An electrician needs to service a 480V panel. The electrical source has been de-energized and locked out. What additional step is required before beginning work?
Correct Answer
B) Test the equipment to verify it is de-energized
LOTO procedures require verification that equipment is de-energized through testing before work begins, not just locking out the energy source.
Why This Is the Correct Answer
OSHA's Lockout/Tagout (LOTO) standard (29 CFR 1910.147, applied in construction via 1926.417) requires workers to verify zero energy state by testing the equipment after lockout. A lock on the disconnect does not guarantee de-energization; capacitors, back-feeds, or other stored energy can remain. Testing confirms it is truly safe.
Why the Other Options Are Wrong
Option A: Wait 24 hours for residual energy to dissipate
Waiting 24 hours has no basis in OSHA LOTO requirements. Residual electrical energy in capacitors can be discharged in seconds to minutes with proper procedures; arbitrary wait times are not a recognized safety step.
Option C: Notify all workers on site
Notifying all site workers is a courteous practice and may be required for certain permit systems, but it is not a formal LOTO verification step. Notification alone does not confirm the panel is de-energized.
Option D: Install temporary grounding
Installing temporary grounding is required for some high-voltage transmission work but is not the primary additional step in standard LOTO procedures for a 480V panel. Verification by testing comes first.
Memory Technique
LOTO acronym expanded: Lock Out, Then Operate (test). Before you touch it, prove it is dead. Think of a surgeon confirming anesthesia before cutting — you verify before you proceed.
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