How to Read an Arc Flash Label

An arc flash warning label is commonly used to alert workers of a potential flash fire. It comes with important safety information about the type of threat or hazard in question, so workers can either avoid this area or make sure they are wearing the proper arc flash clothing before accessing equipment or stepping inside.

“Warning” or “Danger”

The label will feature a “warning” or “danger” heading. “Danger” usually appears in red. It means that the nominal system voltage is over 600 or that the incident energy is over 40 calories per square centimeter (cal/cm2). Anything below these levels receives a “warning” label, which appears in orange.

Arc Flash Boundary

This represents the shortest possible distance in which workers must stand away from the hazard in question when they are not wearing arc flash clothing. Anything inside of this boundary could result in permanent injury, including a second-degree burn or worse.

PPE Hazard Category

This category stipulates the minimum amount of PPE necessary to protect the worker from permanent injury once they step inside the arc flash boundary.

Arc Rating of Clothing

This measures the amount of energy necessary to pass through the given fabric to cause a 50% probability of second-degree burns, represented in calories/cm2.

Incident Energy

This represents the amount of thermal energy impressed on a surface in the event of an electrical arc fire, based on its distance from the arc source. Remember that the incident energy decreases as the distance from the source increases.

Working Distance

Measures the minimum distance from the worker’s face or chest area to arc source, so they can keep a safe distance.

Nominal System Voltage

Shows the nominal value of the voltage system in place.

Limited Approach Boundary

Shows the minimum approach distance from an exposed energized electrical conductor or circuit part, both of which could be a shock hazard.

Restricted Approach Boundary

Sets a limit on the distance from an exposed energized electrical conductor or circuit part where there is a greater risk of shock hazard based on the electrical arc-over combined with inadvertent movement.

Arc-rated/Additional PPE

Sets the minimum rating for arc flash clothing necessary to protect workers when they are in an arc flash boundary.

Equipment ID

Marks the piece of equipment that is associated with the arc flash or shock hazard.

Refer to this information when selecting safety workwear for your team. Use the proper protective clothing to keep your workers safe in the field.