United States
Hong KongLockout and tagging
Controls that are to be de-energized must be tagged, and circuits locked out where possible, under 29 CFR 1926.417. Verification that the circuit is actually dead is part of the procedure.
A short standard whose failure mode is always the same: somebody assumed a circuit was dead.
The requirement
Controls to be de-energized during work are tagged. Equipment or circuits are locked out where the capability exists. Tags are placed to identify the equipment and warn against operation. Then test it.
That is 29 CFR 1926.417, and it is deliberately short.
Lock and tag are not the same
| Does | |
|---|---|
| Lock | Physically prevents the switch being operated |
| Tag | Warns a person not to operate it |
A tag depends on somebody reading it and choosing to comply. A lock does not depend on anybody. Where locking is possible, locking is what is required.
Isolate, lock, tag, then test to confirm the circuit is actually dead. People do the first three and start work. The test is what turns a procedure into safety, and questions describe exactly that omission.
One worker, one lock
Each person working on the equipment applies their own lock, and only they remove it. A multi-lock hasp allows several.
That prevents the situation where one person finishes, removes the isolation and re-energizes a circuit somebody else is still working on.
Stored energy
Capacitors, springs, hydraulic accumulators, raised loads and pressurized systems all hold energy after isolation. Releasing or restraining it is part of the procedure.
Electrical isolation does not make a raised platform safe.
Common questions
What does lockout require?
Tagging controls to be de-energized and locking out circuits where possible, under 29 CFR 1926.417.
What is the difference between a lock and a tag?
A lock physically prevents operation. A tag only warns somebody not to operate it.
What step is most often skipped?
Verification. Testing to confirm the circuit is actually dead after isolating, locking and tagging.
Why does each worker apply their own lock?
So one person finishing cannot re-energize a circuit somebody else is still working on.
What about stored energy?
Capacitors, springs, accumulators and raised loads hold energy after isolation and must be released or restrained.