Before verifying that a circuit has been de-energized, which safety step must be performed first?

• A. Voltage measured first
• B. Breaker opened
• C. Power is off
• D. It's locked out and tagged out

Answer: (D)

Lockout and tagout is the step that must come first because it physically prevents the circuit from being re-energized while you work. By isolating the energy source and applying a lock plus a warning tag, you create a reliable barrier that only the authorized person can remove. This ensures the circuit stays in a de-energized state during verification and maintenance, so you’re not banking on others not flipping a switch or restoring power accidentally.

After the circuit is locked and tagged out, you then check for absence of voltage to confirm de-energization. Relying solely on turning off a breaker or the power being off isn’t enough, since someone could re-energize the circuit or there could be other energy sources. The lockout/tagout procedure provides the hands-on protection and clear warning required for safe work.