CSLB C-10 Electrical ContractorSafety and TestingMedium
A qualified electrical worker is performing maintenance on a 480V motor control center. After de-energizing the equipment and verifying absence of voltage, the worker needs to apply personal protective grounds. According to best safety practices and NFPA 70E, what is the primary purpose of applying personal protective grounds?
- ATo protect workers from accidental re-energization or induced voltages.
- BTo discharge any residual capacitive energy stored in the circuit.
- CTo ensure the equipment cannot be re-energized inadvertently.
- DTo provide a path for fault currents during testing.
Show answer & explanationAnswer & explanation
Correct answer: A. To protect workers from accidental re-energization or induced voltages.
Personal protective grounds are applied after de-energization and absence of voltage verification to protect workers from electric shock due to accidental re-energization, induced voltages from adjacent lines, or stored energy discharge.
Why the other options are wrong
- B. Discharging residual capacitive energy is a function of grounding, but the primary purpose of protective grounds goes beyond this to cover re-energization and induction.
- C. Lockout/tagout ensures equipment cannot be re-energized; grounds provide secondary protection if lockout fails.
- D. While grounds carry fault current, their primary purpose in this context is worker protection, not testing.
Personal Protective Grounds
Temporary grounding conductors applied to de-energized electrical equipment to protect workers from electric shock hazards.
- Applied after lockout/tagout and absence of voltage verification.
- Protects against accidental re-energization.
- Protects against induced voltages and stored energy.
Memory trick: Grounds: Your Safety Net Against Surprises.