70E Presentation

8/10/2019 70E Presentation

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NFPA 70E ElectricalSafety Presentation(updat ed for 2012)

By Bruce Bowman, P.E.


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OSHA and the IEC Alliance

Through the OSHA and Independent Electrical

Contractors (IEC) Alliance, IEC developed thispresen a on or n orma ona purposes on y.does not necessarily reflect the official views of

. . .


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What is the best way to preventthe hazards of electricity?

Stop - Before Action

Think - Risks/Hazards

Options - LOTO Protection - Proper PPE

Avoiding energized circuits is the safest way!


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Electrical Safety

y ec r ca a e y rac ces anProcedures?

1. An estimated 30,000 non-fatal electrical shock accidents occur

each year2. ver 00 peop e e rom e ec rocu on eac year

3. Electrocution remains the fourth (4th) highest cause of industrialfatalities

4. Approximately 3000 flash burn incidents reported annually alongwith approximately 350 deaths


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Electrical Safety

Standard for Electrical Safety in the

Formall Standard or Electrical Sa et Re uirementsfor Employee Workplaces

egan n 7 y o ass s


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Electrical Hazards

oc


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The Effects of Shock

- Muscle contraction - Memory Loss- Vital organs (heart, lungs, etc.) - Nervous disorders

- Tingling - Chemical imbalances

- Pain - Damage to vital organs

- Breathing - Sometimes fatal

- Disorientation

- Dizziness

-


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The body has a natural defense system to shock (skin)

Wh 0 v0lts?

As you can see from the calculation below, a 50 volt exposure would not causemuscles to lock and is insufficient to cause physical harm.

The key to survival is to decrease our exposure to energized circuits.

Ohms Law for electric current (amps), voltage and body resistance

The typical body has a contact resistance of approximately 500 ohmsat the oint of contact with the electrical source.

The body has an internal resistance of approximately 100 ohms.

There is another ac resistance or impedance to ground of.

- 120v / (500 + 100 + 5000) = 21mA- 50v / (500 + 100 + 5000) = 8.9 mA

It is around 10 mA that the cannot let go level is reached.


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Two Types of Burns from Shock

Caused by entrance andexit of electrical currents

nterna ssue urns

Caused by currentflowing through organs

Can be caused by a very

small amount of current

o t e o y

Caused by currents in

excess of 1.5 amps 1 egree o 3 egree

4th degree

Internal organs

T icall fatal


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One Type of Burn from Arc Flash

Caused by exposure to the arc flash Can cause more surface burns if the initial arc flash

gn es o er ma er a suc as c o ng

1st degree to 3rd degree

It has and may cause death!


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Electrical Safety

1. Place circuits in electrically safe working conditions bylocking out and tagging out all sources

Chapter 1, Section 120.2 of NFPA 70E-2012

2. erifying that no electrical energy is presentChapter 1, Section 120.2 of NFPA 70E-2012


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Fire Ignition from Arc Flash

- Primarily covered by installation standards contained

- The incidence of fire ignition has dropped dramatically

installation requirements within the industry

e 7 oes no a ress e o er azar s oelectricity


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Conditions

Panel covers in place.

Panel covers removed.

qu pmen p ugge nnormally.

qu pmen emporar ywired.

orma , es gneprotection in place.

orma , es gneprotection such as guards,limits switches, etc. not in

.

Faulty or Damaged.


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Protection from Abnormal Conditions

NFPA 70E The first line of defense

Electrical Safety

n y you can ru y eep yousafe

roce ures anua

Electrical Safety Training

mp emen sa e yprocedures outlined inSafety Manual

Only you can implementthe procedures that may


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Old School

Electricians have always recognized the shock hazards of electricity.We are taught:

- To consider circuits to be energized

- To insulate and protect ourselves

- Stand to one side if an arc flash/blast is suspected


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New School

rc Flash and Blast hazards were not formall studied until 1(IEEE 1584 began study).

Electricians have not ex erienced arc flash and blasts to the samefrequency as electrical shock.

We have not been trained how to avoid and minimize arc flash andblasts in the past.

The Electrical Ener ized Work Practices outlined in NFPA 0E

incorporates measures to help avoid or minimize damage from arcflash.


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P ctures rom ESA BooPr act ical Solut ion Guide t o Ar c Flash Hazar ds

www.easypower.com


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ectr c arcs pro uce t e g est temperatures on eart up to

35,000 degrees Fahrenheit (4 x temp of the sun)!

e ntense eat rom arc causes t e su en expans on o a r t atresults in a blast with very strong air pressure (Lightning is a

natural arc).

All known materials are vaporized at this temperature.(Copper expands 67,000 times, Water 1,670 times).

Notes are fromPractical Solution Guide to Arc Flash Hazards, byChet Davis, P.E.; Conrad St. Pierre; David Castor, P.E.; Robert Luo, PhD; and

Satish Shrestha.


