



Category Three Hurricane

Winds 111–130 mph (96–113 kt or 178–209 km/hr). Storm surge generally 9–12 ft above normal. Somestructural damage to small residences and utility buildings with a minor amount of curtain wall failures.Damage to shrubbery and trees with foliage blown off trees and large trees blown down. Mobile homes andpoorly constructed signs are destroyed. Low-lying escape routes are cut by rising water 3–5 h before arrivalof the center of the hurricane. Flooding near the coast destroys smaller structures with larger structuresdamaged by battering from floating debris. Terrain continuously lower than 5 ft above mean sea level maybe flooded inland 8 mi (13 km) or more. Evacuation of low-lying residences with several blocks of theshoreline may be required. Hurricanes Roxanne of 1995 and Fran of 1996 were Category Three hurricanes atlandfall on the Yucatan Peninsula of Mexico and in North Carolina, respectively.

Category Four Hurricane

Winds 131–155 mph (114–135 kt or 210–249 km/hr). Storm surge generally 13–18 ft above normal. Moreextensive curtain wall failures with some complete roof structure failures on small residences. Shrubs, trees,and all signs are blown down. Complete destruction of mobile homes. Extensive damage to doors andwindows. Low-lying escape routes may be cut by rising water 3–5 h before arrival of the center of thehurricane. Major damage to lower floors of structures near the shore. Terrain lower than 10 ft above sea levelmay be flooded requiring massive evacuation of residential areas as far inland as 6 mi (10 km). HurricaneLuis of 1995 was a Category Four hurricane while moving over the Leeward Islands. Hurricanes Felix andOpal of 1995 also reached Category Four status at peak intensity.

Category Five Hurricane

Winds greater than 155 mph (135 kt or 249 km/hr). Storm surge generally greater than 18 ft above normal.Complete roof failure on many residences and industrial buildings. Some complete building failures withsmall utility buildings blown over or away. All shrubs, trees, and signs blown down. Complete destruction ofmobile homes. Severe and extensive window and door damage. Low-lying escape routes are cut by risingwater 3–5 h before arrival of the center of the hurricane. Major damage to lower floors of all structures locatedless than 15 ft above sea level and within 500 yards of the shoreline. Massive evacuation of residential areason low ground within 5–10 mi (8–16 km) of the shoreline may be required. Hurricane Mitch of 1998 was aCategory Five hurricane at peak intensity over the western Caribbean. Hurricane Gilbert of 1988 was aCategory Five hurricane at peak intensity and is one of the strongest Atlantic tropical cyclone of record.



Fujita Tornado Damage ScaleDeveloped in 1971 by T. Theodore Fujita of the University of Chicago

www.spc.noaa.gov/faq/tornado/f-scal.html

Important note about F-scale winds: Do not use F-scale winds literally. These precise wind speed numbersare actually guesses and have never been scientifically verified. Different wind speeds may cause similar-looking damage from place to place—even from building to building. Without a thorough engineeringanalysis of tornado damage in any event, the actual wind speeds needed to cause that damage are unknown.

Clapp: (Negative) We have problems with distribution lines coming down due to wind loads only. Extremewind loads should apply to all structures, regardless of pole height.

Now that distribution pole heights have increased to the 40–50 ft range, rather than the 35 poles that were inuse when the decision was made to exempt distribution poles from extreme wind loading. The wires andcables are at elevated levels and experience the full wind loading. In addition, my experience is thatdistribution lines are generally loaded to a higher percentage of allowed loading than in earlier years, and thegreater diameters of conductors and cables located at higher levels are causing loads from storm winds onbase conductors and cables to exceed the old Rule 250B loading.

Every distribution line sections failure I have investigated met Rule 250B loading but was either near to orfailed to meet Rule 250C extreme wind requirements.

Cotant: (Affirmative) The proposal as written will eliminate the “60 ft exemption” in areas of the countrywhere experience does not support such elimination. The evidence presented in support of the proposal failsto provide any root cause analysis of structure failures purported to be caused by extreme wind loading, andno evidence of failures due to extreme ice with concurrent wind loading was offered. I am not convinced thatthe modes of failure that occur during wind storms point to a need to make Code changes that would lead toan increase in the likelihood of survival of structures and supported facilities during such events. Myexperience is that faults/failures affecting safety and causing outages are predominantly due to contact byforeign objects, primarily sustained faults due to conductor contact or broken conductors due to fall-throughcontacts by vegetation, sometimes also causing structure and/or supported facility failure or damage. Thisproposal would impose an unnecessary design burden on designers of distribution facilities that is unlikely toprovide a corresponding improvement in structure survival and safety performance. There may be wisdom ineliminating the “60 ft exemption” on a limited basis, such as coastal areas subjected to Atlantic hurricanes,and possibly only for Grade B construction for structures supporting supply conductors over 750 V.

Scale Wind estimate (mph) Typical damage

F0 < 73 Light damage. Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged.

F1 73–112 Moderate damage. Peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos blown off roads.

F2 113–157 Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars overturned; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground.

F3 158–206 Severe damage. Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and thrown.

F4 207–260 Devastating damage. Well-constructed houses leveled; structures with weak foundations blown away some distance; cars thrown and large missiles generated.

F5 261–318 Incredible damage. Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100 m (360 ft); trees debarked; incredible phenomena will occur.



Fuller: (Negative) Clearly there is much left to discuss about this issue, and whether the wording achievesthe desired results. I vote Negative in an effort to keep this issue on the table.

Joplin: (Affirmative) Within the last 10 years, NCMEC has not experienced significant failures due to windonly. The majority of pole failures were contributed to debris blown on the lines. Based on our experience,this change proposal would not make a significant impact to improve reliability on distribution lines.

Kempner: (Negative) I voted “negative” to reject this CP3371 because I disagree with the stated reason forrejection “does not increase safety.” There is evidence that structures with heights of 60 ft or less fail duringextreme wind events. These failures are NOT caused by flying debris, but by wind only. For the NESC torequire a higher strength design of these structures, 60 ft and below, directly improves the safety to the publicthat the NESC is charged to protect. Recent hurricane events have demonstrated the importance of the powersystem to our society. The report by KEMA (Technical Report, Post Hurricane Wilma Engineering Analysis,Final Report, KEMA Project 05-349, January 12, 2006) documents the failure of electric power towers/polesto wind only. To state that there is no increase in safety with the removal of a 60 ft limit is not correct. Failureof electric power systems and the extended time to restore power systems after a major wind storm eventdirectly effects the safety of the public.

Kluge: (Affirmative) I do not agree with the reason the subcommittee gave for rejecting this proposal. Whenconductor sizes increase or telephone cables are overlashed, the district load may not provide sufficient loadrequirements. This was recognized by transmission companies when their conductor diameter became larger(>1.0 in).

I voted to reject because the proposal is not the best way to address this issue.

I would like to see this change modified where the EXEMPTION in Rule 250C is maintained and instead aminimum wind load without ice would be added to Rule 250B (District Loads). The wind speed proposed inthis CP should be converted to a pressure = 7.2 psf for use in Table 250 as a minimum wind load without ice.

People are suggesting that structures <60 ft tall are not designed to any wind load. Such is not the case. Addinga reasonable wind without ice load in Rule 250B (for medium and heavy load districts) would possiblyresolve that accusation.

The load (7.2 psf) suggested above would only apply to wires with diameters larger than 0.625 in for mediumload districts and 1.25 in for heavy load districts. Light load district already has a wind without ice loadingcase and would not be affected.

Revised Text

CP3310

Part: 2 Section: 26 261 A2e

Submitter

James T. Collins

Proposed Change






2. Wood structures

Wood structures shall be of material and dimensions to meet the following requirements:

a. ...

b. ...

c. ...

d. ...

e. All structures including those below 18 m (60 ft) shall be designed to withstand, withoutconductors, the extreme wind load in Rule 250C applied in any direction on the structureand any supported facilities and equipment which may be in place prior to installation ofconductors.

Supporting Comment

The rule is intended to require strength of the structure to support any applied wind loads prior to installationof conductors. This is to assure that the absence of strength provided by the conductors does not cause astructure failure prior to wires being strung. It is unstated, but can be inferred, that any facilities or equipment(such as transformers, switches, cut-outs, line traps, etc.) that may be in place prior to installation ofconductors should be considered in determining the required strength of the structure for extreme wind loads.This revision would clarify that the loading effect of such facilities and equipment is to be considered.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3311

Part: 2 Section: 26 261 A3a NOTE



Submitter

James T. Collins

Proposed Change


3. Fiber-reinforced polymer structures

a. These structures shall be designed to withstand the loads in Rule 252 multiplied by theappropriate load factors in Table 253-1 without exceeding the permitted load.

NOTE: When determining a fiber stress for column loads, buckling needs to be considered.

b....

Supporting Comment

The buckling NOTE has been included for wood structure strength since the 1997 revision. Buckling is alsoan issue for other types of materials, and the NOTE should be added for them also.


Accept as modified.



a. These structures shall be designed to withstand the loads in Rule 252 multiplied by theappropriate load factors in Table 253-1 without exceeding the permitted load.

NOTE: When determining a fiber stress for axial loads, buckling needs to be considered.

b....


Affirmative: (30) Berlinger, Bingel, Bullinger, Burley, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Fuller, Glaus, Haire, Harrel, Heald, Jones, Joplin, Kempner, Kluge, Lacoursiere,Lynch, Peters, Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (0)

Abstention: (0)



Revised Text

CP3312

Part: 2 Section: 26 261 A3d

Submitter

James T. Collins

Proposed Change



a. ...

b. ...

c. ...

d. All structures including those below 18 m (60 ft) shall be designed to withstand, withoutconductors, the extreme wind load in Rule 250C applied in any direction on the structure andany supported facilities and equipment which may be in place prior to installation ofconductors.

Supporting Comment

The rule is intended to require strength of the structure to support any applied wind loads prior to installationof conductors. This is to assure that the absence of strength provided by the conductors does not cause astructure failure prior to wires being strung. It is unstated, but can be inferred, that any facilities or equipment(such as transformers, switches, cut-outs, line traps, etc.) that may be in place prior to installation ofconductors should be considered in determining the required strength of the structure for extreme wind loads.This revision would clarify that the loading effect of such facilities and equipment is to be considered.


Accept.



Negative: (0)

Abstention: (0)



New Text

CP3351


Submitter

John Plisich

Proposed Change

Add following NOTE after Rule 261B:

B. Strength of foundations, settings, and guy anchors


NOTE: Excessive movement of foundations, settings, and guy anchors or errors in settings canreduce clearances or structure capacity.

NOTE: Soil saturation can have an adverse affect on the strengths of foundations, settings, and guyanchors. When placed in areas where chronic or seasonal saturated soil conditions may exist, thestrengths of foundations, settings, and guy anchors in saturated soils should be considered.

Supporting Comment

The strength of many foundations, settings, and guy anchors used in overhead construction can be reducedwhen soils become saturated. Evaluations conducted after natural hazard events identify the loss of strengthof foundations, settings, and guy anchors from saturated soils as a potential failure mode particularly whensaturated soil conditions coincide with high winds. The proposed note alerts Code users of this fact.

Saturated soils can be encountered in many areas. These include locations with high groundwater levels andlow-lying areas near bodies of water. Saturated soils can also be found in riverine and coastal Special FloodHazard Areas identified on FEMA’s Flood Insurance Rate Maps (FIRMs).

FEMA assesses flood risk for more than 20,400 communities nationwide, resulting in the publication of morethan 80,000 individual Flood Insurance Rate Maps (FIRMs). These are selectively revised as communitiesgrow, and as new or better scientific and technical data concerning flood risks become available.

The NESC is a critically important, used/referenced nationwide Code. There are thousands of electricaldistribution and transmission foundations, settings, and guy anchors located in potentially saturated soil areasthroughout the country. A NOTE regarding saturated soil consideration can help mitigate future damages inthese areas.


Accept as modified.



Add following note after Rule 261 B:

B. Strengths of foundations, settings, and guy anchors


NOTE 1: Excessive movement of foundations, settings, and guy anchors or errors in settings canreduce clearances or structure capacity.

NOTE 2: Soil saturation can have an adverse effect on the strengths of foundations, settings, andguy anchors.



Negative: (0)

Abstention: (0)

New Text

CP3005


Submitter

Robert Whapham

Proposed Change

H. Open supply conductors and overhead shield wires

1. Tensions

a. The supply conductor and overhead shield wire tensions shall be not more than 60% of theirrated breaking strength for the load of Rule 250B in Rule 251 multiplied by a load factor of1.0.

b. The tension at 15º C (60º F), without external load, shall not exceed the followingpercentages of their rated breaking strength:

Initial unloaded tension 35%

Final unloaded tension 25%



EXCEPTION: In the case of conductors with a generally triangular cross section, such ascables composed of three wires, the final unloaded tension at 15º C (60º F) shall notexceed 30% of the rated breaking strength of the conductor.

c. For aluminum and aluminum alloy based conductors (e.g., ACSR, AAC, AAAC, ACAR,ACSS, etc.) the tension shall be limited such that the catenary constant (K) does notexceed 1000 m (3280 ft) for single conductors or 2500 m (8202 ft) for bundledconductors, unless vibration mitigation devices (e.g., dampers) are considered.

Where: K = T/W

T = the conductor initial tension for the bare conductor without external weather loadingat the AAMT in pounds

W = the conductor bare unit weight without external weather loading in pounds/foot

AAMT = the average annual minimal ambient air temperature for the region in which theline facilities are located

Supporting Comment

Significant work has been done and published over the past few years on using the H/W ratio as a guide forsafe working tensions without the use of vibration dampers. This body of work has been published inOverhead Conductor Safe Design Tension with Respect to Aeolian Vibration, CIGRE Task Force B2.11.04,Report #273, June 2005, and in EPRI Transmission Line Reference Book, Wind-Induced Conductor Motion,Final report, November 2006, Section 2.6.

The added text has been submitted to Rule 261H1 to assure that design engineers are aware of these importantrecommendations regarding when damping devices should be considered.


Reject.


The proposed limits are too restrictive.


Affirmative: (25) Bingel, Bullinger, Burley, Byrne, Clapp, Clem, Corzine, Cotant, Denbrock, Erdle,Freimark, Glaus, Haire, Jones, Joplin, Kempner, Kluge, Lacoursiere, Lynch, Schwalm, Shultz, Slavin,Soderberg, Jr., Standford, Wong

Negative: (0)

Abstention: (3) Berlinger, Fuller, Heald

Explanation of Vote

Erdle: (Affirmative) I voted to reject this proposal, but I believe it is the right approach to reduce problemswith Aeolian vibration. The H/W limits appear to be low based upon experience. Also, this proposal does not



take into account the terrain categories in the CIGRE paper. The most conservative values for terrain wereused which will penalize many users.

Fuller: (Abstention) I am not familiar enough with the technical details to comment on this proposal

Heald: (Abstention) I abstain because: (1) the trigger point appears to be too low and (2) I have not reviewedthe CIGRE Task Force paper and the EPRI transmission line reference book Wind-Induced ConductorMotion Final Report, November 2006.

Revised Text

CP3449


Submitter

Subcommittee 5

Proposed Change

Modify Rule 261H1 as follows:

H. Open supply conductors and overhead shield wires

1. Tensions

a. The supply conductor and overhead shield wire tensions shall be not more than 60% oftheir rated breaking strength for the load of Rule 250B in Rule 251 multiplied by a loadfactor of 1.0.

b. The tension at 15 °C (60 °F), the applicable temperature listed in Table 250-1 for Rule250B, without external load, shall not exceed the following percentages of their ratedbreaking strength:

Initial unloaded tension 35%

Final unloaded tension 25%

EXCEPTION: In the case of conductors with a generally triangular cross section, such ascables composed of three wires, the final unloaded tension at 15 °C (60 °F), the applicabletemperature listed in Table 250-1 for Rule 250B shall not exceed 30% of the ratedbreaking strength of the conductor.

NOTE: The above limitations may not protect the conductor or facilities from damage dueto aeolian vibration.

Supporting Comment

Reducing the temperatures at which the tension limits are applied will reduce the risk of conductor damagedue to aeolian vibration.




Accept.


Affirmative: (20) Bingel, Bullinger, Burley, Byrne, Clapp, Corzine, Cotant, Denbrock, Freimark, Glaus,Jones, Kempner, Kluge, Lynch, Ng, Pehosh, Shultz, Slavin, Standford, Wong

Negative: (8) Clem, Erdle, Fuller, Haire, Heald, Joplin, Schwalm, Soderberg, Jr.


Explanation of Vote

Clem: (Negative) It is inappropriate to proceed with this without reviewing the impact on accepted practicethat has yielded good results.

Erdle: (Negative) This proposal was submitted in committee, after CP3005 that was intended to reduceaeolian vibration, was rejected. CP3005 allowed higher tensions if vibration mitigation devices (dampers)were considered. CP3449 does not allow the user to use dampers to mitigate vibration.

There is still a NOTE in this section that refers to aeolian vibration. This should be enough to allow the usersto base tensions on experience in their geographic areas.

Fuller: (Negative) I agree with other comments that we need to be certain we understand the impact ofchanging the values.

Haire: (Negative) The change proposed in SC5CP3 was proposed at the committee meeting and did notprovide adequate time or resources to study the impact on the existing construction. Existing constructionpractices are not producing vibration in either transmission or distribution.

Heald: (Negative) This rule should refer to Table 251-1 for the temperature of the conductor at initialunloaded tension and final unloaded tensions. It is confusing to say “250B loads without external loads.”Section 250 (and Table 250-1) pertains to loading requirements; Section 251 deals with conductor loading.As long as Table 251-1 exists, Rule 261H1b should refer to this table.

Joplin: (Negative) We are presently unsure of the impact of the tensions at reduced temperatures on ourconstruction policies, and we have not experienced extensive damaged due to aeolian vibration.

Schwalm: (Negative) I do not think there is sufficient, reliable data to support this change and maintain safety.

Soderberg: (Negative) In the heavy loading district, the temperature has changed from 60 °F to 0 °F. I did notwant to vote accept without knowing how this change will affect tensions.

New Text

CP3036

Part: 2 Section: 26 261 H1a



Submitter

Ewell Robeson

Proposed Change

Modify the rule as indicated.

1. Tensions

a. The supply conductor and overhead shield wire tensions shall be not more than 60% of theirrated breaking strength for the load of Rule 250B in Rule 251 multiplied by a load factor of1.0. If Rules 250C and 250D are applicable, the supply conductor and overhead shield wiretensions for these loading cases shall be not stressed beyond 80% of their rated breakingstrength under the loads of Rules 250C and 250D in Rule 251 multiplied by a load factor of1.0.

Supporting Comment

Rule 261H1a does not specifically address the wire tension limits for 250C and 250D loads. The changeproposed above to Rule 261H1a provides the same criteria as stated in Rules 261H2a and 261H2c, whichread:

2. Splices, taps, dead-end fittings, and associated attachment hardware

a. Splices should be avoided in crossings and adjacent spans. If it is impractical to avoid such splices,they shall have sufficient strength to withstand the maximum tension resulting from the loads ofRule 250B in Rule 251 multiplied by a load factor of 1.65. If Rules 250C and 250D are applicable,splices shall not be stressed beyond 80% of their rated breaking strength under the loads of Rules250C and 250D in Rule 251 multiplied by a load factor of 1.0.

c. Dead-end fittings, including the associated attachment hardware, shall have sufficient strength towithstand the maximum tension resulting from the loads of Rule 250B in Rule 251 multiplied by aload factor of 1.65. If Rules 250C and 250D are applicable, deadend fittings shall not be stressedbeyond 80% of their rated breaking strength under the loads of Rules 250C and 250D in Rule 251multiplied by a load factor of 1.0.


Accept as modified.

Modify the rule as indicated:

1. Tensions

a. The supply conductor and overhead shield wire tensions shall be not more than 60% of theirrated breaking strength for the load of Rule 250B in Rule 251 multiplied by a load factor of1.0. If Rules 250C and 250D are applicable, the supply conductor and overhead shield wiretensions for these loading cases shall not be stressed beyond 80% of their rated breakingstrength under the loads of Rules 250C and 250D in Rule 251 multiplied by a load factor of1.0.




Affirmative: (30) Bingel, Bullinger, Burley, Busel, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Fuller, Glaus, Guerry, Haire, Harrel, Heald, Jones, Kempner, Kluge, Lynch,Peters, Schwalm, Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (0)


Revised Text

CP3313

Part: 2 Section: 26 261 H1a

Submitter

James T. Collins

Proposed Change

Revise Rule 261H1a as follows:

a. The supply conductor and overhead shield wire tensions shall be not be more than 60% of theirrated breaking strength for the load of Rule 250B in Rule 251 multiplied by a load factor of 1.0. IfRules 250C and 250D are applicable, conductors and overhead shield wires shall not be stressedbeyond 80% of their rated breaking strengths under the loads of Rules 250C and 250D in Rule 251multiplied by a load factor of 1.0.

Supporting Comment

Since Rule 261H1a does not specifically address the wire tension limits for 250C and 250D loads, thisaddition will give direction as to how extreme loading cases are to be considered in determining loading limitsfor conductors.

Using only Rule 250B loading limits, the tensions for Rule 250C and 250D loads can approach or exceedrated breaking strength of conductors or shield wires.

In discussing the appropriate limit to use for conductors and shield wires with a conductor manufacturer, theyconcur with this proposal. As part of their quality testing, conductor samples are routinely tested to verifyloads of up to 80% RBS (based on testing equipment damage limitations) with no detrimental results to theirmechanical properties. Similarly, the test limit for shield wires is 80% RBS also.

Setting this limit will provide a specific, identifiable safety criterion by which conductors and shield wiressubject to NESC extreme loadings can be evaluated.






See CP3036.


Affirmative: (30) Bingel, Bullinger, Burley, Busel, Byrne, Clapp, Clem, Cooke, Corzine, Cotant,Denbrock, Erdle, Freimark, Fuller, Glaus, Guerry, Haire, Harrel, Heald, Jones, Kempner, Kluge, Lynch,Peters, Schwalm, Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (0)


Revised Text

CP3179

Part: 2 Section: 26 261 K1

Submitter

Grant Glaus

Proposed Change

Revise Rule 261K1 as follows:

K. Communication cables

1. Communication cables

There are no strength requirements for communication cables supported by messengers or all-dielectric self-supporting communication cables. See Rule 261K2 for the strengthrequirements for messengers supporting communication cables.

Supporting Comment

This change is desired to make it clear that no breaking strength requirements are specified for all-dielectricself-supporting communication cables. Typically manufacturers’ limits are used as the Code does not specifyany limits.


Accept as modified.

Revise Rule 261K and Rule 261L as follows:

K. Communication cables and messengers



1. Communication cables

a. There are no strength requirements for communication cables supported by messengers.See Rule 261K2 for the strength requirements for messengers supporting communicationcables.

b. Self-supporting cables shall not be stressed beyond the limits stated in Rule 261K2.

c. For paired metallic communication conductors see Rule 261L.

L. Paired metallic communication conductors



Negative: (0)

Abstention: (0)

Revised Text

CP3318

Part: 2 Section: 26 261 N

Submitter

James T. Collins

Proposed Change

N. Climbing and working steps and their attachments to the structure

The strength required for all climbing devices (includes steps, ladders, platforms and theirattachments) shall be capable of supporting 2.0 times the maximum intended load withoutpermanent excessive deformation. Unless otherwise quantified by the owner, the maximumintended load shall be assumed to be 300 lb, which includes the weight of the lineman, harness,tools, and equipment being supported by the lineman.

NOTE: See IEEE Std 1307™-2004 [B52].

Supporting Comment

This proposal will make permanent the changes to Rule 261N tentatively imposed by Tentative InterimAmendment 2007-3. Tests have shown that climbing steps that are commonly used in the utility industry willexperience some deformation under the specified loads; consequently, it is illogical to allow no permanentdeformation. In addition, as explained in the support for the TIA, other applicable industry standards aresignificantly less restrictive. For example, IEEE Std 1307 allows a 15° deformation in climbing steps before



replacement is required.

The proposed revision will make Rule 261N more compatible with other industry standards.


Accept as modified.

N. Climbing and working steps and their attachments to the structure

The strength required for all climbing devices (includes steps, ladders, platforms and theirattachments) shall be capable of supporting 2.0 times the maximum intended load withoutpermanent deformation. Unless otherwise quantified by the owner, the maximum intended loadshall be assumed to be 300 lb, which includes the weight of the lineman, harness, tools, andequipment being supported by the lineman.

NOTE: See IEEE Std 1307™-2004 [B52].



Negative: (0)

Abstention: (0)

Deleted Text

CP3118

Part: 2 Section: 26 261 Table 261-1A


Submitter

Lawrence Slavin

Proposed Change

(1) Revise Table 253-1, as follows:



1Includes pole.2For guys and anchors associated with structures supporting communication conductors and cables only, this factor

may be reduced to 1.33.3Where vertical loads significantly reduce the stress in a structure member a vertical overload factor of 1.0 should be

used for the design of such member. Such member shall be designed for the worst case loading.4For metal or prestressed concrete portions of structures and crossarms, guys, foundations, and anchors, use a value of

1.10.5For metal, prestressed concrete, or fiber-reinforced polymer portions of structures and crossarms, guys, foundations,

and anchors, use a value of 1.50.6This applies only where a line crosses another supply or communication line (see Rule 241C and Table 242-1).7 For wind velocities above 100 mph (except Alaska), a factor of 0.75 may be used.

(2) Revise Table 261-1A, as follows:

Table 253-1- Load factors for structures,1 crossarms, support hardware, guys, foundations, and anchors to be used with the strength factors of Table 261-1a

Load factors

Grade BGrade C


Rule 250B loadsVertical loads 3 1.70 1.50 5 1.70 1.90 5 1.70 1.90 5

Transverse loadsWindWire tension

2.501.65 2

2.20 41.30 5

1.751.304


1.10 1.65 2



Rule 250C loads 1.00 0.87 7 0.87 7

Rule 250D loads 1.00 1.00 1.00



1Includes poles.2Not used. Wood and reinforced concrete structures shall be replaced or rehabilitated when deterioration reduces the

structure strength to 2/3 of that required when installed. If a structure is replaced, it shall meet the strength requiredby Table 261-1A. Rehabilitated portions of structures shall have strength greater than 2/3 of that required when in-stalled.

3Wood and reinforced concrete structures shall be replaced or rehabilitated when deterioration reduces the structurestrength to 3/4 of that required when installed. If a structure is replaced, it shall meet the strength required by Table261-1A. Rehabilitated portions of structures shall have strength greater than 3/4 of that required when installed.

4Where a wood or reinforced concrete structure is built for temporary service, the structure strength may be reducedto values as low as those permitted by footnotes (2) and (3) provided the structure strength does not decrease belowthe minimum required during the planned life of the structure.

5For guy insulator requirements, see Rule 279.6Deterioration during service shall not reduce strength capability below the required strength.

Supporting Comment

The present change proposal is intended to facilitate the introduction of new structural materials into thetelecommunications and power industries.

The NESC implements a load and resistance factor design (LRFD) format to specify basic safety rules for

Table 261-1A - Strength factors for structures,1 crossarms, support hardware, guys, foundations, and anchors for use with overload factors of Table 253-1

[It is recognized that structures will experience some level of deterioration after installation, depending upon materials, maintenance, and service conditions. The table values specify strengths required at

installation.Footnotes specify deterioration allowed, if any. When new or changed facilities add loads to existing structures (a) the strength of the structure when new shall have been great enough to support the

additional loads and (b) the strength of the deteriorated structure shall exceed the strength required at replacement. If either (a) or (b) cannot be met, the structure must be replaced, augmented, or rehabilitated.]

Grade B Grade C

Strength factors for use with loads of Rule 250B

Metal and prestressed-concrete structures 6 1.0 1.0

Wood and reinforced-concrete structures 2 4 0.65 0.85

Fiber-reinforced polymer structures 2 4 1.0 1.0

Support hardware 1.0 1.0

Guy wire 5 6 0.9 0.9

Guy anchor and foundation 6 1.0 1.0

Strength factors for use with loads of Rule 250C and 250D

Metal and prestressed-concrete structures 6 1.0 1.0

Wood and reinforced-concrete structures 3, 4 0.75 0.75

Fiber-reinforced polymer structures 3, 4 1.0 0.75


Guy wire 5, 6 0.9 0.9

Guy anchor and foundation 6 1.0 1.0



structures subject to storm loadings, including specified load factors (Table 253-1) and strength factors (Table261-1A). These factors had been selected subjectively, based upon a combination of judgment and successfulexperience. In the present NESC (2007), both the load and strength factors (wood, reinforced concrete) aredependent upon the grade of construction, which relates to different levels of reliability. Although it is clearthat the load factor should directly depend upon the desired reliability level, it is less intuitive that the strengthfactor should also be dependent upon this parameter. Conversely, it is relatively easy to understand that thestrength factor should depend primarily upon the particular material to adjust for the manner in which thestrength of the product is specified in the relevant industry standard (e.g., minimum strength, average/meanstrength,...) as well other possible characteristics (variability,...).

For example, based upon the ANSI-O5.1 standard, a Class 4 wood pole has a nominal (mean) lateralcantilever strength of 2400 lb. Under current (2007) NESC rules, in order to meet basic safety requirements,this same pole is considered to have a strength ranging from 1560 lb (= 0.65 × 2400) to 1800 lb (= 0.75 ×2400) to 2040 lb (= 0.85 × 2400), depending upon the type storm load and grade of construction. Thus, a“Class 4 equivalent” non-wood pole, with a strength factor of 1.0 for all cases, is required to have a(minimum) strength of 1560, or 1800, or 2040 lb, which is certainly confusing to industry users. To makematters worse, the equivalent Class 4 Grade C-equivalent pole (2040 lb) is actually required to be strongerthan the Class 4 Grade B-equivalent pole (1560 lb) for the common combined ice and wind loading condition.While this is a proper implementation of the present NESC, as has been discussed in various articles (see ADiscussion of “Wood Equivalent” Poles, H. M. Rollins, Technical Bulletin, North American Wood PoleCoalition, January 2001; and Working Load Comparisons of Wood and Thin-Walled Steel Poles Under NESCGrade C Line Construction, Technical Bulletin, North American Wood Pole Coalition), this nonethelessfurther adds to the confusion of the user, tending to discourage the introduction of new pole technologies. Theselection process for various construction materials should be based upon objective criteria, and not basedupon the desire to avoid the confusion introduced by implementation of the present NESC rules.

It is recognized that theoretical reliability analyses will show that, for specified load factors for differentgrades of construction, the strength factor should ideally have some degree of dependence upon the grade ofconstruction in order to maintain precisely equal reliability levels among different “materials” (characterizedby their degree of variability). However, approximately equal reliability may be achieved by adopting a singlestrength factor for both grades of construction, under specified loadings conditions. (This effect had beeninvestigated during the development of the ASCE Manual 111, Reliability-Based Design of Utility PoleStructures, 2005.) The appropriateness of this approach is apparent based upon the recognition that a highdegree of accuracy in structural design for withstanding storm loads is not feasible in any case, due to lack ofprecision in the ability to characterize storm events. Thus, in order to eliminate industry confusion, and helpfacilitate the introduction of new materials, the present change proposal recommends a single, compromisestrength factor value of 0.75 for wood (and reinforced concrete). The value of 0.75 is proposed for wood, …for the following reasons:

Table 261-1A (NESC-2007) specifies 0.75 for Rule 250C (extreme wind) and Rule 250D (extreme ice withconcurrent wind) loads.

Table 261-1A (NESC-2002) specifies a wood, … strength factor of 0.65 for Grade B construction and 0.85for Grade C, for Rule 250B (combined ice and wind) loading—the average of which is 0.75. (An equallyweighted average is reasonable since the 0.85 factor applies to the larger number of Grade C wood poles, butthe 0.65 factor applies to the more “important” Grade B category.)

In summary, the value of 0.75 for wood (or reinforced concrete) is a reasonable compromise value that is thesame as, or close to, present strength factors. The net maximum effect of introducing the 0.75 value would be± one-half of a wood pole class size (± 13% nominal specified pole strength), but would thereby eliminate amajor source of confusion in the industry, facilitating the introduction of new technologies in the utilities.

Based upon the new strength factor (0.75) for wood, … the corresponding load factors for Rule 250B verticalloads in Table 253-1 must be modified to restore the original intended effective “margin” (i.e., load factor



divided by strength factor) established for Grade B and Grade C wood,... construction. Thus, a load factor of1.70 must be used for both Grade B and Grade C wood structures, … based upon 1.70/0.75 (proposed GradeB and Grade C, wood) ≈1.50/0.65 (original Grade B, wood,...) ≈ 1.90/0.85 (original Grade C, wood,...). Inaddition, to retain the original margin for non-wood (metal, prestressed concrete, or fiber-reinforced polymer)structures, Footnote 5 must now also be applied to the Grade B column for Rule 250B vertical loads.


Reject.


Unjustified penalty for Grade C wood poles.


Affirmative: (25) Bingel, Bullinger, Burley, Byrne, Clapp, Clem, Cooke, Corzine, Cotant, Denbrock, Erdle,Freimark, Glaus, Guerry, Haire, Harrel, Jones, Kempner, Kluge, Peters, Schwalm, Shultz, Soderberg, Jr.,Standford, Wong

Negative: (4) Busel, Heald, Lynch, Slavin

Abstention: (2) Berlinger, Fuller

Explanation of Vote

Busel: (Negative) ACMA believes that any variability between Grade B and Grade C construction should bereflected in the load factors of Table 253-1, and not in the strength factors of Table 261-1A. In addition,having a single and separate strength factor for each pole material would allow for an easier transition to theuse of reliability-based design concepts in future editions of the NESC.

Fuller: (Abstention) I need to hear both sides of this argument, rather than just the negative votes.

Heald: (Negative) I basically agree with the CP in principal. Factors for Grade B need to be adjusted. Irecognize there will be a slight hardening of Grade C construction. Grade B load factors need to be adjustedto prevent Grade B from basically being softened.

Lynch: (Negative) The changes proposed in CP3118 only affect the politically based District Loadings (Rule250B) and their subsequent analysis. The scientifically developed and engineering based reliability loadings(Rules 250C and 250D) and their subsequent analysis—assuming they were used to design the structures—are unaffected by this CP and thus the realistic performance and reliability of those structures under this CPwould not be affected. In the case of wood structures less than 60 ft above ground when the loophole to ignoreRules 250C and 250D for satisfactory performance is used, smaller poles or longer spans could have beenused for Grade B construction due to the decrease in the vertical load factor and the increase in thecorresponding strength factor. As it is often insisted by some that structures less than 60 ft above grade do notneed to have any reliability since vegetation always takes them down, this could make the poles even smallerand save utilities even more money over the existing requirements.

This CP would have been a good compromise in attempting to bring the NESC into better correlation withcommonly accepted structural engineering practices and I am disappointed that this effort to make thiscompromise was not more seriously considered.



Slavin: (Negative) See original Supporting Comments.

Revised Text

CP3178


Submitter

Grant Glaus

Proposed Change

Revise the Table 261-1A, the lines for “Fiber-reinforced polymer structures” for both Rule 250B and Rules250C and 250D as follows:

Fiber-reinforced polymer structures, crossarms, and braces

Supporting Comment

Fiber-reinforced polymer crossarms and braces are addressed in Rule 261D3 (which references Table 261-1A); however, Table 261-1A does not address crossarms and braces.




See CP3317.



Negative: (0)

Abstention: (0)

Revised Text

CP3315




Submitter

James T. Collins

Proposed Change

Revise Footnotes 2 and 3 to read as follow:

2Wood and reinforced structures shall be replaced or rehabilitated when deterioration reduces the structurestrength to 2/3 of that required when installed. When loadings are modified during service, the strengthrequired when installed shall be redefined based on the modified loadings. If a structure or component isreplaced, it shall meet the strength required by Table 261-1A. If a structure or component is rehabilitated,the Rrehabilitated portions of the structures shall have strength greater than 2/3 of that required wheninstalled.

3Wood and reinforced structures shall be replaced or rehabilitated when deterioration reduces the structurestrength to 3/4 of that required when installed. When loadings are changed during service, the strengthrequired when installed shall be based on the modified loadings. If a structure or component is replaced, itshall meet the strength required by Table 261-1A. If a structure or component is rehabilitated, theRrehabilitated portions of the structures shall have strength greater than 3/4 of that required when installed.

Supporting Comment

This proposal addresses issues raised in IR 479. The revision will make the wording of these footnotesconsistent with that interpretation.

The term “strength required when installed” in Footnotes 2 and 3 needs clarification that this strength is notreferring to the original strength required when the structure was originally installed. The required strengthat replacement is based on the existing loadings at the time of the inspection and evaluation.

The other change to the footnotes is grammatical. The footnotes start out mentioning two possible actions tobe taken for deteriorated structures which are replacement and rehabilitation. Later on in the footnotes, thefirst “if” specifies the requirement for the replacement case, but there was no second “if.” The proposedchange helps make the footnotes easier to read and understand.


Accept as modified.

Revise Footnotes 2 and 3 to read as follow:

2Wood and reinforced structures shall be replaced or rehabilitated when deterioration reduces the structurestrength to 2/3 of that required when installed. When new or changed facilities add loads to existingstructures, the required strength shall be redefined based on the modified loadings. If a structure orcomponent is replaced, it shall meet the strength required by Table 261-1A. If a structure or component isrehabilitated, the Rrehabilitated portions of the structures shall have strength greater than 2/3 of that requiredwhen installed.

3Wood and reinforced structures shall be replaced or rehabilitated when deterioration reduces the structurestrength to 3/4 of that required when installed. When new or changed facilities add loads to existingstructures, the required strength shall be redefined based on the modified loadings. If a structure orcomponent is replaced, it shall meet the strength required by Table 261-1A. If a structure or component is



rehabilitated, the Rrehabilitated portions of the structures shall have strength greater than 3/4 of that requiredwhen installed.



Negative: (0)

Abstention: (0)

Revised Text

CP3316


Submitter

James T. Collins

Proposed Change

Add load case descriptions for both sets of strength factors in the headings for each section of Table 261-1A.

Grade B Grade C

Strength factors for use with loads of Rule 250B (Combined ice and wind loading)

Metal and prestressed-concrete structures, crossarms, and braces 6 1.0 1.0

Wood and reinforced-concrete structures, crossarms, and braces 2, 6 0.65 0.85

Fiber-reinforced polymer structures 6 1.0 1.0


Guy wire 5, 6 0.9 0.9

Guy anchor and foundations 6 1.0 1.0

Strength factors for use with loads of Rules 250C and 250D (Extreme wind and extreme ice with concurrent wind loadings, respectively)





Guy wire 5, 6 0.9 0.9




NOTE: Table title and footnotes omitted.

Supporting Comment

Identifying loading cases in the table only by reference to the governing NESC rules (i.e., Rules 250B, 250C,and 250D) has led to confusion on the part of some infrequent Code users as to which load case load factorsare being specified. Adding the description to the rule reference in the sections of the table will make theappropriate load cases and strength factors more easily identifiable.


Accept as modified.

Add load case descriptions for both sets of strength factors in the headings for each section of Table 261-1A.




Negative: (0)

Abstention: (0)

Grade B Grade C

Strength factors for use with loads of Rule 250B (Combined ice and wind district loading)





Guy wire 5, 6 0.9 0.9


Strength factors for use with loads of Rules 250C (extreme wind) and 250D (extreme ice with concurrent wind loadings)





Guy wire 5, 6 0.9 0.9




Revised Text

CP3317


Submitter

James T. Collins

Proposed Change

Revise table to include crossarms and braces for fiber-reinforced polymers similar to other materials.


Supporting Comment

CP2614 was accepted for the 2007 NESC revision cycle to include crossarms and braces with “metal andprestressed-concrete structures” and “wood and reinforced-concrete structures” strength factor categories.Fiber reinforced polymer material was added to the table also in 2007, but “crossarms and braces” were notincluded. This results in inconsistent treatment of the different material types without a safety or technicalrationale.


Accept.

Grade B Grade C


Metal and prestressed-concrete structures, crossarms, and braces 1.0 1.0

Wood and reinforced-concrete structures, crossarms, and braces 0.65 0.85

Fiber-reinforced polymer structures, crossarms, and braces 1.0 1.0


Guy wire 0.9 0.9

Guy anchor and foundations 1.0 1.0

Strength factors for use with loads of Rules 250C and 250D

Metal and prestressed-concrete structures, crossarms, and braces 1.0 1.0

Wood and reinforced-concrete structures, crossarms, and braces 0.75 0.75

Fiber-reinforced polymer structures, crossarms, and braces 1.0 1.0


Guy wire 0.9 0.9

Guy anchor and foundations 1.0 1.0





Negative: (0)

Abstention: (0)

Revised Text

CP3439


Submitter

Allen Clapp

Proposed Change

Revise the strength factors for guy anchors and foundations in Table 261-1A and add a new Footnote 7, asreferenced in the table revision.

7 If soil tests are performed by qualified personnel, the following factors may be used: Grade B—0.80; Grade C—0.90.

Supporting Comment

Pole strength increases as to the square of the pole diameter. However, earth reaction only increases with thediameter of the pole. As a result, some soil classes cannot withstand the loadings allowed for the wood in thelarger pole classes. In addition, direct-embedded metal poles and fiber-reinforced polymer poles arephysically smaller in diameter than their wood pole strength equivalent. As a result, as (a) larger pole classeswith higher overturning moments and (b) non-wood poles have become more common, more problems areoccurring due to poles leaning or overturning in the softer soil classes.

If line designers allow loads on poles based only on the pole class and do not consider the capability andvariability of the earth reaction, lines will increasingly lean and/or fall down—as we have recently seen. Atthe least, clearance problems and increased pole stress occur when poles lean. When the earth reaction is notcapable of withstanding the overturning moment and a pole falls, potentially hazardous situations occur.

Grade B Grade C


Guy rods & anchors; metal & reinforced concrete and foundations6 1.00 1.00

Earth reaction to forces from anchors, foundations, & direct-embedded poles7 0.65 0.85

Strength factors for use with loads of Rules 250C and 250D

Guy rods & anchors; metal & reinforced concrete and foundations6 1.00 1.00

Earth reaction to forces from anchors, foundations, & direct-embedded poles7 0.65 0.85



The present strength factor of 1.00 for guy anchors and foundations in Table 261-1A is based upon thestrength factor used for metal and for prestressed concrete structures. Those factors apparently came fromconsideration of metal anchor rods and anchors, reinforced concrete foundations, and steel grillagefoundations themselves.

Since reinforced concrete foundations do not tend to suffer from large cracks under bending like poles do, thesame strength factor used for prestressed concrete and metal has been used for reinforced concrete.

