Lockout Tagout (LOTO) for Electricians — UK Procedure

Lockout tagout — usually abbreviated to LOTO — is a structured method for controlling hazardous energy. In an electrical context that means stopping a circuit, panel, motor, or piece of plant from being re-energised while an electrician is working on it. The "lockout" is a physical padlock or device that holds the isolator in the off position. The "tagout" is a written tag identifying who applied the lock, when, and why.

LOTO originated as a formal discipline in the United States under OSHA Standard 29 CFR 1910.147 ("Control of Hazardous Energy"). It is not a US-only practice. UK industry — particularly manufacturing, food and beverage, pharma, data centres, hospitals, and any multi-contractor commercial site — adopted LOTO decades ago as the practical way of complying with the Electricity at Work Regulations 1989 and the wider duty of care under the Health and Safety at Work etc. Act 1974.

LOTO is referenced throughout HSE guidance HSR25 (Memorandum of guidance on the EAWR 1989) and HSG85 (Electricity at Work — Safe Working Practices), and it sits alongside the safe isolation sequence taught in the IET On-Site Guide. The lock is what makes the isolation enforceable.

It is a common shortcut to flick a breaker off, prove dead, and start work. On a domestic call-out where the electrician is the only person in the property and has the consumer unit in line of sight, the risk of someone restoring the supply is low. On any site bigger than that, an unlocked switch is a hazard waiting to happen — a cleaner, a tenant, a labourer, or another contractor may switch it back on without realising.

See the dedicated guide on the full UK safe isolation method statement for the documented sequence that accompanies a LOTO application.

A working LOTO kit is small, cheap, and lives in every electrician's van. The standard build is:

UK industry has converged on a seven-step LOTO procedure that maps neatly onto the safe isolation sequence in the IET On-Site Guide and HSG85. The steps are sequential — skipping or re-ordering them defeats the safety case.

1. Preparation — review the job pack, the RAMS, and any existing Permit to Work. Identify every source of supply (mains, sub-board, UPS, generator, solar PV, battery, parallel feeds). Confirm the correct isolation point on drawings and on the board schedule.
2. Notify — tell the responsible person, the site manager, the duty holder, and anyone affected by the loss of supply that you are about to isolate. On commercial sites this is usually a written notice or a permit-to-work step.
3. Shutdown — bring the equipment to a controlled stop in the normal way. Do not just trip the breaker on running equipment if a controlled shutdown is available. Soft-stop the motor, allow VSDs to ramp down, close down processes.
4. Isolate — operate the means of isolation: switch off the MCB, withdraw the fuse, open the isolator. The isolation point must be capable of being locked in the off position. Confirm visually that the device is in the off position.
5. Lock and tag — apply your personal padlock (and, for multi-worker jobs, a multi-lock hasp first, then everyone's padlocks). Attach a tag identifying the electrician, the date, the work being carried out, and the expected return-to-service date.
6. Verify (prove dead) — using a GS38-compliant approved voltage indicator (AVI), prove the indicator on a known live source, test at the point of work between every conductor pair (L-E, L-N, N-E for single phase; all combinations for three-phase), then prove the indicator on the known live source again. This is the "prove-test-prove" sequence.
7. Work — only now is it safe to start. Keep the key on your person for the entire duration of the work. Do not hand it to anyone. If you leave site, your lock stays on.

The full prove-test-prove sequence with conductor combinations and AVI selection is covered separately in the safe isolation method statement — that guide and this one are designed to be used together.

A single electrician working on a single isolation needs one padlock. The moment a second person works behind the same isolation, the rules change.

Group lockout is also where LOTO meets the Permit to Work for electrical isolation — the PTW names each worker, the RAMS describes the method, and the locks physically enforce both.

The rule on lock removal is non-negotiable: only the person who applied a lock may remove it. That rule protects every worker behind the isolation. If anyone else could remove your lock, your safety is at the mercy of someone else's judgement.

LOTO does not sit on its own. On any significant site it is one of three layers — the Permit to Work, the Risk Assessment and Method Statement, and the lock itself. Each layer reinforces the others.

Where the work has to be carried out live — which should always be a last resort — a different framework applies entirely. The live working method statement and the working near live mains hazard control guides set out what is required under Regulation 14 of the EAWR 1989. LOTO is the alternative you choose against; live work is the alternative you choose only when LOTO is genuinely impossible.

BS 7671:2018+A4:2026 Part 6 (Inspection and Testing) requires that an installation is isolated before dead testing is carried out. The lock is what keeps it isolated while you test — without it, someone restoring the supply mid-test exposes you to live conductors at the test points.