When is lockout/tagout applied in underground maintenance?

• A. When shutting off power to equipment for maintenance to isolate energy sources.
• B. When cleaning dust from surfaces.
• C. Only during gas testing.
• D. During routine start-up.

Answer: (A)

Lockout/tagout is used to prevent the equipment from starting or releasing stored energy while someone is working on it. In underground maintenance, that means identifying all energy sources—electrical, hydraulic, pneumatic, gravity, stored energy—and isolating them before any servicing begins. Shutting off power to the equipment and securing the energy source with a lock (and a warning tag) ensures the machine cannot be energized accidentally while work is being done. This protects workers from shocks, moving parts, or unexpected energy releases during maintenance. Cleaning dust or routine start-up don’t involve isolating energy sources, and gas testing isn’t the same as ensuring energy cannot be released during service.