Conceptual design

A Better Understanding of NFPA 70E: Correctly Using the Incident Energy Analysis and Arc-Flash PPE Category Methods

The 2009 Edition of NFPA 70E®, Standard for Electrical Safety in the Workplace® clearly stated that one of the two provided methods be used for the selection of personal protective equipment (PPE) when an arc-flash hazard was present. The two methods of choice are the arc-flash PPE category method and incident energy analysis method. Although not as plainly stated before 2009, it has been required to use only one method on a piece of equipment for twenty years. Why do some NFPA 70E users ask how to combine PPE category method requirements with an incident energy analysis?

A few editions ago, the public expressed concern regarding the phrase, one of the following methods shall be used. Apparently, this phrase did not fully convey that only one method could be used on a piece of equipment, or that the two methods could not be combined. So, the requirement was revised to include the statement, either, but not both methods shall be permitted to be used on the same piece of equipment. This was to clarify that one does not include both methods.

I am not sure how the words one, either, and not both are being misunderstood. Also, other requirements state not to use both methods. Section 130.7(C)(15) states its requirements apply when the arc flash PPE category method is used and that it is not permitted to specify an arc flash PPE category based on the results of an incident energy analysis. Each of these were added to further clarify the misunderstanding. However, the question was asked once again last week. When shown these specific requirements prohibiting the use of both methods, their response led me to believe that an untrained or unqualified person is conducting the assessment. It is often revealed that the person has not read NFPA 70E or worse do not possess a copy. Often, a computer program has been used to calculate the incident energy and the person has been supplied with a copy of the PPE Category Table to specify PPE. Sometimes, that program automatically and incorrectly converted the incident energy into a PPE Category. These revelations should be troubling because the employer and the person assigned to do the risk assessments are putting employees at risk of injury.

Make sure that you have been properly trained and fully understand the requirements when conducting assessments. It is also necessary to have access to an entire NFPA 70E to properly apply the requirements since there is more to electrical safety than an using a table. Consider that these people asking this question are not the only ones who have misapplied the requirements. Confirm that the requirements have been properly applied in your workplace. If not, correct the issue before it is too late.

NFPA 70E and the NEC are now available in NFPA LiNK™, the association’s information delivery platform with NFPA codes and standards, supplementary content, and visual aids for building, electrical, and life safety professionals and practitioners. Learn more at

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Christopher Coache
Senior Electrical Engineer

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