It is well known that the ability of earth to withstand forces from anchors, foundations, and poles is extremelyvariable, with some soils having four or more times the overturning capability as other soils. While thevariability can be somewhat reduced by testing the soil at the structure site, it is difficult to determine the exactcapability of the earth at a particular pole or structure location. This is especially true when the soil testing isin the general area and not the specific hole used for a pole, anchor, or foundation. As a result, an appropriatestrength factor should be applied to the reaction of the earth to forces from anchors, foundations, and poles.It is appropriate for the factor to differ when testing is performed by qualified personnel.

This proposal uses the same strength factors now used for wood and reinforced concrete poles as the strengthfactors for earth reactions. The use of such numbers is based upon the expectation that line designers will atleast have made some level of effort to determine likely soil conditions by visual or other means and will havelimited the potential extreme variations by assuming that the soil has the capability of some designated soilclass level.

This proposal will assure that some consideration is given to the facts that (a) even if correctly classified, thesoil strength varies within a class, and (b) the actual soil capability may be that of an adjacent class number.The proposal also recognizes that soil testing can limit the potential variability, but it cannot completelyeliminate that variability.


Reject.


The proposed strength factors are not justified in the proposal. Refer to Working Group to addressfoundation issues for future changes.

Working Group—To prepare appropriate changes for foundation: Peters, Chair; Kempner and associate;Bingel and associate; Jurgenmeyer.


Affirmative: (29) Bingel, Bullinger, Burley, Byrne, Clem, Cooke, Corzine, Cotant, Denbrock, Erdle,Freimark, Fuller, Glaus, Haire, Harrel, Heald, Jones, Joplin, Kempner, Kluge, Lacoursiere, Lynch, Peters,Schwalm, Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (1) Clapp


Explanation of Vote

Clapp: (Negative) We are experiencing line failures as a result of inadequate support of large class poles by



the earth. While I agree that this proposal may require large factors for foundations for which tests are notperformed, I think that large factors need to be applied where soil tests are not performed. The reactioncapability of different soils vary too widely to use a factor of 1.00. See the rationale for the proposal. I supportformation of a working group.

Revised Text

CP3314

Part: 2 Section: 26 261 Tables 261-1A, 261-1B

Submitter

James T. Collins

Proposed Change

Make editorial corrections to tables. Revise footnote reference format to place the reference inside ofassociated punctuation.

Table 261-1A

Title. Reference to Footnote 1 associated with structures.

Table 261-1B

Title. Reference to Footnotes 1 and 2 associated with structures.

Supporting Comment

Placements of footnote references in several Code tables are incorrect in that they are placed after associatedpunctuation. For examples of proper placement of similar references, see Tables 234-1, 234-2, and 234-3.


Accept.



Negative: (0)

Abstention: (0)



Revised Text

CP3319


Submitter

James T. Collins

Proposed Change

Revise Table 277-1 as shown:

Table 277-1—Allowed percentages of strength ratings

Insulator type Percent Strength rating 1 Reference standard

Ceramic

Suspension and dead end 50% Combined mechanical and electric strength

ANSI C29.2-1992

Line post 40%50%

Cantilever strengthTension, compression strength

ANSI C29.7-1996

Station post 40% Cantilever, tension, compressionor torsion strength

ANSI C29.9-1983 [B8]

Station cap and pin 40% Cantilever, tension, compressionor torsion strength

ANSI C29.8-1985 [B7]

Pin 40% Cantilever strength ANSI C29.5-1984 (R2002)and C29.6-1996 (R2002)

Spool 50% Cantilever strengthTension, compression strength

ANSI C29.3-1986 (R2002)



1All strengths shall be those supplied by the respective manufacturers.2 Industry standards do not currently exist (as of June 2008) and are not currently scheduled for development.

Supporting Comment

1. Rule 277 of the 2002 NESC provided the allowed strength percentages of insulator strength ratings asshown below:

Cantilever 40%Compression 50%Tension 50%

The 2007 NESC provides the allowed strength percentages by insulator type as shown by Table 277-1. Withthis change, certain distribution insulators (distribution pin type and spool type) were excluded from Rule277.

Common distribution applications include pin type insulators for primary conductor installations. Theseinsulators fall under ANSI C29.5-1984 (R2002) and ANSI C29.6-1996 (R2002) Standards. Other commondistribution applications include spool type insulators for neutral and secondary applications. Spool insulatorsfall under ANSI 29.3-1986 (R2002) standards. The proposed revision to Table 277-1 includes the allowedstrength percentages for pin insulators and spool insulators as previously provided in the 2002 NESC.Example distribution insulators not included with the 2007 NESC Table 277-1 are shown below.

Nonceramic

Suspension and dead end 50% Specified mechanical load (SML)

ANSI C29.12-1997 [B11]and C29.13-2000 [B12]

Line post 50% Specified cantilever load (SCL) orspecified tension load (STL)

ANSI C29.17-2002 [B13]and C29.18-2003 [B14]

Station post 40% 50% All strength ratings ANSI C29.19-2008

Pin 40% Cantilever strength See Footnote 2

Spool 50% Cantilever strengthTension, compression strength

See Footnote 2

Table 277-1—Allowed percentages of strength ratings (continued)

Insulator type Percent Strength rating 1 Reference standard



2. Nonceramic pin and spool insulator designs are becoming more numerous in the industry. An ANSIstandard does not currently exist for these insulators. Therefore, allowed strength as a percentage ofmanufacturer strength ratings should be applied. This requirement is properly addressed by Footnote 1.

3. To further clarify the intent of the rule, it is proposed to revise references in Table 277-1 from “Suspension”to “Suspension/dead end” insulators.

ANSI C29.19 (nonceramic station post insulators) is unapproved as of June 2008, but it is scheduled to beballoted by the end of 2008. The proposal to reference C29.19 is contingent upon approval of the standard byballot.

Regarding the reference to Footnote 2, industry standards do not currently exist (as of June 2008) and are notcurrently scheduled for development. Load limits for nonceramic insulators are based on limits for similarloading modes of ceramic insulators.




See CP3411.


Affirmative: (30) Bingel, Bullinger, Burley, Byrne, Clapp, Clem, Cooke, Corzine, Cotant, Denbrock, Erdle,Freimark, Fuller, Glaus, Haire, Harrel, Heald, Jones, Joplin, Kempner, Kluge, Lacoursiere, Lynch, Peters,Schwalm, Shultz, Slavin, Soderberg, Jr., Standford, Wong

Negative: (0)


Typical distribution ANSI Class 55-4ceramic pin insulator

Typical distribution ANSI Class 53-2ceramic spool insulator



Revised Text

CP3411


Submitter

Scott Choinski

Proposed Change

Revise Table 277-1 in Rule 277 as follows:

1 All strengths shall be those supplied by the respective manufacturers.

Supporting Comment

ANSI C29 formed a group of manufacturers, utility reps, and NESC Subcommittee 5 members to try to clarifyand resolve questions on insulator strengths and acceptable loadings. The C29 group has held severalmeetings and has had conference calls among themselves and also some with NESC Subcommittee 5members. The above CP is submitted to correct the errors in the 2007 Table in Rule 277. The changes shownalso clarify issues and make the table easier to interpret.

Insulator type Percent Strength/load rating 1 Reference standard

Ceramic

Suspension 50% Combined mechanical and electrical strength

ANSI C29.1 and ANSI C29.2 -1992

Line post 40%

50%

Cantilever strengthTension, compression strengthTension, compression strength

ANSI C29.7 -1996

Station post 40%

50%

Cantilever, tension, compression or torsion strengthTension, compression or torsion strength

ANSI C29.9-1983 [B8]

Station cap and pin 40%

50%

Cantilever tension, compression, or torsion strengthTension, compression or torsion strength

ANSI C29.8 -1985 [B7]

Pin 40% Cantilever strength ANSI C29.5 1984 (R2002) and C29.6 1996 (R2002)

Spool 50% Transverse strength ANSI C29.3 1986 (R2002)

Nonceramic

Suspension 50% Specified mechanical load (SML) ANSI C29.12 -1997 [B11] and C29.13 -2000 [B12]

Line post 50% Specified cantilever load (SCL) orspecified tensile load (STL)

ANSI C29.17 -2002 [B13] and C29.18 -2003 [B14]

Station post 40%50%

All strength ratings ANSI C29.19




Accept as modified.

Revise Table 277-1 in Rule 277 as follows:

1All strengths shall be those supplied by the respective manufacturers.2Industry standards do not currently exist (as of September 2008) and/or are not currently scheduled for development.3Suspension type includes deadend applications.

Insulator type Percent Strength or load rating 1Reference standard

Note: The following standards are referenced for information

Ceramic

Suspension type3 50% Combined mechanical and electrical strength

ANSI C29.1-1988 (R2002) and ANSI C29.2-1992 (R1999)

Line post 40% Cantilever strength ANSI C29.7-1996 (R2002)

50% Tension, compression strength

Station post 40%

50%

Cantilever, tension, compression or torsion strengthTension, compression or torsion strength

ANSI C29.9-1983 (R2002) [B8]

Station cap and pin 40% Cantilever tension, compression, or torsion strength

ANSI C29.8-1985 (R2002) [B7]

Pin 40% Cantilever strength ANSI C29.5-1984 (R2002) and ANSI C29.6-1996 (R2002)

Spool 50% Transverse strength ANSI C29.3-1986 (R2002)

Nonceramic

Suspension type3 50% Specified mechanical load (SML) ANSI C29.12-1997 (R2002) [B11] and ANSI C29.13-2000 [B12]

Line post 50% Specified cantilever load (SCL) orspecified tensile load (STL)

ANSI C29.17-2002 [B13] and ANSI C29.18-2003 [B14]

Station post 40% All strength ratings ANSI C29.19See Footnote 2.

Pin 40% Cantilever strength See Footnote 2.

Spool 50% Transverse strength See Footnote 2.



Supporting Comment

SC5 comments.

Table 277-1—Allowed percentages of strength ratings

1 All strengths shall be those supplied by the respective manufacturers.

Supporting Comment

The percentage values of strength rating for the respective insulator type were supplied by the ASC C29 forinclusion in the 2007 NESC Rule 277. However, the percentage of nonceramic line post insulators do notalign with the proof test values published in ANSI C29.17. This matter has been brought to the attention ofASC C29 by messenger Robert Kluge in June of 2006. Since it has not yet been addressed, this changeproposal is also submitted to NESC to bring the two standards into alignment. If ASC C29 revisesANSI C29.17 prior to the approval of NESC 2012, then this change proposal can and will be withdrawn.

A copy of change request submitted to ASC C29 is attached for your information.

Change proposal for ANSI C29. 17

Section: 9.4.2 Cantilever strength verification

Proposal

The sample insulator shall be loaded at an approximately constant rate of less than 40%50% of the S.C.L. ofthe insulator per minute. The position of the end fitting to which the load is being applied shall be monitored.A load of at least 40%50% of the S.C.L. shall be held for one minute. During the 1 min hold, the position ofthe top end fitting shall be monitored. Where L represents the unloaded section length of the insulator ininches, a position shift exceeding (0.008*L)2 inches shall constitute failure of the test. At the conclusion ofthe 1 min hold, the load shall be removed.

Insulator type Percent Strength rating1 Reference standard

Ceramic

Suspension 50% Combined mechanical and electric strength ANSI C29.2-1992

Line post 40%50%

Cantilever strengthTension, compression strength

ANSI C29.7-1996

Station post 40% Cantilever, tension, compressionor torsion strength

ANSI C29.9-1983 [B8]

Station cap and pin

40% Cantilever, tension, compressionor torsion strength

ANSI C29.8-1985 [B7]

Nonceramic

Suspension 50% Specified mechanical load (SML) ANSI C29.12-1997 [B11]and C29.13-2000 [B12]

Line post 5040% Specified cantilever load (SCL) orspecified tension load (STL)

ANSI C29.17-2002 [B13]and C29.18-2003 [B14]

Station post 40% All strength ratings



Supporting Comments

With the changes approved for the 2007 edition of the NESC, there is now an inconsistency between NESCRule 277 and the material specification for composite type post insulator in ANSI C29.17-2002.

NESC 2007 requires that nonceramic line post insulators be capable of withstanding 50% of the percent ofthe specified cantilever load (SCL). However, manufacturers are only required by ANSI C29.17 to verify thestrength to 40% of SCL.

Therefore, ANSI C29.17 should be revised to change Section 9.4.2 Cantilever Strength Verification as shownabove.

Albeit, differences of opinion remain between the two standards committees regarding what loads relate tothese strength limits. Nevertheless, the strength limit specified and the verification load applied by themanufacturer should be the same.



Negative: (0)

Abstention: (0)

New Text

CP3457


Submitter

Subcommittee 5

Proposed Change

A. Insulators

1. Properties of guy insulators

Where guy insulators are used in accordance with Rule 215C2, the guy insulators shall meetthe following requirements:

a. Material

Insulators shall be made of wet-process porcelain, wood, fiberglass-reinforced polymerplastic, or other material of suitable mechanical and electrical properties.

b. Electrical strength



The guy insulator shall have a rated dry flashover voltage at least double, and a rated wetflashover voltage at least as high as, the nominal line voltage between conductors of theguyed circuit. The dry and wet flashover values shall be determined according to the Low-Frequency Dry and Low-Frequency Wet Withstand Voltage Tests specified in ANSIC29.1. Fiber-reinforced polymer plastic guy insulators, or guy insulators of other suitablematerials, that can reasonably be expected to be degraded by ultraviolet light shall becoated with a UV resistive coating. A guy insulator may consist of one or more units.

c. Mechanical strength

The rated ultimate strength of the guy insulator shall be at least equal to the requiredstrength of the guy in which it is installed.

Supporting Comment

The reference to wood guy insulators needs to be removed from the Code. While clean, dry wood can be anexcellent insulator, as in hot line tools for example, it is not reasonable to anticipate that wood guy insulatorswill be maintained such that they can perform their intended purpose. Practical alternatives are readilyavailable and removing the reference to wood guy strain insulators does not impose unreasonablerequirements.

The industry has safely applied fiberglass strain insulators in guy wires in both distribution and transmissionapplications since the 1960s. However, the current Code wording requires guy strain insulators to have rateddry wet flashover voltages but the Code is not clear as how guy strain insulators are to be rated. Rule 274requires insulators used on operating circuits to be tested by the manufacturer but provides no guidance as tohow to electrically rate a guy stain insulator. This has placed the industry in the position of installing acommercially available product, with a long proven safety record, that does not meet the “letter of the Code.”

The proposed changes provide a direction as how to properly rate guy strain insulators for their intendedpurpose. Guy strain insulators are not installed as circuit insulators and need not have all the same long termrequirements of a circuit insulator. The current requirements that the guy insulator have a rated dry flashoverdouble, and a rated wet flashover voltage at least as high as, the nominal line voltage between conductors ofthe guyed circuit provides for a substantial voltage withstand margin for the intended application.


Accept.


Affirmative: (29) Berlinger, Bingel, Bullinger, Burley, Byrne, Clapp, Clem, Corzine, Cotant, Denbrock,Erdle, Freimark, Fuller, Glaus, Haire, Heald, Jones, Joplin, Kempner, Kluge, Lacoursiere, Lynch, Ng,Peters, Schwalm, Shultz, Slavin, Soderberg, Jr., Wong

Negative: (0)

Abstention: (0)



Revised Text

CP3180


Submitter

Grant Glaus

Proposed Change

Revise Rules 279A2b1 and 279A2b2 as follows:

(1) The guy is otherwise insulated to meet the requirements of Rule 279A1 215C5.

(2) Anchor guys are grounded below the insulator in accordance with Rules 215C5 215C2 and 92C2.

Supporting Comment

The wrong rules are referenced. This is probably due to the formatting changes made in the last edition.


Accept as modified.

Revise Rules 279A2b1 and 279A2b2 as follows:

(1) The guy is otherwise insulated to meet the requirements of Rules 215C5 and 279A1.

(2) Anchor guys are grounded below the insulator in accordance with Rules 215C5 92C2 and 215C2and 92C2.



Negative: (0)

Abstention: (0)

Revised Text

CP3456




Submitter

Subcommittee 5

Proposed Change

Modify the existing rule as follows:

B. Properties of span-wire insulators

Where span-wire insulators are used in accordance with Rule 215C, the span-wire insulators shallmeet the following requirements:

1. Material

Insulators shall be made of wet-process porcelain, wood, fiberglass, or other material ofsuitable mechanical and electrical properties.

Supporting Comment

The reference to wood guy insulators needs to be removed from the Code. While clean, dry wood can be anexcellent insulator, as in hot line tools for example, it isn’t reasonable to anticipate that wood span-wireinsulators will be maintained such that they can perform their intend purpose. Practical alternatives are readilyavailable and removing the reference to wood span-wire insulators does not impose unreasonablerequirements.


Accept.


Affirmative: (28) Berlinger, Bingel, Bullinger, Burley, Clapp, Clem, Corzine, Cotant, Denbrock, Erdle,Freimark, Fuller, Glaus, Haire, Heald, Jones, Joplin, Kempner, Kluge, Lacoursiere, Lynch, Ng, Peters,Schwalm, Shultz, Slavin, Soderberg, Jr., Wong

Negative: (0)

Abstention: (0)



Part 3. Safety Rules for the Installation and Maintenance of

Underground Electric Supply and Communication Lines

Revised Text

CP3037


Submitter

Ewell Robeson

Proposed Change


4. Inspection rRecord of defects

Any conditions defects affecting compliance with this Code revealed by inspection, if not promptlycorrected, shall be recorded; such records shall be maintained until the conditions defects arecorrected.

Supporting Comment

The word “defects” suggests something tangible or physical such as equipment, cable, etc. The word“conditions” is more inclusive and lets users know the intent of this rule also includes separation, securityissues, etc. It is difficult to equate a security or separation violation with being a defect.




See CP3321.



Negative: (0)

Abstention: (0)



Revised Text

CP3321


Submitter

James T. Collins

Proposed Change


4. Inspection record of defects

Any conditions defects affecting compliance with this Code revealed by inspection, if not promptlycorrected, shall be recorded; such record shall be maintained until the defects are the corrections aremade corrected.

Supporting Comment

The word “defects” suggests something tangible or physical such as equipment, cable, etc. The word“condition” is more inclusive and lets users know the intent of this rule also includes separation, securityissues, etc. It is difficult to equate a security or separation violation with being a defect.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3038


Submitter

Ewell Robeson



Proposed Change



Lines and equipment with recorded conditions defects that would endanger life or property shall bepromptly corrected repaired, disconnected, or isolated.

Supporting Comment

The word “defects” suggests something tangible or physical such as equipment, cable, etc. The word“conditions” is more inclusive and lets users know the intent of this rule also includes separation, securityissues, etc. It is difficult to equate a security or separation violation with being a defect. Also the word“corrected” is better and more inclusive than repaired (see Rule 313A4 terminology).




See CP3322.



Negative: (0)

Abstention: (0)

Revised Text

CP3322


Submitter

James T. Collins

Proposed Change



Lines and equipment with recorded conditions revealed by inspections defects that would could be



reasonably be expected to endanger life or property shall be promptly corrected repaired,disconnected, or isolated.

Supporting Comment

The word “defects” suggests something tangible or physical such as equipment, cable, etc. The word“condition” is more inclusive and lets users know the intent of this rule also includes separation, securityissues, etc. It is difficult to equate a security or separation violation with being a defect. Also using the word“corrected” mirrors the language of Rule 313A4 and is more inclusive than “repaired.”


Accept as modified.



Lines and equipment with recorded conditions revealed by inspections defects that wouldreasonably be expected to endanger life or property shall be promptly corrected repaired,disconnected, or isolated.



Negative: (0)

Abstention: (0)

Revised Text

CP3429


Submitter

Allen Clapp

Proposed Change

Revise Rule 314B as shown.

B. Conductive parts to be grounded

Cable sheaths and shields (except conductor shields), equipment frames and cases (including pad-mounted devices), and conductive lighting poles shall be effectively grounded. Conductive-materialducts and riser guards that enclose electric supply lines or are exposed to contact with open supplyconductors of greater than 300 V shall be effectively grounded.



EXCEPTION: This rule does not apply to parts that are 2.45 m (8 ft) or more above readily accessiblesurfaces or are otherwise isolated or guarded.

Supporting Comment

The 300 V limit has been removed from most of the Code relating to exposure of guys and other items—andthis remaining one should be removed as well. Secondary voltage is hazardous.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3325


Submitter

James T. Collins

Proposed Change


C. Circuits

1. Neutrals

Primary neutrals, secondary and service neutrals, and common neutrals shall be effectivelygrounded. as specified in Rule 314A.

EXCEPTION: Circuits designed for ground-fault detection and impedance current-limitingdevices.

2. Other conductors

Conductors, other than neutral conductors, that are intentionally grounded, shall be effectivelygrounded. as specified in Rule 314A.

3. Surge arresters

Surge arresters shall be effectively grounded. as specified in Rule 314A.



Supporting Comment

Since there are no specified methods, nor references to how to effectively ground lines and equipment inSection 9, these references to Section 9 need to be deleted to limit confusion on the user’s part.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3170


Submitter

David Marne

Proposed Change


2. Separations between supply and communication conduit systems ducts

Conduit systems Ducts to be occupied by communication conductors shall be separated fromconduit systems ducts to be used for supply systems by not less than

Supporting Comment

Rule 2320B2 should be changed to reflect the proper use of the terms “conduit systems” and “duct” asdefined in NOTE 1 to Section 32.


Reject.


The present rule is adequate and meets the intent of this section.




Affirmative: (18) Amrhyn, Austin, Bleakley, Bowmer, Cooke, Dyer, Gaunt, Guinn, Gunter, Hiu, Miller,Pehosh, Pool, Pregler, Pristach, Robeson, Spence, Szendre

Negative: (2) Slavin, Vencus

Abstention: (0)

Explanation of Vote

Slavin: (Negative) In spite of the attempts in Section 32 to clarify the distinction between ducts, conduits,conduit systems, etc., confusion continues to exist. The attempt of this change proposal to add greater clarityto Rule 320B2 is welcome and should be encouraged. The apparent erroneous clarification contained in thisCP further emphasizes the need to pursue this further.

Vencus: (Negative) I agree that this rule needs clarification and the intent of the CP. Since a conduit systemcontains more than ducts, separation between conduit systems does not only relate to the separation betweenducts (which appears to be the reference in Rule 320B2).

New Text

CP3340


Submitter

Lawrence Slavin

Proposed Change

Add NOTE to EXCEPTION of Rule 320B2, as follows:

320. Location

A. Routing

...

B. Separation from other underground installations

1. General

...

2. Separations between supply and communication conduit systems

Conduit systems to be occupied by communication conductors shall be separated from conduitsystems to be used for supply systems by not less than



a. 75 mm (3 in) of concrete

b. 100 mm (4 in) of masonry

c. 300 mm (12 in) of well-tamped earth

EXCEPTION: Lesser separations may be used where the parties concur.

NOTE: Compliance with the requirements of Rule 354 for random separation may beconsidered a basis for concurrence. Rules 341A6 and 341A7 remain applicable.

Supporting Comment

The present change proposal is intended to provide guidance for parties considering agreeing to lesserphysical separation between ducts used for communication and supply conductors than that indicated inpresent Rule 320B2.

In particular, Rule 354 provides requirements allowing random separation between communication andsupply cables, including those “installed in a duct not part of conduit system” [see Rules 350G and 354D2a(3)NOTE]. Compliance with such requirements therefore provides a rational basis for the parties to agree tolesser separation than that indicated in present Rule 320B.


Reject.


The proposed NOTE is already covered by the EXCEPTION.



Negative: (0)

Abstention: (0)

Revised Text

CP3092


Submitter

Mickey Gunter



Proposed Change


Radial separation of conduit systems from gas and other lines that transport flammable material shall benot less than 300 mm (12 in). and conduit should have sufficient separation from gas and other lines thattransport flammable material to permit the use of pipe maintenance equipment. Conduit shall not enterthe same manhole, handhole, or vault with gas or other lines that transport flammable material.

Supporting Comment

Added to bring to the attention of the user that a cable fault, even in a conduit system, may transferdetrimental heat that could damage a plastic fuel line.


Accept as modified.


Radial separation of conduit systems from gas and other lines that transport flammable material shall benot less than 300 mm (12 in) and Conduit should have sufficient separation from gas and other lines thattransport flammable material to permit the use of pipe maintenance equipment. Conduit shall not enterthe same manhole, handhole, or vault with gas or other lines that transport flammable material.



Negative: (0)

Abstention: (0)

New Text

CP3408


Submitter

Michael Dyer

Proposed Change

5. Ducts may be identified by color or equally spaced multiple colored stripes extruded in the exteriorsurface to indicate the types of cable contained or planned to be contained. The color shall complywith American Public Works Association (APWA) color code for the type of facility.



Red—Electrical Orange—Communication

Supporting Comment

The use of extruded red stripes or a solid red conduit has been used by numerous electric utilities for manyyears on medium- and high-voltage cables. This color marking is not recognized by the NESC so its use isunrestricted. This causes confusion and errors in identification. IEEE Std 1235, IEEE Guide for the Propertiesof Identifiable Jackets for Underground Power Cables and Ducts, provides performance requirements for thecolor fastness. APWA Guidance Position Statement concerning Permanent Buried Line Markingrecommends “Wherever practical, the outside covering of buried cable, pipe, duct, or conduit be colored orcolor marked in accordance with the APWA Uniform Color Code.”


Reject.


Wrong rule; identification is covered by other parts of the section.



Negative: (0)

Abstention: (0)

Revised Text

CP3442


Also Section: 3 Z535 references SC1











New Text

CP3436

Part: 3 Section: 32 323 E5

Submitter

Allen Clapp

Proposed Change

Add a new Rule 323E5 to address clearances of energized parts from penetrable ventilation openings.

5. Clearance of energized parts and accessible controls from penetrable ventilation openings

Where ventilation openings are not protected with louvers or baffles that limit the opportunity forpenetration from outside the vault by sticks or other objects, energized parts and controls that arenot either (a) enclosed or (b) shielded by guards shall be located so as to have a clearance from theoutside of the ventilation opening not less than that required by the safety clearance zone of Rule110A2 and Table 110-1.

Supporting Comment

This matches the requirements of Rule 110A2 for penetrable substation fences to penetrable ventilationopenings in vaults.

Some vaults are located on the downhill side of the basement floor in buildings and designed where one ormore walls or large sections of walls are covered by fence mesh panels to (a) allow ventilation fortransformers and (b) installation/replacement of equipment. This type of installation is often used in factoryenvironments or back-alley environments where aesthetics is not at a premium and little space is available.

Such enclosure systems have a good history, but should meet the same intrusion limitation requirements as asubstation if energized parts and controls are not enclosed or shielded from outside interference.


Accept as modified.

Add a new Rule 323E5 to address clearances of energized parts from penetrable ventilation openings.

5. Clearance of energized parts and controls from penetrable ventilation openings.

Where ventilation openings in an aboveground vault are not protected with louvers or baffles thatlimit the opportunity for penetration from outside the vault by sticks or other objects, energizedparts and controls that are not guarded shall be located so as to have a clearance from the outside ofthe ventilation opening not less than that required by the safety clearance zone of Rule 110A2 andTable 110-1.





Negative: (0)

Abstention: (0)

Revised Text

CP3409

Part: 3 Section: 32 323 Figure 323-2

Submitter

Michael Dyer

Proposed Change

Distance across the wheel load area: 600 mm (24 in) 508 mm (20 in).

Supporting Comment

This change harmonizes Figure 323-2 with ASTM C857 Figure 2.


Accept.


Change diagram in Figure 323-2 from 24 in to 20 in, and the lines in the picture should line up.



Negative: (0)

Abstention: (0)



New Text

CP3341


Submitter

Lawrence Slavin

Proposed Change

Add new Rule 341C, as follows:

341. Installation

A. General

...

B. Cable in manholes and vaults

1. Supports

...

2. Clearance

a. Adequate working space shall be provided in accordance with Rule 323B.

b. Between supply and communications facilities (cable, equipment, or both):

(1) Where cable, equipment, or both are to be installed in a joint-use manhole or vault, itshall be done only with the concurrence of all parties concerned.

(2) Supply and communication cables should be racked from separate walls. Crossingsshould be avoided.

(3) Where supply and communication cables must be racked from the same wall, thesupply cables should be racked below the communication cables.

(4) Supply and communications facilities shall be installed to permit access to eitherwithout moving the other.

(5) Clearances shall be not less than those specified in Table 341-1.

3. Identification

a. General

(1) Cables shall be permanently identified by tags or otherwise at each manhole or otheraccess opening of the conduit system.



EXCEPTION: This requirement does not apply where the position of a cable, inconjunction with diagrams or maps supplied to workers, gives sufficientidentification.

(2) All identification shall be of a corrosion-resistant material suitable for theenvironment.

(3) All identification shall be of such quality and located so as to be readable withauxiliary lighting.

b. Joint-use manholes and vaults

Cables in a manhole or vault that are operated and maintained by different utilities shall bepermanently identified by markings or tags denoting the utility name and type of cableuse.

C. Joint-use handholes

1. Where cables of different utilities are to be installed in a joint-use handhole, it shall be doneonly with the concurrence of all parties concerned.

2. Cables in a handhole that are operated and maintained by different utilities shall bepermanently identified by markings or tags denoting the utility name and type of cable use.

3. Joint-use handholes containing both communication and supply cables shall contain noequipment, connections, or splices.

NOTE: It is not recommended that joint-use handholes be used or routinely accessed formaintenance or other such purposes.

4. Where communication and supply cables are both to be installed in a joint-use handhole, thesystems shall comply with the requirements of Rule 354 for random separation.

Supporting Comment

Present Rule 341B addresses cables in manholes and vaults. However, in some circumstances it may beadvantageous to route cables of different utilities, including communication and supply conductors, throughcommon (joint-use) handhole, for which there are no explicit rules or guidelines. The proposed new Rule341C addresses this case.

It is not intended to encourage, or possibly even allow, such a joint-use handhole to be used for routinemaintenance purposes. The proximity of the cables discourages such usage. The handhole should thereforenot contain any equipment, connections, or splices. In general, the handhole may be used as a means oftemporarily accessing available ducts for the purpose of installing a new cable along the conduit route, and/or to be routed out a separate port of the handhole to externally located equipment. Thus, the handhole maybe considered to be an extension of a joint-use trench, for which the rules for random separation betweencommunication and supply conductors would be applicable, as appropriate.


Reject.




The majority of handholes have splices. Handholes are used for splicing and are not joint use.


Affirmative: (19) Amrhyn, Austin, Bleakley, Bowmer, Cooke, Dyer, Gaunt, Guinn, Gunter, Hiu, Miller,Pehosh, Pool, Pregler, Pristach, Robeson, Spence, Szendre, Vencus

Negative: (1) Slavin

Abstention: (0)

Explanation of Vote

Slavin: (Negative) See original supporting comments.

New Text

CP3089

Submitter

Mickey Gunter

Proposed Change

Revise Section 35 title and add NOTE as follows:

Section 35.Direct-buried cable and cable in duct not part of a conduit system

NOTE: The term duct or ducts as used in this section refers to duct(s) not part of a conduit system.

Supporting Comment

Since this section contains rules concerning cable in duct not part of a conduit system, it is appropriate tochange the title and add the NOTE to reflect this change.


Accept.



Negative: (0)



Abstention: (0)

New Text

CP3039


Submitter

Ewell Robeson

Proposed Change

Add the following recommendation to Rule 350F.

RECOMMENDATION: If color coding is used as an additional method of identifying cable, theAmerican Public Works Association Uniform Color Code for marking underground utility lines isrecommended.

Supporting Comment

Many utilities are using color as an additional identification of their cables. The color is used on the outerjacket of the cable and/or on the surface of conduits.

“Locate” companies adopted the American Public Works Association Uniform Color Code many years agofor marking the location of underground utilities in areas where construction is to take place. Therefore theentire utility industry is knowledgeable of the color code.

Because there is no “official” code requirement for a given electrical or communication utility to use theAmerican Public Works Association Uniform Color Code, stories abound about contractors using red stripe“flex” conduit to install communication lines, gas lines, water lines, etc., because that is the only conduitreadily available at local supply centers. There are also stories about communications companies using redstripes on the outer jacket of their cables in hopes that it may deter others from cutting their cable.


Accept.



Negative: (0)

Abstention: (0)



New Text

CP3402


Submitter

Michael Dyer

Proposed Change

EXCEPTION 3: Alternate marking.

Three (3) equally spaced extruded colored stripes around the outer circumference of the jacket, or asolid colored jacket. The color shall comply with American Public Works Association (APWA) colorcode for the type of facility.

Red—Electrical Orange—Communication

Supporting Comment

The use of extruded red stripes or a solid red jacket has been used by numerous electric utilities for manyyears on medium- and high-voltage cables. This color marking is not recognized by the NESC so its use isunrestricted. This causes confusion and errors in identification. IEEE Std 1235, IEEE Guide for theProperties of Identifiable Jackets for Underground Power Cables and Ducts, provides performancerequirements for the color fastness. APWA Guidance Position Statement concerning Permanent Buried LineMarking recommends “Wherever practical, the outside covering of buried cable, pipe, duct, or conduit becolored or color marked in accordance with the APWA Uniform Color Code.”


Reject.


See Subcommittee action on CP3039.


Affirmative: (19) Amrhyn, Austin, Bleakley, Bowmer, Cooke, Gaunt, Guinn, Gunter, Hiu, Miller, Pehosh,Pool, Pregler, Pristach, Robeson, Slavin, Spence, Szendre, Vencus

Negative: (1) Dyer

Abstention: (0)



Explanation of Vote

Dyer: (Negative) Acceptance of this proposal would have specified an alternate marking method thataddresses the limited visibility of the present marking requirement. Three extruded colored stripes or a solidcolored jacket complying with ANSI C53.1 and American Public Works Association are visible from anyangle whereas the jacket surface marking in the printed line is only visible when directly viewed.Permanency has been given as the major reason for rejection, jacket color material complying with IEEE Std1235 provides a guide for performance, whereas there is no guide for the performance of jacket surfaceprinting. This change proposal also specifically lists the colors for supply and communication, whereasCP3039 that was accepted, only references American Public Works Association Uniform color code.

Revised Text

CP3171

Part: 3 Section: 35 350 G

Also Part: 3 Section: 32 NOTE 2

Submitter

David Marne

Proposed Change

Revise NOTE 2 to Section 32 as follows:

NOTE 2: For supply and communication cables installed in a single duct that is not part of a conduitsystem: see Rule 350G.

Revise Rule 350G as follows:

G. The rules in this section shall apply to direct-buried supply and communication cables installed induct that is not part of a conduit system.

Supporting Comment

The wording in NOTE 2 to Section 32 and Rule 350G should be updated for consistency between the twolocations.


Accept.



Negative: (0)



Abstention: (0)

Revised Text

CP3172


Submitter

David Marne

Proposed Change

Revise Rule 350G as follows:

G. The rules in this section shall apply to direct-buried supply and communication cables installed induct that is not part of a conduit system. The burial depths in Rule 352D2 are for direct-buriedcables that are not installed in duct. The type of duct or other mechanical protection used must beconsidered when determining the amount of supplemental protection for lesser burial depths.

Supporting Comment

There is confusion as to whether the “duct that is not part of a conduit system” must be buried the same depthas direct-buried cables not in a duct. When reviewing the existing Code rules, one interpretation of the burialdepth required for a 15 kV URD cable installed in duct not part of a conduit system (no matter what type ofduct) is that a 30 in burial depth is required. Another interpretation is that the duct may provide supplementalprotection per Rule 352D2b, and less than a 30 in burial depth from Table 352-1 may be used. The proposedchange clarifies that the duct may be considered supplemental protection depending on the type of duct used.







Negative: (0)

Abstention: (0)



Revised Text

CP3370


Also Part: 3 Section: 32 NOTE 2

Definitions

Submitter

Allen Clapp

Proposed Change

Revise NOTE 2 under the heading of Section 32 and Rule 350G as follows to appropriately reflectrequirements applicable to single-duct conduit.

Section 32

NOTE 2: For direct-buried flexible conduits cables installed in a single duct not part of a conduit system, thespecifications of Section 35 are required to apply, instead of the requirements of Section 32: see Rule 350G.

G. The rules in this sectionSection 35 shall apply to direct-buried supply and communication cablesinstalled in duct that is not part of a conduit systemdirect-buried flexible conduits.


rigid conduit. Rigid conduit may be composed of metal, PVC, concrete, or other materials. Rigid conduitmay have some flexure, but is not considered as flexible conduit. If buried, rigid conduit is installed insections in prepared trenches.

flexible conduit. Flexible conduit is intentionally manufactured to be more flexible than rigid conduit, inorder to make curved runs. If buried, flexible conduit is generally installed in the same manner as rigidconduit.

direct-buried flexible conduit. Direct-buried flexible conduit is designed to be plowed into the ground inthe same manner as direct-buried cable. At the time of plowing, it may contain one or more cables or it maybe empty.

Supporting Comment

These definitions allow Sections 32 and 35 to appropriately distinguish between conduits for purposes ofapplication of those sections.

The previous changes to Sections 32 and 35 have been greatly misunderstood and, in some cases, have beenmisapplied. This is partly due to the definition of conduit system. It is also due to colloquial terms in use invarious areas. For example, some utilities refer to the area under and inside a pad used for a pad-mountedtransformer to be a vault; others do not. This is particularly the case when a pad-mounted transformer sitsupon a fiber-reinforced polymer or concrete structure that keeps soil away from cables entering under atransformer, such structure being mostly or partly aboveground and not large enough for a human to fullyenter.



There is no rationale of which I am aware to force single-duct conduit that is hand laid in a trench to meet therequirements of Section 35. It makes no practical difference if a conduit from a pole to a pad-mountedtransformer travels first to a handhole or manhole—or not. The present language of Sections 32 and 35 wouldapparently make Section 35 apply if the conduit went only from pole to transformer or only betweentransformers—which makes no sense to me. Either the present wording is not appropriate or the presentrequirement is not appropriate.

I agree that the requirements of Section 35 should be required for flexible conduits that are plowed into theground in a manner similar to direct-buried cable.

These changes will apply the correct requirements to the correct cable installations.

Further, I have to add that, at the time of the original codification of this requirement, the language wasdifferent. As the past chair of the NESC, I was a voting member of the main committee at that time. When Iread the original language, it looked to me like the intent was to allow, not require, Section 35 to apply. Iagreed with that and voted affirmative. It was only when preparing the NESC Handbook that I learned fromthe SC7 Chair that the intent was to require all single-duct conduit to meet Section 35. Had the wording ofthe original proposal made that obvious, I and others would have not only voted in the negative, but wouldhave campaigned against the proposal. I have talked to enough of the voting members of that time to believethat it is absolutely certain that this change would not have passed if the original language had been clearenough to state its real intent. It is time to bring these requirements back to practical, reasonable requirementsthat do not apply to inappropriate items.

One of the things that the present requirement did was to require many the gas and electric utilities that usejoint trenches to increase the separation between the gas lines and the electric conduits—without any data thatindicates any problem with their normal standards. There are thousands of miles of joint gas and electrictrench with one electric conduit that do not meet the changed requirement and should not meet it.

This proposal will bring back good practice for rigid conduit, while keeping the application of Section 35 forthe flexible duct that is plowed in similar to direct-buried cable.


Reject.


The present rule is adequate. The Code should not dictate which type of duct to use.



Negative: (0)

Abstention: (0)



New Text

CP3445


Submitter

Subcommittee 7

Proposed Change

G. The rules in this section shall apply to direct-buried supply and communication cables installed induct that is not part of a conduit system.

RECOMMENDATION: If color coding is used as a method of identifying the duct, the AmericanPublic Works Association Uniform Color Code for marking underground utility lines isrecommended.


Accept.



Negative: (0)

Abstention: (0)

New Text

CP3094


Submitter

Mickey Gunter

Proposed Change


A. Trenching

1. Direct-buried cable



The bottom of the trench receiving direct-buried cable should be relatively smooth,undisturbed earth; well-tamped earth; or sand. When excavation is in rock or rocky soils, thecable should be laid on a protective layer of well-tamped backfill. Backfill within 100 mm(4 in) of the cable should be free of materials that may damage the cable. Backfill should beadequately compacted. Machine compaction should not be used within 150 mm (6 in) of thecable.

2. Cable in duct

For cable installed in a duct, the bottom of the trench should be in undisturbed, tamped, orrelatively smooth earth. Where the excavation is in rock, the duct should be laid on a protectivelayer of clean tamped backfill. All backfill should be free of materials that may damage theduct system.

Supporting Comment

Since cable in duct offers some protection to the cable, the installation requirements for cable in duct shouldbe similar to Rule 321A.


Accept as modified.


Delete the word “system” at the end of the last sentence in proposed Rule 352A2.


A. Trenching

1. Direct-buried cable

The bottom of the trench receiving direct-buried cable should be relatively smooth,undisturbed earth; well-tamped earth; or sand. When excavation is in rock or rocky soils, thecable should be laid on a protective layer of well-tamped backfill. Backfill within 100 mm(4 in) of the cable should be free of materials that may damage the cable. Backfill should beadequately compacted. Machine compaction should not be used within 150 mm (6 in) of thecable.

2. Cable in duct

For cable installed in a duct, the bottom of the trench should be in undisturbed, tamped, orrelatively smooth earth. Where the excavation is in rock, the duct should be laid on a protectivelayer of clean tamped backfill. All backfill should be free of materials that may damage theduct.





Negative: (0)

Abstention: (0)

New Text

CP3091


Submitter

Mickey Gunter

Proposed Change


D. Depth of burial

1. The distance between the top of a cable or duct and the surface under which it is installed(depth of burial) shall be sufficient to protect the cable or duct from damage imposed byexpected surface usage. If the duct is installed with 36 in of cover or greater, then no impactloading is required. If the duct has less than 36 in of cover, then Rule 323A applies.

2. Burial depths as indicated in Table 352-1 are considered adequate for supply cables, orconductors, or duct except as noted in a, b, or c following:

a. In areas where frost conditions could damage cables or ducts, greater burial depths thanindicated above may be desirable.

b. Lesser depths than indicated above may be used where supplemental protection isprovided. The supplemental protection should be sufficient to protect the cable or ductfrom damage imposed by expected surface usage.

EXCEPTION: If the cable is installed in duct that is made of material to protect the cablefrom expected surface usage, then additional supplemental protection is not required.

c. Where the surface under which a cable or duct is to be installed is not to final grade, thecable or duct should be placed so as to meet or exceed the requirements indicated above,both at the time of installation and subsequent thereto.

