Key takeaways
- LOTO stops machines from starting up, or releasing stored energy, while someone is servicing them.
- Every energy source gets isolated and locked: electrical, mechanical, pneumatic, hydraulic, thermal, chemical and gravity.
- The core sequence is prepare, shut down, isolate, lock and tag, release stored energy, then verify zero energy.
- A lock physically prevents re-energising. A tag only warns. Use a lock wherever the isolation point can take one.
What lockout-tagout means
Lockout-tagout, usually shortened to LOTO, is the procedure that keeps a machine or line safely de-energised while people clean, repair, adjust or service it. The machine is shut down, every energy source is isolated, and a personal padlock is placed on each isolation point so nobody can switch it back on until the person who applied the lock removes it.
The tag is the second half: a durable label attached to the lock that says who applied it, why, and that the equipment must not be operated. Together, the lock and the tag make the isolation both physical and visible.
Which energy sources need to be locked out?
Most serious isolation incidents happen because one source was missed. A conveyor might be switched off at the motor, while a pneumatic take-up still holds tension. A press might be isolated electrically, while the ram still has gravity working on it.
- Electrical: motors, heaters, control circuits and capacitors that hold charge.
- Mechanical: rotating shafts, flywheels, springs under tension.
- Pneumatic and hydraulic: pressurised lines, accumulators and cylinders.
- Thermal and chemical: steam, hot process fluids, reactive or toxic lines.
- Gravity and stored energy: raised loads, counterweights, material in hoppers.
The six steps of lockout-tagout
Plants word their procedures differently, but every sound LOTO procedure follows the same sequence. It also lines up with the OSHA 29 CFR 1910.147 energy control standard used as a reference by many companies outside the United States.
- Prepare. Identify the equipment, every energy source and every isolation point. Tell affected people what is about to happen.
- Shut down. Stop the machine using its normal stopping procedure.
- Isolate. Operate each energy-isolating device: breakers, valves, blinds, disconnects.
- Lock and tag. Each authorised person applies their own lock and tag to each isolation point.
- Release stored energy. Bleed pressure, block or lower raised parts, discharge capacitors, let hot parts cool.
- Verify zero energy. Try to start the machine, or test with a meter, before any work begins. This is the “try-out” step.
When the work is done, the order reverses: tools are cleared, people are accounted for and kept clear, and each person removes only their own lock.
Lockout vs tagout: what is the difference?
| Lockout | Tagout | |
|---|---|---|
| What it does | Physically prevents the isolation device from being operated | Warns people not to operate it |
| Protection | Holds even if someone ignores the warning | Relies on everyone reading and obeying the tag |
| When to use | Whenever the isolation point can accept a lock | Only where a lock cannot be fitted, with extra measures |
| Who removes it | Only the person who applied it | Only the person who applied it |
The rule of thumb is simple: lock wherever you can. Tagout alone is the weaker control and needs additional measures, such as removing a fuse or blocking a control switch, to give equivalent protection.
Group lockout and shift changes
Large jobs such as a kiln shutdown or a conveyor overhaul involve whole crews. Traditionally, one person isolates the equipment and places the keys in a group lockbox, and every crew member adds their personal lock to the box or to a hasp. The equipment cannot be released until every lock is off.
It works, but it relies on hasps, boxes, registers and a lot of trust at shift change. We cover a digital alternative in Group lockout without the hasp.
Where paper LOTO breaks down
On a well-run site the paper process is followed most of the time. The problem is that you can’t see the times it isn’t. Shared keys, tags nobody reads, try-outs that are skipped when a job is late, and registers that are filled in after the fact all look the same on paper as a perfect isolation. See seven ways paper LOTO fails for the patterns we see most often.
What digital LOTO changes
Smart LOTO® keeps the physical lock and makes it accountable. With a Bluetooth-enabled padlock such as Smart LOTO®, each worker locks and unlocks from their own app, against a specific permit and isolation point. Every action is time-stamped. The rule we built the category around is 1-Man-1-Lock-1-Digital Key®: one person, one lock, one key that nobody else can use.
Read what digital LOTO is and how Bluetooth lockout works for the full picture.
Frequently asked questions
What does LOTO stand for?
LOTO stands for lockout-tagout: isolating a machine’s energy sources, locking the isolation points and tagging them so the machine cannot be started while people work on it.
Is tagout alone enough?
Tagout alone is weaker than lockout because it relies on people reading and obeying a warning. Use a lock wherever the isolation point can take one, and add extra measures where it cannot.
Who is allowed to remove a lock?
Only the person who applied it. Most programmes also define a controlled procedure for the rare case where that person is not on site.
What is the try-out step?
Try-out is the verification that the equipment is truly at zero energy, by attempting a start or testing with a meter, after locks are applied and before work begins.
See Smart LOTO® run on your plant.
Book a demo