What does the arc flash boundary indicate?

• A. A zone defined by the maximum distance a worker can stand near energized equipment.
• B. The distance from live parts within which a person could be exposed to a specified level of incident energy; it is determined by calculations or standards.
• C. The boundary beyond which PPE is not required.
• D. The maximum reach of a worker without PPE.

Answer: (B)

Arc flash boundary is the distance from live electrical parts at which the incident energy from an arc could reach a level that may cause injury to a person if an arc flash occurs. This boundary is defined by calculations or standards, such as NFPA 70E, and it corresponds to a specific incident energy threshold (about 1.2 cal/cm^2) used to determine what PPE is required. It helps you set the right personal protective equipment and safety controls for work near energized equipment. It isn’t just the farthest you can stand or a line beyond which PPE isn’t needed, and it isn’t based on how far you can reach without protection.