Supporting Comment

To clarify the burial depth when cable is installed in duct and that cable in appropriate type duct may not needsupplemental protection.


Accept as modified.




D. Depth of burial

1. The distance between the top of a cable or duct and the surface under which it is installed(depth of burial) shall be sufficient to protect the cable or duct from damage imposed byexpected surface usage.

2. Burial depths as indicated in Table 352-1 are considered adequate for supply cables, orconductors, or duct except as noted in a, b, or c following:

a. In areas where frost conditions could damage cables or ducts, greater burial depths thanindicated above may be desirable.

b. Lesser depths than indicated above may be used where supplemental mechanicalprotection is provided. The supplemental mechanical protection should shall be sufficientto protect the cable or duct from damage imposed by expected surface usage.

If the cable is installed in duct, additional supplemental mechanical protection is notrequired if the duct is of sufficient strength to protect the cable from expected surfaceusage.

c. Where the surface under which a cable or duct is to be installed is not to final grade, thecable or duct should be placed so as to meet or exceed the requirements indicated above,both at the time of installation and subsequent thereto.



Negative: (0)

Abstention: (0)

Revised Text

CP3173

Part: 3 Section: 35 352 D2b

Submitter

David Marne

Proposed Change

Revise Rule 352D2b as follows:



b. Lesser depths than indicated above may be used where supplemental mechanical protection isprovided. The supplemental mechanical protection should be sufficient to protect the cable fromdamage imposed by expected surface usage

Supporting Comment

Add the word “mechanical” to be consistent with other parts of the Code such as Rule 351C1. Nowhere inthe NESC is a buried warning tape required. Without the wording “mechanical protection” it is possible tointerpret the existing rule as allowing a warning tape to provide the supplemental protection. Adding the word“mechanical” removes any confusion.







Negative: (0)

Abstention: (0)

Revised Text

CP3095


Submitter

Mickey Gunter

Proposed Change

Revise Table 352-1 title as follows:

Table 352-1—Supply cable, or conductor, or duct burial depth(See Rule 352D.)

Supporting Comment

Adding duct to the title will clarify that burial depth for duct is included in this Table 352-1.




Accept.



Negative: (0)

Abstention: (0)

New Text

CP3090


Submitter

Mickey Gunter

Proposed Change


2. Radial separation of supply and communications cables or conductors from steam lines, gas, andother lines that transport flammable material shall be not less than 300 mm (12 in) and shall meetRule 353.

EXCEPTION: For supply cables operating at not more than 300 V between conductors installed induct, the radial separation may be less than required by Rule 354A2, provided the duct material isdesigned or supplemental protection is provided to limit the likelihood of detrimental heat transferto steam lines, gas, and other lines that transport flammable material due to a cable fault.

Supporting Comment

Because of construction practices today, sometimes it is difficult to get 12 in radial separation between adirect-buried supply service cable and gas lines. This CP offers a compromise and alternative for low-voltagesupply cables installed in duct that should limit the likelihood of a cable fault damaging a gas line.


Accept as modified.


Accept pending test results.




2. Radial separation of supply and communications cables or conductors from steam lines, gas, andother lines that transport flammable material shall be not less than 300 mm (12 in) and shall meetRule 353.

EXCEPTION: For supply cables operating at not more than 300 V between conductors installed induct, the radial separation may be less than required by Rule 354A2, provided the duct material isdesigned or supplemental mechanical protection is provided to limit the likelihood of detrimentalheat transfer to steam lines, gas, and other lines that transport flammable material due to a cablefault.



Negative: (0)

Abstention: (0)

Revised Text

CP3040


Submitter

Ewell Robeson

Proposed Change


D. Supply and communication cables or conductors

Supply cables or conductors and communication cables or conductors may be buried together at thesame depth, with no deliberate separation between facilities, provided all parties involved are inagreement and the applicable rules in 354D1 are met and either Rules 354D2, or 354D3, or 354D4is met.

Supporting Comment

Since Rule 354D4 is a random-laid rule, it must also meet the requirements of Rule 354D, i.e., agreement ofall parties, grounding and bonding requirements, etc. Rule 354D4 appears to have been inadvertently omittedfrom Rule 354D when it was added in 1993.









Negative: (0)

Abstention: (0)

Revised Text

CP3323


Submitter

James T. Collins

Proposed Change


D. Supply and communication cables or conductors

Supply cables or conductors and communication cables or conductors may be buried together at thesame depth, with no deliberate separation between facilities, provided all parties involved are inagreement and the applicable rules in 354D1 are met and either Rule 354D2, or 354D3, or 354D4 ismet.

Supporting Comment

Since Rule 354D4 is a random separation rule, it must also meet the requirements of Rule 354D, i.e.,agreement of all parties, grounding and bonding requirements, etc. Rule 354D4 appears to have beeninadvertently omitted from Rule 354D when it was added in 1993.


Accept.



Negative: (0)



Abstention: (0)

Revised Text

CP3003

Part: 3 Section: 35 354 D3a

Submitter

Richard Vencus

Proposed Change

Revise 354D3a (as written).

Each phase conductor of a multi-grounded supply system operating above 300 V to ground andhaving an overall insulating jacket shall have an effectively grounded copper concentric conductormeeting all of the following requirements:

a. A conductance of not less than one half that of the phase conductor.

b. ...

Revise to include an EXCEPTION to allow for the use of three-phase cables. The EXCEPTION could read:

EXCEPTION: (1) Phase conductors used in three-phase cables supplying three-phase loadscan have an effectively grounded copper concentric conductor which is not less than one thirdof the conductivity of the phase conductors. (2) Three-phase cables which do not have acopper concentric conductor per phase at least one half that of the phase conductor cansupplement the concentric conductor with a separate bare copper ground conductor. Thecombined phase copper concentric conductor and the separate bare copper ground conductorshall be equivalent to not less than one half of the phase conductor.

Supporting Comment

The above does not recognize that each phase conductor of a multi-phase cable with an insulating jacket canhave an effectively grounded copper concentric conductor that has less than one half the conductivity perphase (typically one third the conductivity per phase). Most three-phase cables have a copper concentricconductor which is nominally one third of the phase conductor conductivity.

ANSI/ICEA S-94-649-2004 “Standard for Concentric Neutral Cables Rated 5 through 46 kV” identifies theappropriate circular mil area for concentric neutral conductors. In this standard, there is a full neutral (Table6-2) for single phase systems and a one-third neutral (Table 6-3) concentric conductor table for three-phasesystems.


Reject.




Insufficient supporting data.


Affirmative: (19) Amrhyn, Austin, Bleakley, Bowmer, Cooke, Dyer, Gaunt, Guinn, Gunter, Hiu, Miller,Pehosh, Pool, Pregler, Pristach, Robeson, Slavin, Spence, Szendre

Negative: (1) Vencus

Abstention: (0)

Explanation of Vote

Vencus: (Negative) Rule 354D3a. The requirement that each phase conductor of a three-phase cable have aconcentric neutral equivalent to 1/2 the conductivity of the phase conductor does not allow for the use of 1/3concentric cables, which are typically specified and commercially available three-phase cables. Althoughseparate grounding conductors are allowed under Rule 92B3, where these separate grounding conductors canbe used to meet the requirement of Rule 354D3a, this is not clear nor referenced in Rule 354D3a. In additionto this, the available fault current at the point of installation (which is highly variable) and the size of theprotective device protecting the cable are as relevant to the clearing time as the difference between a 1/3 or1/2 concentric neutral. The clearing time should be calculated for all installations involving random lay ifdamage to adjacent utilities is a concern. This calculation should consider the available fault current, the sizeand type of protective device, the return path impedance (including the concentric neutral), and theanticipated fault impedance. Requiring a 1/2 neutral is an unneeded restriction and also provides a false senseof security if anyone does not verify the fault clearing time based on the conditions present at the point ofinstallation.

New Text

CP3093


Submitter

Mickey Gunter

Proposed Change

Add new Rule 355 as follows:

355. Additional rules for cable in duct not part of a conduit system

1. Duct material shall be corrosion-resistant and suitable for the intended environment.

2. Duct materials shall be designed or installed so that a cable fault in one duct would not damage theduct to such an extent that it would cause damage to cables in adjacent ducts.



3. The internal surface of the duct shall be free of sharp edges or burrs, which could damage supplycable.

4. Ducts shall be joined in a manner so as to limit solid matter from entering the duct line. Joints shallform a sufficiently continuous smooth interior surface between joining duct sections so that supplycable will not be damaged when pulled past the joint.

5. Duct installed through a building wall shall have internal and external seals intended to limit thelikelihood of the entrance of gas into the building. The use of seals may be supplemented by gas-venting devices in order to limit the building up of positive gas pressures in the conduit.

Supporting Comment

Since the use of duct is being added to Section 35, it is appropriate to have additional rules concerning theuse of duct for cable in duct not part of a conduit system.


Accept as modified.

Add new Rule 355 as follows:

355. Additional rules for duct not part of a conduit system.

1. Duct material shall be corrosion-resistant and suitable for the intended environment.

2. The internal surface of the duct shall be free of sharp edges or burrs, which could damage supplycable.

3. Ducts shall be joined in a manner so as to limit solid matter from entering the duct line. Joints shallform a sufficiently continuous smooth interior surface between joining duct sections so that supplycable will not be damaged when pulled past the joint.

4. Duct installed through a building wall shall have internal and external seals intended to limit thelikelihood of the entrance of gas into the building. The use of seals may be supplemented by gas-venting devices in order to limit the build up of positive gas pressures in the conduit.



Negative: (0)

Abstention: (0)

Revised Text

CP3174




Submitter

David Marne

Proposed Change


D. Pad-mounted equipment, pedestals, and other aboveground enclosures, should be located not lessthan 1.2 m (4 ft) from fire hydrants.

EXCEPTION 1: Where conditions do not permit a clearance of 1.2 m (4 ft), a clearance of not lessthan 900 mm (3 ft) is allowed.

EXCEPTION 2: Clearances in Rule 380D may be reduced by agreement with the local fireauthority and the equipment owner.

Supporting Comment

Add EXCEPTION 2 for consistency with Rule 231A.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3430


Also Part: 2 Section: 23 231 A SC4



New Text

CP3410

Part: 3 Section: 38 380 E



Submitter

Michael Dyer

Proposed Change

The location of pad-mounted equipment shall utilize one or more of the following methods to minimizefire hazards. The method to be applied shall be according to the degree of the fire hazard. Recognizedmethods are the use of less flammable liquids, space separation, fire-resistant barriers.

Supporting Comment

The fire hazard issue is address in Rule 152A2, but this rule applies to electric supply stations. Adding similarlanguage to Rule 380 provides notice of the hazard and methods to be applied to Section 38.


Reject.


Language is unclear and vague.


Affirmative: (19) Amrhyn, Austin, Bleakley, Bowmer, Cooke, Gaunt, Guinn, Gunter, Hiu, Miller, Pehosh,Pool, Pregler, Pristach, Robeson, Slavin, Spence, Szendre, Vencus

Negative: (1) Dyer

Abstention: (0)

Explanation of Vote

Dyer: (Negative) Acceptance of this proposal would have added language to Section 38 similar to Section 15,identifying recognized methods to minimize fire hazard exposure between pad-mounted equipment andstructures. This rule would assist utilities in justifying the location of pad-mounted equipment. The reason forrejection indicated nothing additional provided. If this is true, what purpose does it serve in Rule 152A2?

Revised Text

CP3041


Submitter

Ewell Robeson



Proposed Change


C. Bonding should be provided between all aboveground metallic power supply and communicationsapparatus (pedestals, terminals, apparatus cases, transformer cases, etc.) that are separated by adistance of 1.8 m (6 ft) or less. For the purpose of this rule, pole grounds are not considered anaboveground metallic power apparatus and therefore not required to be bonded to thecommunication apparatus.

Supporting Comment

Replace the word “power” with “supply,” which is the appropriate terminology as used in the Code.




See CP3324.



Negative: (0)

Abstention: (0)

Revised Text

CP3175


Submitter

David Marne

Proposed Change


C. Bonding should be provided between all aboveground metallic power and communicationsapparatus (pedestals, terminals, apparatus cases, transformer cases, etc.) enclosures that areseparated by a distance of 1.8 m (6 ft) or less. For the purpose of this rule, pole grounds are notconsidered an aboveground metallic power apparatus and therefore not required to be bonded to thecommunication apparatus.



Supporting Comment

The bonding requirement should address metallic enclosures, not the metallic parts contained in theenclosure. Currently there is confusion related to bonding when a fiberglass enclosure houses metallicapparatus inside. This change removes that confusion.


Accept as modified.


C. Bonding should be provided between all aboveground metallic power and communicationsapparatus (pedestals, terminals, apparatus cases, transformer cases, etc.) enclosures that areseparated by a distance of 1.8 m (6 ft) or less. For the purpose of this rule, pole grounds are notconsidered an aboveground metallic power apparatus and therefore not required to be bonded to thecommunication apparatus enclosure.


Affirmative: (13) Austin, Bleakley, Gaunt, Guinn, Gunter, Miller, Pehosh, Pregler, Pristach, Robeson,Spence, Szendre, Vencus

Negative: (4) Bowmer, Cooke, Dyer, Korman

Abstention: (2) Hiu, Slavin

Explanation of Vote

Bowmer: (Negative) Consider the second sentence should be deleted. Prefer that bonding should be providedbetween all power and telecommunications that are separated by 6 ft or less. (See supporting comments toCP3352.)

Cooke: (Negative): The negative was cast due to the risk of a difference-of-potential occurring between thebonded components and the pole ground system.

Dyer: (Negative) Accepting this proposal retains the exception of the pole ground. The issue addressed bythis rule is the hazard of a potential difference between adjacent ground electrodes that can be simultaneouslycontacted. In this respect a pole ground has the same hazard.

Hiu: (Abstention) I abstained due to the uncertainty of the step and touch potential. No “expert” has providedconvincing evidence for me to support CP3352 and CP3175. Further research is needed.

Korman: (Negative) See supporting comments to CP3360.

Slavin: (Abstention) The appropriate practice for bonding (or not) between power and communicationsapparatus or enclosures, to help ensure safety for employees and the public, is apparently a non-trivial issueand requires further investigation.



Revised Text

CP3324


Submitter

James T. Collins

Proposed Change


C. Bonding should be provided between all aboveground metallic power supply and communicationsapparatus (pedestals, terminals, apparatus cases, transformer cases, etc.) that are separated by adistance of 1.8 m (6 ft) or less. For the purpose of this rule, pole grounds are not considered anaboveground metallic power supply apparatus and therefore not required to be bonded to thecommunication apparatus

Supporting Comment

Replace the word “power” with “supply,” which is the appropriate terminology as used in the Code.


Accept.



Negative: (0)

Abstention: (0)

Deleted Text

CP3352


Submitter

Trevor Bowmer



Proposed Change


C. Bonding should be provided between all aboveground metallic power and communicationsapparatus (pedestals, terminals, apparatus case, transformer cases, etc.) that are separated by adistance of 1.8 m (6 ft) or less. For the purpose of this rule, pole grounds are not considered anaboveground metallic power apparatus and therefore not required to be bonded to thecommunications apparatus.

Supporting Comment

1. The presence of a bond between the pedestal case and a pole ground that is within 6 ft is a useful procedurethat can help reduce the hazard exposure resulting from a potential difference between pole ground and anadjacent pedestal or closure. The installation of such a bond should be considered where practical and where:

— the process of bonding the pieces does not reduce the effective grounding of the system, — the bonding wire is adequately buried or physically protected.

2. Although nothing in the rule prohibits the bonding practice, several power companies have cited thissentence to support (a) the prohibition of placing such a bond, and (b) request a connection fee and annualpayment for the bond. These are both inappropriate uses of this rule.

3. The pedestal being part of direct-buried plant would be covered by NESC Rule 350F that states:

“Bonding should be provided between all aboveground metallic power and communications apparatus(pedestals, terminals, apparatus cases, transformer cases, etc.) that are separated by a distance of 1.8 m (6 ft)or less.”

Therefore a bond should be made between the pedestal and MGN coming down the pole.

4) NESC Rule 99A (additional requirements for communication apparatus) requires:

“…. the company to ground their plant to an acceptable ground electrode, which in the case of direct-buriedplant would be grounding electrode conductors or grounding electrode conductors’ metal enclosure….”

The pole ground is a convenient attachable point to the main grounding electrode conductor in the area. Thecommunications plant is intended to be as much a part of the MGN area as is the supply company. Clearlythis is the intent of the words in NESC Rule 99A where the first choice ground becomes a part of the MGNgrid, and only if such a choice is not available can an alternate grounding electrode be used.

5) During the investigation, some concerns were relayed that current may regularly travel down these polegrounds and damage communications equipment. However, Rule 92D (Current in grounding conductor)states:

“….Ground connection points shall be so arranged that under normal circumstances there will be noobjectionable flow of current over the grounding conductor....”

This implies that there should or shall be no continuous current flow over a ground (or earth) connection. TheNESC calls it “objectionable current.” The ground-to-earth connection is designed to be for the purpose ofstabilization and protection; rather than as part of any return circuit. If, as claimed by some power companies,electric current can regularly flow down the ground connection from certain transformers and powerapparatus, then it may well be appropriate that the communications company should not bond to grounds



associated with such power circuits. If the sentence is deleted from Rule 384C (as requested by this changeproposal), the power supply company and communications company will fully retain their flexibility todesign safe and reliable plant. This need for, and expectation of, cooperation between power andcommunications companies is also intrinsic throughout the NESC, for example:

Rule 212: “…Rules covering supply-line influence and communication-line susceptiveness have not beendetailed in this Code. Cooperative procedures are recommended in the control of voltages induced fromproximate facilities.”

Rule 222: “…. The choice between joint use of structures and separate lines shall be determined throughcooperative consideration of all factors involved…”


Reject.


Bonding to the pedestal creates a greater hazard. Bonding of pedestals creates the same effect as touchpotential on a fault current passing through the pole ground.


Affirmative: (15) Austin, Bleakley, Cooke, Gaunt, Guinn, Gunter, Miller, Pehosh, Pregler, Pristach,Robeson, Slavin, Spence, Szendre, Vencus

Negative: (3) Bowmer, Dyer, Korman

Abstention: (1) Hiu

Explanation of Vote

Bowmer: (Negative) (See supporting comments provided to CP3352.) Bonding between supply andcommunications plant within 6 ft should be bonded.

Dyer: (Negative) This proposal removes the exception of the pole ground. The issue addressed by this rule isthe hazard of a potential difference between adjacent ground electrodes that can be simultaneously contacted.In this respect a pole ground has the same hazard. The reason given for rejection is the possible hazard whichcould occur during a ground fault. These same conditions exist between pad-mounted devices.

Hiu: (Abstention) I abstained due to the uncertainty of the step and touch potential. No “expert” has providedconvincing evidence for me to support CP3352 and CP3175. Further research is needed.

Korman: (Negative) See supporting comments to CP3360.

Revised Text

CP3360




Submitter

Percy E. Pool

Proposed Change

Change Rule 384C to read:

Bonding should shall be provided between all aboveground metallic power and communicationsapparatus (pedestals, terminals, apparatus cases, transformer cases, etc.) that are separated by a distanceof 1.8 m (6 ft) or less. For the purpose of this rule, pole grounds are not considered an abovegroundmetallic power apparatus and therefore not required to be bonded to the communication apparatus.

Bonding shall also be provided between an aboveground metallic power and communications apparatusand a grounding conductor (such as pole grounds) that are separated by a distance of 1.8 m (6 ft) or less.

Supporting Comment

This CP proposes to delete the second sentence. Also, it extends the requirement to include pole grounds. Itfurther makes the requirement mandatory.

A vertical pole ground within 1.8 m of an aboveground metallic apparatus presents the same hazard as twoaboveground metallic apparatus separated by less than 1.8 m.

Aboveground communications apparatus (such as pedestals and housings) are typically grounded. Thus theyhave a grounding electrode (ground rod). Similarly, power apparatus (such as transformer cases) are alsoconnected to a grounding electrode. The vertical pole ground also terminates at a grounding electrode. If anyof these are within 1.8 m of each other they must be bonded together in order to minimize a voltage differencebetween them. Common bonding is necessary for personnel safety, thus the change from “should” to “shall.”

Common bonding between communications and power apparatus, and including pole grounds helps to reducepotential differences between metallic parts that could be touched simultaneously.

The original intent of this rule was to limit the possibility of technicians (both power and communications)or the general public to contact two metallic surfaces that may be at different voltage levels and thus receivean electrical shock.

The intent of this CP is to require bonding not only between the apparatus cases (either power orcommunications) themselves when located within 1.8 m of each other but also between an apparatus case anda grounding conductor (such as a vertical pole ground) located within 1.8 m.


Reject.


Bonding to the pedestal creates a greater hazard. Bonding of pedestals creates the same effect as touchpotential on a fault current passing through the pole ground.




Affirmative: (17) Amrhyn, Austin, Bleakley, Cooke, Dyer, Gaunt, Guinn, Gunter, Hiu, Miller, Pehosh,Pregler, Pristach, Robeson, Spence, Szendre, Vencus

Negative: (3) Bowmer, Korman, Slavin

Abstention: (0)

Explanation of Vote

Bowmer: (Negative) (See supporting comments provided to CP3352.) Bonding between supply andcommunications plant with 6 ft should be bonded.

Korman: (Negative) Extend the requirements to include pole grounds. Also, make the requirementsmandatory.

A vertical pole ground within 1.8 m of an aboveground metallic apparatus presents the same hazard as twoaboveground metallic apparatus separated by less than 1.8 m.

Aboveground communications apparatus (such as pedestals and housings) are typically grounded. Thus theyhave a grounding electrode (ground rod). Similarly, power apparatus (such as transformer cases) are alsoconnected to a grounding electrode. The vertical pole ground also terminates at a grounding electrode. If anyof these are within 1.8 m of each other they must be bonded together in order to minimize a voltage differencebetween them. Common bonding is necessary for personnel safety, thus the change from “should” to “shall.”

Common bonding between communications and power apparatus, and including pole grounds helps to reducepotential differences between metallic parts that could be touched simultaneously.

The original intent of this rule was to limit the possibility of technicians (both power and communications)or the general public to contact two metallic surfaces that may be at different voltage levels and thus receivean electrical shock.

Slavin: (Negative) Although the appropriate practice for bonding (or not) between power andcommunications apparatus or enclosures apparently requires further investigation, it is appropriate that theproper rule be presented as a mandatory “shall” requirement, and not as a present “should” requirement.



Part 4. Rules for the Operation of Electric Supply and Communication Lines and Equipment

Revised Text

CP3334

Part: 4

Submitter

James T. Collins

Proposed Change

Change the header of each page as follows:

Part 4: Work Rules for the Operation of Electric Lines

Supporting Comment

The existing header on each page does not adequately cover the scope of Part 4 as described in Rule 401. Theexisting header only addresses electric lines whereas the scope specifies electric supply and communicationsystems. Changing this header would include both generation and communication systems.


Accept as modified.

Change the header of each page and title as follows:

Part 4: Work Rules for the Operation of Electric Lines

Work Rules for the Operation of Electric Supply and Communications Lines and Equipment



Negative: (0)




Revised Text

CP3479

Part: 4 Section: 40 402, 410, 411, 420

Submitter

Subcommittee 8

Proposed Change

Editorial Work Group recommendations:

402. Referenced sections

The Introduction (Section 1), Definitions (Section 2), References (Section 3), and Grounding methods(Section 9) of this Code shall apply to the requirements of Part 4.

The standards listed in Section 3 (References) shall be used with Part 4 where applicable.

NOTE: After ANSI C2-1973 [B6] was originally approved, 30 June 1972, the U.S. Occupational Safetyand Health Administration (OSHA) issued 29 CFR 1926, Subpart V [B62], applying to employee safetyin construction. The differences between this document and the editions of the NESC through the 1993Edition were noted in footnotes to the text of Part 4.

In 1989, OSHA published in the Federal Register [01/31/89], vol. 54, no. 19, pp. 4974–5024 inclusive,Docket S–015 [B65], a Notice of Proposed Rulemaking to issue new regulations as 29 CFR 1910.137and 29 CFR 1910.269 to address the work practices to be used during the operation and maintenance ofgeneration, transmission, and distribution facilities. Coordination between these OSHA proposals andthe 1997 Edition of the NESC has been effected such that the technical content of each document isharmonized at this time to the extent possible with the closure of the rulemaking hearing docket. Insome cases, it was thus not possible for the OSHA final rule published as 29 CFR 1910.137 and 29 CFR1910.269 (as published in the Federal Register, [01/31/94] vol. 59, no. 20, pp. 4321–4477 [B66]) toaddress all the technical information considered in this revision of NESC Part 4.

410. General requirements

A. General

4. Employers shall utilize positive procedures to secure compliance with these rules. Cases mayarise, however, where the strict enforcement of some a particular rule could seriously impedethe safe progress of the work at hand; in such cases the employee in charge of the work to bedone should make such a temporary modification of to the particular rules as will accomplishso the work can be accomplished without increasing the hazard.

5. If a difference of opinion arises with respect to the application of these rules, the decision ofthe employer or the employer’s authorized agent shall be final. This decision shall not result inany employee performing work in a manner that is unduly hazardous to the employee or to theother employees fellow workers.



B. Emergency procedures and first aid rules procedures

1. Employees shall be informed of the procedures to be followed in case of emergencies, andrules for first aid including approved methods of resuscitation. Copies of such procedures andrules should be accessible kept in conspicuous locations in vehicles and places where thenumber of employees and the nature of the work warrants.

C. Responsibility

2. If more than one person is engaged in work on or about the same equipment or line, one personshall be designated as in charge of the work to be performed. Where there are separate worklocations, one person may be designated at each location.

411. Methods

A. Methods

3. Employees shall be instructed as to the characteristics of the equipment or lines and methods tobe used before any work is undertaken thereon.

C. Inspection and testing of protective devices

3. Before use, climbing and fall protection equipment Line-worker’s body belts, lanyards, andpositioning straps and other personal equipment, whether furnished by employer or employee,shall be inspected to ensure that they are in safe working condition.

420. Personal general precautions General

Supporting Comment

The report was completed by the editorial working group. Although the Working Group suggests many morechanges, due to the extent of the changes only the above text was agreed upon by SC8.


Accept.


Affirmative: (18) Blackley, Bowmer, Brubaker, Doering, Erga, Granata, Grose, Herbinger, Hunt,McKinney, Poholski, Russell, Shaw, Smoak, Stonerock, Theis, Tomaseski, Tootle

Negative: (0)


Explanation of Vote

Doering: (Affirmative) The change to the second paragraph should be further discussed. The change onlyadds confusion. I believe the intent of the existing language cautions Section 4 readers to realize there arerequirements in the Section 3 “standard” that are covered by Section 4 Purpose.



Revised Text

CP3335


Submitter

James T. Collins

Proposed Change

2. The employer shall provide training to all employees who work in the vicinity of exposedenergized facilities lines and parts. The training shall include applicable work rules required by thisPart and other mandatory referenced standards or rules. The employer shall ensure that eachemployee has demonstrated proficiency in required tasks. The employer shall provide retraining forany employee who, as a result of routine observance of work practices, is not following work rules.

Supporting Comment

“Lines and parts” is consistent with Part 4 language. Generally, facilities are considered to be buildings orstructures.


Accept.



Negative: (0)


Revised Text

CP3042


Submitter

Ewell Robeson



Proposed Change


When exposed to an electric arc or flame, clothing made from the following materials shall not be worn:acetate, nylon, polyester, or polypropylene clothing or clothing system must have an acceptableeffective arc rating or arc thermal performance value.

The effective arc rating of clothing or a clothing system to be worn at voltages 1000 V and above shallbe determined using Tables 410-1 and 410-2 or performing an arc hazard analysis.

For work below 1000 V, applicable rules required by this part and engineering controls shall be utilizedto limit exposure. In lieu of performing an arc hazard analysis, clothing or a clothing system with aminimum effective arc rating of 4 cal/cm2 shall be required to limit the likelihood of ignition.

When an arc hazard analysis is performed, it shall include a calculation of the estimated arc energybased on the available fault current, the duration of the arc (cycles), and the distance from the arc to theemployee.

EXCEPTION 1: If the clothing required by this rule has the potential to create additional and greaterhazards than the possible exposure to the heat energy of the electric arc, then clothing with an arc ratingor arc thermal performance value (ATPV) less than that required by the rule can be worn.

EXCEPTION 2: For secondary systems below 1000 V, applicable work rules required by this part andengineering controls shall be utilized to limit exposure. In lieu of performing an arc hazard analysis,clothing or a clothing system with a minimum effective arc rating of 4 cal/cm2 shall be required to limitthe likelihood of ignition.

NOTE 1: A clothing system (multiple layers) that includes an outer layer of flame resistant material andan inner layer of non-flame resistant material has been shown to block more heat than a single layer.The effect of the combination of these multiple layers can be referred to as the effective arc rating.

NOTE 2: It is recognized that arc energy levels can be excessive with secondary systems. Applicablework rules required by this part and engineering controls should be utilized.

Supporting Comment

The revision to the first paragraph above is in response to IR 544 dated January 27, 2007. This IR stated thatthe intent of this rule was that a clothing system of blended materials was acceptable provided it had anacceptable effective arc rating.

EXCEPTION 2 is not an exception as used herein and the language should be deleted as such and made a partof the second paragraph as shown above.

NOTE 2 is shown to be deleted as the intent of the language is already covered in the addition to the secondparagraph above (formally EXCEPTION 2).


Accept as modified.

Revise 410A3 and add new Table 410-1 and revise old Tables 410-1 and -2.


mailto:[email protected]

mailto:[email protected]


Revisions to Rule 410A3

3. Effective as of January 1, 2009, tThe employer shall ensure that an assessment is performed todetermine potential exposure to an electric arc for employees who work on or near energized lines,parts or equipment.

If the assessment determines a potential employee exposure greater than 2 cal/cm2 exists (see Neal,Bingham, and Doughty [B59]), the employer shall:

a. Perform a detailed arc hazard analysis, or use Table 410-1, Table 410-2, or Table 410-3 todetermine the effective arc rating of clothing or clothing system to be worn by employeesworking on or near energized lines, parts, or equipment at voltages 50 – 800 000 V.

When an The arc hazard analysis is performed, it shall include a calculation of the estimatedarc energy based on the available fault current, the duration of the arc (cycles), and the distancefrom the arc to the employee.

b. rRequire employees to wear clothing or a clothing system that has with an effective arc ratingnot less than the anticipated level of arc energy.

When exposed to an electric arc or flame, clothing or a clothing system made from thefollowing materials, unless flame resistant, shall not be worn: acetate, nylon, polyester, orpolypropylene.

The effective arc rating of clothing or a clothing system to be worn at voltages 1000 V andabove shall be determined using Tables 140-1 and 410-2 or performing an arc hazard analysis.

EXCEPTION 1: If the clothing or clothing system required by this rule has the potential tocreate additional andor greater hazards than the possible exposure to the heat energy of theelectric arc, then clothing with an arc rating or arc thermal performance value (ATPV) lessthan that required by theis rule canmay be worn.

EXCEPTION 2: For secondary systems below 1000 V, applicable work rules required by thispart and engineering controls shall be utilized to limit exposure. In lieu of performing an archazard analysis, clothing or a clothing system with a minimum effective art rating of 4 cal/cm2

shall be required to limit the likelihood of ignition.

NOTE 1: Assessments performed to determine potential exposure to an electric arc considerthe affected employee’s assigned tasks and/or work activities.

NOTE 12: A clothing system (multiple layers) that includes an outer layer of flame resistantmaterial and an inner layer of non-flame resistant natural fiber material has been shown toblock more heat than a single layer. The effect of the combination of these multiple layerscanmay be referred to as the effective arc rating.

NOTE 23: It is recognized thatIt is recognized that arc energy levels can be excessive withsecondary systems. Applicable work rules required by this part and engineering controlsshould be utilized. Engineering controls can be utilized to reduce arc energy levels and workpractices can be utilized to reduce exposure levels.



New Table 410-1

1 This table is based on maximum fault current of 51 kA.

Calculations are based on an 18 in separation distance from the arc to the employee. See IEEE Std 1584-2002.

Other methods are available to estimate arc exposure values and may yield slightly different but equally acceptableresults.

The use of the table in the selection of clothing is intended to reduce the amount or degree of injury but may not pre-vent all burns.2 Industry testing by two separate major utilities has demonstrated that voltages 50 – 240 V will not sustain arcs formore than 0.5 cycles thereby limiting exposure to less than 4 cal/cm2.3 Value based on industry test results and IEEE 1584 formula for motor control centers. (Gap = 1 in) (Xd = 1.641)(18 in distance) 51 kA (Based on a 208 V, 1000 kVA, 5.3% Z, served from a 500 mVA system) Maximum duration(from tests) is 10 cycles: 46.5 cal/s/cm2 * 0.167 s = 7.8 cal/cm2.4 Industry testing on 480 V equipment indicates exposures for self-contained meters do not exceed 20 cal/cm2.5 Industry testing on 480 V equipment indicates exposures for CT meters and control wiring does not exceed 4 cal/cm2.6 Value based on industry test results and IEEE 1584 formula for motor control centers. (Gap = 1 in and Xd = 1.641,18 in distance) 12.7 kA at 480 V (worst case energy value from testing). Maximum duration from tests is 85 cycles:26.2 cal/s/cm2 * 1.42 s = 37 cal/cm2.7 Incident analysis on this equipment indicates exposures do not exceed 8 cal/cm2.8 Incident analysis and industry testing indicates that applying a 150% multiplier to the 480 V exposure values pro-vides a conservative value for equipment and open air lines operating at 501 – 1000 V.

Table 410-1—Clothing and clothing systems (per cm2) for voltages 50 to 1000 V (ac)1(See Rule 410A3)

Nominal voltage range and cal/cm2

Equipment type 50 – 250 V 251 – 500 V 501 – 1000 V

Self-contained meters / pad-mounted transformers / panels and cabinets

4 2 20 4 30 8

CT meters and control wiring 4 2 4 5 6 8

Metal-clad switchgear / motor control centers

8 3 40 6 60 8

Subsurface / pedestal-mounted equipment

4 2 8 7 12 8

Open air (includes lines) 4 2 4 2 6 8



Editorial revisions to Tables 410-1 and 410-2

Table 410-23—Live-line tool work clothing and clothing systems—voltage, fault current, and maximum clearing time for voltages 46.1 to 800 kV 1 ac

(See Rule 410A3.)

Supporting Comments

Currently, Rule 410A3 requires the use of clothing or clothing systems with a minimum effective arc ratingof 4 cal /cm2 for voltages less than 1000 V, in lieu of performing an arc hazard analysis.

Table 410-1 2—Clothing and clothing systems—voltage, fault current, and maximum clearing time for voltages 1.1 to 46 kV 1 ac

(See Rule 410A3.)

Phase-to-phase voltage (kV) Fault current (kA)

4-cal system 8-cal system 12-cal system

Maximum clearing time (cycles)

Maximum clearing time

(cycles)

Maximum clearing time (cycles)

1.1 to 15 5 46.5 93.0 139.5

10 18.0 36.1 54.1

15 10.0 20.1 30.1

20 6.5 13.0 19.5

15.1 to 25 5 27.6 55.2 82.8

10 11.4 22.7 34.1

15 6.6 13.2 19.8

20 4.4 8.8 13.2

25.1 to 36 5 20.9 41.7 62.6

10 8.8 17.6 26.5

15 5.2 10.4 15.7

20 3.5 7.1 10.6

36.1 to 46 5 16.2 32.4 48.6

10 7.0 13.9 20.9

15 4.3 8.5 12.8

20 3.0 6.1 9.1



Subcommittee 8 established a Low-Voltage Arc Flash Work Group (WG) to evaluate the necessary minimumclothing or clothing system requirements for employees working on energized lines and parts operating atvoltages less than 1000 V and to develop a change proposal, if needed, to revise Rule 410A3.

The WG’s initial evaluations concluded that aside from anecdotal evidence no technically substantiated databased upon specific industry testing existed to justify the creation of a new table, similar to existing Tables410-1 and 410-2, for voltages less than 1000 V. However, during the spring and summer of 2008, the PacificGas and Electric Company initiated and completed a series of scientific tests to determine the arc flashcharacteristics of 480 V self-contained metering equipment by creating fault conditions at various kA levels(sans fault protection devices).

Based on PG&E’s test results (which are included with this CP) and the application of an accepted industrystandard (IEEE Std 1584-2002), the WG submitted a report to Subcommittee 8 that included revisions to Rule410A3 and a new Table (410-1).

The revisions to Rule 410A3 seek to clarify the difference between performing an assessment and an archazard analysis, the conditions under which an arc hazard analysis is to be performed, and the employer’srequirements for determining the necessary clothing or clothing systems.

New Table 410-1 [Clothing and clothing systems (per cm2) for voltages 50 to 1000 V (ac)] and existing tables(renumbered to 410-2 and 410-3) are cited in new text 410A3a to offer employers the option of usingtabulated values for clothing and clothing systems in lieu of performing an arc hazard analysis.

The supplemental footnotes to new Table 410-1 identify certain parameters that vary from the preexistingtables (new 410-2 and 410-3). One such difference is the use of an 18 in worker separation distance. On thisparticular topic, it should be noted that the supporting test results are based on the application of IEEE 1584test methodologies and typical working distances for low-voltage motor control centers and panel boards(Table 3, p. 9). It seemed prudent to the workgroup to apply the 18 in working distances to determine the cal/cm2 values for other listed equipment and for other voltage ranges, since 4.8 (IEEE Std 1584) states that arcflash protection is based on the incident energy level on the worker’s face and body, not the incident energyon the hands and arms.

The supplemental footnotes to new Table 410-1 also include statements identical to those in preexisting tables(renumbered 410-2 and 410-3) that allow the user to apply different methods of calculating arc exposurevalues.



Negative: (0)


Explanation of Vote

Doering: (Affirmative) Table 410-3 has no test data to support. The clearing times shown are not realistic asthe lights would be out due to instability. I prefer to assume a typical clearing time (which is reasonable at thehigher voltages) and calculate the permissible approach distances. See my report that was attached.



Proposed Clause 9 (Temporary) 516-2008 FR New Clause 9 Rev 8-08

9. Flame-resistant protective clothing and personal protective equipment

9.1 Introduction

Many of the requirements of this guide are to protect the worker from electric shock. For example, theminimum approach distances (MAD) are the distance at which a flashover could occur, under certainovervoltage conditions, that could result in the worker being part of the circuit and be subject to serious orfatal electric currents. In this clause greater consideration is given to the intense thermal energies that theworker may be subject to due to an electric arc, generally related to equipment failure or the accidentalshorting of energized circuit parts.

The hazard of everyday work clothing being ignited at very low arc exposures may result in the clothingcontinuing to burn and adding to the extent of the injury beyond that of the arc alone. In addition to the useof flame-resistant protective clothing (FR), personal protective equipment (PPE) is required to protect theworker where the incident energy exceeds the rating of the FR clothing, such as flash suits. Of course normalPPE such as hard hats, face protection, gloves, etc., would be required.

This clause will deal with working on electrical utility distribution and transmission systems, includingsubstations in those systems. The equipment is classified as either normally exposed or enclosed. Most workon overhead facilities and substations is considered exposed work. Most underground work involvesenclosed equipment that frequently requires exposing the energized parts before performing work on them.In general incident energy from arcs in enclosed equipment with a door or panel open would be focusedtoward the worker and require using a factor to recognize the higher incident energy level. Substations thatutilize enclosed equipment due to space limitations also requires recognition of the focusing of the incidentenergy, as the equipment must be opened to work on the live parts.

9.2 Evaluation of risk related to a possible arc event

9.2.1 Level of risk

The level of risk related to a possible arc event is the principle factor involved in determining the FR andPPE required. The evaluation is primarily subjective and the worker must be trained to recognize the variousrisk elements involved. Unlike most commercial and industrial systems, the electrical utility system willhave thousands of miles of circuits and the associated equipment. While much of the work may be pre-engineered, and it may be possible to provide some specific exposure information; even then there must beassumptions made to determine the exposure risk. Further, many operation and maintenance workassignments to a crew are to find why the power is off and make the necessary repairs. Therefore, thespecific work location is unknown when the task is assigned. As part of their training, the crews determinethe risk of an arc event as part of their job planning.

9.2.2 Risk factors to consider

9.2.2.1 Equipment condition

a) Equipment failure record (“reputation”).

b) Equipment showing visible signs of distress, or unusual audible sounds.

9.2.2.2 Work method

a) Task requires exposing live part by opening door.



b) Task requires exposing live part by removing access panel.

c) Ease of movement: open area, confined space, or work position.

d) Access method: ladder, structure steel, aerial lift, hooks on wood pole, or helicopter.

e) Level of training required for task.

f) Working “near” energized live parts.

g) Working “on” energized live parts.

h) Work method: de-energized, rubber gloves, live-line tools, or barehand.

i) Status of lockout/tagout procedure if applicable.

9.2.2.3 Task elements

a) Task requires a circuit transitional change, such as opening a breaker, opening a disconnect switch,lifting a jumper, replacing a fuse.

b) Working on exposed live parts, enclosed equipment’s temporarily exposed live parts.

c) Crew has proper compliment of workers and equipment.

d) Task history.

e) Environment: weather conditions, lighting, cleanliness of area.

9.2.2.4 Incident energy specifics

a) Level of possible incident energy.

b) Distance from possible arc location.

c) Voltages involved.

d) Arcing fault current.

9.2.3 Flash hazard analysis

The risk evaluation is part of the study investigating a worker’s exposure to the arc flash energy, conductedfor the purpose of injury prevention and the determination of safe work practices and the appropriate levelsof PPE. The risk evaluation may indicate that the probability of an arc occurring is so low that special FRprecautions are not necessary. The estimated incident energy for the onset of second degree burn is 1.2 cal/cm2 [3].

9.3 Calculation of incident energy, low-voltage systems

9.3.1 Introduction

This clause contains a number of low-voltage system evaluations that provides the incident energy levels fortypical transformer installations. Sample calculations are provided later in this clause that may be used tofind incident energies for systems that are not provided The calculation of the incident energy on nearby



workers from an arc event will be determined based on the following supply transformer configurations.Note that all low-voltage calculations are based on neglecting the primary source impedance.

In evaluating the incident energy due to low-voltage arcs in utility distribution systems, several basic inputsmust be determined. Each of the inputs may have several variations, the preferred one being based on thetype of system. (1) The appropriate clearing time varies with the type of system, (2) the arc powercalculation may be based on theoretical or empirical data, as arcing faults are generally considerably smallerin magnitude than the various bolted faults, (3) the distance from the arc source to the worker, and (4) theappropriate formula that relates the input data to the incident energy impressed on the worker.

