Lock Out/Tag Out

A worker leans into a jammed conveyor to clear a stuck board. Down the line and out of sight, someone hits start to get things moving again. That's all it takes. Lock out/tag out exists because energy that comes back unexpectedly — electrical, hydraulic, pneumatic, or mechanical — gives no second chance.

The hazard

A machine that's switched "off" is not the same as safe to reach into. The real danger is energy that's still there or comes back: a circuit someone re-energizes, a hydraulic arm that drops, a pressurized line or loaded spring that lets go, a flywheel still spinning down, or a capacitor holding a charge after the switch is thrown. Electricity adds its own edge — live circuits kill in a fraction of a second, and arc flash can burn and blind from a distance with no contact at all.

Two different things get called "lockout," and Ontario treats them differently. Isolating a machine's mechanical, hydraulic, and pneumatic energy is one job. Work on or near energized electrical parts is another, and it carries its own rules about who may do it, under written procedures the constructor has to establish. Don't let one word blur that line.

What to do: the steps

Follow these exactly — never skip a line to save time.

• Start from the written procedure. Your employer's equipment-specific procedure is the control here, not memory and not what the last crew did. If there isn't one for this machine, that's the thing to fix before anything else.
• Notify: Tell everyone affected before you isolate. Make sure nobody is mid-task or counting on the equipment running.
• Shut down using the normal stopping procedure.
• Isolate every source, then lock and tag. Not just the main disconnect — every source that can deliver energy into that machine. The tag is made of non-conducting material, placed where it will be seen and secured so it can't fall off, and it says why the equipment is disconnected, who disconnected it, their employer, and the date. It doesn't come off until it's safe.
• One lock per worker. Three people working on it, three locks on the hasp. Never use someone else's lock, and never let someone lock out on your behalf. If a lock has to come off because its owner has gone home, that runs through the employer's controlled removal procedure — it is never a bolt cutter and a judgement call.
• Discharge or contain the stored energy — and keep it that way. Bleed hydraulic and air pressure, block or lower raised parts, restrain loaded springs, deal with capacitors. It has to stay discharged or contained for the whole time the work continues, not just at the start.
• Verify before you touch it, then confirm it's dead. Try the normal start control to confirm the machine won't move — that's the step everyone skips. For the electrical state, verifying absence of voltage is itself electrical work: only a worker qualified under Ontario's electrical trade requirements may do it, following the written measures and procedures, with the mats, shields, and protective equipment those procedures call for. If you're not that person, your verification is the try-the-start-control step and nothing more. Don't put a meter on an exposed circuit.
• Talk to each other. Where more than one worker is involved, there has to be a way to communicate the purpose and status of the lockout — so nobody assumes the job is finished because the noise stopped.
• Power back up only when everyone is clear, all guards are back on, and the person who locked out removes their own lock.

Watch out for

• "I'll just be a second" — most lockout failures happen during quick, unlocked tasks.
• Removing a lock that isn't yours because the job looks done. Never.
• Treating one disconnect as the whole isolation when the machine has hydraulics, air, or a second feed.
• An unqualified worker being handed a meter and told to "check if it's dead."
• Restoring power before everyone's clear of the machine.

Talk it over

• For the machine we're working on today: is there a written, equipment-specific procedure — and has anyone read it?
• Which sources feed it besides the obvious disconnect, and what stored energy has to be released before anyone reaches in?
• Who here is actually qualified to verify the electrical state, and are they on site today?