Lockout/tagout: a step-by-step procedure

Lockout/tagout (LOTO) is a procedure that isolates every source of energy that could move or hurt someone before they service or repair equipment. The energy is locked in the off position, tagged to show who is working on it, and checked to confirm it's dead before work starts. Done properly, it stops a machine restarting while someone's hand, arm or body is inside it.

Most serious plant injuries happen when stored or unexpected energy is released during maintenance. A written, machine-specific LOTO procedure, followed every time, is one of the most effective controls you can put in place. This guide sets out the steps and what your procedure should cover.

What is lockout/tagout?

Lockout is the physical act of locking an energy isolation device, such as a switch, valve or circuit breaker, so it can't be turned back on. Tagout is a warning tag attached to the same device, showing who applied the lock and why it must not be operated. The two work together. A tag alone can be ignored, and a lock alone doesn't explain who is working on the equipment.

Hazardous energy comes in several forms, and each one needs to be isolated:

Remember that some energy is stored. A raised load can drop, a spring can release and a pressurised line can still be full after the power is off.

Who needs a lockout procedure?

Any business that services or repairs plant, machinery or processes that can move or release energy needs one. That includes manufacturing, food processing, mining, transport, warehousing, construction and maintenance contractors. Many electrical and mechanical jobs require LOTO as well.

The procedure should be specific to each machine. A general instruction such as "lock it out" doesn't tell a fitter where every isolator is, how the energy is stored or how to test that it's dead.

Step-by-step lockout/tagout procedure

1. Plan the job

Before anyone touches the machine, decide what work is needed and who will do it. Check the job for other hazards, such as confined spaces, hot surfaces or chemicals. Plan who will supervise, who will be told, and whether any other work is happening nearby. If the job needs an isolation permit to work, complete it before you start.

2. Identify every energy source

Walk the machine with the manuals and drawings, and list every source of energy. Include the obvious (the main switch) and the less obvious (a second power feed, a bypass, a pneumatic line that feeds a clamp, or a hydraulic accumulator). Talk to the operators who know the machine best.

Record each source and its isolation point on the procedure. A machine often has more isolation points than people expect.

3. Notify affected people

Tell the operators and everyone else who could be affected that the machine is going into LOTO, and why. Make sure no one will restart it while the work is in progress.

4. Shut down the equipment

Shut the machine down using its normal stop sequence. Don't use the emergency stop as the isolation, because it's a backup and can be reset by mistake.

5. Isolate and lock out

Isolate each energy source at its isolation point, then apply a personal lock and tag. Each person working on the equipment should have their own lock and key, so that the machine can't be restarted until every person has removed their lock. Use group lock boxes or hasps where several people are working on the same job.

Where it's practical, keep the key with the person who applied the lock. Don't share keys or leave spare keys in a shared drawer.

6. Release stored energy

Release or restrain any stored energy. This can mean bleeding off hydraulic or pneumatic pressure, blocking a raised load, supporting a suspended part, discharging capacitors or letting hot parts cool. Check the gauges to confirm pressure has dropped to zero.

7. Verify the machine is dead

This is the step most often skipped. Before work starts, confirm that the equipment can't move or release energy. Typical checks include:

• trying to start the machine from the normal controls, and checking that it does not start
• checking pressure gauges and thermometers
• testing electrical circuits with a tested and rated tester, following the electrical isolation procedure
• physically checking that a load or moving part is restrained

Only the person doing the work should confirm the test. Once verified, the work can start.

8. Do the work

Work to the procedure and use the right tools and personal protective equipment. Don't work around a lock, and don't bypass a guard or interlock to carry out the job. If the scope changes, stop and review the procedure before you continue.

If work has to be handed over to another shift, the handover should cover the lock, the tag, the stage of the job and any open issues.

9. Remove the locks and return to service

When the work is finished, check that:

• all tools, materials and people are clear of the machine
• guards and safety devices are back in place
• the machine is ready to be energised, and the work has been signed off

Then each person removes their own lock and tag, in the order set by the procedure. Restore energy slowly if the procedure says so, and run the machine through a test before handing it back to operators.

10. Tell people it's back in service

Tell the operators and others that the equipment is back in service, and record the removal of each lock. Keep a record of the job, including who did the work, what was isolated and the test results.

What should your LOTO procedure include?

A good procedure is short enough to use on the floor and detailed enough that a new worker can follow it. It should include:

• the machine or process it covers, and its location
• every energy source and isolation point, with a diagram or photo
• the shutdown sequence and who can carry it out
• how each energy type is isolated and released
• how to verify the machine is dead
• how locks and tags are applied and removed, and who may do it
• what to do if a lock must be removed by someone else, such as after a shift change or if the person is absent
• the training and competency needed for each person
• when and how the procedure is reviewed

You can build the procedure from the plant lock-out/tag-out plan, or use a lock out tag out SOP for a single machine. A lock out tag out SWMS covers the job when the work is high-risk construction work.

SafetyDocs has lock out tag out procedures, plant management plans and isolation forms you can adapt to each machine. Job and site details fill in themselves, and workers sign the procedure from their phone with a text, link or QR code, with no app or account needed. When a machine changes, you update the document once and everyone who signed is asked to sign the new version. This helps you keep your records current. It doesn't make your procedure compliant on its own.

Training and competency

Training should cover how the energy sources work, how to use locks, tags and isolators, and how to verify isolation. It should also cover what can go wrong, such as a lock that's been removed early or an energy source nobody identified. Anyone who applies locks needs to be competent in the procedure for that machine, not just the general idea.

People who work near LOTO jobs also need to know what a lock and tag mean, so they don't restart a machine or touch a tagged isolator. Keep records of training and check competency after any change to the procedure or equipment.

Common mistakes to avoid

• Using the emergency stop or the normal stop as the isolation point
• Missing a secondary energy source, such as a pneumatic line or a stored spring
• Sharing one lock between several people, or using a lock without a tag
• Removing another person's lock without the agreed process
• Skipping the test-to-verify step because the job looks simple
• Treating the procedure as a one-off document that nobody updates after a change to the machine

Why it matters for your duties

Under the WHS Act, the person conducting a business or undertaking (PCBU) must manage the risks from plant so far as is reasonably practicable. LOTO is one of the main ways to do that during maintenance. The Model Code of Practice on managing risks of plant in the workplace explains how to identify and control plant hazards, including isolation.

Under section 19, your primary duty of care covers the risks from plant, and workers have duties under section 28 to follow the procedure. Consultation with workers under section 47 helps you write a procedure people will follow.

Machine guarding is the other half of the picture. Read our guide to the importance of machine guarding and our overview of plant risks in Australian workplaces.

Common questions

Who is allowed to apply a lock? Only trained and authorised people who understand the procedure for that machine. The procedure should name who can apply and remove locks, and what happens when someone is absent.

Can I use one lock for the whole crew? Use a group lockout only if the procedure sets out how it works. Each person should still have their own lock, so the machine can't restart until everyone is clear.

What if a lock is still on when the person has left? Don't remove it unless the procedure says how. Usually this means a supervisor checks the job, contacts the person and follows a set process to clear the lock safely.

How often should the procedure be reviewed? Review it after any change to the machine, after an incident or near miss, and at regular intervals. Many businesses review it every year.

This is general information, not legal advice. Check the current law with your WHS regulator.