What is lockout/tagout and why is it used?

• A. Procedures to prevent unexpected energization during servicing or repair.
• B. A method to lock doors to a job site.
• C. A labeling system for circuit breakers.
• D. A system to test insulation.

Answer: (D)

Lockout/tagout is a safety procedure used to prevent unexpected energization or start-up of equipment during servicing or repair. The idea is to isolate all energy sources—electrical, mechanical, hydraulic, pneumatic, chemical, and thermal—and apply a lock or tag to the energy control devices so the machine cannot be turned on until the work is finished and the area is verified safe. This protects workers from injuries that can occur from stored or released energy when machinery moves, power is re-energized, or parts unexpectedly move during maintenance. The process typically involves identifying energy sources, shutting down the equipment, isolating and locking out or tagging out the controls, verifying de-energization, performing the work, and then removing the locks and re-energizing only when it’s safe. This concept is separate from simply locking doors at a job site, labeling circuit breakers, or testing insulation, which do not address the proactive isolation of equipment energy during maintenance.