9.3.2 Arc clearing time calculations

9.3.2.1 Based on worker reaction time

There are many case histories where burn-down events have lasted for as short as minutes to over an hour,with 10 to 20 minutes being common. Some have lasted till all the primary source feeds are opened or thesecondaries are literally cut open by very brave workers. If workers had been present at the initial failure, thesituation of primarily interested in this guide, assumptions must be made as to the time of exposure and thedistance involved. The reaction time and time to escape the arc can only be estimated. While a particulartask might have unique requirements, for purposes of this guide the following times and distances are usedto determine the incident energy:

a) At 2 ft for 1 s.

b) At 2 ft for 2 s.

c) At 4 ft for 1 s.

d) At 4 ft for 2 s.

9.3.2.2 Based on fire detection system

A continuous fire detection system will have a fast response, as little as 10 cycles to detect and clear faults[9]. Heat detectors that fit in the network protectors also result in clearing in 10 cycles.

9.3.2.3 Based on elaborate ground fault relaying

With the addition of elaborate ground fault relaying, which may require the addition of high side vacuumbreakers on the transformers, arcing faults can be cleared rapidly. Solid-state relaying may clear in 0.04 s or2.4 cycles [10]. From an equipment standpoint, applying sensitive ground fault protection in an attempt tosense and promptly interrupt an arcing fault before it escalates into the more severe forms of arcing faults orbefore it inflicts sever damage to equipment.

9.3.2.4 Based on clearing the primary feeders

Typical feeder breaker back-up settings interval time for arcing faults is 3 to 30 s [10].

9.3.2.5 Based on clearing transformer high side fuse

Use the clearing time for the transformer high side fuse.

9.3.3 Arc power calculations

9.3.3.1 Lee’s theoretical method



For low-voltage utilization systems, 70.7% of the bolted three-phase fault current will be used with the arcvoltage to determine the power in the arc. For low-voltage utilization systems the arc voltage is assumedequal to 70.7% of the phase-to-phase voltage. These two assumptions are based on Lee's theoretical work[1]. The testing performed in [3] demonstrated that Lee’s work needed to be reduced by 79%.

Maximum arc power in kW = 0.5 × bolted fault in kVA × 79%

9.3.3.2 Likely minimum current prior to arc self interruption

The likely minimum values of arcing line-to-ground fault currents, governed by arcing and re-ignitionvoltages are shown in the following table [7] based on the percent of the 3-phase bolted fault. Normally thistable is used to find the minimum current value for relaying or fuse study. As we are interested in average ormaximum, fault currents calculations using these values would be conservative with respect to the arcenergy. On the other hand only three-phase faults have been considered in our calculated incident energytables. The table essentially gives an indication of the probability of arc self interruption for the two voltagesand the different types of faults. Most faults in enclosed equipment (including cables themselves) starts as aline-to-line or line-to-ground fault, and progress to three-phase faults.

Three-phase bolted power = 1.732 × VLL × IBF

The use of silver-sand limiters generally do not play a role in worker protection, as their principle purpose isto prevent faults from cascading and shutting down the system. They coordinate well with network typecable insulation. They are activated by higher currents generally associated with bolted faults, not prolongedlower current values that are more common with the arc hazard to workers.

9.4 Incident energy calculations

The following method of calculating FR values permits calculating exposure values using any selected inputvalues. The tables developed are based on reasonable assumptions for the systems involved. The method ofcalculation permits the use of any selected input values.

The following equation has been developed [3] for incident energy on a surface due to an electric arc:

Einc = [K × Earc] ) D2.2

whereEinc = Incident energy in cal/cm2

K = 0.0000432 ft/cm2

D = Distance from arc in feetEarc = Total arc energy in calories

For arc-in-a-box, multiply the open bus distance by a factor of 2 for faults up to 40 kA and by 3 for over 40kA [5]. Experience also indicates that a factor of 1.5 could be used if a switch substantially shields the busfrom the door.

Type of arc-fault System voltage

480Y/277 208Y/120

Three-phase 89% 12%

Line-to-line 74% 2%

Line-to-ground 38% 0%



To determine a new Α distance from arc≅ for changes in current, time, or other incident energy levels, usethe following formula;

To calculate the DistanceARC TO SURFACE for different fault currents.

D2 = D1{I2 ) I1}1/2.2

To calculate the DistanceARC TO SURFACE for different clearing times.

D2 = D1{T2 ) T1}1/2.2

To calculate the DistanceARC TO SURFACE for different EnergyINCIDENT.

D2 = D1{EnergyINCIDENT1 ) EnergyINCIDENT2}1/2.2

9.5 Low-voltage incident energy and flash hazard analysis trigger

9.5.1 Single-phase, overhead or pad-mounted 120-240 transformers

Based on arc clearing time 9.3.2.5, and arc power calculation 9.3.3.1. Fault at transformer terminals.


Transformer kVA

Maximum bolted fault

current

Arc voltage Arc current

Maximum arc energy

W/s

Distance arc to 1.2 cal/cm2

incident energy

50 12 035 169.7 8 509 34 222 0' - 7''

75 17 180 169.7 12 146 56 993 0' - 9''

100 22 420 169.7 15 853 127 518 1' - 1''

167 35 475 169.7 25 080 134 496 1' - 1''

Voltage Phase Source kVA

Bolted fault amps

Incident energy @

2 s2 ft

Incident energy @

2 s4 ft

Incident energy @

1 s2 ft

Incident energy @

1 s4 ft

120/240 1 50 12,035 5.2 1.1 2.6 0.6

120/240 1 100 22,423 9.7 2.1 4.8 1.1



9.5.2 Three-phase, overhead, or pad-mounted 120/208 and 277/480 transformer banks



9.5.3 Three-phase spot network, 277/480 V 500, 1000, and 2000 kVA transformers in various banks

Based on arc clearing time 9.3.2.1 and arc power calculation 9.3.3.2. Fault at transformer terminals.

Transformer bank total

kVA

Secondary voltage

Maximum bolted fault

currentArc current

Maximum arc energy W/s

Distance arc to 1.2 cal/cm2

incident energy

150 120/208 21 451 15 165 122 017 1' - 1''

150 277/480 9 628 6 807 126 445 1' - 1''

225 120/208 32 080 22 680 205 280 1' - 4''

225 277/480 14 401 10 182 212 519 1' - 4''

300 120/208 20 041 14 168 498 734 2' - 0''

300 277/480 9 402 6 647 539 545 2' - 0''

500 120/208 33 273 23 523 946 350 2' - 7''

500 277/480 15 617 11 041 1 280 333 2' - 11''


Bolted fault amps

Incident energy @

2 s2 ft

Incident energy @

2 s4 ft

Incident energy @

1 s2 ft

Incident energy @

1 s4 ft

120/208Y 3 225 33 433 6.4 1.4 3.2 0.7

120/208Y 3 750 60 450 11.7 2.6 5.9 1.3

277/480Y 3 225 14 401 47.9 10.4 24.0 5.2

277/480Y 3 750 20 334 67.6 14.7 33.8 7.4

VoltageTransformer kVA size and

numberTotal kVA

Bolted fault amps

Incident energy @

2 s2 ft

Incident energy @

2 s4 ft

Incident energy @

1 s2 ft

Incident energy @

1 s4 ft

277/480 V 3–500 1 500 36 000 119.8 26.1 59.3 18.0

277/480 V 6–500 3 000 72 000 239.7 52.1 119.8 26.1

277/480 V 3–1 000 3 000 72 000 239.7 52.1 119.8 26.1

277/480 V 6–1 000 6 000 144 000 479.3 104.2 239.7 53.1

277/480 V 3–2 000 6 000 103 000 342.9 74.6 171.1 37.3



Based on arc clearing time 9.3.2.2, and 9.3.2.4 and arc power calculation 9.3.3.2. Fault at transformerterminals.

9.5.4 Three-phase network, 120/208 V 500, VA transformers in 3 and 6 feeders


9.6 Calculation of incident energy, high voltage systems

Due to the more generous spacing on transmission and distribution structures, the bolted line-to-ground faultcurrent will be used in conjunction with arc voltage to find the power in the arc. For ease of calculation, andgenerally resulting in a conservative result, let the line-to-ground fault current equal the three-phase faultcurrent.

9.6.1 Determining the arc voltage

Three different sources report that for T and D lines, the arc voltage per inch varies between 30 and 38 V perinch [6] [7] [8]. For transmission and distribution system the arc voltage will be assumed to be 40 V per inchof arc length.

Based on unpublished data from Bonneville Power Administration:

— For systems with a 0.25 s clearing time, the initial arc length will assume to lengthen 6 times, whichresults in 6 times the initial arc length times 40 V/in value.

— For systems with a 0.1 s clearing time, the initial arc length will assume to lengthen 3 times, whichresults in 3 times the initial arc length times 40 V/in.

VoltageTransformer

kVA size and number

Total kVA

Bolted fault amps

Incident energy @

2 ft10 cycle (9.3.2.2)

Incident energy @

4 ft10 cycle (9.3.2.2)

Incident energy @

2 ft3 s

(9.3.2.4)

Incident energy @

4 ft3 s

(9.3.2.4)

277/480 3-500 1,500 36,000 10.0 2.2 179.8 39.2

277/480 6-500 3,000 72,000 20.0 4.3 359.6 78.2

277/480 3-1,000 3,000 72,000 20.0 4.3 359.6 78.2

277/480 6-1,000 6,000 144,000 40.0 8.7 719.2 156.4

277/480 3-2,000 6,000 103,000 28.6 6.2 514.2 111.6


Bolted fault amps

Incident energy @

2 s2 ft

Incident energy @

2 s4 ft

Incident energy @

1 s2 ft

Incident energy @

1 s4 ft

120/208Y 3 3 Feeder network 3-500

80,000 15.5 3.4 7.8 1.7

120/208Y 3 6 Feeder network 6-500

154,500 30.0 6.5 15.0 3.3



For transmission and distribution systems the initial gap length is based on the critical flashover voltage(CFO) of a rod-rod gap. The initial arc gap length is based on 120 kV per foot RMS line-to-ground (10 kVper inch or 0.1 in per kV).

The following table tabulates the withstand distance and arc voltage, based on the above criteria:

9.6.2 Determining the arc current for distribution circuits

The three-phase bolted fault current values used in the table for distribution voltages are based on theindicated transformer size. A 5.0% transformers impedance assumed for units less than 10 Mva, and 6% forunits 10 MVA and greater.

9.6.3 Determining the arc clearing time

For systems below 72.6 kV the clearing times will be assumed to be 0.25 s (15 cycles). For systems above72.5 kV the clearing times will be assumed to be 0.1 s (6 cycles).

9.6.4 Determining the incident energy

See 9.4.

System voltageCritical flashover

distance(in)

Lengtheneddistance

(in)

Arc voltage(V)

4370/2520 V 0.25 1.50 60

13 090/7 560 V 0.76 4.56 183

26 190/15 120 V 1.51 9.06 363

36 230/20 920 V 2.09 12.54 502

48 300/27 886 V 2.78 16.68 668

72 500/41 570 V 4.15 24.90 996

121/69.9 kV 6.99 20.97 839

145/83.7 kV 8.37 25.11 1005

169/97.6 kV 9.76 29.28 1172

242/139.7 kV 13.97 41.91 1677

362/209.0 kV 20.90 62.70 2508

550/317.6 kV 31.76 95.28 3812

800/461.9 kV 46.19 138.57 5543



9.6.5 Table of distances that require a flash hazard analysis

9.6.5.1 Adjustment of 9.6.5 table values for different input

To calculate the DistanceARC TO SURFACE for different fault currents, first subtract the adder then use thefollowing formula to find the new distance, then add the adder to the new distance to get the newDistanceARC TO SURFACE.

D2 = D1{I2 ) I1}1/2.2

To calculate the DistanceARC TO SURFACE for different clearing times, first subtract the adder then use thefollowing formula to find the new distance, then add the adder to the new distance to get the newDistanceARC TO SURFACE.

D2 = D1{T2 ) T1}1/2.2

Maximum voltage Bolted fault current -G

Distance at which there is

potential employee

exposure greater than 1.2 cal/cm2,

with no arc movement

Adder for arc movement.

Adder equal to one-half

lengthened arc.

Distance that requires flash

hazard analysis. A potential employee

exposure greater than 1.2 cal/cm2

exists.

4.16 kV 5 MVA Xfmr 13.9 kA 1.32’' 0.07’ 1' - 5"

4.16 kV 10 MVA Xfmr 23.1 kA 1.66' 0.07' 1' - 9"

12.47 kV (10 MVA Xfmr) 7.7 kA 1.67' 0.19' 1' - 11”

12.47 kV (20 MVA Xfmr) 15.4 kA 2.27' 0.19' 2' - 6"

24.95 kV (10 MVA Xfmr) 3.9 kA 1.67' 0.38' 2' - 1"

24.95 kV (15 MVA Xfmr) 5.8 kA 2.00' 0.38' 2' - 5"

34.50 kV (10 MVA Xfmr) 2.8 kA 1.66' 0.53' 2' - 3"

34.50 kV(15 MVA Xfmr) 4.2 kA 2.00' 0.53' 2' - 7"

36 kV 20 kA 4.05' 0.53' 4' - 7"

46 kV 20 kA 4.61' 0.70' 5' - 4"

72.5 kV 20 kA 5.53' 1.04' 7' - 0"

121 kV 30 kA 4.05' 0.88' 5' - 0"

145 kV 30 kA 4.39' 1.05' 5' - 6"

169 kV 30 kA 4.72' 1.22' 6' - 0"

242 kV 30 kA 5.55' 1.75' 7' - 4"

362 kV 30 kA 6.66' 2.62' 9 - 4"

550 kV 30 kA 8.06' 3.97' 12' - 1"

800 kV 30 kA 9.55' 5.78' 15' - 4"

ϕ



To calculate the DistanceARC TO SURFACE for different EnergyINCIDENT, first subtract the adder then use thefollowing formula to find the new distance, then add the adder to the new distance to get the newDistanceARC TO SURFACE.

D2 = D1{EnergyINCIDENT1 ) EnergyINCIDENT2}1/2.2

9.6.6 Distances in air require to limit cal/cm2

NOTE: For arc-in-a-box we would expect a three-phase fault, therefore, multiply the single-phase faultdistance by a factor of (3)1/2.2 or 1.65 to get the three-phase fault distance. Then multiply by 3 to get the arc-in-the-box flash distance.

Voltage kV -

Fault currentkA – G


potential employee

exposure equal to 2.0 cal/cm2,

with arc movement


potential employee


with arc movement


potential employee


with arc movement


potential employee

exposure equal to 12 cal/cm2,

with arc movement

4.4 13.9 1.10’ 0.82’ 0.62’ 0.53’

4.4 23.1 1.37’ 1.02’ 0.76’ 0.64’

13.1 7.7 1.51’ 1.15’ 0.89’ 0.78’

13.1 15.4 1.99’ 1.51’ 1.15’ 0.99’

26.2 3.9 1.70’ 1.34’ 1.09’ 0.97’

26.2 5.8 1.96’ 1.53’ 1.22’ 1.08’

36.2 2.8 1.85’ 1.49’ 1.23’ 1.11’

36.2 4.2 2.11’ 1.69’ 1.37’ 1.23’

36.0 20.0 3.74’ 2.87’ 2.24’ 1.95’

46.0 20.0 4.35’ 3.37’ 2.65’ 2.32’

72.5 20.0 5.46’ 4.28’ 3.41’ 2.10’

121 30.0 4.09’ 3.23’ 2.59’ 2.30’

145 30.0 4.53’ 3.60’ 2.91’ 2.60’

169 30.0 4.96’ 3.95’ 3.21’ 2.88’

242 30.0 6.15’ 4.96’ 4.09’ 3.70’

362 30.0 7.90’ 6.48’ 5.43’ 4.96’

550 30.0 10.36’ 8.63’ 7.37’ 6.80’

800 30.0 13.35’ 11.31’ 9.81’ 9.14’

φ φ φ



9.7 Protective clothing guidelines for electric arc hazards [3]

++ Proposed range of calculated incident energy to avoid a second degree burn.*ATPV is defined as ASTM PS58 standard arc test method for flame resistant (FR) fabrics as the incident energy thatwould just cause the onset of a second degree burn. EBT is reported according to ASTM PS58 and is defined as thehighest incident energy that did not cause FR fabric breakdown and did not exceed the second degree burn criteria. BBTis reported when ATPV cannot be measured due to FR fabric breakopen.

9.8 Sample calculation of incident energy and arc hazard analysis distance

9.8.1 Samples, tables 9.5.1

A sample calculation for a 240 V, 50 kVA transformer, with a bolted fault at the transformer of 12 035 A.Clears in 0.03 s.

VoltageARC = VoltageSOURCE × 0.707 = 240 × 0.707 = 169.7 V

CurrentARC = CurrentSOURCE3 × 0.707 = 12 035 × 0.707 = 8509 A

PowerMAXIMUM = VoltageARC × CurrentARC = 169.7 × 8509 = 1 443 977 W

PowerARC = PowerMAXIMUM × 0.79 = 1 443 977 × 0.79 = 1 140 742 W

EnergyARC = PowerARC × Fault clearing time in seconds

= 1 140 742 W × 0.03 s = 34 222 W/s

EnergyARC = 34 222 W/s 4.184 W/s-cal = 8179 cal

DistanceARC TO SURFACE = {[0.0000432][Earc] ) Einc}1/2.2

Proposed protective clothing class FR clothing class

Estimated incident energy for onset of second degree burn

Proposed range of

calculated incident energy++ cal/cm2

Clothing class No.

Clothing description (number of layers)

Total weight (oz/yd)

Arc thermal energy for exposure value (ATPV)* or breakopen threshold energy

(EBT)* cal/cm2

0–2 0 Untreated cotton (1) 4.5–7 N/A (not recommended)

2–5 1 FR shirt (1) 4.5–8 5–7

5–8 2 T-shirt plus FR shirt and pants (2)

9–12 8–18

8–25 3 T-shirt plus FR shirt plus FR coverall (3)

16–20 25–50

25–40 4 T-shirt plus FR shirt plus double layer switching

cost (4)

24–30 40–>60

ϕϕ

ϕ



EnergyINCIDENT = 1.2 cal/cm2

DistanceARC TO SURFACE = {[0.0000432][8,179 cal] ) 1.2 cal/cm2}1/2.2

= 0.5735 ft = 0' – 7

A sample calculation for a 240 V, 50 kVA transformer, with a bolted fault at the transformer of 12 035 A.Assumes 1 and 2 s clearing time, and 2 ft and 4 ft distance, arc to worker.


CurrentARC = CurrentSOURCE3 × 0.707 = 12,035 × 0.707 = 8509 A

PowerMAXIMUM = VoltageARC × CurrentARC = 169.7 × 8509 = 1 443 977 W


EnergyARC = PowerARC × fault clearing time in seconds

= 1 140 742 W × 1.0 s = 1140742 W/s

EnergyARC = 1 140 742 W/s ) 4.184 W/s-cal = 272 644 cal

DistanceARC TO SURFACE = {[0.0000432][Earc] ) Einc}1/2.2 = 2 ft

2.0' = {[0.0000432][272,644 cal] ) EnergyINCIDENT cal/cm2}1/2.2



A sample calculation for a 277/480 V, 225 kVA transformer, with a bolted fault at the transformer of14 401 A. Clears in 0.045 s.


CurrentARC = CurrentSOURCE3 × 0.707 = 14 401 × 0.707 = 10 182 A

PowerMAXIMUM = VoltageARC × CurrentARC = 1.732 × 339.0 × 10 182 = 5 978 051 W


EnergyARC = PowerARC × Fault clearing time in seconds

= 4 720 660 W × 0.045 s = 212 519 W/s

EnergyARC = 212 519 W/s ) 4.184 W/s-cal = 8179 cal



DistanceARC TO SURFACE = {[0.0000432][50 793 cal] ) 1.2 cal/cm2}1/2.2

ϕϕ

ϕ

ϕϕ

ϕ



= 1.316 ft = 1' – 4

A sample calculation for a 277/480 V, 225 kVA transformer, with a bolted fault at the transformer of14 401 A. Clears in 2 s.

VoltageARC = VoltageSOURCE = 480 V

CurrentARC = CurrentSOURCE3 = 14 401 × 0.89 = 12 817 A

PowerMAXIMUM = VoltageARC × CurrentARC = 1.732 × 480 × 12 817 = 10 655 450 W


= 10 655 450 W × 2 s = 21 310 900 W/s

EnergyARC = 21 310 900 W/s ) 4.184 W/s-cal = 5 093 427 cal


DistanceARC TO SURFACE = 2' = {[0.0000432][5 093 427 cal] ) EnergyINCIDENT}1/2.2



A sample calculation for a spot network 277/480 V, 3-500 transformers with a bolted fault at the transformerof 36 000 A. Clears in 2 s, determine incident energy at a distance of 2'.

VoltageARC = VoltageSOURCE = 480 V

CurrentARC = CurrentSOURCE3 = 36,000 × 0.89 = 32 040 A

PowerMAXIMUM = VoltageARC × CurrentARC = 1.732 × 480 × 32 040 = 26 636 000 W


= 26 636 000 W × 2 s = 53 273 000 W/s



DistanceARC TO SURFACE = 2' = {[0.0000432][2 733 000 cal] ) EnergyINCIDENT}1/2.2


9.8.4 Sample table 9.6.5 table of distances that require a flash hazard analysis

A sample calculation for a 72.5 kV system, with a 20 000 A fault current follows:

VoltageARC = 996 V [from the above table]

CurrentARC = CurrentSOURCE3 = 20 000 A

ϕϕ

ϕ

ϕϕ

ϕ

ϕ



PowerARC =VoltageARC × CurrentARC = 996 V × 20 000 A = 19 920 000 W


= 19 920 000 W × 0.25 s = 4 980 000 W/s



EnergyINCIDENT = 1.2 cal /cm2

DistanceARC TO SURFACE = {[0.0000432][1 190 248 cal] ) 1.2 cal /cm2}1/2.2

= 5.53'

Adjusted DistanceARC TO SURFACE = 5.53' + 1.04' = 6.57' = 7' – 0''

A second sample calculation for a 362 kV system, with a 30 000 A fault current follows:

VoltageARC = 2,508 V [from the above table]

CurrentARC = CurrentSOURCE3 = 30 000 A

PowerARC =VoltageARC × CurrentARC = 2508 V × 30 000 A = 75 240 000 W


= 75 240 000 W × 0.1 s = 7 524 000 W/s




DistanceARC TO SURFACE = {[0.0000432][1,798,279 cal] ) 2.0 cal/cm2}1/2.2

= [77.686 ) 2.0]1/2.2 = 5.28 ft

Adjusted DistanceARC TO SURFACE 5.28' + 2.62' = 7.90' = 7' - 11''

9.9 Background and references

There are extensive references publications and informational references dealing with all phases of protectingfrom FR injuries. As the references are too extensive to repeat in this guide, the reader is directed to thefollowing documents:

IEEE Std 1584-2002, IEEE Guide for Performing Arc-Flash Hazard Calculations.

NFPA 70E-2004, Standard for Electrical Safety in the Workplace.

The emphasis in much of the above reference material is on the lower voltages, 240 and 480 V systems, withsome of the material applicable to 15 kV. Further, the emphasis is on commercial and industrial systems,

ϕ



where the equipment is generally enclosed, and the maintenance of the equipment requires opening doors,removing barriers, or panels to access the exposed electrical parts. The preferred work method is to de-energize the circuit/equipment and place it in a safe operating condition (test and ground where applicable).

As has been indicated in this clause, the emphasis is on electrical utility work, most of which is on energizedlines and equipment. Most overhead work is on energized exposed lines and equipment. Underground andsome substation work involves enclosed equipment that may require open doors or panels. Most of thetechnical back-up for this clause is from the following references:

[1] R. H. Lee, “The Other Electrical Hazard: Electric Arc Blast Burns,” IEEE Transactions On IndustryApplications, Vol. 1A-18, No. 3, May/June 1982.

[2] R. L. Doughty, R. A. Epperly, and R. A. Jones, “Maintaining Safe Electrical Work Practices in aCompetitive Environment,” IEEE Transactions On Industry Applications, Vol. 28, No. 1, January/February1992.

[3] T. E. Neal, A. H. Bingham, and R. L. Doughty, “Protective Clothing Guidelines for Electric ArcExposure,” IEEE Transactions On Industry Applications, Vol. 33, No. 4, July/August 1997.

[4] R. L. Doughty, T. E. Neal, T. A. Daer, and A. H. Bingham, “Testing Update on Protective Clothing andEquipment for Electric Arc Exposure,” IEEE/PCIC paper, September 1997.

[5] R. L. Doughy, T. E. Neal, and H. Landis Floyd, II, “Predicting Incident Energy to Better Mange theElectric Arc Hazard on 600 V Power Distribution Systems,” IEEE IAS 45th Annual Petroleum and ChemicalConference, September 1998.

[6] A. D. Stokes and D. K. Sweeting, “Electric Arcing Burn Hazards,” Electronic copy available [email protected] or [email protected].

[7] R. H. Kaufmann and J. C. Page, “Arcing Fault Protection for Low-Voltage Power Distribution Systems,Nature of the Problem,” AIEE Trans. Power Apparatus and Systems, Vol.79-1960.

[8] J. R. Dunki-Jacobs, “The Impact of Arcing Ground Faults on Low-Voltage Power System Design,”General Electric Low Voltage Switchgear Publication, August 1, 1970.

[9] William F. Johnson, “How Do You Protect Your Spot Networks?” Electric Light and Power, January1970.

[10] B. G. Bailey, “Ground-Fault Protection on 480 volt Industrial System Saves Equipment,” Transmissionand Distribution Magazine, November 1967.

[11] J. C. Cranos and S. R. Gilligan, “Spot Networks and Connected Building Systems,” IEEE Transactionson Industry and General Applications, November/December 1970.

Revised Text

CP3329




Submitter

James T. Collins

Proposed Change


When exposed to an electric arc or flame, clothing made from the following materials shall not be wornunless flame resistant: acetate, nylon, polyester, or polypropylene.

The effective arc rating of clothing or a clothing system to be worn at voltages 1000 V and above shall bedetermined using Tables 410-1 and 410-2 or performing an arc hazard analysis.

When an arc hazard analysis is performed, it shall include a calculation of the estimated arc energy based onthe available fault current, the duration of the arc (cycles), and the distance from the arc to the employee.

EXCEPTION 1: If the clothing required by this rule has the potential to create additional and greater hazardsthan the possible exposure to the heat energy of the electric arc, then clothing with an arc rating or arcthermal performance value (ATPV) less than that required by the rule can be worn.

EXCEPTION 2: For secondary systems below 1000 V, applicable work rules required by this part andengineering controls shall be utilized to limit exposure. In lieu of performing an arc hazard analysis, clothingor a clothing system with a minimum effective arc rating of 4 cal/cm2 shall be required to limit thelikelihood of ignition.

NOTE 1: A clothing system (multiple layers) that includes an outer layer of flame resistant material and aninner layer of non-flame resistant material has been shown to block more heat than a single layer. The effectof the combination of these multiple layers can be referred to as the effective arc rating.

NOTE 2: It is recognized that arc energy levels can be excessive with secondary systems. Applicable workrules required by this part and engineering controls should be utilized.

Supporting Comment

The revision to the first paragraph above is in response to IR 544 dated January 27, 2007. This IR stated thatthe intent of this rule was that a clothing system of blended materials was acceptable provided it had anacceptable effective arc rating.

NOTE 2 is shown to be deleted as the intent of the language is already covered in EXCEPTION 2.




See CP3042.





Negative: (0)


Deleted Text

CP3404


Submitter

R. Paul Barnett

Proposed Change


Effective as of January 1, 2009,For systems with nominal phase voltages below 60 kV, the employer shallensure that an assessment is performed to determine potential exposure to an electric arc for employees whowork on or near energized parts or equipment. If the assessment determines a potential employee exposuregreater than 2 cal/cm2 exists (see Neal, Bingham, and Doughty [B59]), the employer shall requireemployees to wear clothing or a clothing system that has an effective arc rating not less than the anticipatedlevel of arc energy.

When exposed to an electric arc or flame, clothing made from the following materials shall not be worn:acetate, nylon, polyester, or polypropylene.

The effective arc rating of clothing or a clothing system to be worn at voltages 1000 V and above shall bedetermined using Tables 410-1 and 410-2 or performing an arc hazard analysis. The effective arc rating ofclothing or a clothing system to be worn at voltages below 1000 V shall be determined using IEEE Std 1584or NFPA 70E.

When an arc hazard analysis is performed, it shall include a calculation of the estimated arc energy based onthe available fault current, the duration of the arc (cycles), and the distance from the arc to the employee.

For systems with nominal phase voltages 60 kV and above, applicable work rules required by this part andengineering controls shall be utilized to limit exposure. If an employee is working on or near energized partsor equipment, the employer shall require employees to wear clothing or a clothing system with a minimumeffective arc rating of 4 cal/cm2 shall be required to limit the likelihood of ignition.

EXCEPTION 1: If the clothing required by this rule has the potential to create additional and greater hazardsthan the possible exposure to the heat energy of the electric arc, then clothing with an arc rating or arcthermal performance value (ATPV) less than that required by the rule can be worn.



EXCEPTION 2: For secondary systems below 1000 V, applicable work rules required by this part andengineering controls shall be utilized to limit exposure. In lieu of performing an arc hazard analysis, clothingor a clothing system with a minimum effective arc rating of 4 cal/cm2 shall be required to limit thelikelihood of ignition.

NOTE 1: A clothing system (multiple layers) that includes an outer layer of flame resistant material and aninner layer of non-flame resistant material has been shown to block more heat than a single layer. The effectof the combination of these multiple layers can be referred to as the effective arc rating.

NOTE 2: It is recognized that arc energy levels can be excessive with secondary systems. Applicable workrules required by this part and engineering controls should be utilized.

Delete Rule 410A3 Table 410-2.

Supporting Comment

The method for determining arc flash hazard for voltages above 60 kV has not been empirically validated inlaboratory or real world situations. Additionally, factors such as arc convection, wind, and worker positionare not considered in the model. For transmission system voltages, these factors must be included in someform. Additionally, a post-accident investigation of an arc flash event determined the calculations performedsimilar to those of Table 410-2 yielded results that are not consistent with actual hazards. To better protectworkers from a hazard that is unknown, some form of arc flash PPE should be required while performingwork on or in the vicinity of energized equipment. Respectfully, this body is not tasked with developing thetechnical aspects of any procedure to calculate the arc flash hazard on transmission system voltages. The workshould come from the IEEE/PES ESMOL Subcommittee or other consensus organization, or from a generalbody of knowledge that does not currently exist.

The arc flash hazard for system voltages below 1000 V can be excessively high because of close space, highfault currents, and protection methodology. The 4 cal/cm2 clothing system required by the 2007 version ofthis standard is not only inadequate in most cases, but misleading about the true nature of the hazard. Thehazard has been well documented and defined in two consensus documents, IEEE Std 1584 and NFPA 70E.Additionally, these methods have gained national acceptance in their application in industrial, commercial,and generating facilities. This document should recognize the hazard at this voltage level and point the userto these documents.


Reject.


The use of Tables 410-1 and 410-2 is optional and represents reasonable estimates of exposure levels basedon accepted industry work methods.



Negative: (0)




Explanation of Vote

Doering: (Affirmative) (1) Tables 410-1 may be of some use as is IEEE Std 1584 and NFPA 70E for voltagesup to 15 kV. (2) Above 15 kV and Table 410-2 have little or no test data to support. (3) Further, I much preferto assume a typical clearing time (which is reasonable at the higher voltages) and calculate the permissibleapproach distance. (4) Most of the clearing times in Table 410-2 would have the lights out due to instability.(5) See my attached report on the whole subject of arc flash. See comment on CP3042.

Revised Text

CP3143


Submitter

Charles Grose

Proposed Change

Table 410-1—Clothing and clothing systems—voltage, fault current, and maximum clearing time for voltages 1 to 46 kV 1

(See Rule 410A3.)

Phase-to-phase Line-to-line voltage (kV) Fault current (kA)



(cycles)


(cycles)


(cycles)

1 to 15 5 46.5 93.0 139.5

10 18.0 36.1 54.1

15 10.0 20.1 30.1

20 6.5 13.0 19.5

15.1 to 25 5 27.6 55.2 82.8

10 11.4 22.7 34.1

15 6.6 13.2 19.8

20 4.4 8.8 13.2

25.1 to 36 5 20.9 41.7 62.6

10 8.8 17.6 26.5

15 5.2 10.4 15.7

20 3.5 7.1 10.6



1 These calculations are based on open air phase-to-ground line-to-ground arc. This table is not intended for phase-to-phase line-to-line arcs or enclosed arcs (arc in a box).These calculations are based on a 15 in separation distance from the arc to the employee and arc gaps as follows:

1 to 15 kV = 2 in, 15.1 to 25 kV = 4 in, 25.1 to 36 kV = 6 in, 36.1 to 46 kV = 9 in. See IEEE Std 4-1995.

These calculations were derived using a commercially available computer software program. Other methods are avail-able to estimate arc exposure values and may yield slightly different but equally acceptable results.

The use of the table in the selection of clothing is intended to reduce the amount or degree of injury but may not preventall burns.

Supporting Comment

In order to conform with present day industry terminology, the terms “phase-to-phase” is being replaced with“line-to-line” and “phase-to-ground” is being replaced with “line-to-ground.” This change permits the use ofthe term for ac and dc.


Reject.


Phase-to-phase is accepted industry terminology.


Affirmative: (18) Blackley, Bowmer, Brooks, Brubaker, Erga, Granata, Herbinger, Hunt, McKinney,Poholski, Russell, Schweitzer, Shaw, Smoak, Stonerock, Theis, Tomaseski, Tootle

Negative: (3) Doering, Grose, Verdecchio


Explanation of Vote

Doering: (Negative) I accept the original proposal to use “line” rather than “phase.” The AuthoritativeDictionary of IEEE Standards Terms has one and a half pages of words using “line,” of which 18 terms are

36.1 to 46 5 16.2 32.4 48.6

10 7.0 13.9 20.9

15 4.3 8.5 12.8

20 3.0 6.1 9.1

Table 410-1—Clothing and clothing systems—voltage, fault current, and maximum clearing time for voltages 1 to 46 kV 1 (continued)

(See Rule 410A3.)




(cycles)


(cycles)


(cycles)



referring to a physical line conductor in some way, while there are four pages of words using “phase” but onlyone reference referring to the conductor. The term “phase” is generally used with reference to the phase anglein some way. Polyphase circuits have two sets of voltages, line-to-line and line-to-neutral (ground).

Grose: (Negative) The use of phase when referring to line conductors is confusing especially when P is usedfor phase. It can also mean phase or pole. The use of live covers ac and dc.

Tomaseski: (Affirmative) The issue requiring consideration with this CP is the introduction of the terms “line-to-ground” and “line-to-line.” Historically, “phase-to-ground” and “phase-to-phase” have been used both inpublications and in the spoken terms. The submitter of the CP is correct that in dc circuits phase does not exist.So, to be technically correct, “line-to-ground” and “line-to-line” would be the terms to use.

Most linemen do not use these revised terms, but it should not be that difficult in introducing these terms tothe field personnel. What should be considered are the technical aspects of the terms, and the continuity ofterms within industry publications. The minimum approach distance tables in IEEE Std 516, IEEE Guide forMaintenance Work on Energized Power Lines, are being revised with these terms and the NESC minimumapproach distance tables should follow.

Verdecchio: (Negative) The language of phase-to-phase should be the same as IEEE 516 line-to-line.

Revised Text

CP3144


Submitter

Charles Grose

Proposed Change

Table 410-2—Live-line tool work clothing and clothing systems—voltage, fault current, and maximum clearing time for voltages 46.1 to 800 kV 1

(See Rule 410A3.)




(cycles)


(cycles)


(cycles)

46.1 to 72.5 20 8.5 17.0 25.5

30 5.3 10.5 15.8

40 3.7 7.3 11.0

50 2.8 5.5 8.3

72.6 to 121 20 8.2 16.5 24.7



1 Arc gap—calculated by using the phase-to-ground line-to-ground voltage of the circuit and dividing by 10. The di-electric strength of air is taken at 10 kV per in. See IEEE Std 4-1995.

Distance from arc—calculated by using the minimum approach distance from Table 441-2 and subtracting two times

30 4.7 9.4 14.1

40 3.1 6.2 9.3

50 2.2 4.4 6.6

138 to 145 20 9.8 19.5 29.3

30 5.6 11.2 16.8

40 3.7 7.4 11.1

50 2.6 5.3 7.9

161 to 169 20 9.3 18.6 27.9

30 5.7 11.5 17.2

40 4.0 8.0 12.0

50 3.0 6.0 9.0

230 to 242 20 10.4 20.9 31.3

30 6.4 12.9 19.3

40 4.5 9.0 13.5

50 3.4 6.8 10.1

345 to 362 20 22.6 45.3 67.9

30 14.0 28.1 42.1

40 9.8 19.6 29.4

50 7.4 14.7 22.1

500 to 550 20 18.9 37.8 56.7

30 11.7 23.3 35.0

40 8.1 16.3 24.4

50 6.1 12.2 18.3

765 to 800 20 43.6 87.3 130.9

30 27.0 53.9 80.9

40 18.9 37.8 56.7

50 14.2 28.4 42.6

Table 410-2—Live-line tool work clothing and clothing systems—voltage, fault current, and maximum clearing time for voltages 46.1 to 800 kV 1 (continued)

(See Rule 410A3.)




(cycles)


(cycles)


(cycles)



the assumed arc gap length.

These calculations were derived using a commercially available computer software program. Other methods are avail-able to estimate arc exposure values and may yield slightly different, but equally acceptable results.

The use of the table in the selection of clothing is intended to reduce the amount or degree of injury but may not preventall burns.

Supporting Comment



Reject.




Affirmative: (18) Blackley, Bowmer, Brooks, Brubaker, Erga, Granata, Herbinger, Hunt, McKinney,Poholski, Russell, Schweitzer, Shaw, Smoak, Stonerock, Theis, Tomaseski, Tootle

Negative: (3) Doering, Grose, Verdecchio


Explanation of Vote

Doering: (Negative) I accept the original proposal to use “line” rather than “phase.” The AuthoritativeDictionary of IEEE Standards Terms has one and a half pages of words using “line,” of which 18 terms arereferring to a physical line conductor in some way, while there are four pages of words using “phase” but onlyone reference referring to the conductor. The term “phase” is generally used with reference to the phase anglein some way. Polyphase circuits have two sets of voltages, line-to-line and line-to-neutral (ground).


Verdecchio: (Negative) Support IEEE 516 line-to-line and line-to-ground verses phase-to-phase and phase-to-ground in the tables.

New Text

CP3337




Submitter

James T. Collins

Proposed Change

5. Employees shall be required to conduct a Job Briefing before beginning work. A Job Briefingshould include at least the following items: work procedures, personal protective equipmentrequirements, energy source controls, hazards associated with the job, and special precautions.

Supporting Comment

The NESC does not contain a specific requirement to conduct a job briefing. This is a basic safety tool toidentify hazards and ensure that each employee understands the work to be performed.


Accept as modified.

New 421A6

6. Conduct a job briefing with the employees involved before beginning each job. A job briefingshould include at least the following items: work procedures, personal protective equipmentrequirements, energy source controls, hazards associated with the job, and special precautions.

Supporting Comment

The NESC does not contain a specific requirement to conduct a job briefing. This is a basic safety tool toidentify hazards and ensure that each employee understands the work to be performed.


Affirmative: (20) Blackley, Brooks, Brubaker, Doering, Erga, Granata, Grose, Herbinger, Hunt, McKinney,Poholski, Russell, Schweitzer, Shaw, Smoak, Stonerock, Theis, Tomaseski, Tootle, Verdecchio

Negative: (1) Bowmer


Explanation of Vote

Bowmer: (Negative) Although the intent of a job briefing is acceptable, the addition of this rule is notconsidered necessary. It is covered already under Rules 421A1–6. It will be burdensome to single-person jobswhich are completed solely through adequate training. Those small jobs may involve single worker. Smallerelectric supply companies will also be burdened since many smaller companies may have only one or twoemployees. Job briefing implies a documented process that needs to generate an official record which isimpractical. Maybe better placed in Rule 443.



Revised Text

CP3442


Also Section: 3Z535 references SC1









Revised Text

CP3336

Part: 4 Section: 41 411 F2

Submitter

James T. Collins

Proposed Change

2. The employer shall not permit employees the use of 100% leather positioning straps and non-locking snaphooks.

Supporting Comment

The Code should require the use of locking snaphooks in positioning straps. Locking snaphooks are widelyused in the industry and provide employees protection from accidental disengagement.


Accept as modified.

2. The employer shall not permit employees the use of 100% leather positioning straps or non-lockingsnaphooks.




Affirmative: (19) Blackley, Brooks, Brubaker, Doering, Erga, Granata, Grose, Herbinger, Hunt, McKinney,Poholski, Russell, Schweitzer, Shaw, Smoak, Stonerock, Theis, Tomaseski, Tootle

Negative: (2) Bowmer, Verdecchio


Explanation of Vote

Bowmer: (Negative) Non-locking snap hooks are widely used in the telecommunications industry and theyhave proven safe and reliable. Review of the known reported fall incidents have not shown that opening ofthe snap hooks was a problem.

Needing to complete a two-stage process (snap and lock) while climbing a pole can be less safe than a singlestep operation. This change will require a significant increase in cost without a corresponding increase insafety.

At least, the committee should consider phasing in the change in that all newly purchased or supplied beltswill have the locking snap hooks but permitting the use of belts with non-locking snap hooks until they needto be replaced.

Doering: (Affirmative) The subcommittee should consider phasing in the change in that all newly purchasedor supplied belts will have the locking snap hooks but permitting the use of belts with non-locking snaphooks until they need to be replaced.

Verdecchio: (Negative) All climbing must be compliance with ANSI Z359 ASTM 887 standards.

Revised Text

CP3009


Submitter

Brian Erga

Proposed Change

D. Energized or unknown conditions

Employees shall consider electric supply equipment and lines to be energized, unless they arepositively known to be de-energized and grounded. Before starting work, employees shall performpreliminary inspections or tests to determine existing conditions. Operating voltages of equipmentand lines should be known before working on or in the vicinity of energized parts.



Supporting Comment

Electric supply lines and equipment must be considered energized even if they are de-energized and theMAD distance must apply, unless the line or equipment is grounded. Adding the words “and grounded” isconsistent with the industry’s definition.