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rcs n enc osures, suc as a o or on ro en ers s or

switchgear, magnify blast and energy transmitted as the blast isforced to the open side of the enclosure.

Arcs spray droplets of molten metal at high-speed pressure. Blastshrapnel can penetrate the body.

knocked them off ladders. Pressure on the chest can be higher than2000 lbs/sq. ft.

Notes are fromPractical Solution Guide to Arc Flash Hazards, byChet Davis, P.E.; Conrad St. Pierre; David Castor, P.E.; Robert Luo, PhD; and

Satish Shrestha.


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Clothing can be ignited from several feet away. Clothed areas can be

burned more severely than exposed skin.

Hearing loss from sound blast. The sound can have a magnitude ashigh as 140dB at a distance of 2 feet from the arc.

Energy released is a function of:

System voltage

Fault current ma nitude

Fault duration

Notes are romPractica So ution Gui e to Arc F as Hazar s, yChet Davis, P.E.; Conrad St. Pierre; David Castor, P.E.; Robert Luo, PhD; andSatish Shrestha.


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Pr act i cal Solut i on Guide t o Ar c Flash Hazar ds


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Approach BoundariesNFPA 70E-2012 Ch. 1, Section 130

Entered only by qualified persons or unqualified persons thathave been advised and are escorted by a qualified person

Entered only by qualified persons required to use shockprotection techniques and PPE

Entered only by qualified persons requiring same protectionas if direct contact with live part

Linear distance to prevent any more than 2nd degree burnsfrom a potential arc-flash (typically 4 feet)


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SHOCK Hazard Analysis

. 1, ec. 130 oc azar na ys s.

Shock hazard analysis shall determine the voltage to whichpersonne w e expose , oun ary requ rements, an t enecessary in order to minimize the possibility of electric shock to

personnel.

What is required?

1. Determine the Operating Voltage of the System

2. Determine Shock Protection Boundaries3. Determine the Personnel Protective Equipment


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SHOCK Hazard Analysis

ow to comp y w t 70

1. Determine the Operating Voltage.2. Determine the Three Shock Protection Boundaries by using

Table 130.4(c)(a) of NFPA 70E-2012

A. Limited Approach Boundary

10 t or 80 V or movable ener ized ob ect

3 ft 6 in. for fixed energized object

B. Restricted Approach Boundary

.

C. Prohibited Approach Boundary

1 in. for 480 V


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SHOCK Hazard

How to comply with NFPA 70E?

.

NOTE: Short-Circuit Current and Clearing Time Limitations

Apply for use of tables!

a. Determine risk category from Table 130.7 (c)(15)(a) onNFPA 70E-2012

b. Determine specific PPE & clothing from Table 130.7(c)(16) ofNFPA 70E-2012


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Flash Hazard

. , . . .

An arc flash hazard analysis shall determine the arc flashoun ary, e nc en energy a e wor ng s ance, an e

personal protective equipment that people within the arc flash

boundary shall use.

How to comply with NFPA 70E for Flash Protection?

1. Determine the flash protection boundary

2. Determine the incident energy exposure level3. Determine the protective clothing and PPE


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Flash Hazard

ow o omp y w 70 or ro ec on

1. Determine Flash Protection Boundary:Calculate usin the I - & the clearin time or the-overcurrent protection(see Formula below & Annex D of NFPA 70E-2012 or default to the

distances listed in the Table 130.7(C)(15)(a) if the IShort-Circuit Amperes &

Flash Protection Boundary Formula (600 V or less)DC = [53 x MVA x t]

1/2

where Dc = Arc Flash Boundary (AFB) in FeetMVA = Transformer capacity in MVA

t = clearing time in seconds

econ egree urn res o1.2 cal/cm1.2 cal/cm22


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Flash Hazard Analysis

2. Determine the Incident Energy Level:Calculate incident energy exposure level for the distance

typical) ORuse 130.7(C)(15)(a) and 130.7(C)(16)

EMB = 1038.7DA

-1.4738 tA[0.0093F2 0.3453F + 5.9675]

Where EMB = cal/cm2 in 20 inch Cubic Box

DA = distance from electrode in inches

(typically this value would be 18)tA = clearing time

F = Ishort-CircuitAmperes available (rangeo 1 to 50


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Example 3 - An electrician is to operate a circuit breaker in the main switchgear (with some of thecovers removed from the switchgear) to de-energize a circuit that is operating at 480 V for lock-out

F as Hazar Ana ys s

tagout an t e IShort-Circuit Amperes & t e c earing time imitations are not excee e .

Table 130.7(C)(15)(a) > Hazard Risk Category (HRC) = 1(No V-Rated Gloves & No V-Rated Tools Required )

Table 130.7(C)(16) specifies the following required: AR Pants & Shirt or Coveralls of at least 4 cal/cm2

Hard Hat

Arc Rated Face Shield Hearing Protection Leather Shoes Leather Gloves

Electrician goes to machine disconnect to open and test for presence ofvoltage What is the HRC level? (Ans: 2)


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Flash Hazard Analysis Example 2

ClassJ,

200

A

fuse

clearingtimeof1/4cycleunder

as rotect on

Boundary

CalculationCircuitusingcurrentlimitingfuses

40896Amperes

Available

shortcircuitconditions.

