Lockout, tagout: the order that keeps the power off while you are inside

Before working on equipment you turn it off, open the disconnect that feeds it, put your own lock and tag on that disconnect, release any energy still stored, and prove it dead with a meter; only then do hands go in, and only you remove your lock.

Hone is a place to practise a career, one idea a day. This is one of its lessons, written out in full and free to read without an account.

What it is for

The disconnect is off. You are in the box. Somebody on the other side of the plant sees a machine down and flips it back on. Every step of lockout exists because that has happened, and the lock with your name on it is the only thing that makes the switch yours instead of anyone's.

How to think about it

Say the steps in order until they are a rhythm: notify, shut down, isolate, lock and tag, release stored energy, verify. Verify means a meter, on a known-live source first, then the circuit, then the known-live source again. When the job is done the order runs backwards: clear, close up, notify, remove your own lock, restore, test.

Worked example

1. Tell the people it affects that the machine is coming down

The operator, the shift lead. Nobody is surprised.

2. Shut it down by its normal controls

Stop button first. Killing the feed to a running machine is its own hazard.

3. Open the disconnect or breaker that feeds it

Isolate. The one that actually feeds it: check the label, then check with a meter later.

4. Apply your lock and your tag

Your lock, your key, your name and the date. One lock per person working.

5. Release stored energy: capacitors, springs, raised loads, pressure

Off is not the same as safe. A drive's capacitors can hold a lethal charge for minutes.

6. Verify: known live, then the circuit, then known live again

The three-point test. Only a meter can tell you the isolation worked.

7. Work

And nobody but you removes your lock.

Your turn

Write the step that comes right after the disconnect is opened.

4. Apply your  and your tag

The trap

Taking a lock off for someone who went home. The lock says its owner may be inside the machine. If they are not reachable, there is a written procedure with a supervisor and a search; there is no shortcut, and cutting it is the one thing on this list that gets people killed.

Practise lockout, tagout on HoneA question on it now, a coding challenge where there is one, and it is remembered for review. Free, no email needed.