Arc Flash Warning Label

An arc flash warning label is placed on equipment to provide warning of the potential arc flash hazards present during energized or potentially energized work and to document the required PPE. Arc flash labels should be located in a place that is easily visible and readable from some distance. Consistency in the format of the label and its location on the equipment helps in compliance with arc-flash PPE requirements.

Arc flash and shock hazard warning safety labels are specifically designed to help protect qualified workers who have to examine, adjust, service, or maintain electrical equipment while energized. It is important for workers to understand the information given on the label in order to protect themselves.



Electrical equipment labeling in NFPA 70E Section 130.5(H) includes the following information:

• Nominal system voltage
• Arc flash boundary

And at least one of the following three list items:

- 1. Available incident energy and the corresponding working distance, or arcflash PPE category in Table 130.7(C)(15)(a) or Table 130.7(C)(15)(b) for the equipment, but not both
- 2. Minimum arc rating of clothing


3. A site-­specific level of PPE.

It is important for the worker to read NFPA 70E and understand the last sentence in Section 130.5(H). This sentence clarifies that the electrical equipment’s owner is responsible for the documentation, installation and maintenance of the marked label. If the owner chooses not to label the equipment and there is not an installation requirement in the NEC mandating labeling, the discussion ends because NFPA 70E does not contain installation requirements.


Six Steps To Understanding an Arc Flash Warning Label

1. The owner of the electrical equipment is responsible for providing information on arc flash stickers which is required on high performance electrical equipment over 50V that could be accessed while energized.

2. An arc flash boundary is the distance at which the incident energy equals 1.2 cal/cm2, and arc rated PPE is required for any employee within the arc flash boundary.

3. The working distance is the distance from a person’s face and chest to the prospective arc source. Typical working distances, primarily based on equipment type, are published in IEEE standard 1584 and used in studies to perform the incident energy calculations.

4. While performing two sets of calculations for the load side and the line side of the main breaker on specific equipment is not specified in NFPA 70E, it is standard practice to enhance productivity and safety for equipment that has adequate isolation of the main protective device.

5. Calculated incident energy is the amount of thermal energy (cal/cm2) at a distance from an electrical arc event and indicates the level of PPE required to protect workers.

6. Nominal voltage, limited and restricted approach boundaries, and PPE glove rating are also displayed on the label to help protect workers from electric shock.


Related Articles