Arc Flash Study Top 10 FAQs Part #3

How Does Everyone Else Do This?

By Jim Phillips

3-Part Series



  1. What do you list on an arc flash label when 
the prospective incident energy is greater 
than 40 cal/cm2?

This question is a variation of the one about the 40 cal/cm2 limit in Informational Note 3 of NFPA 70E 130.7. However, this question concerns arc flash labels.

Where the calculated incident energy exceeds 40 cal/cm2, many arc flash labels use a red background with white “Danger” as the signal word. However, many of these labels also have language that states, “No Safe PPE Available,” or something similar, even though PPE is available with arc ratings upward of 100 cal/cm2.

 Question: For locations where the incident energy is greater than 40 cal/cm2, which of the following are used for your companies or client’s labels?

Danger: 37%

No safe PPE exists: 29%

Energized work prohibited: 28%

None of these: 1%

Something else: 2%

We don’t have locations > 40 cal/cm2

(Respondents were instructed to select up to three options.)


  1. Do you still have equipment without arc flash labels?

You might think having label requirements defined by NFPA 70E as well as calculation methods from IEEE 1584 for more than a decade that most equipment would have an arc flash warning label by now. That is not the case, according to the answers to this question.

Question: Do you still find electrical equipment without an arc flash label (that should have one)?

Yes: 97%

No: 3%


  1. What do you do with arc flash labels now that the 2015 edition of NFPA 70E has eliminated Category 0?

Many still correlate the calculated incident energy with categories or levels. Often this has meant that, if the prospective incident energy was less than 1.2 cal/cm2 at the working distance, it would be listed as “Level 0.” This question was asked a few months after the 2015 edition of NFPA 70E was published.

Question: How do/will you label equipment with a calculated incident energy less than 1.2 cal/cm2?

We still use “0”: 56%

We will list the incident energy: 25%

We will list a minimum arc rating such as 4 or 8 cal/cm2: 12%

Something else: 7%


  1. Should the date be listed on the arc flash label?

NFPA 70E lists the minimum requirements for information to be included on the arc flash label. The list does not include the date.

Question: Do you feel the date of the study should be included on the arc flash warning labels?

Yes: 93%

No: 7%

So you think you are the only person with a particular question? Highly unlikely. Many questions are quite common and also frequently asked.

Note: The survey responses and accompanying commentary may not necessarily reflect the official policy or position of NFPA, IEEE or other standards and organizations.

Attend an upcoming Arc flash safety training course by Jim Phillips to:

  • Learn how to perform an arc flash study
  • Create an arc flash study report
  • Set appropriate Arc flash boundaries
  • Avoid Arc Flash accidents

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