Every compliant lockout/tagout follows the same six-step sequence. The order is not arbitrary — each step neutralizes a specific failure mode, and skipping or reordering them is exactly how energy-control incidents happen. This guide walks through all six, with the practical mistakes that defeat each one.
The authorized employee identifies every energy source feeding the equipment and the magnitude and hazards of each. This is where an accurate, equipment-specific procedure matters: the most common root cause of LOTO incidents is an unidentified secondary energy source. Affected employees are notified that a lockout is about to begin.
The machine is stopped using its normal stopping procedure — the controlled sequence the equipment was designed for. Slamming a disconnect on a running machine can itself release energy or damage the asset. An orderly shutdown brings the equipment to a known, safe state before isolation.
Each energy source is isolated at its isolating device: opening disconnect switches, closing valves, blanking lines, blocking moving parts. Isolation must happen at a device that physically interrupts the energy, not merely at a control button or PLC stop, which can be bypassed or fail.
Every authorized worker applies their own individually-keyed lock and a tag identifying who applied it and why. The principle is one worker, one lock, one key. The tag communicates; the lock enforces. For multiple isolation points or multiple workers, group lockout with a lockbox keeps each person in control of their own protection.
Isolation stops new energy from entering, but stored and residual energy remains: capacitors hold charge, hydraulic and pneumatic systems hold pressure, springs stay compressed, raised loads stay elevated, and surfaces stay hot. Each must be discharged, bled, blocked, restrained or allowed to dissipate until it can no longer cause harm.
Before any work begins, the authorized employee verifies isolation by attempting to operate the equipment with its normal controls (then returning them to off) and by testing with instruments where appropriate — for example, a voltage tester confirmed against a known live source. Verification is the last barrier; it is also the most frequently skipped step under schedule pressure, which is why a system that forces verification before releasing the work order materially reduces risk.
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