CSLB C-10 Electrical ContractorSafety and TestingMedium
A qualified electrical worker is preparing to perform maintenance on a 480V motor control center. Before commencing work, they must de-energize the equipment and apply appropriate lockout/tagout devices. According to NFPA 70E, which of the following is the LAST step a qualified person must perform to verify an electrically safe work condition?
- AVisually inspect the equipment for any signs of re-energization.
- BApply personal protective equipment (PPE) before approaching the equipment.
- CConfirm that all disconnects are in the 'OFF' position and locked out.
- DUtilize a properly rated test instrument to test each phase conductor or circuit part for the absence of voltage.
Show answer & explanationAnswer & explanation
Correct answer: D. Utilize a properly rated test instrument to test each phase conductor or circuit part for the absence of voltage.
NFPA 70E outlines a specific sequence for establishing an electrically safe work condition. The final step, after de-energizing and locking out, is to verify the absence of voltage using a test instrument.
Why the other options are wrong
- A. Visual inspection is part of the overall process but is not the final verification step for absence of voltage.
- B. Applying PPE is necessary for arc flash protection but is not a step in verifying the absence of voltage itself.
- C. Confirming disconnects are off and locked out is an earlier step in the lockout/tagout procedure, not the final verification of absence of voltage.
Absence of Voltage Verification
The final step in establishing an electrically safe work condition, involving the use of a rated test instrument to confirm no voltage is present on circuit parts.
- Performed by a qualified person
- Requires a properly rated test instrument
- Confirms de-energization before touching conductors
Memory trick: Safe Work: Don't Touch, Test First!