Which practice helps ensure the high‑voltage system remains de-energized during maintenance?

• A. Lockout/Tagout and verified zero voltage using a tester.
• B. Relying on a single switch position.
• C. Keeping the system energized while working.
• D. Not notifying anyone.

Answer: (A)

The essential practice is to isolate the energy source and prove there is zero energy before any maintenance. Lockout/Tagout means you apply a lock to the energy source so it cannot be re-energized, and attach a tag that identifies who is working and why. This creates a physical barrier to accidental re-energizing. After locking out, you use a proper voltage tester to verify that there is no voltage present and that any stored energy (like capacitors) has been discharged. This two-step approach—isolation plus verification—ensures the high‑voltage system stays de-energized while work is being done, greatly reducing the risk of shock or arc flash.

Relying on a single switch position doesn’t guarantee safety because power can still be present through other paths, and the switch could be bypassed or reset. Keeping the system energized or not notifying anyone ignores the critical need for a controlled, communicative, and verifiable safety process.