Which are the shock approach boundaries?

• A. Limited approach boundary
• B. Restricted approach boundary
• C. Limited approach boundary; Restricted approach boundary; Prohibited approach boundary
• D. Prohibited approach boundary only

Answer: (C)

Electrical safety around exposed energized parts is governed by shock approach boundaries that define how close a person can get before taking protective measures. There are three: the limited approach boundary, the restricted approach boundary, and the prohibited approach boundary. The limited approach boundary is the outer distance in which a shock could occur if something goes wrong with the equipment; entering this zone typically requires awareness, training, and safeguards. The restricted approach boundary is closer, and only qualified persons who have received proper training and who follow specific procedures and use appropriate PPE may operate within it. The prohibited approach boundary is the innermost limit where entry is not allowed for unqualified personnel under any ordinary circumstances; crossing it requires de-energizing the equipment or special authorization and protections. Since all three boundaries are used to segment levels of risk and access, the correct answer includes all three. Distances change with voltage and fault current, and are defined in standard electrical safety guidelines.