How to read Arc Flash Warning Labels

How to read Arc Flash Warning Labels

We all know just how vital Arc Flash Safety is for those that work in environments where the risk of arc flash is present, but do you know how to read an arc flash warning label properly?

Understanding these labels is critical for keeping safe and selecting the appropriate PPE for the task at hand. Here’s what to look out for:


The purpose of an Arc Flash Label is pretty self-explanatory; it is a warning that the piece of equipment you are looking at carries a risk of Arc Flash. However, the information you'll need to absorb is located in the two columns below that, so let's move on to those.

Working Distance

Working distance often gets confused with the Limited Approach Boundary, but this part of the warning label actually refers to the distance required between the torso of the worker and the potential source of Arc Flash.

Incident Energy

This part of the warning label refers to the amount of Thermal Energy you will be exposed to in the event of Arc Flash from the source. This information is crucial as it will help you to select the appropriate Arc Flash PPE for the job as it will need to withstand the incident energy listed.


Arc Flash Boundary

This part of the label tells you how far away you will need to place a barricade to stop unqualified workers or those wearing everyday clothing rather than appropriate protective equipment. The boundary actually refers to the distance where someone without PPE would receive second-degree burns, so be sure to place your barricades further away than the figure listed. According to the Stoll skin burn injury model, the onset of a second degree burn on unprotected skin is likely to occur at an exposure of 1.2 cal/cm2 (5 J/cm2) for one second.

Shock Hazard

On the second column of your Arc Flash Warning label, you’ll be given information regarding the shock hazard of the source when the cover is removed.

The Voltage Level is present to help you select the right instrument to test the equipment. This will also help you to identify the right rubber insulated gloves to use if the glove class isn’t detailed on the label.

Limited Approach

This part of the label refers to the boundary distance from an exposed energized electrical conductor or circuit part where a shock hazard can be felt. This is the distance where untrained, unqualified or members of the public should be kept away from the source.

Restricted Approach

Once inside the restricted approach boundary, you need to ensure that you are wearing the appropriate PPE as at this distance from an exposed conductor, the risk of arc over is increased.

Ensure that you have the correct PPE including insulated rubber gloves within this boundary.

Glove Class

Some (but not all) Arc Flash Warning labels will tell you the glove class you need to work with the equipment once the cover has been removed, so make sure that any gloves you have are suitable to avoid burns.