How do you verify a circuit is isolated after performing LOTO and before energizing?

How do you verify a circuit is isolated after performing LOTO and before energizing?

• A. Attempt to energize using test equipment and confirm no voltage at the circuit; ensure lockout is intact
• B. Visual inspection only
• C. Assume isolation after a delay
• D. Switch off the main power and walk away

Answer: (A)

Verifying isolation means proving there is no energy available to the circuit before work begins. The best approach is to actively confirm absence of voltage at the circuit while the lockout device and tag are in place, using properly rated test equipment. This ensures that all energy sources are truly isolated and cannot energize the circuit again. In practice, you apply a tested instrument to the circuit and observe a zero-voltage reading, which confirms that the line is de-energized and the lockout is intact. Relying on visual checks alone isn’t enough because energized parts can be hidden or stored energy can remain in components. Merely turning off power and waiting, or assuming isolation after a delay, does not verify that all energy sources are blocked or that the lockout is properly applied. Also, verify you’re testing at the correct points and address any stored-energy sources as required before proceeding.

Verifying isolation means proving there is no energy available to the circuit before work begins. The best approach is to actively confirm absence of voltage at the circuit while the lockout device and tag are in place, using properly rated test equipment. This ensures that all energy sources are truly isolated and cannot energize the circuit again. In practice, you apply a tested instrument to the circuit and observe a zero-voltage reading, which confirms that the line is de-energized and the lockout is intact. Relying on visual checks alone isn’t enough because energized parts can be hidden or stored energy can remain in components. Merely turning off power and waiting, or assuming isolation after a delay, does not verify that all energy sources are blocked or that the lockout is properly applied. Also, verify you’re testing at the correct points and address any stored-energy sources as required before proceeding.