What is the essential element of lockout/tagout that ensures safety during maintenance?

• A. A visual placard only.
• B. A lock and tag placed on energy sources to prevent startup.
• C. A written note left by maintenance.
• D. An audible alarm only.

Answer: (B)

Preventing unexpected energization during maintenance is achieved by applying a lock and tag to the equipment's energy sources. The lock physically prevents the energy source from being re-energized, while the tag provides warning and identifies who locked it and what work is being done. This combination ensures that no one can restart the equipment until the lock is removed by the person who applied it, following proper procedures. Relying on a placard or a written note doesn't stop energy, and an audible alarm alone doesn't block startup. Therefore, the lock and tag on energy sources to prevent startup during maintenance is the essential element.