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1Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
National Electrical Safety Code® (NESC®) Rules for
Joint Use Construction
Marne and Associates, Inc.
Experts in Electrical Code
619 S.W. Higgins, Suite C
Missoula, MT 59803
(406) 544-8997
www.marneassociates.com
David J. Marne, P.E. Grant D. Glaus, P.E.
2Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 01. Introduction
• Rule 011. Scope
• Used by engineers and linemen
• Administrative authority is
typically the state public service or
utility commission.
• Used by engineers and electricians
• Administrative authority is typically a
state, city, or local electrical
inspector.
3Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
NESC® Rules for Joint Use Construction
• Joint Use
– NESC defines joint use as simultaneous use by two
or more kinds of utilities.
– Power and
communications.
4Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Part 2. Overhead Lines
WORK RULES
UNDERGROUND LINES
PART 4
OVERHEAD LINES
PART 3
ELECTRIC SUPPLY STATIONS
PART 2
PART 1
S afety
is
#1
5Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
INFO General
SAG chart needed to check clearance?
YES NO
Clearances of supporting structures from other objects
NOYES
Vertical clearances of wires, conductors, cables, and equipment above ground, roadway, rail, or water surfaces
RULE 232YES NO
RULE 230
RULE 231
Clearances between wires, conductors, and cables carried on different supporting structures
RULE 233YES NO
Clearances of wires, conductors, cables, and equipment from buildings, bridges, rail cars, swimming pools, and other installations
RULE 234YES NO
Section 23. Clearances
6Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
Clearance for wires, conductors, or cables carried on the same supporting structure
RULE 235YES NO
Climbing spaceRULE 236YES NO
Working spaceRULE 237YES NO
Vertical clearance between certain communications and supply facilities
RULE 238YES NO
Clearance of vertical and lateral facilities from other facilities and surfaces on the same supporting structure
RULE 239YES NO
7Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
8Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
• Clearances are based on:
– Reference component.
– Mechanical and electrical component.
Section 23. Clearances
9Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
• 235C4. Communication
Worker Safety Zone
– Rules 235C and 238 create a communication worker safety
zone.
– No supply or communication facility may be located in the
communication worker safety
zone except as allowed by Rules 238C (light fixtures and traffic
signals), 238D (light fixture and
traffic signal drip loops), and 239 (vertical risers).
10Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
11Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
• Clearance from supply conductors
– NESC Table 235-5
• 40 in
– Rule 235C2b(1)(a)
• 75% of that required at
the pole
– Rule 238
• No hardware in
communication work safety zone
30"
40"
12.47/7.2 KV, 3Ø, 4Wdistribution line
Comm
unica
tion
Comm
unica
tion
Cable
TV
Telep
hone
12Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Comm
unica
tion
Comm
unica
tion
Cable
TV
Telep
hone
distribution line24.94/14.4 KV, 3Ø, 4W
43"
33" • Clearance from supply conductors
– NESC Table 235-5
• 40 in plus 0.4 in per kV
over 8.7kV
– Rule 235C2b(1)(a)
• 75% of that required at the pole
– Rule 238
• No hardware in communication work
safety zone
Section 23. Clearances
13Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
• Clearance from a neutral
in the supply space
– NESC Table 235-5
• 30 in at the pole
– Rule 235C2b(1)(a)
• 12 in in span (by
exception)
– Rule 238
• No hardware in communication work
safety zone
12"
30"
Effective
ly grou
nded
neutral (
230E1)
Commu
nicatio
n Com
munica
tion
Cable T
V
Teleph
one
14Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
30"
40"Effectively grounded
neutral (23
0E1)
12.47/7.2 kV, 3Ø, 4W distribution line
Comm
unica
tions
(Tele
phone)
Comm
unications
(Cable TV)
120/2
40V, 1Ø
, 3W
secondary
triple
x (230C3)
• Clearance from secondary
– NESC Table 235-5
• Clearance at the pole
– Rule 235C2b(1)(a)
• 75% of that required
at the pole
– Rule 238
• No hardware in
communication work safety zone
15Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
• Rule 235H. Clearance and spacing between
communication conductors, cables, and equipment
– The spacing between
communication messengers
should not be less than 12 inches.
– The clearance between the
conductors, cables, and
equipment of one communication utility to those of
another shall not be less than 4
inches anywhere in the span.
– Both requirements may be reduced by agreement of the
parties involved.
