Which component of lockout/tagout physically prevents re-energizing?

• A. A lockout device physically prevents re-energizing.
• B. A tag alone prevents re-energizing.
• C. A fuse prevents re-energizing.
• D. A control switch prevents re-energizing.

Answer: (A)

Lockout devices physically block re-energizing by locking the energy-isolating device (like a switch, breaker, or valve) in the off position. When a worker applies the lock and keeps it in place, no one else can restore power until that lock is removed by the same person who applied it. A tag provides warning information but does not stop energy flow, so it cannot prevent re-energizing on its own. A fuse can interrupt current, but it isn’t a controlled lockout and can be replaced, which could re-energize the equipment. A control switch might de-energize or energize the system, but without a lock, someone else could flip it back on, bypassing the safety measure.