Reject.


Proposed language impacts more than electric lines and does not consider supply stations. Many worksituations do not require grounding, and grounding may not be practical in all work situations. See Rule 444D.



Negative: (0)


Explanation of Vote

Doering: (Affirmative) Would accept the original proposal if it stated “and meets the groundingrequirements of 444D.” There are times grounding is not required.

Revised Text

CP3338


Submitter

James T. Collins

Proposed Change

6. Snaphooks shall be dimensionally compatible with the member to which they are connected so asto prevent unintentional disengagement of the connection.

NOTE:

(a) The possibility exists for some snaphooks to roll out of D-rings. Attachment of a mismatchedor multiple snaphooks, either of the nonlocking or locking type, to a single D-ring needs toshould be avoided. Multiple locking snaphooks may be attached to a single D-ring if they have



been evaluated in the combination to be used. Locking snaphooks reduce the potential for roll-out.

(b) Disengagement through contact of the snaphook keeper with the connected member may beprevented by the use of a locking snaphook.

(c) Hardware compatibility can be verified. Simply attach the snaphook to the D-ring, then roll thesnaphook placing the latch towards the body of the D-ring. This is similar to the action thatoccurs when the strap is twisted. If the rivet falls beyond the edge of the inside of the D-ring,placing pressure on the latch, the hardware is not compatible, and a roll-out potential exists.

(d) Other factors may increase the potential for accidental disengagement even if the hardware iscompatible (e.g., foreign objects carried on the D-rings, condition of the snaphook, the shape ofthe D-ring).

Supporting Comment



Accept.



Negative: (0)


Revised Text

CP3339


Submitter

James T. Collins

Proposed Change

8. One hundred percent leather positioning straps and non-locking snaphooks shall not be used.



Supporting Comment



Accept as modified.



Revise 420K8

8. One hundred percent leather positioning straps or non-locking snaphooks shall not be used.


Affirmative: (20) Blackley, Brooks, Brubaker, Doering, Erga, Granata, Grose, Herbinger, Hunt, McKinney,Poholski, Russell, Schweitzer, Shaw, Smoak, Stonerock, Theis, Tomaseski, Tootle, Verdecchio

Negative: (1) Bowmer


Explanation of Vote

Bowmer: (Negative) Non-locking snap hooks are widely used in the telecommunications industry and theyhave proven safe and reliable. Review of the known reported fall incidents have not shown that opening ofthe snap hooks were a problem.

Needing to complete a two-stage process (snap and lock) while climbing a pole can be less safe than a singlestep operation. This change will require a significant increase in cost without a corresponding increase insafety.

At least, the committee should consider phasing in the change in that all newly purchased or supplied beltswill have the locking snap hooks but permitting the use of belts with non-locking snap hooks until they needto be replaced.

Doering: (Affirmative) The subcommittee should consider phasing in the change in that all newly purchasedor supplied belts will have the locking snap hooks but permitting the use of belts with non-locking snap hooksuntil they need to be replaced.

Revised Text

CP3043




Submitter

Ewell Robeson

Proposed Change


b. When openings or obstructions in the street, sidewalk, walkways, or on private property are beingworked on or left unattended during the day, danger signals, such as safety warning signs and flags,shall be effectively displayed. Under these same conditions at night, warning lights shall beprominently displayed and excavations shall be enclosed with protective barricades.

Supporting Comment

The word “warning” as it applies to signs is a specific signal word used in ANSI Z535, which providesstandards for safety signs that include the signal words caution, warning, and danger. The use of the word“safety” is inclusive and more appropriate and will be consistent with its use in the Code.


Accept.



Negative: (0)


Revised Text

CP3011

Part: 4 Section: 42 421 B1a

Submitter

Brian Erga

Proposed Change

a. Before engaging in work that may endanger the public, safety signs or traffic control devices, orboth, shall be placed conspicuously to alert approaching traffic. Where further protection is needed,suitable barrier guards shall be erected. Where the nature of work and traffic requires it, a personshall be stationed to warn traffic while the hazard exists. Before any vehicles or equipment requiredfor the work to be preformed are located along public or private roadways, all traffic controlprocedures required by Federal, State, or local jurisdictions shall be implemented.



Supporting Comment

Federal, state, and local jurisdictions have very specific regulations on traffic control and the specifics shouldbe left to others. The requirements of traffic control is outside the scope of this Code.


Reject.


The proposed language does not address pedestrian safety.


Affirmative: (17) Blackley, Bowmer, Brooks, Brubaker, Doering, Granata, Herbinger, Hunt, Poholski,Russell, Shaw, Smoak, Stonerock, Theis, Tomaseski, Tootle, Verdecchio

Negative: (4) Erga, Grose, McKinney, Schweitzer


Explanation of Vote

Erga: (Negative) Current rules do not require Federal, state, and local traffic control procedures.

Grose: (Negative) The present rule needs further clarification, however the CP does not include all aspects.

McKinney: (Negative) The proposed revision allows traffic control decisions to be made by governingtraffic entities. The existing rules may or may not encompass governmental requirements. Therefore we mayoperate with one set of rules from NESC and one from governing entities.

Schweiter: (Negative) The existing rule attempts to be specific but stops without addressing all potentialactions. New language addresses all Fed, state, and local Rules.

Revised Text

CP3010


Submitter

Brian Erga

Proposed Change

B. Area protection

1. Areas accessible to vehicular and pedestrian traffic



b. When Excavations, openings, or obstructions in the streets, sidewalks, walkways, or otherareas accessible to the public on private property shall be properly barricaded to ensuresafety for the public. are being worked on or left unattended during the day, dangersignals, such as warning signs and flags, shall be effectively displayed. Under these sameconditions at night, warning lights shall be prominently displayed and excavations shall beenclosed with protective barricades.

Supporting Comment

The proposed revision provides a better explanation of the need to barricade a construction zone for publicprotection. How the barricading is accomplished is up to the company.


Reject.


Proposed language unnecessarily requires barricading under all conditions.



Negative: (0)


Revised Text

CP3332


Submitter

James T. Collins

Proposed Change


b. When openings or obstructions in the street, sidewalk, walkways, or on private property are beingworked on or left unattended during the day, danger signals, such as safety warning signs and flags,shall be effectively displayed. Under these same conditions at night, warning lights shall beprominently displayed and excavations shall be enclosed with protective barricades.



Supporting Comment

The word “warning” as it applies to signs is a specific signal word used in ANSI Z535, which providesstandards for safety signs that include caution, warning, and danger signal words. The use of the word“safety” is inclusive and more appropriate and will be consistent with its use in the Code.


Accept.





Negative: (0)


Revised Text

CP3012


Submitter

Brian Erga

Proposed Change

2. Contact with trucks, or other equipment that is not bonded to an effective ground being used to set,move, or remove poles in or in the vicinity of energized lines shall be avoided by employeesstanding on the ground or in contact with grounded objects unless employees are wearing suitableprotective equipment. Protection for employees working on or near mechanical equipment used toset, move, or remove poles near energized lines and equipment shall be provided by following therequirements in Rule 446B.

Supporting Comment

Simply grounding a truck or other equipment to an effective ground does not provide effective protection inall cases. Refer to the CP for 446B.


Accept as modified.



2. Contact with trucks, or other equipment that is not bonded to an effective ground being used to set,move, or remove poles in or in the vicinity of energized lines shall be avoided by employeesstanding on the ground or in contact with grounded objects unless employees are wearing suitableprotective equipment.



Negative: (0)


Revised Text

CP3013


Submitter

Brian Erga

Proposed Change

C. Installing and removing wires or cables conductors

1. Precautions shall be taken to prevent wires or cables conductors that are being installed orremoved from contacting energized wires conductors or equipment. Wires or cablesConductors that are not bonded to an effective ground and which are being installed orremoved in the vicinity of near energized conductors shall be considered as being energized.

2. Sag of wire or cables conductors being installed or removed shall be controlled to preventdanger to pedestrian and vehicular traffic.

3. Before installing or removing wires or cables conductors, the strains to which poles andstructures will be subjected shall be considered and necessary action taken to prevent failure ofsupporting structures.

4. Employees should avoid contact with moving winch lines, especially in the vicinity of sheaves,blocks, and take-up drums.

5. Employees working on or in the vicinity of near equipment or lines exposed to voltages higherthan those guarded against by the safety appliances provided shall take steps to be assured thatthe equipment or lines on which the employees are working are free from dangerous leakage orinduction or have been effectively grounded.



Supporting Comment

Rule 422 is titled “Overhead line operating procedures” and cables are considered underground conductorsnot overhead. This proposal recommends the words “wires or cables” be replaced with “conductors.” Also,that term “in the vicinity of” be replaced with “near” to parallel the changes in IEEE Std 516.


Reject.


The current CP proposed language unnecessarily narrows the scope of the Rule to Overhead Electric SupplyLines.



Negative: (0)


Revised Text

CP3432


Submitter

Allen Clapp

Proposed Change

Revise Rule 430 as shown.

430. General

Communications employees shall observe the following rules in addition to the rules contained inSection 42.

Section 43 does not apply to work on communication conductors, cables, or equipment located inthe supply space in accordance with Rule 224. Employees performing work on communicationconductors, cables, or equipment located in the supply space shall comply with the provisions ofthe additional rules for supply employees contained in Section 44, as well as those of Section 42.



Supporting Comment

Rule 224A requires use of the supply space work rules when working on the communication facilities locatedin the supply space. In addition, the necessary requirement of Rule 432 for those working on communicationlines in the communication space to keep all parts of their bodies below the lowest supply conductor is notappropriate when working on communication lines in the supply space.


Reject.


The existing Sections 42 and 44 rules for communication workers are adequate and need no furtherclarification.



Negative: (0)


Revised Text

CP3349


Submitter

Lawrence Slavin

Proposed Change

Delete the word “storm” from Rule 431A, as follows:

431. Approach to energized conductors or parts

A. No employee shall approach, or bring any conductive object, within the distances to any exposedenergized part as listed in Table 431-1. When repairing damage to direct-buried communicationlines that are at random (i.e., less than 12 in) separation from supply cables or when repairing stormdamage to overhead communication lines that are joint use with electric supply lines, at that oranother point, employees shall:

1. Treat all such supply and communication lines as energized to the highest voltage to whichthey are exposed, or



2. Assure that the supply lines involved are de-energized and grounded in accordance withSection 44.

NOTE: Rule 354 provides requirements for random (less than 12 in) separation betweensupply and communication cables.

Supporting Comment

The present change proposal is intended to extend the application of Rules 431A1 and 431A2 to the repair ofdamage to direct-buried communication lines at random separation (i.e., less than 12 in separation) fromsupply cables.


Accept as modified.

Add Rule 431 C.

431. Approach to energized conductors or parts

C. When repairing underground communication lines that are joint use with damaged electric supplycables, employees shall:

1. Treat all such supply and communication lines as energized to the highest voltage to whichthey are exposed, or

2. Assure that the supply lines involved are de-energized and grounded in accordance withSection 44.



Negative: (0)


New Text

CP3388


Submitter

Nelson Bingel

Proposed Change

Add a new Rule 431C, as follows:



C. Insulating bucket trucks and ladders

1. All ladders used by employees to approach communication lines or equipment on overheadstructures containing electric supply lines or equipment shall have insulating side rails.

2. All aerial man-lift apparatus purchased after 28 January 2012 and used by employees toapproach communication lines or equipment on overhead structures containing electric supplylines or equipment shall have insulating buckets and insulating booms.

3. On and after 1 August 2016, all aerial man-lift apparatus used by employees to approachcommunication lines or equipment on overhead structures containing electric supply lines orequipment shall have insulating buckets and insulating booms.

Supporting Comment

A requirement should be added to give the communications utilities 3–5 years to change over to usinginsulated bucket trucks when working on joint-use overhead lines with power and working on any installationwhere the worker can potentially be positioned within 10 ft of an energized power line. We have had entirelytoo many fatal and loss-of-limb accidents that would have been prevented by requiring the use of an insulatedbucket. Power utilities and power utility customers foot the bills for the lack of training and supervision bycommunication utilities and contractors. The litigation hits are exceeding $20 million per instance (notincluding costs of defense), when a plaintiff verdict occurs.

OSHA Regulations contained in 29 CFR 1910.333(c)(3)(iii)(A)(3) allows only aerial lifts insulated for thevoltage involved to be used by a qualified person to approach within the 10 ft zone and requires that theinsulated bucket remain at the minimum approach distances required for the voltage involved. Uninsulatedmetal basket aerial lifts should not be used on joint-use power/communication lines.

OSHA regulations contained in 29 CFR 1910.333(c)(7) and 29 CFR 1926.1053(b)(12) require side rails ofladders used near power lines to be nonconductive.


Reject.


OSHA already requires non-conductive side rails; insulating bucket trucks by themselves will not protectcommunication workers and the proposed changes are already covered by Rule 420J3.



Negative: (0)




Explanation of Vote

Doering: (Affirmative) We could consider adding to 420J2: “Metal ladders shall have side walls insulatedfor the voltage involved.”

Revised Text

CP3181

Part: 4 Section: 43 431 Table 431-1 and footnotes

Submitter

Charles Grose

Proposed Change

(m)

1 For single-phase lines off three-phase systems, use the phase-to-phase line-to-line voltage of that system. 2 For single-phase systems, use the highest voltage available. 3 The data used to calculate Table 431-1(m) was derived from test data taken under standard atmospheric conditions

for dry and clean insulators. Standard atmospheric conditions are defined as temperatures above freezing, wind lessthan 24 km per hr, and normal barometric pressure with unsaturated and uncontaminated air.

Table 431-1—Communication work minimum approach distances (See Rule 431 in its entirety.)

Voltage range phase-to-phase

line-to-line (rms)1 Distance to employee at altitudes from sea level to 3600 m

0 to 50 V 2 Not specified

51 to 300 V 2 Avoid contact

301 to 750 V 2 0.31 m

751 V to 15 kV 0.65 m

15.1 kV to 36 kV 0.91 m

36.1 kV to 46 kV 1.06 m

46.1 kV to 72.5 kV 1.22 m

Voltage rangephase-to-phase

line-to-line (rms)1

At altitudes from

0 to 900 m 90 to 1800 m 1801 to 3600 m

72.6 to 121 kV 1.43 m 1.50 m 1.64 m

121.1 to 169 kV 1.75 m 1.85 m 2.04 m

169.1 to 362 kV 3.70 m 3.95 m 4.48 m

362.1 to 800 kV 7.19 m 7.72 m 8.84 m



(ft)

1 For single-phase lines off three-phase systems, use the phase-to-phase line-to-line voltage of that system.

2 For single-phase systems, use the highest voltage available.

3 The data used to calculate Table 431-1(ft) was derived from test data taken under standard atmospheric conditionsfor dry and clean insulators. Standard atmospheric conditions are defined as temperatures above freezing, wind lessthan 15 mi per hr, and normal barometric pressure with unsaturated and uncontaminated air.

Supporting Comment

In order to conform with present day industry terminology, the terms “phase-to-phase” is being replacedwith “line-to-line” and “phase-to-ground” is being replaced with “line-to-ground.” This change permits theuse of the term for ac and dc.


Reject.



Table 431-1—Communication work minimum approach distances(See Rule 431 in its entirety.)


line-to-line (rms) 1 Distance to employee at altitudes from sea level to 12 000 ft



301 to 750 V 2 1 ft-0 in

751 V to 15 kV 2 ft-2 in

15.1 kV to 36 kV 3 ft-0 in

36.1 kV to 46 kV 3 ft-6 in

46.1 kV to 72.5 kV 4 ft-0 in


line-to-line (rms) 1

At altitudes from

0 to 3000 ft 3001 to 6000 ft 6001 to 12 000 ft

72.6 kV to 121 kV 4 ft-9 in 4 ft-11 in 5 ft-5 in







Affirmative: (18) Blackley, Bowmer, Brooks, Brubaker, Doering, Erga, Granata, Herbinger, Hunt,McKinney, Poholski, Russell, Shaw, Smoak, Stonerock, Theis, Tomaseski, Tootle

Negative: (3) Grose, Schweitzer, Verdecchio


Explanation of Vote

Doering: (Affirmative) See comment on CP3200.


Schweitzer: (Negative) Support of the change to IEEE 516 standards. Phase-to-phase applies to ac voltages,table applies to both dc and ac.

Tomaseski: (Affirmative) This CP should be carefully reviewed. More specifically, Table 431-1 providesminimum approach distances (MAD) for communications employees. The three highest MAD distances arebeing reduced because of revisions IEEE Std 516, IEEE Guide for Maintenance Methods on Energized PowerLines. These distances are based on minimum air insulation distance (MAID) calculations similar to the 441series of MAD tables. Changes to IEEE Std 516 are being made because of, in part, to an error that wasdiscovered in the equations used to calculate MAID.

What is important to consider with Table 431-1 is who it is designed for. Communications workers do notobtain or are required to obtain the same level of electrical training as the workers covered under Section 44—supply employees. While it is understandable that the errors in the calculation methods utilized in IEEEStd 516 need to be corrected, is it necessary or logical to reduce the MAD for communication workers?

The following chart compares current and proposed MAD distances for Tables 431-1 and 441-1.

At a minimum, the distances in Table 431-1 should not be reduced. If anything, it would seem logical forMAD distances designed to protect communications workers the distances should be greater than they are,especially compared to the current and proposed distances for supply workers.

Verdecchio: (Negative) Support IEEE 516 line-to-line and line-to-ground versus phase-to-phase and phase-to-ground in the tables.

CurrentTable 431-1

ProposedTable 431-1

CurrentTable 441-1

ProposedTable 441-1

0 to 50 V 2 Not specified Not specified Not specified Not specified

51 to 300 V 2 Avoid contact Avoid contact Avoid contact Avoid contact

301 to 750 V 2 1 ft-0 in 1 ft-0 in 1 ft-0 in 1 ft-0 in

751 V to 15 kV 2 ft-2 in 2 ft-3 in 2 ft-2 in 2 ft-2 in

15.1 kV to 36 kV 3 ft-0 in 2 ft-10 in 2 ft-7in 2 ft-5 in

36.1 kV to 46 kV 3 ft-6 in 3 ft-1in 2 ft-9 in 2 ft-7 in

46.1 kV to 72.5 kV 4 ft-0 in 3 ft-9 in 3 ft-3 in 2 ft-11 in



Revised Text

CP3200

Part: 4 Section: 43 431 Table 431-1 and footnotes

Submitter

Charles Grose

Proposed Change

(m)

1 For single-phase lines off of a three-phase systems, use the phase-to-phaseline-to-line voltage of that system.


3 The data used to calculate Table 431-1(m) was derived from test data taken under standard atmospheric conditionsfor dry and clean insulators. Standard atmospheric conditions are defined as temperatures above freezing, wind lessthan 24 km per hr, and normal barometric pressure with unsaturated and uncontaminated air.


Voltage range phaseline-to-phaseline (rms)1 Distance to employee at altitudes from sea level to 3600 m



301 to 750 V 2 0.31 m

751 V to 15 kV 0.65 m

15.1 kV to 36 kV 0.91 m

36.1 kV to 46 kV 1.06 m

46.1 kV to 72.5 kV 1.22 m

Voltage range phaseline-to-phaseline (rms)1

At altitudes from

0 to 900 m 90 to 1800 m 1801 to 3600 m

72.6 to 121 kV 1.431.36 m 1.501.42 m 1.64155 m

121.1 to 169 kV 1.751.66 m 1.851.75 m 2.041.93 m

169.1 to 362 kV 3.703.43 m 3.953.66 m 4.484.14 m

362.1 to 800 kV 7.196.35 m 7.726.81 m 8.847.79 m



(ft)

1 For single-phase lines off of a three-phase systems, use the phase-to-phaseline-to-line voltage of that system. 2 For single-phase systems, use the highest voltage available. 3 The data used to calculate Table 431-1(ft) was derived from test data taken under standard atmospheric conditions

for dry and clean insulators. Standard atmospheric conditions are defined as temperatures above freezing, wind lessthan 15 mi per hr, and normal barometric pressure with unsaturated and uncontaminated air.

Supporting Comment

1. Table has been adjusted to conform with the latest edition of IEEE Std 516.

2. In order to conform with present day industry terminology, the terms “phase-to-phase” is being replacedwith “line-to-line” and “phase-to-ground” is being replaced with “line-to-ground.” This change permits theuse of the term for ac and dc.


Reject.


Numerical values are not based on an approved standard. See CP3143 on the verbiage of line-to-line.

The Subcommittee welcomes further comments on IEEE Std 516 once approved.


Voltage range phaseline-to-phaseline (rms)1 Distance to employee at altitudes from sea level to 12 000 ft



301 to 750 V 2 1 ft-0 in

751 V to 15 kV 2 ft-2 in

15.1 kV to 36 kV 3 ft-0 in

36.1 kV to 46 kV 3 ft-6 in

46.1 kV to 72.5 kV 4 ft-0 in

Voltage range phaseline-to-phaseline (rms)1

At altitudes from

0 to 3000 ft 3001 to 6000 ft 6001 to 12 000 ft




362.1 kV to 800 kV 23 20 ft-8 10 in 2522 ft-4 in 2925 ft-70 in




Affirmative: (14) Blackley, Bowmer, Doering, Granata, Herbinger, Hunt, McKinney, Poholski, Russell,Shaw, Smoak, Stonerock, Theis, Tootle

Negative: (4) Brubaker, Erga, Grose, Tomaseski


Explanation of Vote

Brubaker: (Negative) I would have preferred to see “Accept in principle” in order to facilitate more commentsfrom affected public once the final version of IEEE Std 516 is approved. The table includes some changes theare very small but rejecting these changes brings into question accepting changes that all more substantive.

Doering: (Affirmative) The communication tables should be based on Tables 441-1 and 441-2, plus a seriesof inadvertent movement factors: 750 V 0 ft, 15 kV 0 ft, 36 kV 5 in, 46 kV 9 in, 72.5 kV 9 in, 121 kV 1 ft-5 in, 169 kV 1 ft-9 in, 362 kV 3 ft-1 in, 800 kV 7 ft-9 in.

The change in the approach distances opens up a major question, where do they come from? It would seemto me that we should start with the MAID distance and add a unique, inadvertent movement factor forqualified communication workers. It could be a single value, or vary with voltage level. Note, I would expectunqualified communication workers to observe the “10 ft rule” seen in OSHA regulations. This type ofapproach distance table (431-1) in the NESC first appeared in the 1990 NESC. This latter table appears inOSHA 1910.268 Telecommunications, but I do not know when it first appeared in the OSHA tables. Maybethe answer to the above lies in some Telecom standard that I am not familiar with.

Erga: (Negative) To support the wording used in IEEE Std 516 and to keep the NESC C-2 Code consistentwith IEEE Std 516.

Grose: (Negative) To support the wording used in IEEE Std 516 and to keep the NESC C-2 Code consistentwith IEEE Std 516.

Tomaseski: (Negative) The issue requiring consideration with this CP is the introduction of the terms “line-to-ground” and “line-to-line.” Historically, “phase-to-ground” and “phase-to-phase” have been used both inpublications and in the spoken terms. The submitter of the CP is correct that in dc circuits phase do not exist.So, to be technically correct, “line-to-ground” and “line-to-line” would be the terms to use.

Most linemen do not use these revised terms, but it should not be that difficult in introducing these terms tothe field personnel. What should be considered are the technical aspects of the terms, and the continuity ofterms within industry publications. The minimum approach distance tables in IEEE Std 516, IEEE Guide forMaintenance Work on Energized Power Lines, is being revised with these terms and the NESC minimumapproach distance tables should follow.

Revised Text

CP3195




Submitter

Charles Grose

Proposed Change

441. Energized conductors or parts

Employees shall not approach, or knowingly permit others to approach, any exposed ungrounded partnormally energized except as permitted by this rule.

A. Minimum approach distance (MAD) to live parts

1. General

Employees shall not approach or bring any conductive object within the minimum approachdistance (MAD) listed in Table 441-1 or 441-4 to exposed parts unless one of the following ismet:

a. The line or part is de-energized and grounded per Rule 444D.

b. The employee is insulated from the energized line or part. Electrical protective equipmentinsulated for the voltage involved, such as tools, gloves, rubber gloves, or rubber gloveswith sleeves, shall be considered effective insulation for the employee from the energizedpart being worked on.

c. The energized line or part is insulated from the employee and from any other line or part ata different voltage.

d. The employee is performing barehand live-line work according to Rule 446.

e. When air is the insulating medium, the minimum air insulation distance (MAID) shall bepresent to prevent a flashover of the air insulation at the worksite.

f. When insulated tools which are not subject to inadvertent movement are used in the airgap, minimum tool insulation distance (MTID) shall be used to determine the minimumclear insulation of the tool.

g. When insulated tools which are subject to inadvertent movement are used in the air gap,MAD for Tools insulation distance shall be used to determine the minimum clearinsulation of the tool.

2. Precautions for approach—Voltages from 51 V to 300 V

Employees shall not contact exposed energized parts operating at 51 V to 300 V, unless theprovisions of Rule 441A1 are met.

3. Precautions for approach—Voltages from 301 V to 72.5 kV

At voltages from 301 V to 72.5 kV, employees shall be protected from phase-to-phase line-to-line and phase-line-to-ground differences in voltage. See Table 441-1 for the minimumapproach distances to live parts.



a. When exposed grounded lines, conductors, or parts are in the work area, they shall beguarded or insulated.

b. When the Rubber Glove Work Method is employed, rubber insulating gloves, insulatedfor the maximum use voltage as listed in Table 441-6, shall be worn whenever employeesare within the reach or extended reach of the minimum approach distances listed in Table441-1, supplemented by one of the following two protective methods:

(1) The employee shall wear rubber insulating sleeves, insulated for the maximum usevoltage as listed in Table 441-6, in addition to the rubber insulating gloves.

EXCEPTION: When work is performed on electric supply equipment energized at750 V or less, rubber sleeves are not required if only the live parts being worked onare exposed.

(2) All exposed energized lines or parts, other than those temporarily exposed to performwork and maintained under positive control, located within maximum reach of theemployee’s work position, shall be covered with insulating protective equipment.

EXCEPTION: When work is being performed on parts energized between 300 V and750 V within enclosed spaces, (e.g., control panels and relay cabinets), insulating orguarding of all exposed grounded lines, conductors, or parts in the work area is notrequired provided that employees use insulated tools and/or gloves and that exposedgrounded lines, conductors, or parts are covered to the extent feasible.

c. When the Rubber Glove Work Method is employed at voltages above 15 kV phase-to-phaseline-to-line, supplementary insulation (e.g., insulated aerial device or structure-mounted insulating work platform), tested for the voltage involved shall be used tosupport the worker.

d. Cover-up equipment used to insulate phase-to-phaseline-to-line exposure shall be ratedfor not less than the phase-to-phaseline-to-line voltage of the circuit(s) in the work area.All other cover-up equipment shall be rated for not less than the phaseline-to-groundvoltage of the circuit(s). The determination of whether phase-to-phaseline-to-line orphaseline-to-ground exposure exists shall be based on factors such as but not limited to:work rules, conductor spacing, worker position, and task being performed.

e. Cover-up equipment, when used, shall be applied to the exposed facilities as the employeefirst approaches the facilities from any direction, be that from the structure or from anaerial device, and shall be removed in the reverse order. This protective cover-up shallextend beyond the reach of the employee’s anticipated work position or extended reachdistance.

4. Precautions for approach above 72.5 kV

The minimum approach distance (distance to employee) for live work is determined by therequirements in Rule 441A4a or 441A4b. If the requirements in Rule 441A4b cannot be met intheir entirety, Rule 441A4a shall be used.

a. For work on exposed parts operating at phase-to-phaseline-to-line voltage above 72.5 kV,where the maximum anticipated per-unit overvoltage factor (T) at the worksite has notbeen determined by the line operator using an engineering analysis, the ac live workminimum approach distances (distance to employee) in Tables 441-2, 441-3, and 441-4shall be used with a T of 3.0 for voltages up to 362.0 kV, 2.4 for voltages between



362.1 kV and 550.0 kV, and 2.0 for 550.1 kV to 800 kV. However, if the system isprotected by single break interrupter devices, the ac live work minimum approachdistances (MAD) (distance to employee) in Tables 441-2, 441-3, and 441-4 shall be usedwith the maximum T for the specific voltage.

b. For work on exposed parts operating at phase-to-phaseline-to-line voltage above 72.5 kV,where the T at the worksite has been determined by the line operator using an engineeringanalysis the live work minimum approach distances (MAD) (distance to employee) inTables 441-2, 441-3, and 441-4 may be used with the determined value of T, providingthat all of the following conditions are met.

EXCEPTION: If a temporary (transient) overvoltage control device (TTOCD), as definedin Rule 441A6, has been installed adjacent to the worksite to limit the maximum worksitemaximum anticipated overvoltage (TOV), the value of the T to be used to determine thelive work minimum approach distance in Tables 441-2, 441-3, and 441-4 shall be the Tvalue determined in Rule 441A5 or the maximum anticipated per-unit overvoltage factorof the TTOCD (TTTOCD) value obtained from Rule 441A6, plus 0.2 p.u., whichever issmaller. When installing or removing the TTOCD adjacent to the worksite, the T valuedetermined by the line operator’s engineering analysis shall be used.

(1) All of the equipment evaluated in determining the T value by the line operator’sengineering analysis shall be operational.

(2) Automatic reclosing shall be disabled at all terminals of the line on which live work isbeing performed.

EXCEPTION: If required for system stability, one high-speed automatic reclose maybe permitted, providing that the circuit interrupters or isolating devices to be reclosedcannot produce at the worksite an overvoltage value exceeding the value of the Tbeing used at the worksite. This value shall be determined from an the line operator’sengineering analysis.

(3) The altitude corrections according to Rule 441A6b shall be used when the elevationof the worksite is above 900 m (3000 ft) above sea level.

(4) For dc work, the relative humidity at the worksite shall be less than 85%.

5. Temporary (transient) overvoltage control device (TTOCD)

TTOCD, which are designed and tested for installation adjacent to the worksite to limit theTOV at the worksite, may be used to obtain a lower value of T.

An engineering analysis, including laboratory testing, of the TTOCD shall be performed todetermine and identify the range of sparkover voltages. The withstand and sparkovercharacteristics of a TTOCD are determined by sparkover probability data for the particularprotective gap geometry, gap distance, and conductor bundle geometry. The TOV rating forthe TTOCD device shall be determined from test data and shall be the voltage at which thedevice sparks over 50% of the time. The TTTOCD is calculated by dividing the TOV rating ofthe device by nominal peak voltage rounded-up to one decimal place.

As an example of determining TTTOCD, for a line operating at 345 kV, using TTOCD whichhas been installed adjacent to the worksite to limit the maximum worksite TTTOCD, having aTOV rating of 510 kV:



TTTOCD = 510 / (( ) / 1.732)

TTTOCD = 510 / 295.53 = 1.72 or 1.8

6. Altitude correction

Altitude correction shall be applied to all working distances when working on lines andequipment operated above 72.5kV line-to-line.

The distances in Tables 441-2, 441-3, and 441-4 shall be used at elevations below 900 m(3000 ft). Above that altitude, the minimum approach distance shall be increased by:

When the worksite altitudes is above 900 m (3000 ft), the MAID and MTID distance shall beadjusted by multiplying the electrical component of the minimum approach distance by theapplicable altitude correction factors of Table 441-5. The MAD distance shall be calculated byadding the inadvertent factor required by rule 441A7a to the altitude corrected MAID distance.The MAD for Tools distance shall be calculated by adding the inadvertent factor required byRule 441A7a to the altitude corrected MTID distance.

a. Multiplying the electrical component of the minimum approach distance by the applicablealtitude correction factors of Table 441-5, and

b. Adding the result to the values for inadvertent movement required by Rule 441A7a.

NOTE: The electrical component of clearance included in Tables 441-2, 441-3, and 441-4is the table value less the value for inadvertent movement for that voltage shown in Rule441A7a.

7. Determining the minimum approach distances (MAD and MAD for Tools) (distances toemployee)

a. Minimum approach distances (MAD) calculated under this rule for 0.301 kV to 0.750 kVcontain the electrical component plus 0.30 m (1 ft) for inadvertent movement. Voltages0.751 kV to 72.5 kV contain the electrical component plus 0.61 m (2 ft) for inadvertentmovement. Above 72.5 kV, the inadvertent movement distance is 0.31 m (1 ft) and isapplied to both the MAD and MAD for Tools distances.

b. Data for minimum approach distances MAID between 1.1 and 72.5 kV shown in Table441-1 was obtained from rod gap data measured in metric units; the values in Table 441-1are derived from metric and converted to feet and inches.

c. Data for minimum approach distancesMAID above 72.5 kV shown in Tables 441-2, 441-3, and 441-4 was taken from IEEE Std 516-2003. In IEEE Std 516-2003, the customaryunit tables are calculated in feet to two decimal places. The second decimal place isrounded up if the third decimal place is other than zero. The metric tables were calculatedfrom the ft tables and rounded up to two decimal places, using a conversion factor of0.3048 m per ft. For this reason, the customary-unit tables do not exactly convert into thevalues shown in the metric tables.

d. The voltage ranges are contained in ANSI C84.1-1995, Table 1.

B. Additional approach requirements

362 1.414⋅



1. The MTID (clear insulation distance) associated with insulators shall be the shortest straight-line air-gap distance from the nearest energized part to the nearest grounded part.

2. When working on insulators under live work procedures employing rubber gloves or live-linetools, the clear insulation distance shall be not less than the straight-line distance in air requiredby Rule 441A4.

3. Work may be performed at the grounded end of an open switch if all of the followingconditions are met:

a. The air-gap distance of the switch shall not be reduced in any manner. This distance shallbe not less than the minimum approach distances determined by Rules 441A2, 441A3, and441A4 less the inadvertent movement values. The inadvertent movement values of Rule441A7(a) are not required in this distance.

b. The minimum approach distance to the energized part of the switch shall be not less thanthat required by Rules 441A2, 441A3, and 441A4.

4. Special rules for working on insulator assemblies operating above 72.5 kV

a. When work is to be performed at the ground end of an insulator assembly, the minimumapproach distance to the nearest energized part may equal the straight-line distancemeasured along the insulators.

b. For suspension insulator assembly installations (see ANSI C29.2-1992) operating above72.5 kV (ac), the first insulator at the grounded end may be temporarily shorted out as partof the work procedure. Before temporarily shorting out any insulator units, as part of thework procedure, each of the insulator units in the string shall be tested to determine thenumber and location of any failed units.

EXCEPTION: For voltages at 230 kV (ac) and above, up to three insulator units may betemporarily shorted out as part of the work procedure, provided that the minimumapproach distance requirements of Rule 441A4 are met.

c. When performing live work employing the barehand technique on installations operatingabove 72.5 kV (ac), the first insulator at the energized (hot) end of a suspension insulatorassembly (see ANSI C29.2-1992) may be shorted out during the work. Before temporarilyshorting out any insulator units, as part of the work procedure, each of the insulator unitsin the string shall be tested to determine the number and location of any failed units.


(1) The minimum approach distance (MAD) to the grounded end of the insulatorassembly may be equal to the straight-line distance from the nearest energized part tothe closest grounded part across the insulators.

(2) The straight-line insulation distance shall be not less than the values required by Rule441A4.

C. MTID and MAD for Tools (Live-line tool clear insulation length)

1. Clear live-line tool MTID and MAD for Tools length



The MTID and MAD for Tools clear live-line tool distance shall be not less than the distancemeasured longitudinally along the live-line tool from the conductive part at the working end ofthe tool and any part of the employee. Distances for conducting sections (such as metallicsplices and hardware) shall be subtracted from the clear live-line length. The MTID and MADfor Tools clear live-line tool length shall equal or exceed the values for the minimum approachdistance in Tables 441-1, 441-2, 441-3, and 441-4 for the indicated voltage ranges. Theminimum clear live-line tool distance shall be the distance measured longitudinally along thelive-line tool from the conductive part at the working end of the tool to any part of theemployee.

2. Live-line conductor support tool length

Conductor support tools such as link sticks, strain carriers, and insulator cradles may be usedprovided that the clear insulating distance is at least as long as the insulator string or themaximum distance specified in Rule 441A4. When installing this equipment, the employeeshall maintain the minimum approach distance (MAD) required equal to the MTID and MADfor Tools clear insulating length for the support tools.

NOTE: Conductive components of tools disturb the field in the gap and decrease the insulationvalue of the tool more than the linear subtraction of the length(s) of the conductivecomponents.

Supporting Comment

1. The text has been adjusted to conform with the latest edition of IEEE Std 516. The addition of the MAID,MTID, MAD, and MAD for Tools gives the user additional choices. Previous editions of the NESC onlylisted the “Mad for Tools” distance. The NESC MAD is therefore different from the IEEE 516 MAD.

2. The present text does not designate who should determine T. Only the line operator has enough data andinformation required to make this determination. For this rule, the line operator is the organization that hascontrol and jurisdiction of the line.



Reject.


CP was offered in support of CP3197, which was rejected. Additional language revisions are unnecessary ascurrent Code language is acceptable.


Affirmative: (20) Blackley, Bowmer, Brooks, Brubaker, Doering, Erga, Granata, Herbinger, Hunt,McKinney, Poholski, Russell, Schweitzer, Shaw, Smoak, Stonerock, Theis, Tomaseski, Tootle, Verdecchio

Negative: (1) Grose




Explanation of Vote

Doering: (Affirmative) The tables listed in A1 are not MAD tables or are they? A1e and f are acceptable, butA1g should read to use MAD for air with the understanding that a value of inadvertent movement should beadded as the job dictates. This will permit developing a “universal” table without forcing to observe toolclearances for situations where only air is involved.

Grose: (Negative) The reference to IEEE Std 516 does allow the use of the addition distances under the Codesince they are not part of the rule. These additional distances are necessary if you are going to have aneffective live maintenance program.

Revised Text

CP3196


Submitter

Charles Grose

Proposed Change



A. Minimum approach distance (MAD) to live parts

1. General

Employees shall not approach or bring any conductive object within the minimum approachdistance (MAD) listed in Table 441-1 or 441-4 to exposed parts unless one of the following ismet:





2. Precautions for approach—Voltages from 51 V to 300 V



Employees shall not contact exposed energized parts operating at 51 V to 300 V, unless theprovisions of Rule 441A1 are met.

3. Precautions for approach—Voltages from 301 V to 72.5 kV At voltages from 301 V to 72.5kV, employees shall be protected from phase-to-phase line-to-line and phase line-to-grounddifferences in voltage. See Table 441-1 for the minimum approach distances to live parts.

a. When exposed grounded lines, conductors, or parts are in the work area, they shall beguarded or insulated.

b. When the Rubber Glove Work Method is employed, rubber insulating gloves, insulatedfor the maximum use voltage as listed in Table 441-6, shall be worn whenever employeesare within the reach or extended reach of the minimum approach distances listed in Table441-1, supplemented by one of the following two protective methods:

(1) The employee shall wear rubber insulating sleeves, insulated for the maximum usevoltage as listed in Table 441-6, in addition to the rubber insulating gloves.

EXCEPTION: When work is performed on electric supply equipment energized at750 V or less, rubber sleeves are not required if only the live parts being worked onare exposed.

(2) All exposed energized lines or parts, other than those temporarily exposed to performwork and maintained under positive control, located within maximum reach of theemployee’s work position, shall be covered with insulating protective equipment.

EXCEPTION: When work is being performed on parts energized between 300 V and750 V within enclosed spaces, (e.g., control panels and relay cabinets), insulating orguarding of all exposed grounded lines, conductors, or parts in the work area is notrequired provided that employees use insulated tools and/or gloves and that exposedgrounded lines, conductors, or parts are covered to the extent feasible.

c. When the Rubber Glove Work Method is employed at voltages above 15 kV phase-to-phase line-to-line, supplementary insulation (e.g., insulated aerial device or structure-mounted insulating work platform), tested for the voltage involved shall be used tosupport the worker.

d. Cover-up equipment used to insulate phase-to-phaseline-to-line exposure shall be rated fornot less than the phase-to-phaseline-to-line voltage of the circuit(s) in the work area. Allother cover-up equipment shall be rated for not less than the phaseline-to-ground voltageof the circuit(s). The determination of whether phase-to-phaseline-to-line or phaseline-to-ground exposure exists shall be based on factors such as but not limited to: work rules,conductor spacing, worker position, and task being performed.

e. Cover-up equipment, when used, shall be applied to the exposed facilities as the employeefirst approaches the facilities from any direction, be that from the structure or from anaerial device, and shall be removed in the reverse order. This protective cover-up shallextend beyond the reach of the employee’s anticipated work position or extended reachdistance.





a. For work on exposed parts operating at phase-to-phase line-to-line voltage above 72.5 kV,where the maximum anticipated per-unit overvoltage factor (T) at the worksite has notbeen determined by the line operator using an engineering analysis, the ac live workminimum approach distances (distance to employee) in Tables 441-2, 441-3, and 441-4shall be used with a T of 3.0 for voltages up to 362.0 kV, 2.4 for voltages between362.1 kV and 550.0 kV, and 2.0 for 550.1 kV to 800 kV. However, if the system isprotected by single break interrupter devices, the ac live work minimum approachdistances (MAD) (distance to employee) in Tables 441-2, 441-3, and 441-4 shall be usedwith the maximum T for the specific voltage.

b. For work on exposed parts operating at phase-to-phase line-to-line voltage above 72.5 kV,where the T at the worksite has been determined by the line operator using an engineeringanalysis, the live work minimum approach distances (MAD) (distance to employee) inTables 441-2, 441-3, and 441-4 may be used with the determined value of T, providingthat all of the following conditions are met.

EXCEPTION: If a temporary (transient) overvoltage control device (TTOCD), as definedin Rule 441A6, has been installed adjacent to the worksite to limit the maximum worksitemaximum anticipated overvoltage (TOV), the value of the T to be used to determine thelive work minimum approach distance in Tables 441-2, 441-3, and 441-4 shall be the Tvalue determined in Rule 441A5 or the maximum anticipated per-unit overvoltage factorof the TTOCD (TTTOCD) value obtained from Rule 441A6, plus 0.2 p.u., whichever issmaller. When installing or removing the TTOCD adjacent to the worksite, the T valuedetermined by engineering analysis shall be used.



EXCEPTION: If required for system stability, one high-speed automatic reclose maybe permitted, providing that the circuit interrupters or isolating devices to be reclosedcannot produce at the worksite an overvoltage value exceeding the value of the Tbeing used at the worksite. This value shall be determined from the line operator’s anengineering analysis.

(3) The altitude corrections according to Rule 441A6b shall be used when the elevationof the worksite is above 900 m (3000 ft) above sea level.


