What is the correct sequence in lockout-tagout (LOTO) to perform a maintenance task?

• A. Isolate energy sources; apply locks/tags; verify zero energy; perform task; remove devices; re-energize.
• B. Verify zero energy; perform task; remove devices; re-energize; apply locks.
• C. De-energize, then proceed without checks.
• D. Remove locks before testing.

Answer: (A)

Controlling energy sources before maintenance is essential to prevent accidental startup or release of stored energy that could injure someone. The proper sequence makes sure the equipment is truly safe to work on and cannot be re-energized until the work is finished.

First, isolate the energy sources to prevent any power, fluid, or other energy from feeding the equipment. Then, apply locks and tags to the energy-isolation devices so that no one can remove them and re-energize the system while work is underway. After that, verify zero energy to confirm there is no residual or stored energy—and that all potential energy forms are released or blocked—before starting the task. With the system confirmed safe, perform the maintenance. Once the work is complete, remove the devices and then re-energize the equipment only after all locks and tags are removed and everyone is clear of the area.

Why this sequence fits best is that it creates a verified safe state before any work begins and keeps that state throughout the task. Skipping the lockout-tagout steps, or proceeding without verifying zero energy, or removing locks before testing, could allow an unexpected restart or energy release.