Which boundary is central to arc‑flash hazard assessment in electrical work?

• A. Arc‑Flash Boundary
• B. Ground Boundary
• C. Isolation Boundary
• D. Safe Distance Boundary

Answer: (A)

Arc-flash hazard assessment hinges on the Arc-Flash Boundary—the distance from the equipment within which an arc flash could deliver enough energy to cause injury. This boundary marks where incident energy reaches the threshold used to determine required PPE and protective measures. In NFPA 70E terms, it helps decide what protective clothing, tools, and procedures are necessary and whether work can proceed with appropriate controls. Distances beyond this boundary have lower, typically negligible, arc energy and don’t drive the same PPE requirements. The other boundaries mentioned aren’t used to define arc-flash risk; they relate to grounding or de-energization concepts and don’t define the energy-based zone used for arc-flash protection.