What safety step is essential when replacing a fuse or breaker?

• A. Tag the device and re-energize after replacement
• B. Securely lock out the circuit and verify zero energy state before replacement
• C. Inform supervisor only and proceed
• D. Use insulated tools only

Answer: (B)

Lockout/tagout procedures are used to ensure the equipment is truly de-energized before you replace a fuse or breaker. The idea is to isolate the circuit from all energy sources, put a lock on the disconnecting device so no one can re-energize it, and attach a tag that communicates that work is being done. Before touching the fuse or breaker, you verify there is zero energy with the proper testing equipment and by ensuring stored energy sources (like capacitors) are discharged. Only after this confirmation do you proceed with the replacement. This approach prevents unexpected re-energization, protects you from shock or arc flash, and accounts for any stored or residual energy. After the work is finished, you remove the lockout only when the area is safe and clear, following the established procedure.

Tagging alone isn’t enough because a tag doesn’t physically stop someone from re-energizing the circuit. Re-energizing after replacement defeats the safety purpose, and simply informing a supervisor without isolating energy doesn’t protect you. Relying on insulated tools helps reduce some risk, but it doesn’t control the energy sources or prevent re-energization or stored-energy hazards.