At what incident energy level does the arc flash boundary lie?

The arc flash boundary is defined as the distance at which a person can be safely positioned without suffering a second-degree burn from an arc flash event. This boundary is typically set at the incident energy level of 1.2 cal/cm². At this energy level, it is considered that the radiant heat energy exposure is low enough to prevent serious injury, assuming appropriate personal protective equipment (PPE) is not used.

The 1.2 cal/cm² threshold is based on research and testing that determined it to be the level at which thermal protection can be expected to be effective in preventing burns. This is critical for establishing safety practices in the workplace, ensuring that workers are maintained at a safe distance from potential arc flash hazards.

Understanding this specific incident energy level is crucial for electrical safety as it guides the development of safety procedures, risk assessments, and the selection of PPE. Knowing that this boundary is set at 1.2 cal/cm² helps organizations adhere to OSHA requirements and NFPA 70E standards, prioritizing employee safety when working with or near energized electric equipment.