Define arc flash boundary and the two common approach boundaries used for worker protection.

• A. Arc flash boundary is the distance at which the incident energy is 1.2 cal/cm^2; limited and restricted approach boundaries define safe entry distances for unqualified/qualified workers with different PPE.
• B. Arc flash boundary is the distance to the nearest transformer; limited approach boundary is irrelevant.
• C. Arc flash boundary is the distance where PPE is not needed; limited and restricted boundaries refer to only entry with PPE.
• D. Arc flash boundary is always equal to the work zone boundary; no approach boundaries.

Answer: (A)

Arc flash boundaries define how close workers can get to energized equipment and what PPE is required. The arc flash boundary is the distance from the electrical source where the incident energy is 1.2 cal/cm^2, a level associated with the potential for a second‑degree burn in a brief exposure. Inside this boundary, workers must wear appropriate arc-rated PPE and follow safe work practices.

Two common approach boundaries help manage different worker qualifications and PPE needs. The limited approach boundary is the closest distance an unqualified worker may approach an exposed energized conductor or circuit part. The restricted approach boundary is closer still and applies to qualified workers who may approach with the proper PPE and protective procedures. These boundaries, along with the arc flash boundary, organize safety zones and dictate entry permissions and protective equipment.