CSLB C-20 HVAC ContractorControls, Electrical and SafetyMedium
A technician has locked and tagged out the disconnect for a rooftop condensing unit before servicing it. According to Cal/OSHA lockout/tagout procedures, what must be done immediately after applying the lock and tag but before beginning work?
- AVerify zero energy state by testing the circuit with a meter
- BProceed directly to disassembly since the lock alone guarantees zero energy
- CRemove the disconnect fuses and place them in a pocket for the day
- DNotify the client verbally that the unit is off
Show answer & explanationAnswer & explanation
Correct answer: A. Verify zero energy state by testing the circuit with a meter
Cal/OSHA lockout/tagout procedures require a verification step after isolating and locking the energy source: the technician must attempt to start the equipment (try-out) and/or test the circuit with a meter to confirm it is actually de-energized before beginning work. Relying on the lock alone without verification is a common and dangerous shortcut.
Why the other options are wrong
- B. Locks can fail or be applied to the wrong disconnect, so verification is required.
- C. Removing fuses is not a substitute for verifying de-energization with a meter.
- D. Verbal notification does not verify the electrical state of the equipment.
Lockout/Tagout Verification
After isolating and locking an energy source, Cal/OSHA requires the worker to verify de-energization by testing the circuit with a meter or attempting to operate the equipment.
- Steps: identify, notify, isolate, lock/tag, verify (try-out/test)
- A meter reading of zero volts confirms de-energization
- Skipping verification is a leading cause of electrical injuries
Memory trick: Lock it, tag it, then TEST it.