Lockout / tagout verification
Lockout kills people not because it is hard but because it is easy to do most of. De-energizing a machine is a four-link chain — isolate, lock, release stored energy, verify — and skipping any one link gives up the whole thing. Six machines, four checks, five broken links and one that holds. Find the break before anyone reaches in.
Before you start — job brief
This trainer is a drill, not a substitute for your site's energy-control procedure or your own locks. A coworker has locked out a machine and told you it is safe to work on. Your job is to prove that before you trust it. Lockout/tagout exists because "I'm sure it's off" is how people are killed — the only proof of a dead machine is a test at the point of work.
- Isolate every energy source — electrical, hydraulic, pneumatic, gravity, spring, thermal
- Lock the disconnecting means, not a control button, an E-stop, or a PLC
- Release or block stored energy — zero volts is not zero energy
- Verify: try-to-start and test for zero energy at the point of work before you touch it
Lockout · check isolation, the lock, stored energy and zero-energy verify
Check isolation, the lock, stored energy, and the zero-energy test.
Safety check
Checks made
- No checks yet.
Your call
Lockout is a chain, and every link has to hold
Lockout/tagout kills people not because it is hard, but because it is easy to do most of. A worker opens the disconnect, hangs a lock and a tag, and reaches in — and dies, because the one step they skipped was the one that mattered. De-energizing a machine is a chain of four links: isolate every energy source, lock the disconnecting means, release the stored energy, and verify zero energy with a test at the point of work. Skip or fumble any one and the whole thing gives, no matter how careful the other three were. This trainer walks six machines; five have exactly one broken link, and the sixth is whole. Your job is to find the break — or confirm there isn't one.
Isolate every source — not just the obvious one
Most machines have more than one way for energy to get in. A 480-volt main feed is the obvious one, but the control circuit is often fed from a separate transformer with its own disconnect; there may be a second panel, a backfeed from a UPS or a variable-frequency drive, a pneumatic supply, a gravity load, or a spring. Lock the big feed and miss the little one and the machine is still live where you are working. The habit that prevents it is reading the machine's drawings — or surveying it — to list all the energy sources before you lock anything. The verify test at the end is your backstop: if you missed a source, the meter at the point of work finds it.
Lock the energy, not the controls
The only thing worth locking is a device that physically isolates energy — a disconnect switch, a breaker you can lock off, a valve you can chain shut. An E-stop, a start button, a selector switch, a PLC output, a soft "off" on an HMI: these tell the control system to stop the machine, but they do not disconnect power. Locking one of them is one of the deadliest mistakes in the trade, because it feels like a lockout and looks like a lockout and does nothing at all. If the padlock is on a button, it is on the wrong thing.
Field note — a tag is a sentence, a lock is a wall
Tagout and lockout are not interchangeable. A tag is a written warning: it says "do not operate," and it depends entirely on everyone reading and obeying it. A lock is a physical barrier: the switch cannot be closed while your key is in your pocket. Wherever a disconnect can accept a lock, it must be locked — tagout-only is a last resort reserved for the rare device with no locking means, and even then it demands extra precautions. If you find a tag hanging alone on a lockable disconnect, that machine is not locked out, however official the tag looks.
Zero volts is not zero energy
Electrical isolation is only part of the job. A hydraulic accumulator can hold a press up for hours after the power is off; a raised ram, a suspended load, or a counterweight holds gravitational energy; a compressed spring, a charged capacitor bank, a pressurized air receiver, a hot surface, a flywheel still spinning — all of these will hurt you with the main locked out and the meter reading zero. Releasing stored energy means bleeding pressure to zero, lowering or blocking raised loads, discharging capacitors, and letting rotation and heat come down — and then proving it, the same way you prove the electrical side.
Verify — the step that is never optional
Everything above can be done right and the machine can still be live, because a disconnect can lie. A pole welds closed and passes power with the handle off. A disconnect is mislabeled and you locked the wrong one. A drawing is out of date. The verify step is what catches all of it: try to start the machine from the normal controls to confirm it will not run, then test for zero energy with a meter at the point where you will put your hands — and test the meter on a known live source before and after, so you know the meter itself works. This is the link people skip most, because by the time they get here they are sure the machine is dead. Sure is not the standard. Tested is. The only proof of a de-energized machine is a live-dead-live test at the point of work, every single time.