5. Temporary (transient) overvoltage control device (TTOCD)

TTOCD, which are designed and tested for installation adjacent to the worksite to limit theTOV at the worksite, may be used to obtain a lower value of T.

An engineering analysis, including laboratory testing, of the TTOCD shall be performed todetermine and identify the range of sparkover voltages. The withstand and sparkovercharacteristics of a TTOCD are determined by sparkover probability data for the particular



protective gap geometry, gap distance, and conductor bundle geometry. The TOV rating forthe TTOCD device shall be determined from test data and shall be the voltage at which thedevice sparks over 50% of the time. The TTTOCD is calculated by dividing the TOV rating ofthe device by nominal peak voltage rounded-up to one decimal place.

As an example of determining TTTOCD, for a line operating at 345 kV, using TTOCD whichhas been installed adjacent to the worksite to limit the maximum worksite TTTOCD, having aTOV rating of 510 kV:

TTTOCD = 510 / (( ) / 1.732)

TTTOCD = 510 / 295.53 = 1.72 or 1.8

6. Altitude correction

Altitude correction shall be applied to all working distances when working on lines andequipment operated above 72.5 kV line-to-line.

The distances in Tables 441-2, 441-3, and 441-4 shall be used at elevations below 900 m(3000 ft). Above that altitude, the minimum approach distance shall be increased by:

a. Multiplying the electrical component of the minimum approach distance by the applicablealtitude correction factors of Table 441-5, and

b. Adding the result to the values for inadvertent movement required by Rule 441A7a.

NOTE: The electrical component of clearance included in Tables 441-2, 441-3, and 441-4is the table value less the value for inadvertent movement for that voltage shown in Rule441A7a.

7. Determining the minimum approach distances (MAD) (distances to employee)

a. Minimum approach distances (MAD) calculated under this rule for 0.301 kV to 0.750 kVcontain the electrical component plus 0.30 m (1 ft) for inadvertent movement. Voltages0.751 kV to 72.5 kV contain the electrical component plus 0.61 m (2 ft) for inadvertentmovement. Above 72.5 kV, the inadvertent movement distance is 0.31 m (1 ft) and isapplied to the MAD distance.

b. Data for minimum approach distances (MAD) between 1.1 and 72.5 kV shown in Table441-1 was obtained from rod gap data measured in metric units; the values in Table 441-1are derived from metric and converted to feet and inches.

c. Data for minimum approach distances (MAD) above 72.5 kV shown in Tables 441-2,441-3, and 441-4 was taken from IEEE Std 516-2003. In IEEE Std 516-2003 thecustomary unit tables are calculated in feet to two decimal places. The second decimalplace is rounded up if the third decimal place is other than zero. The metric tables werecalculated from the ft tables and rounded up to two decimal places, using a conversionfactor of 0.3048 m per ft. For this reason, the customary-unit tables do not exactly convertinto the values shown in the metric tables.


B. Additional approach requirements

362 1.414⋅



1. The clear insulation distance associated with insulators shall be the shortest straight-line air-gap distance from the nearest energized part to the nearest grounded part.

2. When working on insulators under live work procedures employing rubber gloves or live-linetools, the clear insulation distance shall be not less than the straight-line distance in air requiredby Rule 441A4.

3. Work may be performed at the grounded end of an open switch if all of the followingconditions are met:

a. The air-gap distance of the switch shall not be reduced in any manner. This distance shallbe not less than the minimum approach distances determined by Rules 441A2, 441A3,and 441A4 less the inadvertent movement values. The inadvertent movement values ofRule 441A7(a) are not required in this distance.

b. The minimum approach distance to the energized part of the switch shall be not less thanthat required by Rules 441A2, 441A3, and 441A4.

4. Special rules for working on insulator assemblies operating above 72.5 kV

a. When work is to be performed at the ground end of an insulator assembly, the minimumapproach distance to the nearest energized part may equal the straight-line distancemeasured along the insulators.

b. For suspension insulator assembly installations (see ANSI C29.2-1992) operating above72.5 kV (ac), the first insulator at the grounded end may be temporarily shorted out as partof the work procedure. Before temporarily shorting out any insulator units, as part of thework procedure, each of the insulator units in the string shall be tested to determine thenumber and location of any failed units.


c. When performing live work employing the barehand technique on installations operatingabove 72.5 kV (ac), the first insulator at the energized (hot) end of a suspension insulatorassembly (see ANSI C29.2-1992) may be shorted out during the work. Before temporarilyshorting out any insulator units, as part of the work procedure, each of the insulator unitsin the string shall be tested to determine the number and location of any failed units.


(1) The minimum approach distance (MAD) to the grounded end of the insulatorassembly may be equal to the straight-line distance from the nearest energized part tothe closest grounded part across the insulators.

(2) The straight-line insulation distance shall be not less than the values required by Rule441A4.

C. Live-line tool clear insulation length

1. Clear live-line tool length



The clear live-line tool distance shall be not less than the distance measured longitudinallyalong the live-line tool from the conductive part at the working end of the tool and any part ofthe employee. Distances for conducting sections (such as metallic splices and hardware) shallbe subtracted from the clear live-line length. The clear live-line tool length shall equal orexceed the values for the minimum approach distance in Tables 441-1, 441-2, 441-3, and 441-4 for the indicated voltage ranges. The minimum clear live-line tool distance shall be thedistance measured longitudinally along the live-line tool from the conductive part at theworking end of the tool to any part of the employee.

2. Live-line conductor support tool length

Conductor support tools such as link sticks, strain carriers, and insulator cradles may be usedprovided that the clear insulating distance is at least as long as the insulator string or themaximum distance specified in Rule 441A4. When installing this equipment, the employeeshall maintain the minimum approach distance (MAD) required equal to the clear insulatinglength for the support tools.

NOTE: Conductive components of tools disturb the field in the gap and decrease the insulationvalue of the tool more than the linear subtraction of the length(s) of the conductivecomponents.

Supporting Comment

1. Previous editions of the NESC only listed the “Mad for Tools” distance from IEEE Std 516. The NESCMAD is therefore different from the IEEE 516 MAD.

2. The present text does not designate who should determine T. Only the line operator has enough data andinformation required to make this determination. For this rule, the line operator is the organization that hascontrol and jurisdiction of the line.



Reject.





Negative: (1) Grose




Explanation of Vote

Grose: (Negative) See CP supporting comments.

Revised Text

CP3326


Submitter

James T. Collins

Proposed Change

Move current Rule 441A7 to Rule 441A1 as attached notes.



A. Minimum approach distance to live parts

1. General

Employees shall not approach or bring any conductive object within the minimum approachdistance listed in Table 441-1 or 441-4 to exposed parts unless one of the following is met:



c. The energized line or part is insulated from the employee and from any other line or part atdifferent voltage.


NOTE 1: Minimum approach distances calculated under this rule for 0.301 kV to0.750 kV contain the electrical component plus 0.30 m (1 ft) for inadvertent movement.Voltages 0.751 kV to 72.5 kV contain the electrical component plus 0.61 m (2 ft) forinadvertent movement. Above 72.5 kV, the inadvertent movement distance is 0.31 m(1 ft).

NOTE 2: Data for minimum approach distances between 1.1 and 72.5 kV shown in Table441-1 was obtained from rod gap data measured in metric units; the values in Table 441-1are derived from metric and converted to feet and inches.



NOTE 3: Data for minimum approach distances above 72.5 kV shown in Tables 441-2,441-3, and 441-4 was taken from IEEE Std 516-2003. In IEEE Std 516-2003, thecustomary unit tables are calculated in feet to two decimal places. The second decimalplace is rounded up if the third decimal place is other than zero. The metric tables werecalculated from the ft tables and rounded up to two decimal places, using a conversionfactor of 0.3048 m per ft. For this reason, the customary-unit tables do not exactly convertinto the values shown in the metric tables.

NOTE 4: The voltage ranges are contained in ANSI C84.1-1995, Table 1.

Supporting Comment

Rule 441A7 rule contains only background technical information on the methodology by which the minimumapproach distances specified in other rules are determined. As such, it constitutes a series of notes and shouldbe associated within the General paragraph of Rule 441.


Accept.



Negative: (0)


Explanation of Vote

Doering: (Affirmative) I certainly agree with using the IEEE Std 516-2003 method of calculating theapproach distances. For the “historical” peak voltages the same values of “a” have been used starting in IEEEStd 516-1987, through IEEE Std 516-2003. Later editions of IEEE 516 introduce small changes due to fittingequations to the curves. The result is to introduce unnecessary complexities in calculation, following thereasoning involved. NOTE 4 calls for using the voltage ranges in ANSI C84.1.

Revised Text

CP3328


Submitter

James T. Collins

Proposed Change

Revise rule to include omitted MAD tables.



1. General

Employees shall not approach or bring any conductive object within the minimum approachdistance listed in Tables 441-1, 441-2, 441-3, or 441-4 to exposed parts unless one of the followingis met:

a. ….

b. …

c. …

d. …

Supporting Comment

As written in the 2007 NESC, minimum approach distances for ac voltages above 72.5 kV are omitted in theGeneral part of Rule 441. Table 441-1 applies to voltages up to 72.5 kV, and Table 441-4 applies to dcvoltages to 750 kv; tables for ac voltages above 72.5 are not referenced. In reviewing CP2524 from the 2007revision cycle, it appears that the full range of ac voltages were covered by the tables that were included inthe original change proposal; however, in accepting the change proposal with modifications, Subcommittee8 omitted Tables 441-2 and 441-3. This appears to be an oversight.

Further, reference is made to Tables 441-2 and 441-3 in both Rules 441A4a and 441A4b for purposes ofdetermining appropriate MAD values for voltages above 72.5 kV.

Addition of the omitted tables will make the General rule applicable to the entire range of energized workvoltages.


Accept.



Negative: (0)


Revised Text

CP3431


Submitter

Allen Clapp



Proposed Change

Revise Rule 432 and Rule 441A1 as follows:

432. Joint-use structures

When working on jointly used poles or structures, employees shall not either (a) approach closer thandistances specified in Table 431-1 and with any portion of their body or a conductive object or shallnot(b) position themselves any portion of their body or a conductive object above the level of the lowestelectric supply conductor exclusive of vertical runs and street lighting.

EXCEPTION: On voltages 140 kV and below, this rule does not apply where communications facilitiesare attached above electric supply conductors if a rigid fixed barrier has been installed between thesupply and communications facilities.



A. Minimum approach distance to live parts

1. General

Employees shall not approach or bring any part of their body or a conductive object within theminimum approach distance listed in Table 441-1 or 441-4 to exposed parts unless one of thefollowing is met:





Supporting Comment

The language of these rules did not match with the requirements of OSHA. Both the person’s body andconductive objects should be recognized in the rule.

A large proportion of communication and supply worker accidents have occurred where the individual moveda tool or conductive material within the MAD zone around energized parts without wearing appropriate PPEand using appropriate insulated cover-up to remove energized parts from the work area.


Reject.




Proposed language revision is unnecessary. Current rules are sufficient.



Negative: (0)


Explanation of Vote

Doering: (Affirmative) I am concerned that I do not understand the background that determined the distancesin Table 431-1. See comments on CP3200.

Revised Text

CP3182


Submitter

Charles Grose

Proposed Change

441A3:

3. Precautions for approach—Voltages from 301 V to 72.5 kV At voltages from 301 V to 72.5 kV,employees shall be protected from phase-to-phase line-to-line and phase-to-ground line-to-grounddifferences in voltage. See Table 441-1 for the minimum approach distances to live parts.

Supporting Comment



Reject.






Affirmative: (16) Blackley, Bowmer, Brooks, Brubaker, Granata, Herbinger, Hunt, McKinney, Poholski,Russell, Shaw, Smoak, Stonerock, Theis, Tomaseski, Tootle

Negative: (5) Doering, Erga, Grose, Schweitzer, Verdecchio


Explanation of Vote

Doering: (Negative) This proposal should be accepted. See CP3144 comment.

Erga: (Negative) Denying this CP will leave the 2012 NESC different from IEEE Std 516.


Schweitzer: (Negative) In support of 516 Subcommittee we feel that the term line-to-line is more appropriatefor tables that address both ac and dc voltages versus phase-to-phase that only deals with ac.

Verdecchio: (Negative) Support IEEE 516 line-to-line, line-to-ground versus phase-to-phase, phase-to-ground.

Revised Text

CP3007


Submitter

Brian Erga

Proposed Change

b. When the Rubber Glove Work Method is employed, At voltages from 301 V to 36 kV rubberinsulating gloves, insulated for the maximum use voltage as listed in Table 441-6, shall be wornwhenever employees are within the reach or extended reach of the minimum approach distanceslisted in Table 441-1, supplemented by one of the following two protective methods:

Supporting Comment

This proposed change makes the rubber glove and hot stick work method consistent when workers arewithin reach and extended reach of energized conductors and equipment. This will also make the NESC ruleconsistent with the proposed OSHA 1910.269 and Subpart V standard.


Accept as modified.




Employees shall not approach (within the reach or extended reach), or knowingly permit others toapproach, any exposed ungrounded part normally energized except as permitted by this rule.

A. Minimum approach distance to energized live lines or parts

1. General

Employees shall not approach or bring any conductive object within the minimum approachdistance listed in Table 441-1 or through 441-4 to exposed parts unless one of the following ismet:


b. The employee is insulated from the energized line or part. Electrical protective equipmentinsulated for the voltage involved, such as tools, gloves, rubber gloves, or rubber gloveswith sleeves, shall be considered effective insulation for the employee from the energizedline or part being worked on.


d. The employee is performing barehand live-line work according to Rule 446

Rule 441A3b(2)

(2) All exposed energized lines or parts, other than those temporarily exposed to perform work andmaintained under positive control, located within the maximum reach or extended reach of theemployee’s work position, shall be covered with insulating protective equipment.

Rule441A4

4. Precautions for approach—Voltages above 72.5 kV




Negative: (0)




Revised Text

CP3183

Part: 4 Section: 44 441 A3c and 3d

Submitter

Charles Grose

Proposed Change

441A3c

c. When the Rubber Glove Work Method is employed at voltages above 15 kV phase-to-phase line-to-line, supplementary insulation (e.g., insulated aerial device or structure-mounted insulating workplatform), tested for the voltage involved shall be used to support the worker.

441A3d

d. Cover-up equipment used to insulate phase-to-phase line-to-line exposure shall be rated for not lessthan the phase-to-phase line-to-line voltage of the circuit(s) in the work area. All other cover-upequipment shall be rated for not less than the phase-to-ground line-to-ground voltage of thecircuit(s). The determination of whether phase-to-phase line-to-line or phase-to-ground line-to-ground exposure exists shall be based on factors such as but not limited to: work rules, conductorspacing, worker position, and task being performed.

Supporting Comment



Reject.









Explanation of Vote






Revised Text

CP3199


Submitter

Charles Grose

Proposed Change

441A4



a. For work on exposed parts operating at phase-to-phase voltage above 72.5 kV, where themaximum anticipated per-unit overvoltage factor (T) at the worksite has not been determinedby line operator using an engineering analysis, the ac live work minimum approach distances(distance to employee) in Tables 441-2, 441-3, and 441-4 shall be used with a T of 3.0 forvoltages up to 362.0 kV, 2.4 for voltages between 362.1 kV and 550.0 kV, and 2.0 for 550.1 kVto 800 kV. However, if the system is protected by single break interrupter devices, the ac livework minimum approach distances (distance to employee) in Tables 441-2, 441-3, and 441-4shall be used with the maximum T for the specific voltage.

b. For work on exposed parts operating at phase-to-phase voltage above 72.5 kV, where the T atthe worksite has been determined by the line operator using an engineering analysis, the livework minimum approach distances (distance to employee) in Tables 441-2, 441-3, and 441-4may be used with the determined value of T, providing that all of the following conditions aremet.

EXCEPTION: If a temporary (transient) overvoltage control device (TTOCD), as defined inRule 441A6, has been installed adjacent to the worksite to limit the maximum worksite



maximum anticipated overvoltage (TOV), the value of the T to be used to determine the livework minimum approach distance in Tables 441-2, 441-3, and 441-4 shall be the T valuedetermined in Rule 441A5 or the maximum anticipated per-unit overvoltage factor of theTTOCD (TTTOCD) value obtained from Rule 441A6, plus 0.2 p.u., whichever is smaller. Wheninstalling or removing the TTOCD adjacent to the worksite, the T value determined by the lineoperator’s engineering analysis shall be used.



EXCEPTION: If required for system stability, one high-speed automatic reclose may bepermitted, providing that the circuit interrupters or isolating devices to be reclosed cannotproduce at the worksite an overvoltage value exceeding the value of the T being used atthe worksite. This value shall be determined from anthe line operator’s engineeringanalysis.

(3) The altitude corrections according to Rule 441A6b shall be used when the elevation of theworksite is above 900 m (3000 ft) above sea level.


Supporting Comment

The present text does not designate who should determine T. Only the line operator has enough data andinformation required to make this determination. For this rule, the line operator is the organization that hascontrol and jurisdiction of the line.


Reject.





Negative: (1) Grose


Explanation of Vote

Grose: (Negative) The purpose of this CP was to provide additional information and optimal informationneeded for live work.



Revised Text

CP3184


Submitter

Charles Grose

Proposed Change

a. For work on exposed parts operating at phase-to-phaseline-to-line voltage above 72.5 kV, wherethe maximum anticipated per-unit overvoltage factor (T) at the worksite has not been determinedby an engineering analysis, the ac live work minimum approach distances (distance to employee) inTables 441-2, 441-3, and 441-4 shall be used with a T of 3.0 for voltages up to 362.0 kV, 2.4 forvoltages between 362.1 kV and 550.0 kV, and 2.0 for 550.1 kV to 800 kV. However, if the systemis protected by single break interrupter devices, the ac live work minimum approach distances(distance to employee) in Tables 441-2, 441-3, and 441-4 shall be used with the maximum T for thespecific voltage.

Supporting Comment



Reject.







Explanation of Vote








Deleted Text

CP3331


Submitter

James T. Collins

Proposed Change

Revise Rule 441A4a as follows:

However, if the system is protected by single break interrupter devices, the ac live work minimum approachdistances (distance to employee) in Tables 441-2, 441-3, and 441-4 shall be used with the maximum T forthe specific voltage.

Supporting Comment

This statement implies that circuit interrupters that have single or multiple breaks without pre-insertiongradient resistors or capacitors, are susceptible to re-striking. Single breaker interrupters are common placein the modern HV and EHV system. EHV (550 kV) dead tank circuit breakers with single break interruptershave been available for 10+ years [1–3] and are a common choice among many utility companies. Thesecircuit breakers have high current interrupting capability, e.g. 63 kA and are designed to have a very lowprobability of restrike as defined by IEC and IEEE standards [4–7].This statement further implies thatutilizing circuit breakers which have multiple breaker interrupters will result in lower values of T. It isincorrect to imply that utilizing this type of equipment would result in a lower value of T, based on the factthat modern circuit breakers with single break interrupters are no more likely to restrike than those with amulti-break interrupters (assuming that both are tested per IEEE and IEC standards). Note that the switchgearstandards (IEEE and IEC) make no distinction between single break interrupters and multi-break interrupters.Breaker restrike performance is based solely on tests [4–7]. Furthermore, breaker restrikes are ignored in theevaluation of T [8]; thus, the distinction made about single break interrupters is meaningless.

References:

[1] K. Suzuki, et al., “Development of 550 kV 1-Break GCB (Part 1) Investigation of Interrupting ChamberPerformance,” IEEE Transactions on Power Delivery, Vol. 8, No. 3, July 1993.

[2] H. Toda, et al., “Development of 550 kV 1-Break GCB (Part 2) Development of Prototype,” IEEETransactions on Power Delivery, Vol. 8, No. 3, July 1993.



[3] Mitsubishi Technical Specification for 63 kA 550 kV Dead Tank Circuit Breaker

[4] IEC 62271-100, High-Voltage Switchgear and Controlgear—Part 100: High-Voltage Alternating-currentCircuit-Breakers.

[5] C. J. Solver, “Line-Charging Current Interruption by HV and EHV Circuit Breakers: Standard and Non-Standard Test Requirements as Determined by the Stresses Applied and by Breaker-CapabilityConsiderations,” 2001 International Conference on Power Systems Transients.

[6] C. J. Solver, “Line-Charging Current Interruption by HV and EHV Circuit Breakers: Standard and Non-Standard Test Requirements as Determined by the Stresses Applied and by Breaker-CapabilityConsiderations,” 2001 International Conference on Power Systems Transients.

[7] IEEE Std C37.12, IEEE Application Guide for Capacitance Current Switching for AC High-VoltageCircuit Breakers.

[8] IEEE Std C37.04, IEEE Standard Rating Structure for AC High-Voltage Circuit Breakers.

[9] IEC 61472:2004, Live working—Minimum approach distances for ac systems in the voltage range72.5 kV to 800 kV—A method of calculation.


Accept.



Negative: (0)


Revised Text

CP3185


Submitter

Charles Grose

Proposed Change

b. For work on exposed parts operating at phase-to-phaseline-to-line voltage above 72.5 kV, wherethe T at the worksite has been determined by engineering analysis, the live work minimumapproach distances (distance to employee) in Tables 441-2, 441-3, and 441-4 may be used with thedetermined value of T, providing that all of the following conditions are met.



Supporting Comment



Reject.







Explanation of Vote






Revised Text

CP3330

Part: 4 Section: 44 441 A4b EXCEPTION 1

Submitter

James T. Collins



Proposed Change

Revise 441A4b EXCEPTION 1.

EXCEPTION 1: All of the equipment evaluated in determining the T value by the engineering analysisshall be operational. The system is not operated in such a way that allows T to exceed the valuedetermined by engineering analysis or the values listed in Rule 441A4a.

Supporting Comment

The existing statement is too vague. What is meant by “all of the equipment”? This statement implies that ifyou have any equipment out of service (e.g. a circuit breaker, transformer, etc.) then the values provided inthe study are no longer valid. The intent of the statement should be to require companies to operate theirsystem in such a way that the T value determined by study are not exceeded while live-line work is beingperformed.


Accept as modified.

Revise 441A4b(1).

(1) All of the equipment evaluated in determining the T value by the engineering analysis shall beoperational. T values reflect the actual operating conditions.



Negative: (0)


Revised Text

CP3327


Submitter

James T. Collins

Proposed Change

Delete Rule 441A7 and add the information in subparts to Rule 441A1 as NOTEs.

7. Determining the minimum approach distances (distances to employee)



a. Minimum approach distances calculated under this rule for 0.301 kV to 0.750 kV contain theelectrical component plus 0.30 m (1 ft) for inadvertent movement. Voltages 0.751 kV to 72.5kV contain the electrical component plus 0.61 m (2 ft) for inadvertent movement. Above 72.5kV, the inadvertent movement distance is 0.31 m (1 ft).

b. Data for minimum approach distances between 1.1 and 72.5 kV shown in Table 441-1 wasobtained from rod gap data measured in metric units; the values in Table 441-1 are derivedfrom metric and converted to feet and inches.

c. Data for minimum approach distances above 72.5 kV shown in Tables 441-2, 441-3, and 441-4was taken from IEEE Std 516-2003. In IEEE Std 516-2003, the customary unit tables arecalculated in feet to two decimal places. The second decimal place is rounded up if the thirddecimal place is other than zero. The metric tables were calculated from the ft tables androunded up to two decimal places, using a conversion factor of 0.3048 m per ft. For this reason,the customary-unit tables do not exactly convert into the values shown in the metric tables.


Supporting Comment

This rule contains only background technical information on the methodology by which the minimumapproach distances specified in other rules are determined. As such, it constitutes a series of notes andshould be associated with in the General paragraph of Rule 441.


Accept.


See Subcommittee action on CP3326.



Negative: (0)


Revised Text

CP3191

Part: 4 Section: 44 441 Appendix D-2

Submitter

Charles Grose



Proposed Change

1 The maximum use voltage is the ac voltage (rms) rating of the protective equipment thatdesignates the maximum nominal design voltage of the energized system that may be safelyworked. The nominal design voltage is equal to the phase-to-phase line-to-line voltage onmultiphase circuits.

EXCEPTION 1: If there is no multiphase exposure in a system area (at the worksite) and thevoltage exposure is limited to the phase (polarity on dc systems) to ground potential, the phase(polarity on dc systems) to ground potential shall be considered to be the nominal design voltage.

EXCEPTION 2: If electric equipment and devices are insulated, isolated, or both, such that themultiphase exposure on a grounded wye circuit is removed and if supplemental insulation (e.g.,insulated aerial device or structure-mounted insulating work platform) is used to insulate theemployee from ground, then the nominal design voltage may be considered as the phase-to-groundline-to-ground voltage on that circuit.

Supporting Comment



Reject.






Table 441-6—Maximum use voltage for rubber insulating equipment

Class of equipment Maximum use voltage1

00 500

0 1000

1 7500

2 17 000

3 26 500

4 36 000




Explanation of Vote






Revised Text

CP3193


Submitter

Charles Grose

Proposed Change


Table 441-1—AC live work minimum approach distance4

(See Rule 441 in its entirety.)

Voltage in kilovolts phase-to-phaseline-to-line1, 2

Distance to employee

PhaseLine-to-ground Phase-to-phaseLine-to-line

(m) (ft-in) (m) (ft-in)

0 to 0.0501 Not specified Not specified

0.051 to 0.3001 Avoid contact Avoid contact

0.301 to 0.7501 0.310.30 1-0 0.310.30 1-0

0.751 to 15 0.65 2-2 0.670.69 2–32-4

15.1 to 36.0 0.770.74 2–72-6 0.860.87 2–102-11

36.1 to 46.0 0.840.78 2–92-7 0.960.95 3-2

46.1 to 72.5 1.000.9732 3–33-132 1.201.18 3-11



2 For single-phase lines off three-phase systems, use the phase-to-phaseline-to-line voltage of the system. 3 The 46.1 to 72.5 kV phase-to-ground 3.3 distance contains a 1.3 electrical component and a 2.0 inadvertent component.

43 Distances listed are for standard atmospheric conditions. The data used to formulate this table was obtained from testdata taken with standard atmospheric conditions. Standard atmospheric conditions are defined as temperatures abovefreezing, wind less than 15 mi per hr or 24 km per hr, unsaturated air, normal barometer, uncontaminated air, and cleanand dry insulators. If standard atmospheric conditions do not exist, extra care must be taken.

Supporting Comment

1. Table values have been adjusted to conform with the latest edition of IEEE Std 516



Reject.






Negative: (0)


Explanation of Vote

Tomaseski: (Affirmative) See comment on CP3198.

Revised Text

CP3194


Submitter

Charles Grose



Proposed Change

Replace existing Table 441-1 with the following:

Table 441-1—AC live work minimum approach distance4 (See Rule 441 in its entirety.)

Voltageline-to-

linekV

Line-to-ground work Line-to-line work

MAID MAD MAID MAD MAID MAD MAID MAD

M M Ft-in Ft-in M M Ft-in Ft-in

0.00 to 0.050

Notspecified

Notspecified

Notspecified

Notspecified

Notspecified

Notspecified

Notspecified

Notspecified

0.051 to 0.300

Avoid Avoid Avoid Avoid Avoid Avoid Avoid Avoid

Contact Contact Contact Contact Contact Contact Contact Contact

0.301 to 0.750

0.02 0.30 0-1 1-0 0.02 0.30 0-1 1-0

0.750 to 5.00

0.02 0.61 0-1 2-1 0.02 0.61 0-1 2-1

5.01 to 7.50

0.02 0.61 0-1 2-1 0.03 0.64 0-2 2-2

7.51 to 10.00

0.02 0.61 0-1 2-1 0.04 0.65 0-2 2-2

10.01 to 13.00

0.03 0.64 0-2 2-2 0.05 0.66 0-2 2-2

13.01 to 16.00

0.04 0.65 0-2 2-2 0.08 0.69 0-4 2-4

16.01 to 19.00

0.04 0.65 0-2 2-2 0.11 0.72 0-5 2-5

19.01 to 22.00

0.05 0.66 0-2 2-2 0.14 0.75 0-6 2-6

22.01 to 25.00

0.07 0.68 0-3 2-3 0.16 0.77 0-7 2-7

25.01 to 28.00

0.08 0.69 0-4 2-4 0.19 0.80 0-8 2-8

28.01 to 31.00

0.10 0.71 0-4 2-4 0.21 0.82 0-9 2-9

31.01 to 34.00

0.11 0.72 0-5 2-5 0.24 0.85 0-10 2-10

34.01 to 37.00

0.13 0.74 0-6 2-6 0.26 0.87 0-11 2-11

37.01 to 40.00

0.14 0.75 0-6 2-6 0.29 0.90 1-0 3-0

40.01 to 43.00

0.16 0.77 0-7 2-7 0.32 0.93 1-1 3-1



1 For single-phase systems, use the highest voltage available. For single-phase lines off three-phase systems, use the phase-to-phase voltage of the system.

2 Distances listed are for standard atmospheric conditions. The data used to formulate this table was obtained from testdata taken with standard atmospheric conditions. Standard atmospheric conditions are defined as temperaturesabove freezing, wind less than 15 mi per hr or 24 km per hr, unsaturated air, normal barometer, uncontaminated air,and clean and dry insulators. If standard atmospheric conditions do not exist, extra care must be taken.

Supporting Comment

1. Table has been adjusted to conform with the latest edition of IEEE Std 516



Reject.

43.01 to 46.00

0.17 0.78 0-7 2-7 0.34 0.95 1-2 3-2

46.01 to 49.00

0.19 0.80 0-8 2-8 0.37 0.98 1-3 3-3

49.01 to 52.00

0.20 0.81 0-8 2-8 0.39 1.00 1-4 3-4

52.01 to 55.00

0.22 0.83 0-9 2-9 0.42 1.03 1-5 3-5

55.01 to 58.00

0.23 0.84 0-10 2-10 0.45 1.06 1-6 3-6

58.01 to 61.00

0.25 0.86 0-10 2-10 0.47 1.08 1-7 3-7

61.01 to 64.00

0.26 0.87 0-11 2-11 0.50 1.11 1-8 3-8

64.01 to 67.00

0.28 0.89 1-0 3-0 0.52 1.13 1-9 3-9

67.01 to 70.00

0.29 0.90 1-0 3-0 0.55 1.16 1-10 3-10

70.01 to 72.50

0.31 0.92 1-1 3-1 0.57 1.18 1-11 3-11

Table 441-1—AC live work minimum approach distance4 (continued)(See Rule 441 in its entirety.)

Voltageline-to-

linekV

Line-to-ground work Line-to-line work

MAID MAD MAID MAD MAID MAD MAID MAD

M M Ft-in Ft-in M M Ft-in Ft-in




Existing structure of the table is sufficient.



Negative: (0)


Revised Text

CP3186

Part: 4 Section: 44 441 Table 441-1 and NOTEs

Submitter

Charles Grose

Proposed Change


2 For single-phase lines off three-phase systems, use the phase-to-phase line-to-line voltage of the system.

Table 441-1—AC live work minimum approach distance4


Voltage in kilovolts phase-to-phaseline-to-line1, 2


Phase-to-groundLine-to-ground

Phase-to-phaseLine-to-line




0.301 to 0.7501 0.31 1-0 0.31 1-0

0.751 to 15 0.65 2-2 0.67 2-3

15.1 to 36.0 0.77 2-7 0.86 2-10

36.1 to 46.0 0.84 2-9 0.96 3-2

46.1 to 72.5 1.003 3-33 1.20 3-11



3 The 46.1 to 72.5 kV phase-to-ground line-to-ground 3-3 distance contains a 1-3 electrical component and a 2-0inadvertent movement component.

4 Distances listed are for standard atmospheric conditions. The data used to formulate this table was obtained from testdata taken with standard atmospheric conditions. Standard atmospheric conditions are defined as temperatures abovefreezing, wind less than 15 mi per hr or 24 km per hr, unsaturated air, normal barometer, uncontaminated air, and cleanand dry insulators. If standard atmospheric conditions do not exist, extra care must be taken.

Supporting Comment



Reject.







Explanation of Vote






Revised Text

CP3187

Part: 4 Section: 44 441 Table 441-2(m)



Submitter

Charles Grose

Proposed Change

m

Supporting Comment



Reject.







Explanation of Vote


Table 441-2—AC live work minimum approach distances for altitudes less than 900 m above sea level, where T has been determined according to Rule 441A51, 2


Maximum anticipated

per unit overvoltage

factor T

Distance to employee—phase-to-ground line-to-ground work, in air, barehand, and clear live-line tool

Maximum phase-to-phase line-to-line voltage in kV

72.5 to 121.0

121.1 to 145.0

145.1 to 169.0

169.1 to 242.0

242.1 to 362.0

362.1 to 550.0

550.1 to 800.0

1.5 0.72 0.73 0.80 1.01 1.36 1.96 3.16

1.6 0.79 0.76 0.83 1.05 1.43 2.12 3.46

1.7 0.86 0.78 0.86 1.10 1.50 2.28 3.78







Revised Text

CP3188

Part: 4 Section: 44 441 Table 441-2(ft)

Submitter

Charles Grose

Proposed Change

ft

Supporting Comment



Reject.

Table 441-2—AC live work minimum approach distances for altitudes less than 3000 ft above sea level, where T has been determined according to Rule 441A51, 2


Maximum anticipated per unit overvoltage

factor T

Distance to employee— phase-to-ground line-to-ground work, in air, barehand, and clear live-line tool


72.5 to 121.0

121.1 to 145.0

145.1 to 169.0

169.1 to 242.0

242.1 to 362.0

362.1 to 550.0

550.1 to 800.0

ft in ft in ft in ft in ft in ft in ft in

1.5 2 2 2 5 2 8 3 4 4 6 6 6 10 5









Explanation of Vote






Revised Text

CP3197

Part: 4 Section: 44 441 Tables 441-2 and 441-3

Submitter

Charles Grose

Proposed Change

Replace Tables 441-2 and 441-3 and their footnotes with the following:



72.51 to 121 kV line-to-line m

Table 441-2—AC live work minimum distances for altitudes less than 900 m above sea level, where T has been determined according to Rule 441A51, 2


Line-to-ground Line-to-line

T MAID MTID MAD MAD for Tools MAID MTID MAD MAD

for Tools

p.u. m m m m m m m m

1.5 0.32 0.36 0.62 0.66 0.53 0.58 0.83 0.88

1.6 0.35 0.38 0.65 0.68 0.56 0.62 0.86 0.92

1.7 0.37 0.40 0.67 0.70 0.59 0.65 0.89 0.95

1.8 0.39 0.43 0.69 0.73 0.62 0.68 0.92 0.98

1.9 0.41 0.45 0.71 0.75 0.65 0.71 0.95 1.01

2.0 0.43 0.47 0.73 0.77 0.68 0.74 0.98 1.04

2.1 0.45 0.50 0.75 0.80 0.70 0.77 1.00 1.07

2.2 0.47 0.52 0.77 0.82 0.73 0.81 1.03 1.11

2.3 0.49 0.54 0.79 0.84 0.76 0.84 1.06 1.14

2.4 0.52 0.57 0.82 0.87 0.79 0.87 1.09 1.17

2.5 0.54 0.59 0.84 0.89 0.82 0.90 1.12 1.20

2.6 0.56 0.61 0.86 0.91 0.85 0.93 1.15 1.23

2.7 0.58 0.64 0.88 0.94 0.88 0.96 1.18 1.26

2.8 0.60 0.66 0.90 0.96 0.91 1.00 1.21 1.30

2.9 0.62 0.68 0.92 0.98 0.93 1.03 1.23 1.33

3.0 0.64 0.71 0.94 1.01 0.96 1.06 1.26 1.36

3.1 0.67 0.73 0.97 1.03 0.99 1.09 1.29 1.39

3.2 0.69 0.75 0.99 1.05 1.02 1.12 1.32 1.42

3.3 0.71 0.78 1.01 1.08 1.05 1.15 1.35 1.45

3.4 0.73 0.80 1.03 1.10 1.08 1.19 1.38 1.49

3.5 0.75 0.82 1.05 1.12 1.11 1.22 1.41 1.52



72.51 to 121 kV line-to-line ft

Table 441-2—AC live work minimum distances for altitudes less than 900 m above sea level, where T has been determined according to Rule 441A51, 2




