NFPA 70E – 2012 Edition

 

Standard for Electrical Safety in the Workplace

The most recent update to NFPA 70E – the 2012 edition – became effective January 1, 2012. Changes of note related to flame resistant protective apparel include:

  • New terminology (Arc-Rated): Flame resistant (FR) has been changed to “arc-rated (AR)” in regard to personal protective equipment (PPE) throughout the standard.
  • Arc flash calculations in Annex D now align with the 2012 version of the NESC.
  • Hazard/risk category tables have been changed to include short-circuit current, fault clearing time, and potential arc flash boundary in each of the major equipment categories instead of in specific notes at the end of the table.
  • Head Protection Requirement:
    • Hazards Less than 12 cal/cm2: An arc-rated hood or balaclava with an arc-rated faceshield must be used when the back of the head is exposed within the arc flash boundary when the hazard is between 1.2cal/cm2 and 12 cal/cm2.
    • Hazards Greater than 12 cal/cm2: An arc rated hood alone must be used for hazards greater than 12 cal/cm2.
  • DC Voltages: Historically, NFPA 70E has focused primarily on AC (alternating current) voltages. The 2012 NFPA 70E includes more information about calculating and protecting against DC (direct current) voltages. Table 130.4(C)(b) is used for calculating distances for system voltages.
  • Arc flash boundary: A specific boundary is now listed under a new column for each task. This addition aligns with the deletion of the “four foot rule” in the 2009 Edition.
  • Building Clarification: Section 90.2(A)(4) has been revised to say, “Installations used by the electric utility, such as office buildings, warehouses, garages, machine shops and recreational buildings.” This deletion clarifies that NFPA 70E applies to these areas, even if they are part of a generating plant, substation or control center.

NFPA 70E addresses electrical safety requirements necessary to safeguard employees during activities such as the installation, operation, maintenance, and demolition of electric conductors, electric equipment, signaling and communications conductors and equipment, and raceways.

In regards to work practices and electrical system maintenance, NFPA 70E provides key information that is lacking in the National Electric Code (NEC). While the NEC is useful for those responsible for maintenance and engineering of electrical equipment, NFPA 70E is a voluntary standard purposely geared toward workers and employers to understand and implement safety precautions. While OSHA uses the General Duty Clause as the basis for citations, OSHA commonly cites information from NFPA 70E for support in order to enforce compliance regarding electrical safety.

  • Exclusions: A few industries are excluded from NFPA 70E: electric utility transmission, distribution and generation workers (who are covered by OSHA 1910.269), as well as the marine, railway rolling stock, and mining industry. Despite the exclusion, many of these industries protect workers with FR clothing as a general practice.
  • Five System Classes: NFPA 70E breaks all electrical procedures into five classes and assigns minimum flame resistant clothing layers and performance characteristics for each class based on the hazard present. 

 

Hazard / Risk Category

Clothing Description

Required Minimum Arc Rating of PPE

(cal/cm2)

0

Non-melting, flammable materials (i.e. untreated cotton, wool, rayon or silk, or blends of these materials) with a fabric weight of at least 4.5 oz/yd2.

N/A

1

Arc rated FR shirt and FR pants or FR coverall.

4

2

Arc rated FR shirt and FR pants or FR coverall, and arc flash suit so that the system arc rating meets the required minimum.

8

3

Arc rated FR shirt and pants or FR coverall, and arc flash suit selected so that the system arc rating meets the required minimum.

25

4

Arc rated FR shirt and pants or FR coverall, and arc flash suit selected so that they system arc rating meets the minimum.

40

 

Other practical recommendations made within NFPA 70E address commonly asked questions:

 

  • Underlayers.  Meltable fibers such as acetate, nylon, polyester, polypropylene and spandex shall not be permitted in fabric underlayers (underwear) next to the skin.  “Informational Note No. 1: Arc-rated garments… generally provide a higher system arc rating than nonmelting, flammable fiber underlayers.  “Informational Note No. 2: Arc-rated underwear or undergarments…generally provide a higher system arc rating than nonmelting, flammable fiber underwear or undergarments used as underlayers” (NFPA 70E-2012 p.33).
  • Layering. “Nonmelting, flammable fiber garments shall be permitted to be used as underlayers in conjunction with arc-rated garments in a layered system for added protection. If nonmelting, flammable fiber garments are used as underlayers, the system arc rating shall be sufficient to prevent breakopen of the innermost arc-rated layer at the expected arc exposure incident energy level to prevent ignition of flammable underlayers. Garments that are not arc rated shall not be permitted to be used to increase the arc rating of a garment or of a clothing system” (NFPA 70E p. 32).
  • Coverage.  “Clothing shall cover potentially exposed areas as completely as possible.  Shirt sleeves shall be fastened at the wrist and shirts and jackets shall be closed at the neck” (NFPA 70E-2012, p. 33).
  • Fit.  “Tight-fitting clothing shall be avoided.  Loose-fitting clothing provides additional thermal insulation because of air spaces.  Arc-rated apparel shall fit properly such that it does not interfere with the work task” (NFPA 70E-2012, p.33).

The standard is available to view online at no charge or to purchase a downloadable copy: 

https://www.nfpa.org/codes-and-standards/document-information-pages?mode=code&code=70E

 

 

 

 

 

 

 

 

 

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