480Volt,

3phase

6000EquivalentRMSLetThrough

Answer

MainLug

OnlyPanelDC =

.23

ft

This example provided by Bussmann


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IncidentEnergyCalculation@18

Overcurrentprotectivedevice

Circuitusingnoncurrentlimiting

circuitbreaker

withclearingtimeof6cycles

480Volt,

3phaseAnswer

EMB =10.92cal/cm2

OnlyPanel

This example provided by Bussmann


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IncidentEnergyCalculation@18

ClassJ,200Afuse

clearingtime

of

1/4

cycle

Circuitusingcurrentlimitingfuses

40896AmperesAvailable

.

480Volt,

3phase

Main Lu

Answer

EMB


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Section 110.16 of the2011 NECRequires Arc Flash

Hazards Labels


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Arc Flash Labeling by NEC & NFPA 70E MinimumRequirement

Arc Flash Hazard & 480 V Shock Hazard:

1 PPE/HRC Level 2 Re uired2) Arc Flash Boundary is 30

Generic labels prior to September 30, 2011 are acceptable ifthey at least have the incident energy or required PPE/HRC

level.


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Arc Flash Labeling Required by NEC & NFPA 70E

WARNING!Arc Flash and Shock Hazard

Appropriate PPE Required

24 inch Flash Hazard Boundary3 cal/cm2 Flash Hazard at 18 inches

HRC 1 PPE Level, AR Pants & Shirt or Coveralls2

480 VAC Shock Hazard when42 inch Limited Approach12 inch Restricted Approach - 500 V Class 00 Gloves1 inch Prohibited Approach - 500 V Class 00 Gloves

EquipmentName: Pump#1Starter


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What are the OSHA Regulations and NFPA 70ERequirements for Working on Live

Equipment?


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NFPA 70E: Safety in WorkplaceOSHA 29CFR 1910 Subpart S & 29CFR 1926 Subpart K

Before we go any further, it is important for you to understand afew important definitions:

- Guarded Covered, fenced, enclosed, or otherwise

protected by means of suitable covers or casings, barrierrails or screens, mates or platforms designed to minimize the

possibility, under normal conditions, of dangerous approachor accidental contact by persons or objects.

No t e: W i r es w h i c h a r e i n su l a t ed , b u t n o t o t h er w i se

p r o t ect ed a r e n o t con si d er ed a s gu a r ded .


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NFPA 70 E: Safety in WorkplaceOSHA 29CFR 1910.333 & NFPA 70E 130.2

Qualified electrical workers shall not be asked to work on equipment that is hot or live

except for these demonstrable reasons:1. Deenergizing introduces additional or increased hazards

Interruption of life support equipment

Deactivation of emergency alarm systems

Cutting ventilation to a hazardous location

2. Infeasible due to equipment design or operational limitations

Voltage testing for diagnostics

Start u testin

Or3. Live parts that operate at less than 50 volts to ground need not be deenergized if

there will be no increased exposure to electrical burns or to explosion due to electric.


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NFPA 70 E: Safety in WorkplaceOSHA 29 CFR 1926.416(a)(1) & NFPA 70E 130.2

This article disallows work in such close proximity to any part of an

the course of their work, unless the employee is protected againstelectric shock by deenergizing and grounding the circuit, or

guarding it effectively by insulation or other means.


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Safety-Related Work Practices1910.335 Safe guards for personnel protection

(a) (2) (ii) Protective shields, protective barriers, or insulating, ,

or other electrically related injuries while that employee is workingnear exposed energized parts which might be accidentally contacted

or where dangerous electric heating or arcing might occur. Whennormally enclosed live parts are exposed for maintenance or repair,they shall be guarded to protect unqualified persons from contact

with live parts.


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W o s Respons e or Sa ety

The Employer is responsible for

OSHA requirements

Electrical Safety Program Safet Policies and Procedures

Safety Training and Retraining

Implementing employers safety procedures

The Owner and Contractors are both responsible tocoordinate and document hazards and safety procedures

Contractors on site with Owner


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Responses to an Electrical Accident

attempt to remove the victim from the power with dry wood or other

insulating type of materials to remove the hazard!

SECOND step: CALL 911 or the local emergency number

N o t e: 2 9CFR 1926 .50 ( c) r equ i r es t h a t i n t h e absen ce o f a

,

w i t h v a l i d CPR / F i r st -a i d t r a i n i n g b e o n si t e.


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What is the best way to preventthe hazards of electricity?

Stop - Before Action

Think - Risks/Hazards

Options - LOTO Protection - Proper PPE

Avoiding energized circuits is the safest way!

Documents

70E Presentation