for Tools

p.u ft-in ft-in ft-in ft-in ft-in ft-in ft-in it-in

1.5 1-1 1-2 2-1 2-2 1-9 1-11 2-9 2-11

1.6 1-2 1-3 2-2 2-3 1-10 2-1 2-10 3-1

1.7 1-3 1-4 2-3 2-4 2-0 2-2 3-0 3-2

1.8 1-4 1-5 2-4 2-5 2-1 2-3 3-1 3-3

1.9 1-4 1-6 2-4 2-6 2-2 2-4 3-2 3-4

2.0 1-5 1-7 2-5 2-7 2-3 2-6 3-3 3-6

2.1 1-6 1-8 2-6 2-8 2-4 2-7 3-4 3-7

2.2 1-7 1-9 2-7 2-9 2-5 2-8 3-5 3-8

2.3 1-8 1-10 2-8 2-10 2-6 2-9 3-6 3-9

2.4 1-9 1-11 2-9 2-11 2-7 2-11 3-7 3-11

2.5 1-9 2-0 2-9 3-0 2-9 3-0 3-9 4-0

2.6 1-10 2-0 2-10 3-0 2-10 3-1 3-10 4-1

2.7 1-11 2-1 2-11 3-1 2-11 3-2 3-11 4-2

2.8 2-0 2-2 3-0 3-2 3-0 3-4 4-0 4-4

2.9 2-1 2-3 3-1 3-3 3-1 3-5 4-1 4-5

3.0 2-2 2-4 3-2 3-4 3-2 3-6 4-2 4-6

3.1 2-3 2-5 3-3 3-5 3-3 3-7 4-3 4-7

3.2 2-3 2-6 3-3 3-6 3-5 3-9 4-5 4-9

3.3 2-4 2-7 3-4 3-7 3-6 3-10 4-6 4-10

3.4 2-5 2-8 3-5 3-8 3-7 3-11 4-7 4-11

3.5 2-6 2-9 3-6 3-9 3-8 4-0 4-8 5-0






for Tools


1.5 0.39 0.43 0.69 0.73 0.64 0.70 0.94 1.00

1.6 0.41 0.45 0.71 0.75 0.67 0.74 0.97 1.04

1.7 0.44 0.48 0.74 0.78 0.71 0.78 1.01 1.08

1.8 0.46 0.51 0.76 0.81 0.74 0.81 1.04 1.11

1.9 0.49 0.54 0.79 0.84 0.77 0.85 1.07 1.15

2.0 0.52 0.57 0.82 0.87 0.81 0.89 1.11 1.19

2.1 0.54 0.59 0.84 0.89 0.84 0.93 1.14 1.23

2.2 0.57 0.62 0.87 0.92 0.88 0.96 1.18 1.26

2.3 0.59 0.65 0.89 0.95 0.91 1.00 1.21 1.30

2.4 0.62 0.68 0.92 0.98 0.95 1.04 1.25 1.34

2.5 0.64 0.71 0.94 1.01 0.98 1.08 1.28 1.38

2.6 0.67 0.73 0.97 1.03 1.02 1.12 1.32 1.42

2.7 0.69 0.76 0.99 1.06 1.05 1.15 1.35 1.45

2.8 0.72 0.79 1.02 1.09 1.08 1.19 1.38 1.49

2.9 0.75 0.82 1.05 1.12 1.12 1.23 1.42 1.53

3.0 0.77 0.85 1.07 1.15 1.15 1.27 1.45 1.57

3.1 0.80 0.88 1.10 1.18 1.19 1.31 1.49 1.61

3.2 0.82 0.90 1.12 1.20 1.22 1.34 1.52 1.64

3.3 0.85 0.93 1.15 1.23 1.26 1.38 1.56 1.68

3.4 0.87 0.96 1.17 1.26 1.29 1.42 1.59 1.72

3.5 0.90 0.99 1.20 1.29 1.33 1.46 1.63 1.76






for Tools


1.5 1-4 1-5 2-4 2-5 2-1 2-4 3-1 3-4

1.6 1-5 1-6 2-5 2-6 2-3 2-5 3-3 3-5

1.7 1-6 1-7 2-6 2-7 2-4 2-7 3-4 3-7

1.8 1-7 1-8 2-7 2-8 2-6 2-8 3-6 3-8

1.9 1-8 1-9 2-8 2-9 2-7 2-10 3-7 3-10

2.0 1-9 1-11 2-9 2-11 2-8 2-11 3-8 3-11

2.1 1-10 2-0 2-10 3-0 2-10 3-1 3-10 4-1

2.2 1-11 2-1 2-11 3-1 2-11 3-2 3-11 4-2

2.3 2-0 2-2 3-0 3-2 3-0 3-4 4-0 4-3

2.4 2-1 2-3 3-1 3-3 3-2 3-5 4-2 4-5

2.5 2-2 2-4 3-2 3-4 3-3 3-7 4-3 4-7

2.6 2-3 2-5 3-3 3-5 3-4 3-8 4-4 4-8

2.7 2-4 2-6 3-4 3-6 3-6 3-10 4-6 4-10

2.8 2-5 2-7 3-5 3-7 3-7 3-11 4-7 4-11

2.9 2-6 2-9 3-6 3-9 3-8 4-1 4-8 5-1

3.0 2-7 2-10 3-7 3-10 3-10 4-2 4-10 5-2

3.1 2-8 2-11 3-8 3-11 3-11 4-4 4-11 5-4

3.2 2-9 3-0 3-9 4-0 4-0 4-5 5-0 5-5

3.3 2-10 3-1 3-10 4-1 4-2 4-7 5-2 5-7

3.4 2-11 3-2 3-11 4-2 4-3 4-8 5-3 5-8

3.5 3-0 3-3 4-0 4-3 4-5 4-10 5-5 5-10






for Tools


1.5 0.45 0.50 0.75 0.80 0.74 0.81 1.04 1.11

1.6 0.48 0.53 0.78 0.83 0.78 0.86 1.08 1.16

1.7 0.51 0.56 0.81 0.86 0.82 0.90 1.12 1.20

1.8 0.54 0.59 0.84 0.89 0.86 0.95 1.16 1.25

1.9 0.57 0.63 0.87 0.93 0.90 0.99 1.20 1.29

2.0 0.60 0.66 0.90 0.96 0.94 1.04 1.24 1.34

2.1 0.63 0.69 0.93 0.99 0.98 1.08 1.28 1.38

2.2 0.66 0.72 0.96 1.02 1.02 1.12 1.32 1.42

2.3 0.69 0.76 0.99 1.06 1.06 1.17 1.36 1.47

2.4 0.72 0.79 1.02 1.09 1.10 1.21 1.40 1.51

2.5 0.75 0.82 1.05 1.12 1.14 1.26 1.44 1.56

2.6 0.78 0.86 1.08 1.16 1.18 1.30 1.48 1.60

2.7 0.81 0.89 1.11 1.19 1.23 1.36 1.53 1.66

2.8 0.84 0.92 1.14 1.22 1.29 1.42 1.59 1.72

2.9 0.87 0.95 1.17 1.25 1.36 1.49 1.66 1.79

3.0 0.90 0.99 1.20 1.29 1.42 1.55 1.72 1.85

3.1 0.93 1.02 1.23 1.32 1.48 1.62 1.78 1.92

3.2 0.96 1.05 1.26 1.35 1.55 1.69 1.85 1.99

3.3 0.99 1.08 1.29 1.38 1.61 1.76 1.91 2.06

3.4 1.02 1.12 1.32 1.42 1.68 1.83 1.98 2.13

3.5 1.05 1.15 1.35 1.45 1.75 1.90 2.05 2.20






for Tools


1.5 1-6 1-8 2-6 2-8 2-6 2-8 3-6 3-8

1.6 1-7 1-9 2-7 2-9 2-7 2-10 3-7 3-10

1.7 1-8 1-10 2-8 2-10 2-9 3-0 3-9 4-0

1.8 1-10 2-0 2-10 3-0 2-10 3-2 3-10 4-2

1.9 1-11 2-1 2-11 3-1 3-0 3-3 4-0 4-3

2.0 2-0 2-2 3-0 3-2 3-1 3-5 4-1 4-5

2.1 2-1 2-4 3-1 3-4 3-3 3-7 4-3 4-7

2.2 2-2 2-5 2-2 3-5 3-5 3-9 4-5 4-9

2.3 2-3 2-6 3-3 3-6 3-6 3-10 4-6 4-10

2.4 2-5 2-7 3-5 3-7 3-8 4-0 4-8 5-0

2.5 2-6 2-9 3-6 3-9 3-9 4-2 4-9 5-2

2.6 2-7 2-10 3-7 3-10 3-11 4-4 4-11 5-4

2.7 2-8 2-11 2-8 3-11 4-1 4-6 5-1 5-6

2.8 2-9 3-1 3-9 4-1 4-3 4-8 5-3 5-8

2.9 2-10 3-2 3-10 4-2 4-6 4-11 5-6 5-11

3.0 3-0 3-3 4-0 4-3 4-8 5-1 5-8 6-1

3.1 3-1 3-4 4-1 4-4 4-11 5-4 5-11 6-4

3.2 3-2 3-6 4-2 4-6 5-1 5-7 6-1 6-7

3.3 3-3 3-7 4-3 4-7 5-4 5-10 6-4 6-10

3.4 3-4 3-8 4-4 4-8 5-6 6-0 6-6 7-0

3.5 3-6 3-10 4-6 4-10 5-9 6-3 6-9 7-3






for Tools


1.5 0.64 0.71 0.94 1.01 1.06 1.16 1.36 1.46

1.6 0.69 0.75 0.99 1.05 1.12 1.23 1.42 1.53

1.7 0.73 0.80 1.03 1.10 1.17 1.29 1.47 1.59

1.8 0.77 0.85 1.07 1.15 1.23 1.35 1.53 1.65

1.9 0.81 0.90 1.11 1.20 1.31 1.43 1.61 1.73

2.0 0.86 0.94 1.16 1.24 1.39 1.53 1.69 1.83

2.1 0.90 0.99 1.20 1.29 1.48 1.62 1.78 1.92

2.2 0.94 1.04 1.24 1.34 1.58 1.72 1.88 2.02

2.3 0.98 1.08 1.28 1.38 1.67 1.82 1.97 2.12

2.4 1.03 1.13 1.33 1.43 1.77 1.93 2.07 2.23

2.5 1.07 1.18 1.37 1.48 1.87 2.03 2.17 2.33

2.6 1.11 1.22 1.41 1.52 1.98 2.14 2.28 2.44

2.7 1.15 1.27 1.45 1.57 2.08 2.26 2.38 2.56

2.8 1.20 1.32 1.50 1.62 2.19 2.37 2.49 2.67

2.9 1.24 1.36 1.54 1.66 2.30 2.49 2.60 2.79

3.0 1.28 1.41 1.58 1.71 2.42 2.61 2.72 2.91

3.1 1.33 1.46 1.63 1.76 2.53 2.73 2.83 3.03

3.2 1.37 1.51 1.67 1.81 2.65 2.86 2.95 3.16

3.3 1.43 1.57 1.73 1.87 2.77 2.98 3.07 3.28

3.4 1.49 1.64 1.79 1.94 2.90 3.11 3.20 3.41

3.5 1.55 1.70 1.85 2.00 3.02 3.25 3.32 3.55






for Tools


1.5 2-2 2-4 3-2 3-4 3-6 3-10 4-6 4-10

1.6 2-3 2-6 3-3 3-6 3-8 4-1 4-8 5-1

1.7 2-5 2-8 3-5 3-8 3-11 4-3 4-11 5-3

1.8 2-7 2-10 3-7 3-10 4-1 4-6 5-1 5-6

1.9 2-8 3-0 3-8 4-0 4-4 4-9 5-4 5-9

2.0 2-10 3-1 3-10 4-1 4-7 5-0 5-7 6-0

2.1 2-12 3-3 3-12 4-3 4-11 5-4 5-11 6-4

2.2 3-1 3-5 4-1 4-5 5-2 5-8 6-2 6-8

2.3 3-3 3-7 4-3 4-7 5-6 6-0 6-6 7-0

2.4 3-5 3-9 4-5 4-9 5-10 6-4 6-10 7-4

2.5 3-6 3-11 4-6 4-11 6-2 6-8 7-2 7-8

2.6 3-8 4-0 4-8 5-0 6-6 7-1 7-6 8-1

2.7 3-10 4-2 4-10 5-2 6-10 7-5 7-10 8-5

2.8 4-0 4-4 5-0 5-4 7-3 7-10 8-3 8-10

2.9 4-1 4-6 5-1 5-6 7-7 8-2 8-7 9-2

3.0 4-3 4-8 5-3 5-8 8-0 8-7 9-0 9-7

3.1 4-5 4-10 5-5 5-10 8-4 9-0 9-4 10-0

3.2 4-6 5-0 5-6 6-0 8-9 9-5 9-9 10-5

3.3 4-9 5-2 5-9 6-2 9-2 9-10 10-2 10-10

3.4 4-11 5-5 5-11 6-5 9-6 10-3 10-6 11-3

3.5 5-2 5-7 6-2 6-7 9-11 10-8 10-11 11-8






for Tools


1.5 0.96 1.06 1.26 1.36 1.72 1.88 2.02 2.18

1.6 1.02 1.13 1.32 1.43 1.87 2.04 2.17 2.34

1.7 1.09 1.20 1.39 1.50 2.03 2.20 2.33 2.50

1.8 1.15 1.27 1.45 1.57 2.19 2.37 2.49 2.67

1.9 1.22 1.34 1.52 1.64 2.35 2.55 2.65 2.85

2.0 1.28 1.41 1.58 1.71 2.53 2.73 2.83 3.03

2.1 1.34 1.48 1.64 1.78 2.70 2.91 3.00 3.21

2.2 1.42 1.56 1.72 1.86 2.89 3.11 3.19 3.41

2.3 1.52 1.66 1.82 1.96 3.08 3.30 3.38 3.60

2.4 1.61 1.77 1.91 2.07 3.27 3.51 3.57 3.81

2.5 1.71 1.87 2.01 2.17 3.47 3.72 3.77 4.02

2.6 1.81 1.97 2.11 2.27 3.68 3.93 3.98 4.23

2.7 1.91 2.08 2.21 2.38 3.89 4.15 4.19 4.45

2.8 2.02 2.19 2.32 2.49 4.11 4.38 4.41 4.68

2.9 2.12 2.31 2.42 2.61 4.33 4.61 4.63 4.91

3.0 2.23 2.42 2.53 2.72 4.54 4.83 4.84 5.13

3.1 2.35 2.54 2.65 2.84 4.75 5.05 5.05 5.35

3.2 2.46 2.67 2.76 2.97 4.96 5.27 5.26 5.57

3.3 2.58 2.79 2.88 3.09 5.18 5.50 5.48 5.80

3.4 2.70 2.92 3.00 3.22 5.41 5.73 5.71 6.03

3.5 2.82 3.04 3.12 3.34 5.63 5.96 5.93 6.26






for Tools


1.5 3-2 3-6 4-2 4-6 5-8 6-2 6-8 7-2

1.6 3-5 3-9 4-5 4-9 6-2 6-9 7-2 7-9

1.7 3-7 3-11 4-7 4-11 6-8 7-3 7-8 8-3

1.8 3-10 4-2 4-10 5-2 7-2 7-10 8-2 8-10

1.9 4-0 4-5 5-0 5-5 7-9 8-5 8-9 9-5

2.0 4-3 4-8 5-3 5-8 8-4 9-0 9-4 10-0

2.1 4-5 4-10 5-5 5-10 8-11 9-7 9-11 10-7

2.2 4-8 5-2 5-8 6-2 9-6 10-3 10-6 11-3

2.3 5-0 5-6 6-0 6-6 10-2 10-10 11-2 11-10

2.4 5-4 5-10 6-4 6-10 10-9 11-6 11-9 12-6

2.5 5-8 6-2 6-8 7-2 11-5 12-3 12-5 13-3

2.6 6-0 6-6 7-0 7-6 12-1 12-11 13-1 13-11

2.7 6-4 6-10 7-4 7-10 12-10 13-8 13-10 14-8

2.8 6-8 7-3 7-8 8-3 13-6 14-5 14-6 15-5

2.9 7-0 7-7 8-0 8-7 14-3 15-2 15-3 16-2

3.0 7-4 8-0 8-4 9-0 14-11 15-10 15-11 16-10

3.1 7-9 8-5 8-9 9-5 15-7 16-7 16-7 17-7

3.2 8-1 8-9 9-1 9-9 16-4 17-4 17-4 18-4

3.3 8-6 9-2 9-6 10-2 17-0 18-1 18-0 19-1

3.4 8-11 9-7 9-11 10-7 17-9 18-10 18-9 19-10

3.5 9-3 10-0 10-3 11-0 18-6 19-7 19-6 20-7






for Tools


1.5 1.50 1.64 1.80 1.94 3.24 3.48 3.54 3.78

1.6 1.64 1.80 1.94 2.10 3.54 3.80 3.84 4.10

1.7 1.79 1.96 2.09 2.26 3.86 4.13 4.16 4.43

1.8 1.95 2.12 2.25 2.42 4.19 4.47 4.49 4.77

1.9 2.11 2.29 2.41 2.59 4.53 4.83 4.83 5.13

2.0 2.28 2.47 2.58 2.77 4.86 5.16 5.16 5.46

2.1 2.45 2.65 2.75 2.95 5.19 5.50 5.49 5.80

2.2 2.63 2.84 2.93 3.14 5.53 5.86 5.83 6.16

2.3 2.81 3.04 3.11 3.34 5.88 6.22 6.18 6.52

2.4 3.01 3.24 3.31 3.54 6.24 6.59 6.54 6.89

2.5 3.20 3.44 3.50 3.74 6.60 6.97 6.90 7.27

2.6 3.40 3.66 3.70 3.96 6.98 7.37 7.28 7.67

2.7 3.61 3.87 3.91 4.17 7.37 7.77 7.67 8.07

2.8 3.82 4.09 4.12 4.39 7.77 8.18 8.07 8.48

2.9 4.04 4.32 4.34 4.62 8.18 8.60 8.48 8.90

3.0 4.27 4.56 4.57 4.86 8.60 9.04 8.90 9.34






for Tools


1.5 4-11 5-5 5-11 6-5 10-8 11-5 11-8 12-5

1.6 5-5 5-11 6-5 6-11 11-8 12-6 12-8 13-6

1.7 5-11 6-5 6-11 7-5 12-8 13-7 13-8 14-7

1.8 6-5 7-0 7-5 8-0 13-9 14-8 14-9 15-8

1.9 6-11 7-7 7-11 8-7 14-11 15-10 15-11 16-10

2.0 7-6 8-2 8-6 9-2 16-0 17-0 17-0 18-0

2.1 8-1 8-9 9-1 9-9 17-1 18-1 18-1 19-1

2.2 8-8 9-4 9-8 10-4 18-2 19-3 19-2 20-3

2.3 9-3 10-0 10-3 11-0 19-4 20-5 20-4 21-5

2.4 9-11 10-8 10-11 11-8 20-6 21-8 21-6 22-8

2.5 10-6 11-4 11-6 12-4 21-8 22-11 22-8 23-11

2.6 11-2 12-0 12-2 13-0 22-11 24-2 23-11 25-2

2.7 11-11 12-9 12-11 13-9 24-3 25-6 25-3 26-6

2.8 12-7 13-6 13-7 14-6 25-6 26-10 26-6 27-10

2.9 13-3 14-3 14-3 15-3 26-10 28-3 27-10 29-3

3.0 14-0 15-0 15-0 16-0 28-3 29-8 29-3 30-8







for Tools


1.5 2.60 2.81 2.90 3.11 5.79 6.14 6.09 6.44

1.6 2.87 3.09 3.17 3.39 6.31 6.68 6.61 6.98

1.7 3.15 3.39 3.45 3.69 6.85 7.24 7.15 7.54

1.8 3.44 3.69 3.74 3.99 7.42 7.82 7.72 8.12

1.9 3.75 4.01 4.05 4.31 8.00 8.42 8.30 8.72

2.0 4.06 4.34 4.36 4.64 8.60 9.05 8.90 9.35

2.1 4.39 4.69 4.69 4.99 9.23 9.69 9.53 9.99

2.2 4.73 5.04 5.03 5.34 9.87 10.36 10.17 10.66

2.3 5.07 5.40 5.37 5.70 10.54 11.04 10.84 11.34

2.4 5.40 5.74 5.70 6.04 11.23 11.75 11.53 12.05

2.5 5.74 6.09 6.04 6.39 11.94 12.48 12.24 12.78



for Tools


1.5 8-7 9-3 9-7 10-3 19-0 20-2 20-0 21-2

1.6 9-5 10-2 10-5 11-2 20-9 21-11 21-9 22-11

1.7 10-4 11-2 11-4 12-2 22-6 23-9 23-6 24-9

1.8 11-4 12-2 12-4 13-2 24-4 25-8 25-4 26-8

1.9 12-4 13-2 13-4 14-2 26-3 27-8 27-3 28-8

2.0 13-4 14-3 14-4 15-3 28-3 29-9 29-3 30-9

2.1 14-5 15-6 15-5 16-6 30-4 31-10 31-4 32-10

2.2 15-7 16-7 16-7 17-7 32-5 34-0 33-5 35-0

2.3 16-8 17-9 17-8 18-9 34-7 36-3 35-7 37-3

2.4 17-9 18-10 18-9 19-10 36-11 38-7 37-11 39-7

2.5 18-10 20-0 19-10 21-0 39-2 41-0 40-2 42-0



1 Distances listed are for standard atmospheric conditions. The data used to formulate this table was obtained from testdata taken with standard atmospheric conditions. Standard atmospheric conditions are defined as temperaturesabove freezing, wind less than 24 km per hr, unsaturated air, normal barometer, uncontaminated air, and clean anddry insulators. If standard atmospheric conditions do not exist, extra care must be taken.

2 Distances are based on altitudes below 900 m above sea level. For altitudes above 900 m, Rule 441A6 applies.

Supporting Comment

Table values have been adjusted to conform with the latest edition of IEEE Std 516. The addition of theMAID, MTID, MAD, and MAD for Tools gives the user addition choices. Previous editions of the NESConly listed the “Mad for Tools” distance.


Reject.


The committee believes that the existing practice of using MAD with Tools from IEEE Std 516 as theminimum approach distances is the clearest way to present this information to users. Adding columns to thetable may confuse users.


Affirmative: (18) Blackley, Bowmer, Brooks, Brubaker, Doering, Erga, Granata, Herbinger, Hunt,McKinney, Poholski, Russell, Schweitzer, Shaw, Smoak, Stonerock, Tomaseski, Tootle

Negative: (3) Grose, Theis, Verdecchio


Explanation of Vote

Grose: (Negative) The purpose of this CP was to provide additional information and optimal informationneeded for live work.

Theis: (Negative) The present charts are inadequate for live-line work. The proposed charts would be moreinformative to those performing the work.

Verdecchio: (Negative) The present table is too limited for users to do live work.

Revised Text

CP3198

Part: 4 Section: 44 441 Tables 441-2 and 441-3

Submitter

Charles Grose



Proposed Change

m

1 Distances listed are for standard atmospheric conditions. The data used to formulate this table was obtained from testdata taken with standard atmospheric conditions. Standard atmospheric conditions are defined as temperatures abovefreezing, wind less than 24 km per hr, unsaturated air, normal barometer, uncontaminated air, and clean and dry insulators.If standard atmospheric conditions do not exist, extra care must be taken. 2 Distances are based on altitudes below 900 m above sea level. For altitudes above 900 m, Rule 441A6 applies. 3 See Rule 441A4a.

Table 441-2—AC live work minimum approach distances for altitudes less than 900 m above sea level, where T has been determined according to Rule 441A51, 2


Maximum anticipated


factor T

Distance to employee—PhaseLine-to-ground, in air, barehand, and clear live-line tool

Maximum phaseline-to-phaseline voltage in kV

72.5 to 121.0

121.1 to 145.0

145.1 to 169.0

169.1 to 242.0

242.1 to 362.0

362.1 to 550.0

550.1 to 800.0

1.5 0.720.66 0.73 0.80 1.01 1.36 1.961.94 3.163.11

1.6 0.790.68 0.760.75 0.83 1.05 1.43 2.122.10 3.463.39

1.7 0.860.70 0.78 0.86 1.10 1.50 2.28 2.26 3.783.69

1.8 0.930.73 0.81 0.900.89 1.15 1.57 2.452.42 4.113.99

1.9 1.010.75 0.84 0.93 1.20 1.64 2.622.59 4.454.31

2.0 1.070.77 0.87 0.96 1.24 1.71 2.822.77 4.8434.64

2.1 1.100.80 0.900.89 0.99 1.29 1.78 3.012.95 5.224.99

2.2 1.120.82 0.92 1.031.02 1.34 1.881.86 3.203.14 5.605.34

2.3 1.140.84 0.95 1.06 1.38 1.981.96 3.403.34 6.005.70

2.4 1.160.87 0.98 1.09 1.43 2.082.07 3.6133.54 6.46 6.04

2.5 1.180.89 1.01 1.12 1.48 2.192.17 3.843.74 6.896.39

2.6 1.200.91 1.041.03 1.16 1.52 2.302.27 4.063.96

2.7 1.230.94 1.06 1.19 1.57 2.412.38 4.304.17

2.8 1.250.96 1.09 1.22 1.62 2.542.49 4.564.39

2.9 1.270.98 1.12 1.261.25 1.66 2.652.61 4.804.62

3.033.0 1.291.01 1.15 1.29 1.71 2.772.72 5.074.86

3.1 1.311.03 1.18 1.32 1.76 2.892.84

3.2 1.331.05 1.20 1.35 1.821.81 3.02 2.97

3.3 1.361.08 1.23 1.391.38 1.881.87 3.153.09

3.4 1.371.10 1.26 1.42 1.94 3.273.22

3.5 1.391.12 1.29 1.45 2.022.00 3.403.34



ft



Maximum anticipated


factor T

Distance to employee—phaseline-to-ground, in air, barehand, and clear live-line tool


72.5 to 121.0

121.1 to 145.0

145.1 to 169.0

169.1 to 242.0

242.1 to 362.0

362.1 to 550.0

550.1 to 800.0


1.5 2 2 2 5 2 8 3 4 4 6 6 6 5 10 5 3

1.6 2 3 2 6 2 9 3 6 4 9 7 6 011 11 5 2

1.7 2 4 2 7 2 10 3 8 4 11 7 6 5 12 5 2

1.8 2 5 2 8 3 0 3 10 5 2 8 1 0 13 6 2

1.9 2 6 2 9 3 1 4 0 5 5 8 8 7 14 8 2

2.0 2 7 2 11 3 2 4 1 5 8 9 4 2 15 113

3

2.1 2 8 3 0 3 4 4 3 5 10 9 11 9

17 16

2 6

2.2 2 9 3 1 3 5 4 5 6 2 10 74 18 17

5 7

2.3 2 10 3 2 3 6 4 7 6 6 11 2 0 19 18

9

2.4 2 11 3 3 3 7 4 9 6 10 1111

103

821 19

3 10

2.5 3 0 3 4 3 9 4 11 7 3 2 12 8 4 22 21

8 0

2.6 3 0 3 5 3 10 5 0 7 7 6 13 4 0

2.7 3 1 3 6 3 11 5 2 7 11 10

14 13

2 9

2.8 3 2 3 7 4 1 5 4 8 4 3 14 12 6

2.9 3 3 3 9 4 2 5 6 8 9 7 15 93

3.03 3 4 3 10 4 3 5 8 9 2 0 16 8 0

3.1 3 5 3 11 4 4 5 10 9 6 5

3.2 3 6 4 0 4 6 6 0 9 11 9

3.3 3 7 4 1 4 7 6 3 2 10 4 2

3.4 3 8 4 2 4 8 6 5 10 9 7

3.5 3 9 4 3 4 10 6 8 7 11 3 0



1 Distances listed are for standard atmospheric conditions. The data used to formulate this table was obtained from testdata taken with standard atmospheric conditions. Standard atmospheric conditions are defined as temperatures abovefreezing, wind less than 15 mi per hr, unsaturated air, normal barometer, uncontaminated air, and clean and dryinsulators. If standard atmospheric conditions do not exist, extra care must be taken.

2 Distances are based on altitudes below 3000 ft above sea level. For altitudes above 3000 ft, Rule 441A6 applies.

3 See Rule 441A4a.

m

Table 441-3—AC live work minimum approach distances for altitudes less than 900 m above sea level, where the T has been determined according to Rule 441A51, 2



factor T

Distance to employee phaseline-to-phaseline, in air, barehand, and clear live-line tool


72.5 to 121.0

121.1 to 145.0

145.1 to 169.0

169.1 to 242.0

242.1 to 362.0

362.1 to 550.0

550.1 to 800.0

1.5 0.760.88 0.851.0 0.941.11 1.211.46 1.652.18 2.433.78 3.966.44

1.6 0.840.92 0.941.04 1.051.16 1.361.53 1.892.34 2.864.10 4.766.98

1.7 0.92 0.95 1.041.08 1.161.20 1.531.59 2.132.50 3.334.43 5.627.54

1.8 1.000.98 1.131.11 1.271.25 1.681.65 2.362.67 3.804.77 6.518.21

1.9 1.081.01 1.231.15 1.381.29 1.851.73 2.612.85 4.325.13 7.488.72

2.0 1.151.04 1.321.19 1.481.34 2.001.83 2.833.03 4.845.46 8.4739.35

2.1 1.181.07 1.351.23 1.531.38 2.051.92 2.913.21 5.095.80 9.00 9.99

2.2 1.201.11 1.381.26 1.561.42 2.092.02 3.033.41 5.326.16 9.4710.66

2.3 1.221.14 1.411.30 1.591.47 2.142.12 3.153.60 5.57 6.52 9.9911.34

2.4 1.251.17 1.441.34 1.621.51 2.192.23 3.273.81 5.8236.89 10.5812.05

2.5 1.271.20 1.461.38 1.651.56 2.232.33 3.394.02 6.117.27 11.1012.78

2.6 1.291.23 1.491.42 1.691.60 2.282.44 3.534.23 6.397.67

2.7 1.321.26 1.521.45 1.721.66 2.332.56 3.674.45 6.718.07

2.8 1.351.30 1.551.49 1.761.72 2.382.67 3.834.68 7.038.48

2.9 1.371.33 1.581.53 1.79 2.432.79 3.974.91 7.328.90

3.03 1.391.36 1.611.57 1.821.85 2.482.91 4.105.13 4.649.34

3.1 1.411.39 1.631.61 1.851.92 2.523.03 4.245.35

3.2 1.431.42 1.661.64 1.881.99 2.583.16 4.375.57

3.3 1.461.45 1.691.68 1.922.06 2.663.28 4.545.80

3.4 1.481.49 1.711.72 1.942.13 2.713.41 4.676.03

3.5 1.501.52 1.731.76 1.972.20 2.803.55 4.806.26



1 Distances listed are for standard atmospheric conditions. The data used to formulate this table was obtained from testdata taken with standard atmospheric conditions. Standard atmospheric conditions are defined as temperaturesabove freezing, wind less than 24 km per hr, unsaturated air, normal barometer, uncontaminated air, and clean anddry insulators. If standard atmospheric conditions do not exist, extra care must be taken.

2 Distances are based on altitudes below 900 m above sea level. For altitudes above 900 m, Rule 441A6 applies. 3 See Rule 441A4a.

ft



Maximum anticipated


factor T

Distance to employee—phaseline-to-phaseline work, in air, barehand, and clear live-line tool


72.5 to 121.0

121.1 to 145.0

145.1 to 169.0

169.1 to 242.0

242.1 to 362.0

362.1 to 550.0

550.1 to 800.0


1.5 2 610 32 10 4

3 1 8 4 0 10

5 7 6 2 8 12

0 5 13 21

0 2

1.6 2 3 9 1 3 25 3 6 10

4 5 6 1 6 7 3 9 9 13

5 6 15 22

8 11

1.7 3 1 2 3 5 7 3 4 10 0

5 13 7 8 03 11 14

0 7 18 24

6 9

1.8 3 4 3 3 9 8 4 3 2 5 7 6 7 8 9 10

12 15

6 8 21 26

5 8

1.9 3 7 4 4 3 1 10

4 7 3 6 5 1 9 8 9 7 5 14 16

3 10

24 28

7 8

2.0 3 10 6

4 3 4 11

4 11 5

6 7 0 9 10

4 0 15 18

11 0

2730

103

9

2.1 3 11 7

4 6 1 5 4 71 6 9 4 9 10

7 16 19

9 1 29 32

7 10

2.2 43 0 8 4 7 2 5 4 2 9 6 11 8

10 11

0 3 17 20

6 3 31 35

1 0

2.3 4 3 19 4 8 3 5 4 3 10

7 1 0 10 11

5 10

18 21

4 5 32 37

10 3

2.4 4 3 2 11

4 9 5 5 4 0 7 3 4 10 12

9 6 1922

238 34 39

9 7

2.5 4 3 0 4 10 7

5 6 2 7 4 8 11 13

2 3 20 23

1 11

36 42

6 0

2.6 4 3 1 4 11 8

5 7 4 7 8 6 1 1113

7 11

21 25

0 2

2.7 4 4 2 5 4 0 10

5 8 6 7 8 8 5 12 14

1 8 22 26

0 6

2.8 4 6 4 5 4 1 11

5 10 8

7 8 10 12 15

7 5 23 27

1 10



1 Distances listed are for standard atmospheric conditions. The data used to formulate this table was obtained from testdata taken with standard atmospheric conditions. Standard atmospheric conditions are defined as temperatures abovefreezing, wind less than 15 mi per hr, unsaturated air, normal barometer, uncontaminated air, and clean and dryinsulators. If standard atmospheric conditions do not exist, extra care must be taken.

2 Distances are based on altitudes below 3000 ft above sea level. For altitudes above 3000 ft, Rule 441A6 applies. 3 See Rule 441A4a.

Supporting Comment

1. Table values have been adjusted to conform with the latest edition of IEEE Std 516.



Reject.



2.9 4 6 5 5 3 1 5 11 8 9 0 2 13 16

1 2 24 29

0 3

3.03 4 7 6 5 4 2 6 0 1 8 9 2 7 13 16

6 10

25 30

1 8

3.1 4 8 7 5 5 4 6 1 4 8 10

4 0 13 17

11 7

3.2 4 9 5 6 5 6 2 7 8 10

6 5 14 18

5 4

3.3 4 10 5 7 6 4 10

8 10

9 10

14 19

11 1

3.4 4 11 5 8 6 7 5 0 8 11

11 3

15 19

4 10

3.5 5 0 5 9 10

6 7 6 3 9 11

3 8 15 20

9 7

Table 441-3—AC live work minimum approach distances for altitudes less than 3000 ft above sea level, where T has been determined according to Rule 441A51, 2 (continued)


Maximum anticipated


factor T

Distance to employee—phaseline-to-phaseline work, in air, barehand, and clear live-line tool


72.5 to 121.0

121.1 to 145.0

145.1 to 169.0

169.1 to 242.0

242.1 to 362.0

362.1 to 550.0

550.1 to 800.0






Affirmative: (17) Blackley, Bowmer, Brubaker, Doering, Erga, Granata, Grose, Herbinger, Hunt,McKinney, Poholski, Russell, Shaw, Smoak, Stonerock, Theis, Tootle

Negative: (1) Tomaseski


Explanation of Vote

Tomaseski: (Negative) Minimum approach distances in the NESC have, for several years, followed thecalculation method and resulting distances published in IEEE Std 516, IEEE Guide for Maintenance Methodson Energized Power Lines. The minimum approach distance (MAD) is determined from the minimum airinsulation distance (MAID), plus a factor for inadvertent movement (M). M is an established distance: 2 ftbelow 72.5 kV voltage levels, and 1 ft for voltage levels at 72.5 kV and above. M has not been a subject ofrevision in IEEE Std 516 nor the NESC.

The industry needs to be cognizant of the fact that the NESC, IEEE Std 516, and OSHA regulations all publishMAD tables. OSHA depends on the NESC, and also depends on IEEE Std 516 for this information. The threedocuments need to be in concert with each other. OSHA will most likely follow IEEE Std 516 and proposethose MAD distances in the ongoing revision of Subpart V and 1910.269, and the NESC should be technicallybe doing the same.

The method of calculating MAID has been revised several times over the years, and it appears it may continuealong that path. Depending on how the MAID calculation method is changed, the resulting MAD distancescan be affected slightly, or affected a great deal in terms of adding or subtracting from previously publisheddistances. NESC MAD distances are regularly used by regulators, both at the Federal and state level, and byemployers. Regularly changing MAD distances, for example in every edition of the NESC, understandablycreates issues for all affected parties. Where and when will this end? Revisions to IEEE 516 MAD tables arebased on, in part, that some of the calculations were found to be incorrect. The problem is the changes willnot be just simple corrections. That in itself leaves the possibility that during the next revision cycle of IEEEStd 516, the method could change again, thereby changing the MAD distances again.

Most of the changes in MAD distances over the years have been minimal, specifically inches in most of thevoltage levels. But the potential for significant changes will continue to be a subject of a change proposalaffecting Part 4 of the NESC. The question has to now be asked, is it necessary to change the MAD distancesin the NESC by one or two inches each time IEEE 516 MAID calculation methods are revised?

Part 4 of the NESC is designed to provide practical work rules as one means of safeguarding workers frominjury. It may be time to study MAD concepts, specifically how MAD distances should be published in theNESC. At a minimum, these questions should be considered:

1. Is it necessary for NESC MAD tables to publish distances as precise as in IEEE Std 516?

2. Is it necessary for the NESC MAD distances to be published in feet/inches, or can the distances be rounded?

3. Is there a method to publish rounded MAD distances that will provide the level of safety the currentpublishing method provides?

4. If a user of the NESC requires more precise distances, i.e., in feet/inches, would referencing and directing



the user to IEEE Std 516 (where those numbers will be published) be acceptable?

An example of a simplified MAD Table for voltages 0 V to 72.5 kV only:

Most of these distances have been rounded up by a few inches. Proposed changes in IEEE Std 516 and futurechanges should fit within these distances. The higher voltage tables include more calculated distances becauseof per unit overvoltage factors. The concept of how those distances are published in the NESC should beconsidered also. Rounded distances would not technically fit those tables.

Revised Text

CP3189

Part: 4 Section: 44 441 Table 441-3(m)

Submitter

Charles Grose

Proposed Change

Voltage in kilovolts phase-to-phase1


Phase-to-ground Phase-to-phase




0.301 to 0.7501 0.30 1-0 0.30 1-0

0.751 to 15 0.76 2-6 0.76 2-6

15.1 to 36.0 0.91 3-0 0.91 3-0

36.1 to 46.0 0.91 3-0 0.91 3-0

46.1 to 72.5 0.91 3-0 1.22 4-0



m

Supporting Comment



Reject.







Explanation of Vote





Table 441-3—AC live work minimum approach distances for altitudes less than 900 m above sea level, where the T has been determined according to Rule 441A51, 2


Maximum anticipated


factor T

Distance to employee— phase-to-phase line-to-line work, in air, barehand, and clear live-line tool


72.5 to 121.0

121.1 to 145.0

145.1 to 169.0

169.1 to 242.0

242.1 to 362.0

362.1 to 550.0

550.1 to 800.0

1.5 0.76 0.85 0.94 1.21 1.65 2.43 3.96

1.6 0.84 0.94 1.05 1.36 1.89 2.86 4.76




Revised Text

CP3190

Part: 4 Section: 44 441 Table 441-3(ft)

Submitter

Charles Grose

Proposed Change

ft

Supporting Comment



Reject.





Maximum anticipated


factor T

Distance to employee— phase-to-phase line-to-line e work, in air, barehand, and clear live-line tool


72.5 to 121.0

121.1 to 145.0

145.1 to 169.0

169.1 to 242.0

242.1 to 362.0

362.1 to 550.0

550.1 to 800.0


1.5 2 6 2 10 3 1 4 0 5 6 8 0 13 0

1.6 2 9 3 2 3 6 4 6 6 3 9 5 15 8







Explanation of Vote




Schweitzer: (Negative) In support of 516 Subcommittee we feel that the term line-to-line is more appropriatefor Tables that address both ac and dc voltages versus phase-to-phase that only deals with ac.


Revised Text

CP3201


Submitter

Charles Grose

Proposed Change



Table 441-4—DC live work distance for altitudes less than 900 m above sea level (See Rule 441 in its entirety.)

Pole-to-ground work

Voltage

VP-Gkv

T MAID MTID MADMAD

for Tools

MAID MTID MADMAD

for Tools

p.u m m m m ft-in ft-in ft-in ft-in

250 1.5 0.81 0.89 1.11 1.19 2-8 3-0 3-8 4-0

250 1.6 0.87 0.95 1.17 1.25 2-10 3-2 3-10 4-2

250 1.7 0.92 1.01 1.22 1.31 3-1 3-4 4-1 4-4

250 1.8 0.98 1.07 1.28 1.37 3-3 3-7 4-3 4-7

400 1.5 1.30 1.43 1.60 1.73 4-3 4-9 5-3 5-9

400 1.6 1.38 1.52 1.68 1.82 4-7 5-0 5-7 6-0

400 1.7 1.51 1.65 1.81 1.95 5-0 5-5 6-0 6-5

400 1.8 1.63 1.79 1.93 2.09 5-5 5-11 6-5 6-11

500 1.5 1.73 1.89 2.03 2.19 5-9 6-3 6-9 7-3

500 1.6 1.90 2.08 2.20 2.38 6-3 6-10 7-3 7-10

500 1.7 2.10 2.28 2.40 2.58 6-11 7-6 7-11 8-6

500 1.8 2.28 2.48 2.58 2.78 7-6 8-2 8-6 9-2

600 1.5 2.28 2.48 2.58 2.78 7-6 8-2 8-6 9-2

600 1.6 2.52 2.73 2.82 3.03 8-3 9-0 9-3 10-0

600 1.7 2.76 2.98 3.06 3.28 9-1 9-10 10-1 10-10

600 1.8 3.02 3.25 3.32 3.55 9-11 10-8 10-11 11-8

750 1.5 3.21 3.46 3.51 3.76 10-7 11-4 11-7 12-4

750 1.6 3.55 3.81 3.85 4.11 11-8 12-6 12-8 13-6

750 1.7 3.91 4.18 4.21 4.48 12-10 13-9 13-10 14-9

750 1.8 4.28 4.57 4.58 4.87 14-1 15-0 15-1 16-0




factor T

Distance to employee—pole-to-ground, air, barehand, clear live-line tool

Maximum pole-to-pole voltage in kV

0 to 250 251 to 400 401 to 500 501 to 600 601 to 750

1.5 or lower 1.12 1.60 2.06 2.62 3.61

1.6 1.17 1.69 2.24 2.86 3.98

1.7 1.23 1.82 2.42 3.12 4.37

1.8 1.28 1.95 2.62 3.39 4.79

Table 441-4—DC Live work minimum approach distance for altitudes less than 3000 ft above sea level


Pole-to-pole work

Ftvoltage

VP-PkV

T MAID MTID MADMAD

for Tools

MAID MTID MADMAD

for Tools


500 1.5 1.35 1.49 1.65 1.79 5-4 5-11 6-4 6-11

500 1.6 1.41 1.55 1.71 1.85 4-8 5-1 5-8 6-1

500 1.7 1.49 1.64 1.79 1.94 6-2 6-9 7-2 7-9

500 1.8 1.57 1.72 1.87 2.02 6-8 7-3 7-8 8-3

800 1.5 2.68 2.90 2.98 3.20 10-7 11-5 11-7 12-5

800 1.6 2.85 3.07 3.15 3.37 11-6 12-5 12-6 13-5

800 1.7 3.02 3.25 3.32 3.55 12-6 13-5 13-6 14-5

800 1.8 3.19 3.43 3.49 3.73 13-6 14-6 14-6 15-6

1000 1.5 3.79 4.06 4.09 4.36 14-11 16-0 15-11 17-0

1000 1.6 4.03 4.31 4.33 4.61 16-4 17-5 17-4 18-5

1000 1.7 4.28 4.57 4.58 4.87 17-9 18-11 18-9 19-11

1000 1.8 4.54 4.84 4.84 5.14 19-2 20-5 20-2 21-5

1200 1.5 5.07 5.40 5.37 5.70 20-0 21-3 21-0 22-3

1200 1.6 5.41 5.74 5.71 6.04 21-10 23-3 22-10 24-3

1200 1.7 5.75 6.10 6.05 6.40 23-9 25-3 24-9 26-3

1200 1.8 6.10 6.47 6.40 6.77 25-9 27-4 26-9 28-4



NOTES for Table 441-4 (m and ft)

1. When the value of T at the worksite has not been determined according to Rule 441A5, T = 1.8 shall be used.

2. The data used to calculate these tables was obtained from test data taken with standard atmospheric conditions. Stan-dard atmospheric conditions are defined as temperatures above freezing, wind less than 15 mi per hr or 24 km perhr, unsaturated air, normal barometer, uncontaminated air, and clean and dry insulators. If standard atmospheric con-ditions do not exist, extra care must be taken.

3. For altitudes above 3000 ft or 900 m, Rule 441A6 applies.

Supporting Comment

Table has been adjusted to conform with the latest edition of IEEE Std 516


Reject.

1500 1.5 7.32 7.73 7.62 8.03 28-10 30-5 29-10 31-5

1500 1.6 7.82 8.24 8.12 8.54 31-7 33-4 32-7 34-4

1500 1.7 8.34 8.77 8.64 9.07 34-6 36-3 35-6 37-3

1500 1.8 8.87 9.32 9.17 9.62 37-5 39-4 38-5 40-4

Maximum anticipated per

unit overvoltage

factor T



0 to 250 251 to 400 401 to 500 501 to 600 601 to 750

ft in ft in ft in ft in ft in

1.5 or lower 3 8 5 3 6 9 8 7 11 10

1.6 3 10 5 7 7 4 9 5 13 1

1.7 4 1 6 0 7 11 10 3 14 4

1.8 4 3 6 5 8 7 11 2 15 9

Table 441-4—DC Live work minimum approach distance for altitudes less than 3000 ft above sea level (continued)


Pole-to-pole work

Ftvoltage

VP-PkV

T MAID MTID MADMAD

for Tools

MAID MTID MADMAD

for Tools





The committee believes that the existing practice of using MAD for Tools from IEEE Std 516 as theminimum approach distances is the clearest way to present this information to users. Adding columns to thetable may confuse users.



Negative: (0)


Revised Text

CP3202


Submitter

Charles Grose

Proposed Change

mTable 441-4—DC live work distance for altitudes less than 900 m above sea level



factor T



0 to 250 251 to 400 401 to 500 501 to 600 601 to 750

1.5 or lower 1.121.19 1.601.73 2.062.19 2.622.48 3.61 3.76

1.6 1.171.25 1.691.82 2.242.38 2.863.03 3.984.11

1.7 1.231.31 1.821.95 2.422.58 3.123.28 4.374.48

1.8 1.281.37 1.952.09 2.622.78 3.393.55 4.794.87



ft

NOTES for Table 441-4 (m and ft) 1. When the value of T at the worksite has not been determined according to Rule 441A5, T = 1.8 shall be used. 2. The data used to calculate these tables was obtained from test data taken with standard atmospheric conditions. Stan-

dard atmospheric conditions are defined as temperatures above freezing, wind less than 15 mi per hr or 24 km perhr, unsaturated air, normal barometer, uncontaminated air, and clean and dry insulators. If standard atmospheric con-ditions do not exist, extra care must be taken.

3. For altitudes above 3000 ft or 900 m, Rule 441A6 applies.

Supporting Comment

Table has been adjusted to conform with the latest edition of IEEE Std 516


Reject.


Numerical values are not based on an approved standard.




Negative: (0)


Table 441-4—DC Live work minimum approach distance for altitudes less than 3000 ft above sea level


Maximum anticipated


factor T



0 to 250 251 to 400 401 to 500 501 to 600 601 to 750

ft in ft in ft in ft in ft in

1.5 or lower 3 4 8 0 5 3 9 6 7 9 3 8 9 7 2 11 12 10 4

1.6 3 4 10 2 5 6 7 0 7 4 10 9 10 5 0 13 1 6

1.7 4 1 4 6 0 5 7 8 11 6 10 3 10 14 4 9

1.8 4 3 7 6 5 11 8 9 7 2 11 2 8 15 16 9 0



Explanation of Vote

Tomaseski: (Affirmative) See comment on CP3198.

Revised Text

CP3192


Submitter

Charles Grose

Proposed Change

1 The maximum use voltage is the ac voltage (rms) rating of the protective equipment thatdesignates the maximum nominal design voltage of the energized system that may be safelyworked. The nominal design voltage is equal to the phase-to-phase line-to-line voltage onmultiphase circuits.

EXCEPTION 1: If there is no multiphase exposure in a system area (at the worksite) and thevoltage exposure is limited to the phase (polarity on dc systems) to ground potential, the phase(polarity on dc systems) to ground potential shall be considered to be the nominal designvoltage.

