Reading Warning Labels

NFPA 70E 2015 Article 130.5 (D). Equipment Labeling requires that electrical equipment that are in locations other than dwelling places (residential housing), such as:

  • Electrical switchboards
  • Electrical panels
  • Panelboards
  • Electrical control panels
  • Meter socket enclosures
  • Motor controls centers

and are likely to be serviced by a worker when in an energized sate, must be field marked with a warning label including all the following information:

  1. The nominal system voltage.
  2. The arc flash boundary.
  3. At least one of the following:
  • Available incident energy and the corresponding working distance (Calorie Rating @ 18″).
  • Minimum arc rating of clothing (PPE).
  • Required level of PPE to use.

Article 130.5(D) also states that it is the electrical equipment owner's responsibility for the field-marked label documentation, installation, and maintenance.


There are many versions of the Arc Flash Label which dispense different information depending on the standard's time period it was issued. The following are examples of arc flash labels that may be encountered in the field:


Labels headers are specified to be based on ANSI Z535.4 - Product Safety Signs and Labels.


Signal Words

Caution (black letters on yellow background): ANSI Z535 standard uses "Caution" labels for hazards that could result in minor or moderate personal injury, but not death. Since arc flashes usually involve enough power to cause serious injury, the Caution labels are not typically used for arc flash.


Warning (black letters on orange background): labels and signs, under the ANSI Z535 standard, should be used when a hazard could result in death or serious injury. Some facilities use "Warning" when they have the required PPE for energized equipment work.


Danger (white letters on red background): should be used for the most severe hazards, which would probably result in death or serious injury. May be used when the equipment must be powered down instead of doing energized work. Some facilities use an incident energy of 40 cal/cm² as the cut-off, with more powerful flashes being marked with "Danger."


And may include an arc flash symbol or graphic (pictogram) though not specifically required.


Minimal Generic Label

A basic label with no details that would that meet OSHA's and the NEC's basic requirements to inform a worker about a hazard, but it does not meet the NFPA's standard for providing useful arc flash information.


2012 Label

Notice that this is the same as the 2015 release but the fourth provision under the NFPA 70E 2012 Article 130.5 (C) 1, "Highest Hazard Risk Category (HRC) to use" has been removed. This is now replaced with the results from either an incident energy analysis or the Arc Flash PPE Category method but not both.

All references to the Prohibited Approach Boundary are deleted in the 2015 edition. The flash protection, limited approach and restricted approach boundaries are defined.

Hazard/Risk Category Classifications (eliminated in NFPA 70E 2015)

Prior to the 2015 update to the NFPA 70E this was the standard method to determine the level of PPE required and is used by some manufacturers to identify the arc-flash rating of their garments and equipment though not required—they are required that the cal/cm2 garment rating be shown. However, it is still very common to see on labels, tags, specifications, and other information provided.


Figure 1: Arc Flash Label on Electrical Disconnect Switch


Figure 2: Arc Flash Label 2015 NFPA 70E Requirements



Figure 3: Minimal Generic Arc Flash Labels


Figure 4: Arc Flash Label 2012 NFPA 70E Requirements