Lockout / tagout, walked through

Lockout is four things in order: find every source of energy, shut each one off and put your lock on it, prove the equipment dead, and keep the key in your pocket until you are finished. Everything else on this page is detail on those four. The reason it gets its own page is that the detail is where people get hurt — the source nobody counted, the tag with no lock behind it, the meter that read zero because it was broken.

One thing before the steps. Your employer has a written lockout procedure, and your province has rules that procedure answers to. Those govern. What is here is the shape of the habit so the procedure makes sense the first time you read it — not a substitute for reading it.

A lock is a barrier; a tag is a note

Think about what each one does to the next person who walks up to the disconnect. A tag asks them not to close it. A lock makes it impossible to close without cutting the lock off, which is a deliberate act nobody does by accident. That is the whole difference, and it is why a tag on its own is only used where a lock physically cannot be fitted — and then with extra measures your procedure spells out. The tag still matters: it puts a name, a date and a reason on the lock, so the person standing there knows who to find.

The walk-through

The order matters. Read it once as a story: you are about to open a motor starter that has been tripping.

1. Tell the people it affects. The operator, the foreman, anyone else working on the same equipment or fed from the same source. A machine that stops without warning is a hazard in itself.
2. Find every energy source. Not just the one disconnect you can see. The control circuit may come from a different panel. A drive holds a charge in its capacitors after the supply is off. A spring-charged breaker is loaded. A raised load can fall; a hydraulic line stays pressurised; a generator, a UPS or a second feed can put voltage back on the circuit. The drawings and the equipment's own manual are where you find these — and if you cannot find all of them, you are not ready to lock out.
3. Shut it down the normal way. Stop the machine with its own controls first. Pulling a disconnect under load is hard on the disconnect and can throw an arc at you.
4. Isolate at the disconnect. Open every source you found. The disconnect handle goes to OFF; a breaker goes off and, where your procedure calls for it, a breaker lockout device goes on it.
5. Lock and tag each one. Your own lock, keyed to you alone, with your tag on it. If more than one person is on the job, a hasp goes on first and every worker hangs their own lock on the hasp. Nobody works under someone else's lock.
6. Release the stored energy. Discharge capacitors the way the manufacturer says to, bleed pressure, block or lower raised loads, release charged springs. This step is its own step — shutting the disconnect did nothing to any of it.
7. Prove it dead. First, try to start it from its own controls — press the start button, turn the selector — and watch that nothing happens. Then meter it: prove the meter on a known live source, test every conductor to every other and to ground, prove the meter again. The live-dead-live check is not optional here; it is the only step that actually proves the lockout worked.
8. Do the work. The key stays in your pocket the whole time. If you leave the site, your lock comes off only when your part of the job is done — or your employer's procedure for a shift change is followed.
9. Restore in reverse. Tools and parts out, guards back on, everyone clear, people told. Then locks off — each worker their own, the last person's last — then the disconnect closed, then a normal start.

Three things you never do

You never borrow a lock. A lock is a statement that its owner is working on that equipment; a borrowed lock is a lie with a name on it. You never cut a lock, and you never ask someone to cut one for you. Every written procedure has a specific process for a lock whose owner cannot be found, with verification and authority and a record — that process exists because cutting locks is how people die, and it is never a decision made at the disconnect. And you never work under a lock you did not hang. If the journeyman's lock is on and you are about to put your hands in, your lock goes on the hasp beside theirs.

"Your employer's written procedure governs"

That line appears twice on this page and it is not a disclaimer, it is an instruction. The procedure names who is authorised to lock out, what the forms look like, how a group lockout is run, what happens at a shift change, how a lost-key lock comes off, and which pieces of equipment need their own specific procedure because their energy sources are unusual. The training that goes with it is where you learn your site's answers. What this page gives you is the reason each step exists, so the procedure reads as sense rather than as a checklist to get through.

Sur le chantier

Questions fréquentes

Voir aussi

• Meter safety and CAT ratings — the live-dead-live check that proves the lockout.
• Troubleshooting a control circuit — the work you lock out for.
• Reading a panel schedule — finding the right breaker to open.
• All on-the-job pages