EXCEPTION 2: If electric equipment and devices are insulated, isolated, or both, such that themultiphase exposure on a grounded wye circuit is removed and if supplemental insulation (e.g.,insulated aerial device or structure-mounted insulating work platform) is used to insulate theemployee from ground, then the nominal design voltage may be considered as the phase-to-ground line-to-ground voltage on that circuit.

Supporting Comment


Table 441-6—Maximum use voltage for rubber insulating equipment

Class of equipment Maximum use voltage1

00 500

0 1000

1 7500

2 17 000

3 26 500

4 36 000




Reject.







Explanation of Vote




Schweitzer: (Negative) In support of 516 Subcommittee we feel that the term line-to-line is more appropriatefor Tables that address both ac and dc voltages versus phase-to-phase that only deals with ac.


Revised Text

CP3050


Submitter

Brian Erga

Proposed Change

444D

D. Employee’s protective grounds

When all the switches and disconnectors designated have been operated, rendered inoperable wherepractical, and tagged in accordance with Rule 444C, and the employee has been given permission



to work by the designated person, the employee in charge should immediately proceed to make theemployee’s own protective grounds or verify that adequate grounds have been applied (see Rule445) on the disconnected lines or equipment. During the testing for potential and/or application ofgrounds, distances not less than those shown in Tables 441-1 to 441-3, as applicable, shall bemaintained.

Grounds shall be placed at each side of the work location and as close as practical to the worklocation, or a worksite ground shall be placed at the work location. If work is to be performed atmore than one location on a line section, the line section shall be grounded and short-circuited atone location in the line section and the conductor to be worked on shall be grounded at each worklocation.

The distance in Table 441-1, 441-2, or 441-3, as applicable, shall be maintained from ungroundedconductors at the work location. Where the making of a ground is impractical, or the conditionsresulting therefrom are more hazardous than working on the lines or equipment without grounding,the ground may be omitted by special permission of the designated person.

444D

D. De-energized work methods

The following work methods may be performed on de-energized conductors, cables, andequipment:

1. The conductors, cables, and equipment may be worked as energized using hot stick, rubberglove, or barehand work methods.

2. The conductors, cables, and equipment may be worked as isolated if the conductor, cable, orequipment has been de-energized as specified in Rule 444C, there are no possibilities of backfeed or accidental re-energization, and there is no possibility of induction.

3. The conductors, cables, and equipment may be de-energized as specified in Rule 444C, andtemporary protective grounding equipment is installed as specified in Rule 445.

Supporting Comment

Revise rule by moving grounding requirements to Rule 445 and change this rule to discuss de-energizedwork. The three paragraphs are options of working de-energized in the industry. Paragraph 2 is common inunderground work methods.


Accept as modified.

444D

D. Employee’s protective grounds

When all the designated switches and disconnectors designated have been operated, renderedinoperable where practical, and tagged in accordance with Rule 444C, and the employee has beengiven permission to work by the designated person, the employee in charge should immediatelyproceed to make the employee’s own protective grounds or verify that adequate grounds have beenapplied (see Rule 445) on the disconnected lines or equipment. During the testing for potential and/



or application of grounds, distances not less than those shown in Tables 441-1 to 441-3, asapplicable, shall be maintained.

Grounds shall be placed at each side of the work location and as close as practical to the worklocation, or a worksite ground shall be placed at the work location. If work is to be performed atmore than one location on a line section, the line section shall be grounded and short-circuited atone location in the line section and the conductor to be worked on shall be grounded at each worklocation.

Temporary protective grounds shall be placed at such locations and arranged in such a manner thataffected employees are protected from hazardous differences in electrical potential.

NOTE: Hazardous touch and step potentials may exist around grounded equipment or betweenseparately grounded systems. Additional measures for worker protection may include barriers,insulation, isolation or grounding mats.

The distance in Table 441-1, 441-2, or 441-3, as applicable, shall be maintained from ungroundedconductors at the work location. Where the making of a ground is impractical, or the conditionsresulting there from are more hazardous than working on the lines or equipment without grounding,the ground may be omitted by special permission of the designated person.

EXCEPTION: Alternative work methods such as isolation of equipment, lines, and conductorsfrom all sources including induced voltages may be employed when the employer has assuredworker protection from hazardous differences in electrical potential.



Negative: (0)


Revised Text

CP3051


Submitter

Brian Erga

Proposed Change

445. Protective grounds

A. Installing grounds



When placing protective grounds on a previously energized part, the following sequence andprecautionary measures shall be observed.

EXCEPTION: In certain situations, such as when grounding conductors are supported on somehigh-voltage towers, it may be appropriate to perform the voltage test before bringing thegrounding device into the work area.

1. Current-carrying capacity of grounds

The grounding device shall be of such size as to carry the induced current and anticipated faultcurrent that could flow at the point of grounding for the time necessary to clear the line.

2. Initial connections

Before grounding any previously energized part, the employee shall first securely connect oneend of the grounding device to an effective ground. Grounding switches may be employed toconnect the equipment or lines being grounded to the actual ground connections.

3. Test for voltage

The previously energized parts that are to be grounded shall be tested for voltage except wherepreviously installed grounds are clearly in evidence. The employee shall keep every part of thebody at the required distance by using insulating handles of proper length or other suitabledevices.

4. Completing grounds

a. If the part shows no voltage, the grounding may be completed.

b. If voltage is present, the source shall be determined to ensure that presence of this voltagedoes not prohibit completion of the grounding.

c. After the initial connections are made to ground, the grounding device shall next bebrought into contact with the previously energized part using insulating handles or othersuitable devices and securely clamped or otherwise secured thereto. Where bundledconductor lines are being grounded, grounding of each subconductor should be made.Only then may the employee come within the distances from the previously energizedparts specified in Rule 441A or proceed to work upon the parts as upon a grounded part.

445. Temporary protective grounding methods

Conductors, cables and equipment shall be grounded only after they have been de-energized asspecified in Rule 444C.

The clearances specified in Table 441-1, 441-2, 441-3, or 441-4 shall be maintained from all de-energized conductors, cables, and equipment until they have been properly grounded as required in thisrule.

Conductors, cables, and equipment shall be tested with an approved voltage detector to ensure they arede-energized before temporary protective grounding equipment is installed.

Temporary protective grounding equipment shall be installed in a method that develops an equipotentialzone around the work area and ensures each employee will not be exposed to hazardous potentialdifferences.



Only temporary protective grounding equipment meeting the specifications of ASTM F-855 shall beused to provide employee protection during de-energized and grounded work on conductors, cables,and equipment. The grounding clamps and other grounding equipment and shall be used and applied toconductors, cables, and equipment only as specified by the manufacturer.

Temporary protective grounding equipment shall be installed as short and straight as possible andshould not be coiled while in use. Violent movement should be anticipated if the grounding cables aretoo long, the fault current is high (typically above 35 000 A), and the X/R ratio of the system is high.Special precautions must be taken when any of these conditions are possible.

The possibility of electric field induction hazards may develop in de-energized conductors andequipment if they parallel or cross energized transmission systems. Hazards due to electric fieldinduction should always be considered when these conditions exist. Proper temporary protectivegrounding practices will reduce the hazard but may not totally eliminate the hazard.

The possibility of magnetic field induction hazards may develop in de-energized conductors or cables ifthey are grounded at more than one location, and the de-energized conductors or cables parallelenergized transmission systems. The use of temporary grounding equipment in multiple locations alongthe conductor or cable, or the use of ground switches, can greatly increase the hazard to employees.

Temporary protective grounding equipment shall be sized to carry anticipated induced current and themaximum available fault current that could flow at the worksite until protective devices are able toclear.

The ground-end clamp of the temporary protective grounding equipment shall always be connected toan effective ground first and removed last. The conductor-end of the temporary protective groundingequipment shall be connected last and disconnected first with approved hotline tools.

Temporary protective grounding equipment shall be visually inspected and repairs made if needed eachday before use. If any damage is found the equipment should be replaced.

Personal protective grounding equipment SHALL not be removed until all employees are clear of thelines, cables, or devices. Personal protective grounding equipment shall be removed from the phaseconductors using hot-line tools, with the last connection removed at the ground location.

Personal protective grounding equipment may be removed temporarily during testing. However,insulating equipment, rubber gloves, and hot line tools shall be used to isolate all workers from the linesand devices. Refer to OSHA 1910.269 (O) “Testing and test facilities.”

B. Removing grounds

1. The employee shall first remove the grounding devices from the de-energized parts usinginsulating tools or other suitable devices.

2. In the case of multiple ground cables connected to the same grounding point, all phaseconnections shall be removed before removing any of the ground connections.

EXCEPTION: If the application of Rule 445B2 produces a hazard such as unintentionalcontact of the ground with ungrounded parts, then the grounds may be removed individuallyfrom each phase and ground connection.

3. Extreme caution shall be exercised that the proper sequence of installing or removing groundsis followed. The connection to the effective ground shall be removed last. Otherwise, electricshock and injury may result.



4. Workers on the ground may be exposed to step and touch potentials when all types ofgrounding procedures are used. While work is in progress, ground personal should stay at aminimum of 10 ft from the structure being worked. If ground workers must contact thestructure, approved insulated rubber gloves should be worn or conductive mats used.

Supporting Comment

Revise rule to follow OSHA 1910.269, IEEE Std 1048, and industry practices.


Accept as modified.

445. Protective grounds

A. Installing grounds

When placing protective grounds on a previously energized part, the following sequence andprecautionary measures shall be observed.

EXCEPTION: In certain situations, such as when grounding conductors are supported on somehigh-voltage towers, it may be appropriate to perform the voltage test before bringing thegrounding device into the work area.

1. Current-carrying capacity of grounds

The grounding device shall be of such size as to carry the induced current and anticipated faultcurrent that could flow at the point of grounding for the time necessary to clear the line.

NOTE: Refer to ASTM F-855 for specifications for protective grounding equipment.

Add two NOTEs under B3.

NOTE 1: Electric and magnetic field induction hazards may develop in de-energized conductors,cables, and equipment. Hazards due to electric and magnetic field induction may exist whenconductors, cables, and equipment are parallel or cross other energized circuits.

NOTE 2: Refer to IEEE Std 1048 and IEEE Std 1246 for additional information for personalprotective grounding.



Negative: (0)




New Text

CP3052


Submitter

Brian Erga

Proposed Change

448. Mechanical equipment

Only employees trained to operate mechanical equipment near energized lines and equipment shall beallowed to do so.

A designated employee other than the equipment operator shall observe the approach distance toexposed energized lines and equipment and give timely warnings before the distance specified in Table441-1, 441-2, 441-3, or 441-4, is reached, unless the operator can accurately determine the approachdistance themself.

When mechanical equipment is operated near energized lines and equipment, but outside the distancesspecified in Table 441-1, 441-2, 441-3, or 441-4, each employee shall be protected by the use of at leastone of the work practices listed below:

1. Energized lines and equipment exposed to contact by the mechanical equipment shall be coveredwith insulating protective equipment rated for the voltage involved. Adequate insulating protectiveequipment shall be installed so that the mechanical equipment cannot contact the exposedenergized lines or equipment.

2. The mechanical equipment shall be insulated for the voltage involved. The un-insulated portions ofthe mechanical equipment shall not approach the exposed energized lines and equipment any closerthan the distances specified in Table 441-1, 441-2, 441-3, or 441-4.

3. The mechanical equipment should be grounded to the best available ground to minimize the timethe exposed energized lines and equipment remains energized, and at least one of the followingpractices shall be used:

a. Permanent or temporary insulated platforms, conductive grids or mats bonded to theequipment chassis, shall be installed at points where employees could contact the mechanicalequipment.

b. Employees shall use protective equipment, such as insulated gloves or insulated footwear,rated for the voltage involved, to protect from touch and step potentials around the mechanicalequipment.

c. The mechanical equipment shall be barricaded to prevent employees from contacting themechanical equipment.

Such factors as the task to be performed, length of the boom, stability of the ground supportingthe mechanical equipment, wind and other weather conditions, skill of the operator,



responsiveness of the mechanical equipment's controls, and type of winch line, wire or rope,should be considered to determine if an additional distance should be added to the distancesspecified in Table 441-1, 441-2, 441-3, or 441-4.

If mechanical equipment is operated within the distances specified in Table 441-1, 441-2, 441-3, or 441-4, the operation of the mechanical equipment shall comply with one or more of thefollowing:

— Energized lines and equipment exposed to contact by the mechanical equipment shall becovered with insulating protective equipment rated for the voltage involved. Adequateinsulating protective equipment shall be installed so that the mechanical equipment doesnot enter the distances specified in Table 441-1, 441-2, 441-3, or 441-4.

— The equipment should be insulated for the voltage involved. The un-insulated portions ofthe mechanical equipment should not approach the exposed energized lines and devicesany closer than the distances specified in Table 441-1, 441-2, 441-3, or 441-4.

When any two or more pieces of mechanical equipment at a worksite, having their boom’snear exposed energized lines and devices, and are positioned in a way that allow both to becontacted by employees at one time, shall be bonded together to minimize potentialdifferences.

Supporting Comment

Add new rule covering mechanical equipment.


Reject.


This CP is already covered by Rules 410, 420, and 441.


Affirmative: (15) Blackley, Bowmer, Doering, Granata, Herbinger, Hunt, McKinney, Poholski, Russell,Shaw, Smoak, Stonerock, Theis, Tomaseski, Tootle

Negative: (3) Brubaker, Erga, Grose


Explanation of Vote

Brubaker: (Negative) Mechanical equipment for use in energized lines requires trained operators andunderstanding of energized minimum approach distances. This change proposal would address some of theseconcerns and the differences in equipment that can be used for this type of work.

Erga: (Negative) See CP supporting comments.

Grose: (Negative) Mechanical equipment for use in energized lines requires trained operators andunderstanding of energized minimum approach distances.



Appendix A

Revised Text

CP3294

Part: A Figure A-1

Submitter

James T. Collins

Proposed Change

Revise 5.6 m (18.5 ft) dimension to indicate clearance to low point of conductor sag.

Supporting Comment

This is an editorial correction. In the 1997, 2002, and 2007 and editions of the NESC, the dimension has notcorresponded with the cumulative dimension for the reference, mechanical, and electrical componentclearances. See the following excerpted portion of Figure A-1:



This revision will clarify that the cumulative of the reference, mechanical, and electrical dimensions areequivalent to the total required basic clearance illustrated.


Accept as modified.

Revise Figure 1-A 5.6 m (18.5 ft) dimension to indicate clearance to low point of conductor sag. Move theRigid Live Part Clearance to line up to match the 1990 Edition of the NESC. Add the Mechanical ElectricalComponent reference also as shown in the 1990 Edition of the NESC.



Negative: (0)

Abstention: (0)



Revised Text

CP3440

Part: A Table A-1

Submitter

Allen Clapp

Proposed Change

Move the present column in Table A-1 labeled M&E (mm/m) to the extreme right of the table.

Supporting Comment

The feet version of this column was moved to the right side of the table in the 2007 Edition and, due toinadvertent omission not caught until after the 2007 Edition was printed, the metric version of the columnstayed on the left.

The values in this table were derived from the feet values; metric values are conversions and should be shownon the extreme right.


Accept.



Negative: (0)

Abstention: (0)

Deleted Text

CP3024

Part: A Table A-1 NOTE 1

Submitter

Ewell Robeson



Proposed Change

Revise Appendix A, Table A-1, NOTE 1 as follows:

NOTES:

1. Ungrounded guys and ungrounded pPortions of guys between guy insulators have clearances based on thehighest voltage to which they are exposed.

Supporting Comment



Accept as modifed.


NOTES:

1. Ungrounded guys and ungrounded The portion(s) of guys between guy insulators and the portion(s) ofanchor guys above guy insulators have clearances based on the highest voltage to which they are exposed.



Negative: (0)

Abstention: (0)

Revised Text

CP3293

Part: A Table A-1 NOTE 1

Submitter

James T. Collins

Proposed Change


NOTES:



1. Ungrounded guys and ungrounded Pportions of guys between guy insulators have clearances based on thehighest voltage to which they are exposed.

Supporting Comment

According to Rule 215C2, guys are to be effectively grounded or insulated and this change needs to bereflected in this NOTE 1.




See CP3024.



Negative: (0)

Abstention: (0)



Appendix C

Revised Text

CP3320

Part: C Appendix C

Submitter

James T. Collins

Proposed Change

Make editorial corrections and revisions as noted. See attached documents: (1) Item list of proposedrevisions of Appendix C, and (2) proposed text revisions.

Supporting Comment

During detailed review of Appendix C for the NESC Subcommittee 5 panel discussion for the IEEE-PESJoint Technical Conference in January 2007, a number of errors were discovered. These errors are noted inthe itemized list of proposed revisions.

Other than editorial corrections, proposed revisions to Appendix C are:

1. In Examples 1 and 3, which illustration calculation of wind pressures on lattice towers, force coefficientsof 1.0 were used for wind on the structures. Unless the towers are assumed to be built of round or curvedmembers, the correct force coefficient values would be 3.2. A statement indicating flat-surfaced latticemember is added, and the examples are revised to reflect use of the 3.2 force coefficient.

2. In addition, for Example 2, the center-of-pressure for the conductors arranged in a delta configuration isassumed to be at one-half of the distance between the top and bottom two conductors. With the assumptionstated, the example is correct but can be confusing to the infrequent Code user. Each time this example hasbeen presented to unfamiliar Code users, it has been questioned why the calculated center-of-pressure is notused. Given that the position of the center-of-pressure for the delta arrangement can be readily calculatedand would probably be more easily understood by users, it is proposed that Example 2 be revised to use thecalculated center-of-pressure rather than a value based on engineering judgment.

NESC Appendix C Proposed Revisions

Example 1, Initial paragraph Added sentence to specify that the structure is lattice with flat-sidedmembers.

Example 1, Figure Corrected customary dimension to 79.4 ft (as equivalent to 24.2 m).Also corrected misaligned height dimensions notations

Example 1, Step 1: Cd replaced by Cf.

Example 1, Step 2: Cd replaced by Cf.



Example 1, Step 3: Cd replaced by Cf. For wind on flat-surfaces the force coefficientshould be 3.2 instead of 1.0. Pressure values recalculated with Cf =3.2.

Example 2, Initial paragraph Revised “mid-height” to “calculated center-of-force” for center ofwire location.

Example 2, Figure Revised center of wire location dimension from assumed mid-height of wire configuration, (22.1 m, 74.5 ft), to calculated center-of-force of the conductor loads, (20.6 m, 67.7 ft). Also correctedother misaligned height dimensions notations.

Example 2 Cd replaced by Cf.

The calculated height of the horizontal force resultant for windforces on the phases is 67.7 ft (20.6 m). A height of 72.5 ft (22.1 m)was assumed for the example. A revision of the example isincluded that shows the results based on the calculated center-of-pressure. (Note that the final calculated pressure in the examplebased on tabulated values does not change.) This question has comeup each time I have discussed Example 2.

Example 3, Initial paragraph Meters dimension (m) replaced with feet dimension (ft). Addedsentence to specify that the structure is lattice with flat-sidedmembers.

Example 3, Figure The tower figure is edited to correct the misaligned heightdimension notations in the NESC.

Example 3, All steps Wind pressures for all four tower sections are recalculated using aforce coefficient value of 3.2.

Example 3, Step 2, WS#1 Cd replaced by Cf.

Equal sign (=) added in both velocity pressure coefficientequations. Omitted in the NESC.

Pressure values recalculated using a force coefficient value of 3.2(lattice, flat-surfaced).


Equal sign (=) added in second velocity pressure coefficientequation. Omitted in the NESC.









Example 1 Revisions

Example 1 demonstrates the basic application for determining the tower and wire wind loads. The towerwind load is uniformly distributed over the tower height (h). The structure is a lattice tower with flat-surfaced members.

Example 1, Step 1:

The wire wind pressure, assuming 40 m/s (90 mph), I and Cd Cf equal 1.0, and the table values for kz andGRF, is

Example 1, Step 2:

The overhead groundwire wind pressure, assuming 40 m/s (90 mph), I and Cd Cf equal 1.0, and the tablevalues for kz and GRF, is

Example 1, Step 3:

Step 3: Determine the wind pressure for the structure

Using Table 250-2, select the structure kz value, velocity pressure exposure coefficient:

The kz for the structure is based on the total structure height, h, above the ground line (Rule 250C1), h =31.7 m (104 ft); therefore from Table 250-2, kz = 1.20. The equations of Table 250-2 can be used todetermine the exact value of kz.


Example 4, all five steps Cd replaced by Cf.



It should be noted that the structure center of wind pressure is assumed at 2/3 the structure height for thevalues obtained from Table 250-2. This assumption is included in the table values and the table equation Eswith the adjustment factor 0.67. This assumption is appropriate when the wind speed is assumed uniformlydistributed over the structure height and the structure height is equal to or less than 75 m. Example 3 willdemonstrate when the 2/3 assumption should not be used.

Using Table 250-3, select a structure GRF value, gust response factor:

The structure gust response factor, GRF, is determined using the total structure height, h = 31.7 m (104 ft).Using Table 250-3, the structure GRF equals 0.89. The equations of Table 250-3 can be used to determinethe exact value of GRF.

The structure wind pressure (uniformly distributed), assuming 40 m/s (90 mph), I equals 1.0, and Cd Cfequals 1.0 3.2, and the table values for kz and GRF, is:

Example 2 Revisions

Example 2 demonstrates the engineer’s judgment that the center of wind pressure for a Delta wireconfiguration is at the mid-height calculated center-of-force of the wire configuration.

kz = 2.01 · (0.67 · 31.7 m/275 m)(2/9.5) = 1.172

kz = 2.01 · (0.67 · 104 ft/900 ft)(2/9.5) = 1.172

Bs = 1/(1 + 0.375 · 31.7 m/67) = 0.849

Es = 0.346 · (10/[0.67 · 31.7 m])1/7 = 0.311

GRF = [1 + (2.7 · 0.311 · (0.849)0.5)]/ (1.43)2 = 0.867

Bs = 1/(1 + 0.375 · 104 ft/220) = 0.849

Es = 0.346 · (33/[0.67 · 104 ft])1/7 = 0.311

GRF = [1 + (2.7 · 0.311 · (0.849)0.5)]/ (1.43)2 = 0.867

Wind pressure = 0.613 · (40 m/s)2 · 1.20 · 0.89 · 1.0 · 1.0 3.2 = 1047 3352 newtons/m2 0.172

Wind pressure = 0.00256 · (90 mph)2 · 1.2 · 0.89 · 1.0 · 1.0 3.2 = 22.15 70.87 psf



Determine the wind pressure for the phase conductors.

Using Table 250-2, select a wire kz value, velocity pressure exposure coefficient:

The kz for the wire is based on the height, h, of the center of the wire locations, h = 20.6 m (67.7 ft);therefore from Table 250-2, kz = 1.20. The equations of Table 250-2 can be used to determine the exactvalue kz.

Using Table 250-3, select a wire GRF value, gust response factor:

The wire gust response factor, GRF, is determined using the height of the wire at the center of the wire Deltaconfiguration, h = 20.6 m (67.7 ft), and the design wind span, L. The design wind span for this example isassumed to be 275 m (900 ft). Using the Table the Wire GRF equals 0.71. The equations of Table 250-3 canbe used to determine the exact value of GRF.

kz = 2.01 · (22.1 20.6 m/275 m)(2/9.5) = 1.182 1.165

kz = 2.01 · (72.5 67.7 ft/900 ft)(2/9.5) = 1.182 1.165

Bw = 1/(1 + 0.8 · 275 m/67) = 0.233

Ew = 0.346 · (10/22.1 20.6 m)1/7 = 0.309 0.312

GRF = [1 + (2.7 · 0.309 0.312 · (0.233)0.5)] / (1.43)2 = 0.686 0.688

Bw = 1/(1 + 0.8 · 900 ft/220) = 0.233

Ew = 0.346 · (33/ 72.5 67.7 ft)1/7 = 0.309 0.312

GRF = [1 + (2.7 · 0.309 0.312 · (0.233)0.5)] / (1.43)2 = 0.686 0.688




Example 3 Revisions

Example 3 demonstrates the application of a non-uniform wind load distribution for structures taller than250 m ft. This procedure may also be used on structures less than 250 m ft when in the engineer’s judgmenta detailed wind load distribution is desired. The example structure is a lattice tower with flat-surfacedmembers.

Step 1: Determine assumed wind load distribution

This structure is assumed to have 4 different wind sections (WS) each with its specific uniform wind load.Wind Section #1 (WS#1) was determined by engineering judgment to be the height, h, from the ground lineto the top of the tapered leg, h = 69.5 m (228 ft). The center of wind pressure for WS#1 is assumed to be 2/3the height of 69.5 m (228 ft). WS#2 is assumed to be the distance between the top of the tapered leg to thebottom of the middle crossarm. The center of wind pressure for WS#2 is assumed to be at the mid-height ofthis wind section, h = 75.8 m (248 ft). Similar assumptions are made for WS#3, h = 88.3 m (290 ft), andWS#4, h = 100.3 m (329 ft).

Step 2: Determine the wind load for each structure wind section

For WS#1, determine the uniformly distributed wind load.

Determine kz, h = 69.5 m (228 ft), using Table 250-2, kz = 1.40, using the equations:

Determine GRF. The structure gust response factor is a function of the structure’s dynamic response.Therefore a single value of GRF using the total structure height should be used on all structure wind sections.Given h = 106.1 m (348 ft), using the equations:

Wind pressure = 0.613 · (38 m/s)2 · 1.2 · 0.71 · 1.0 · 1.0 = 754 newtons/m2

Wind pressure = 0.00256 · (85 mph)2 · 1.2 · 0.71 · 1.0 · 1.0 = 15.76 psf

kz = 2.01 · (0.67 · 69.5 m/275 m)(2/9.5)) = 1.383

kz = 2.01 · (0.67 · 228 ft/900 ft)(2/9.5) = 1.383

Bs = 1/(1 + 0.375 · 106.1 m/67) = 0.627

Es = 0.346 · (10/[0.67 · 106.1 m])1/7 = 0.261

GRF = [1 + (2.7 · 0.261 · (0.627)0.5)] / (1.43)2 = 0.762

Bs = 1/(1 + 0.375 · 348 ft/220) = 0.627

Es = 0.346 · (33/[0.67 · 348 ft])1/7 = 0.261

GRF = [1 + (2.7 · 0.261 · (0.627)0.5)]/ (1.43)2 = 0.762



The structure wind pressure (uniformly distributed over WS#1) assuming 40 m/s (90 mph), I equals 1.0, andCd Cf equals 1.0 3.2:


Determine kz, h = 75.8 m (248 ft), using the equations:

GRF = 0.762 for the overall structure, thus the structure wind pressure (uniformly distributed over WS#2)assuming 40 m/s (90 mph), I equals 1.0, and Cd Cf equals 1.0 3.2:



Wind pressure = 0.613 · (40 m/s)2 · 1.40 · 0.762 · 1.0 · 1.0 3.2 = 1046 3348 newtons/m2


kz = 2.01 · (75.8 m/275 m)(2/9.5) = 1.53

kz = 2.01 · (248 ft/900 ft)(2/9.5) = 1.53





GRF = 0.762. The structure wind pressure (uniformly distributed over WS#3) assuming 40 m/s (90 mph), Iequals 1.0, and Cd Cf equals 1.0 3.2:

For WS#4, determine the uniformly distributed wind load. Determine kz, h = 100.3 m (329 ft), using theequations:

GRF = 0762. The structure wind pressure (uniformly distributed over WS#4) assuming 40 m/s (90 mph), Iequals 1.0, and Cd Cf equals 1.0 3.2:

Example 4 Revisions

kz = 2.01 · (88.3 m/275 m)(2/9.5) = 1.58

kz = 2.01 · (290 ft/900 ft)(2/9.5) = 1.58



kz = 2.01 · (100.3 m/275 m)(2/9.5) = 1.63

kz = 2.01 · (329 ft/900 m)(2/9.5) = 1.63





Example 4, Step 1:


Example 4, Step 2:


Example 4, Step 3:

The structure wind pressure (uniformly distributed), assuming 40 m/s (90 mph), I and Cd Cf equal 1.0, andthe table values for kz and GRF, is

Example 4, Step 4:

The communication wire wind pressure, assuming 40 m/s (90 mph), I and Cd Cf equal 1.0, and the tablevalues for kz and GRF, is

Example 4, Step 5:

The transformer wind pressure, assuming 40 m/s (90 mph), I and Cd Cf equal 1.0, and the table values for kzand GRF, is




To refer to a working group to appropriately update the appendix. Kempner: Chair; Slavin, Shultz, Cantrell,Burley.


Affirmative: (27) Bingel, Bullinger, Burley, Busel, Byrne, Clapp, Clem, Corzine, Denbrock, Erdle,Freimark, Fuller, Glaus, Guerry, Haire, Heald, Jones, Kempner, Kluge, Lynch, Pehosh, Peters, Schwalm,Shultz, Soderberg, Jr., Standford, Wong

Negative: (0)


Explanation of Vote

Shultz: (Affirmative) During discussion of this change proposal by Subcommittee 5, the subcommitteeagreed with corrections of the typos and Cf values. The subcommittee accepted the proposal in principle.However, concern was expressed that the situation where a downwind tower section is spaced at a distancefrom a windward tower section such that shelter from the windward section could not be assumed for thedownwind section is not covered in Appendix C.



A working group was assigned to address this concern and recommend a solution to the subcommittee. Theworking group did not make a recommendation prior to the December 31, 2008, deadline; however, amodification of the change proposal to address the concern was in circulation within the working group atthat time.

Because of the significance Appendix C in providing direction to Code users as to how wind loads may bedetermined per Rule 250C, it is important that it be as complete and technically valid as possible for the2012 NESC. Therefore, this comment includes a work-in-progress suggested solution within the workinggroup at the deadline in order to make it available for consideration during the public review process.

To address the wind loading situation described above, the following modification to Example 1 andaddition of a new Example 5 for Appendix C are proposed. These modifications would be in addition toother corrections of the typos and Cf values noted in the original change proposal.

Modification of Example 1:

Example applications for Rule 250C, Tables 250-2 and 250-3

The following four five examples demonstrate the use of Tables 250-2 and 250-3. The method of selectingthe design parameters should not be considered the recommended method for the structures presented inthese examples. The method used for determining the design values should be based on engineeringjudgment.

Example 1 demonstrates the basic application for determining the tower and wire wind loads. The towerwind load is assumed to be uniformly distributed over the tower height (h). The structure is a lattice towerwith flat-surfaced members. (NOTE: Example 5 demonstrates determination of wind loads on a tower basedupon more detailed analysis, including application of loads at centers-of-pressure of tower sections.)

Step 1: Determine the wind pressure for the phase conductors




The kz for the wire is based on the height, h, of the wire at the structure (Rule 250C1), h = 24.2 m (79.4 ft);therefore from Table 250-2, kz = 1.20. The Table kz values represent, approximately, the upper limit for therange of heights, h. The equations of Table 250-2 can be used to determine the exact value of kz.


The wire gust response factor, GRF, is determined using the height of the wire at the structure, h = 24.2 m(79.4 ft), and the design wind span, L. The design span for this example is assumed to be 400 m (1310 ft).Using Table 250-3, the Wire GRF equals 0.69. The table values represent, approximately, the upper limit ofthe GRF value based on the upper limit for the range of heights, h, and lower limit for the range of spanlengths, L. The equations of Table 250-3 can be used to determine the exact value of GRF.


Step 2: Determine the wind pressure for the overhead groundwire


The kz for the wire is based on the height, h, of the wire at the structure (Rule 250C1), h = 31.4 m (103 ft);therefore from Table 250-2, kz = 1.30. The equations of Table 250-2 can be used to determine the exactvalue of kz.

kz = 2.01 · (24.2 m/275 m)(2/9.5) = 1.205

kz = 2.01 · (79.4 ft/900 ft)(2/9.5) = 1.205

Bw = 1/(1 + 0.8 · 400 m/67) = 0.173

Ew = 0.346 · (10/24.2 m)1/7 = 0.305

GRF = [1 + (2.7 · 0.305 · (0.173)0.5)]/ (1.43)2 = 0.657

Bw = 1/(1 + 0.8 · 1310 ft/220) = 0.173

Ew = 0.346 · (33/79.4 ft)1/7 = 0.305

GRF = [1 + (2.7 · 0.305 · (0.173)0.5)] / (1.43)2 = 0.657



kz = 2.01 · (31.4 m/275 m)(2/9.5) = 1.273

kz = 2.01 · (103 ft/900 ft)(2/9.5) = 1.273




The wire gust response factor, GRF, is determined using the height of the wire at the structure, h = 31.4 m(103 ft), and the design wind span, L = 400 m (1310 ft). Using Table 250-3, the overhead groundwire GRFequals 0.68. The equations of Table 250-3 can be used to determine the exact value of GRF.


Step 3: Determine the wind pressure for the structure

Using Table 250-2, select the structure kz value, velocity pressure exposure coefficient:

The kz for the structure is based on the total structure height, h, above the ground line (Rule 250C1), h =31.7 m (104 ft); therefore from Table 250-2, kz = 1.20. The equations of Table 250-2 can be used todetermine the exact value of kz.

It should be noted that the structure center of wind pressure is assumed at 2/3 the structure height for thevalues obtained from Table 250-2. This assumption is included in the table values and the table equation Eswith the adjustment factor 0.67. This assumption is appropriate when the wind speed is assumed uniformlydistributed over the structure height and the structure height is equal to or less than 75 m. Example 3 willdemonstrate when the 2/3 assumption should not be used.

Using Table 250-3, select a structure GRF value, gust response factor:

Bw = 1/(1 + 0.8 · 400 m/67) = 0.173

Ew = 0.346 · (10/31.4 m)1/7 = 0.294

GRF = [1 + (2.7 · 0.294 · (0.173)0.5)] / (1.43)2 = 0.650

Bw = 1/(1 + 0.8 · 1310 ft/220) = 0.173

Ew = 0.346 · (33/103 ft)1/7 = 0.294

GRF = [1 + (2.7 · 0.294 · (0.173)0.5)] / (1.43)2 = 0.650



kz = 2.01 · (0.67 · 31.7 m/275 m)(2/9.5) = 1.172

kz = 2.01 · (0.67 · 104 ft/900 ft)(2/9.5) = 1.172



The structure gust response factor, GRF, is determined using the total structure height, h = 31.7 m (104 ft).Using Table 250-3, the structure GRF equals 0.89. The equations of Table 250-3 can be used to determinethe exact value of GRF.

The structure wind pressure (uniformly distributed), assuming 40 m/s (90 mph), I equals 1.0, and Cd Cfequals 1.0 3.2, and the table values for kz and GRF, is

Add all new Example 5:

Example 5 demonstrates the application of a non-uniform wind load distribution for a lattice tower structurewith a large window section and two separate groundwire support peaks. Wind loads on the window sectionand the groundwire peaks differ from the loading model discussed in Example 3. This example suggestsmethodology to account for loading of these specific tower features. This procedure may be used when, inthe engineer’s judgment, a detailed wind load distribution is desired.

Bs = 1/(1 + 0.375 · 31.7 m/67) = 0.849

Es = 0.346 · (10/[0.67 · 31.7 m])1/7 = 0.311

GRF = [1 + (2.7 · 0.311 · (0.849)0.5)] / (1.43)2 = 0.867

Bs = 1/(1 + 0.375 · 104 ft/220) = 0.849

Es = 0.346 · (33/[0.67 · 104 ft])1/7 = 0.311

GRF = [1 + (2.7 · 0.311 · (0.849)0.5)]/ (1.43)2 = 0.867





Step 1: Determine assumed wind load distribution

This structure is assumed to have four different wind sections (WS), each with its specific uniform windload.

Wind Section #1 (WS #1) was determined by engineering judgment to be the height, h, from the ground lineto the tower waist, h = 12.2 m (40 ft). The center of wind pressure for WS#1 is assumed to be 2/3 the heightof 12.2 m (40 ft). The second section of the tower, WS#2, is assumed to be the distance from the tower waistto the bottom of the crossarm. The center of wind pressure for WS#2 is assumed to be at the mid-height ofthis wind section, h = 19.8 m (65 ft). The third tower section, WS#3, is the crossarm, and its center-of-pressure is assumed to be at its mid-height, h = 28.3 m (93 ft). The fourth tower section, WS#4, is thegroundwire peak section (both peaks will be considered together as one tower section), and its center-of-pressure is assumed to be at its mid-height, h = 31.7 m (100 ft).

Step 2: Determine the wind load for each structure wind section, beginning with section WS#1.

Determine kz, h = 12.2 m (40 ft), using Table 250-2, kz = 1.0, using the equations:

Determine GRF. The structure gust response factor is a function of the structures dynamic response.Therefore a single value of GRF using the total structure height should be used on all structure wind sections.Given h = 31.7 m (104 ft), using the equations:

The structure wind pressure (uniformly distributed over WS#1) assuming 40 m/s (90 mph), I equals 1.0 andCf equals 3.2:

kz = 2.01 · (0.67 · 12.2 m/275 m)(2/9.5) = 0.959

kz = 2.01 · (0.67 · 40 ft/900 ft)(2/9.5) = 0.959



Step 3: Determine the wind load structure wind section WS#2.

In the engineer’s judgment the large window of the tower presents twice the wind exposure of a normalboxed-type lattice structure. That is, the wind exposure on each side of the window would constitute twotower sections upon which wind pressure would be applied. Therefore, the judgment is made to apply aforce coefficient, Cf, of 3.2 to the windward surface on each side of the window (or a single force coefficientof 6.4 to the most windward exposed surface).


GRF = 0.867 for the overall structure, thus the structure wind pressure (uniformly distributed over WS #2)assuming 40 m/s (90 mph), I equals 1.0, and a Cf value of 6.4 will be used (double the normal 3.2 value foropen lattice structures to account for the two sides of the window effectively independently subjected towind pressures):



Bs = 1/(1 + 0.375 · 31.7 m/67) = 0.849

Es = 0.346 · (10/[0.67 · 31.7 m])1/7 = 0.311

GRF = [1 + (2.7 · 0.311 · (0.849)0.5)] / (1.43)2 = 0.867

Bs = 1/(1 + 0.375 · 104 ft/220) = 0.849

Es = 0.346 · (33/[0.67 · 104 ft])1/7 = 0.311

GRF = [1 + (2.7 · 0.311 · (0.849)0.5)] / (1.43)2 = 0.867


Wind pressure = 0.00256 · (90 mph)2 · 1.0 · 0.867· 1.0 · 3.2 = 57.53 psf

kz = 2.01 · (19.8 m/275 m)(2/9.5) = 1.16

kz = 2.01 · (65 ft/900 ft)(2/9.5) = 1.16



kz = 2.01 · (28.3 m/275 m)(2/9.5) = 1.25

kz = 2.01 · (93 ft/900 ft)(2/9.5) = 1.25



GRF = 0.867. The structure wind pressure (uniformly distributed over WS #3) assuming 40 m/s (90 mph), Iequals 1.0 and Cf equals 3.2:


Again, in the engineer’s judgment the two groundwire peaks are separated such that they may be consideredto be independently subjected to wind pressures, which would result in twice the wind exposure of a normalboxed-type lattice section. That is, the wind exposure on the two peak tower components would double theresulting wind load on the peak section of the tower. Therefore, the judgment is made to apply a forcecoefficient, Cf, of 3.2 to the windward surface of each peak (or a single force coefficient of 6.4 to the mostwindward exposed face of the peak section).

For WS#4, determine the uniformly distributed wind load. Determine, h = 30.5 m (100 ft), using theequations:

GRF = 0.867. The structure wind pressure (uniformly distributed over WS#4) assuming 40 m/s (90 mph), Iequals 1.0 and a Cf value of 6.4 will be used (double the normal 3.2 value for open lattice structures toaccount for independent wind loading of the two groundwire peaks):



kz = 2.01 · (30.5 m/275 m)(2/9.5) = 1.27

kz = 2.01 · (100 ft/900 ft)(2/9.5) = 1.27





Appendix E

Revised Text

CP3353

Appendix E Ref B34

Submitter

Percy E. Pool

Proposed Change

In Appendix E, Bibliography, change reference B34 to read:

[B34] IEEE Std 487™-2000 2007, IEEE Recommended Practice for the Protection of Wire-LineCommunication Facilities Serving Electric Supply Locations.

Supporting Comment

This CP updates the year for reference B34.


Accept.



Negative: (0)

Abstention: (0)

Revised Text

CP3354

Appendix E Ref B54

Submitter

Percy E. Pool



Proposed Change

In Appendix E, Bibliography, change reference B54 to read:

[B54] IEEE Std 1590™-2003 2009, IEEE Recommended Practice for the Electrical Protection of OpticalFiber Communication Facilities Serving, or Connected to, Electrical Supply Locations CommunicationFacilities Serving Electric Supply Locations Using Optical Fiber Systems.

Supporting Comment

This CP updates the title and year for reference B54.

IEEE Std 1590-2003 is presently under revision. The title has been changed (as shown above). The revisionprocess should be completed in 2009.




Pending approval and review.



Negative: (0)

Abstention: (0)





Time schedule for the next revision of the National Electrical Safety Code

The revision schedule for the 2012 NESC is as follows:

July 17, 2008 Final date to receive change proposals from the public for revision of the2007 Edition of the National Electrical Safety Code, preparatory to thepublication of a 2012 Edition.

September–October 2008 NESC Subcommittees consider change proposals to the NESC and preparetheir recommendations.

September 1, 2009 Preprint of the change proposals for incorporation into the 2012 Edition ofthe NESC published for distribution to the NESC Committee and otherinterested parties. This opens the comment period, by interested parties, onthe submitted change proposals and the subcommittee recommendations.

May 1, 2010 The final date to submit comments on the submitted change proposal andthe subcommittee recommendations. All comments and recommendationson these proposals are due to the Secretary, NESC Committee.

September–October 2010 Period for NESC Subcommittee Working Groups and NESCSubcommittees to reconsider all recommendations concerning theproposed amendments and prepare final report.

January 15, 2011 Proposed revision of the NESC, Accredited Standards Committee C2,submitted to NESC Committee for letter ballot and to the AmericanNational Standards Institute for concurrent public review.

May 15, 2011 NESC Committee approved revisions of the NESC submitted to theAmerican National Standards Institute for recognition as an ANSIstandard.

August 1, 2011 Publication of the 2012 Edition of the National Electrical Safety Code


Documents

Notice to purchaser - s3.amazonaws.coms3.amazonaws.com/zanran_storage/standards.ieee.org/ContentPages/... · This Preprint provides the full text of each proposal to revise the 2007