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Arc-Flash Hazard Study

Flash Protection

Boundary

An approach limit,

at a distance from

an exposed live

part, within which

a person could

receive a second-

degree burn if an

electrical arc-flash

were to occur.

Shock Protection Boundaries:

Limited Approach Boundary

An approach limit at a distance from an exposed live part

within which a shock hazard exists.

Restricted Approach Boundary

An approach limit at a distance from an exposed live part within

which there is an increased risk of shock, due to electrical arc

over combined with inadvertent movement, for personnel

working in close proximity to the live part.

Prohibited Approach Boundary

An approach limit at a distance from an exposed live part within

which work is considered the same as making contact with

the live part.

Required Clothing Class

In accordance with NFPA 70E guidelines, the calculated incident

energy provided by GE's arc-flash hazard study, will identify the

appropriate PPE class for each system location, through the use

of the following NFPA 70E table.

From NFPA 70E 2009 Edition

Note: Arc rating is defined in Article 100 and can be either ATPV or E

. ATPV is defined in

ASTM F 1959,

Standard Test Method for Determining the Arc Thermal Performance Value

of Materials for Clothing

, as the incident energy on a material or a multilayer system of

materials that results in a 50% probability that sufficient heat transfer through the tested

specimen is predicted to cause the onset of a second-degree skin burn injury based on the

Stoll curve, cal/cm

. E

is defined in ASTM F 1959 as the incident energy on a material or

material system that results in a 50% probability of breakopen. Arc rating is reported as

either ATPV or E

, whichever is the lower value.

Accurate Results

For consistency of results, limited

duplication and lower overall PPE

recommendations, GE recom-

mends that the short-circuit and

coordination studies be completed

concurrently with the arc-flash

hazard study:

• Short Circuit Study – Calculates

three-phase bolted faults

• Protective Device Coordination

Study – Uses equipment

settings to determine devices'

opening times

For more information, contact your local GE Energy office or call 1-888-GE4-Serv or 540-378-3280.

©2009, General Electric Company. All rights reserved. The contents of this document are the property of General Electric Company. No part of this work may be reproduced or transmitted in any form or by any means, except

as permitted in written license agreement with General Electric Company. General Electric Company has made every reasonable attempt to ensure the completeness and accuracy of this document. However, the informa-

tion contained in this document is subject to change without notice, and does not represent a commitment on the part of General Electric Company. The GE logo is a registered trademark of General Electric Company.

1) Reprinted with permission from 2008 National Electrical Code

2) Reprinted with permission from NFPA 70E, Standard for Electrical Safety In the Workplace 2009 Edition, Copyright © 2008, National Fire Protection Association, Quincy, MA 02269. National Electric Code and

NEC are registered trademarks of the National Fire Protection Association, Quincy, MA.

This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety.

TABLE 130.7(C)(11) Protective Clothing Characteristics

Required Min Arc

Hazard/Risk

Rating of PPE

Category Clothing Description

[J/cm

(cal/cm

)]

Nonmelting, flammable materials (i.e.,

N/A

untreated cotton, wool, rayon, or silk, or

blends of these materials) with a fabric

weight at least 4.5 oz/yd

Arc-rated FR shirt and FR pants or

16.74 (4)

FR coverall

Arc-rated FR shirt and FR pants

33.47 (8)

or FR coverall

Arc-rated FR shirt and pants or

104.6 (25)

FR coverall, and arc flash suit selected

so that the system arc rating meets the

required minimum

Arc-rated FR shirt and pants or

167.36 (40)

FR coverall, and arc flash suit selected

so that the system arc rating meets the

required minimum

NEC Handbook Exhibit 110.7

Electrical worker clothed in

personal protective equipment

(PPE) appropriate for the hazard

involved