After isolating the HV system, what is the proper procedure to verify it is safe to work?

• A. Rely on visual inspection alone.
• B. Power the system on to see if it operates.
• C. Use a rated HV presence tester to confirm zero voltage at accessible points, following OEM verification steps.
• D. Ask a coworker if they think it's safe.

Answer: (C)

Ensuring there is zero voltage after isolating the high‑voltage system is essential for worker safety. Visual checks won’t reveal stored energy, and attempting to power the system on to test it can expose you to shock or arc flash. Relying on a coworker’s opinion isn’t reliable either, and this isn’t a situation where guesswork is acceptable.

The proper method is to use a rated HV presence tester to confirm zero voltage at accessible points, and to follow the OEM verification steps. The tester must be designed for the system’s voltage and tested at the manufacturer’s specified points and sequence. By measuring at the designated accessible test points, you verify there is no residual energy and that the isolation is complete before starting work. This approach accounts for energy stored in capacitors or backfeed paths and aligns with the vehicle’s safety procedures, PPE requirements, and energy‑isolation rules. Once zero voltage is confirmed, you can proceed with the task and re‑verify as needed during the work.