Communications
(Cable TV)
Communications
(Telephone)
Section 23. Clearances
16Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
• Rule 235I. Clearances in any
direction from supply line conductors to communication
antennas in the supply space attached to the same
supporting structure
– Antennas should be installed and maintained only by
personnel authorized and
qualified to work in the supply space
– The clearance between a
communication antenna
operated at a radio frequency of 3 kHz to 300 GHz and a supply
line shall be not less than
specified in Table 235-6, row 1b.
– See Rule 420Q
17Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
• Rule 235I. Clearances in any
direction from supply line conductors to communication
antennas in the supply space attached to the same
supporting structure
18Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
• 238E. Communication
Worker Safety Zone
– Rules 235C and 238 create a communication worker safety
zone.
– No supply or communication facility may be located in the
communication worker safety
zone except as allowed by Rules 238C (light fixtures and traffic
signals), 238D (light fixture and
traffic signal drip loops), and 239 (vertical risers).
19Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
• Table 238-1
– Row 2
Telephone
CATV
40"
Highest communications equipment
12.47/7.2 kV, 3Ø, 4W distribution line
Lowest supply equipment
20Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
• Table 238-1
– Row 3
Section 23. Clearances
Telephone
CATV
24.94/14.4 kV, 3Ø, 4W distribution line
43"
Highest communications equipment
Lowest supply equipment
21Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Lowest supply equipment
Telephone
CATV
30"
Highest communications equipment
Effectively grounded neutral (230E1) • Table 238-1
– Row 1
Section 23. Clearances
22Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
Highest communicationsequipment
Lowest supply equipment
CATV
Telephone
40"
• Table 238-1
– Row 2
23Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
• Table 238-1
– Row 2
24Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
• Rule 239G. Requirements for vertical
supply conductors and cables passing through the communication space on
jointly used line structures
– Conduit must guard the supply cable:
• 40” above the highest communication
attachment.
• 6’ below the lowest communication attachment.
– Rule 239D requires guarding within 8’ of the
ground.
40"
6’
8’
Section 23. Clearances
25Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
• Rule 239G. Requirements for vertical supply …
26Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
• Rule 239G. Requirements for
vertical supply …
– 40” clearance required from highest communication
equipment to top of secondary
riser.
40" min.
Section 23. Clearances
27Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 23. Clearances
• Rule 239G. Requirements for
vertical supply …
– 40” clearance required from highest communication
equipment to top of secondary riser.
28Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Strength and Loading
• Section 24 – Grades of construction
• Section 25 – Loadings for Grades B and C
• Section 26 – Strength requirements
• Section 27 – Line insulation
29Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Part 3. Underground Lines
WORK RULES
UNDERGROUND LINES
PART 4
OVERHEAD LINES
PART 3
ELECTRIC SUPPLY STATIONS
PART 2
PART 1
S afety
is
#1
30Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 32. Underground conduit systems
• Rule 320B2. Separation
between supply and communication conduit
systems
– Conduit systems to be occupied by communication lines shall be
separated from conduit systems
to be used for supply systems by not less than
• 3 in of concrete
• 4 in of masonry
• 12 in of well-tamped earth
3"
12"
4"
31Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
• Table 353-1
– No burial depths are specified for communication cables, however, the burial depth must be “sufficient to protect the cable from damage” per Rule
352D1.
– NESC® Table 353-1 applies to direct-buried supply cables only
Supply cable601V − 50KV
Over 50KVSupply cable
0−600VSupply cable
24"30"
42"
Any surface
CommunicationCable
Rule 352D1
Section 35. Direct buried cable
32Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Part 4. Work Rules
WORK RULES
UNDERGROUND LINES
PART 4
OVERHEAD LINES
PART 3
ELECTRIC SUPPLY STATIONS
PART 2
PART 1
S afety
is
#1
33Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Supply
AND
Communications
General Rules for Employees
Employee Employee
ELECTRIC COMPANY
Supply and Communications SystemsRules for Employers
AND
COMMUNICATIONSCOMPANY
Additional Rules for Communications Employees
Communications Employees Only!
Additional Rules for Supply Employees
Supply Employees Only!
Section 41 Section 42
Section 44Section 43
Part 4. Rules for the Operation of Electric Supply and Communications
Lines and Equipment
34Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 43. Additional rules for communication employees
• Rule 431. Approach to
energized parts
– No employee shall approach, or
bring any conductive object, closer to exposed energized
parts than the distances shown
in Table 431-1
– Treat all supply lines and equipment as energized unless
they are deenergized and grounded following the rules in
Section 44
35Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Section 43. Additional rules for communication employees
36Copyright © 2007 Marne and Associates, Inc. (with Permission from the McGraw-Hill Companies, Inc.)
All Rights Reserved – Do Not Duplicate.
Books and Training
Training:
www.marneassociates.com
Books:
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