A machine has stopped, the screen is dark and the emergency-stop button is pressed. None of those facts proves that the equipment is safely isolated. Electrical supply may remain live, pressure may be trapped and a raised component may still fall. Before cleaning, clearing a blockage, adjusting or maintaining work equipment, employers need a reliable system that identifies every source of energy, prevents reconnection, controls stored energy and verifies the safe state.
A stop control is not an isolator
Regulation 19 of the Provision and Use of Work Equipment Regulations 1998 (PUWER) requires suitable means to isolate work equipment from all its energy sources where appropriate. The means must be identifiable and accessible, and reconnection must not expose anyone to risk. Regulation 22 adds that risky maintenance should, so far as reasonably practicable, be carried out while equipment is shut down.
A normal stop button, emergency stop or software command may interrupt operation without physically separating the equipment from its energy supply. A fault, reset, remote signal or another person's action may therefore restart the equipment. Isolation needs a defined energy-separation point and a method that keeps it in the safe position for the whole intervention.
“Lockout-tagout” is a useful generic description, not a separate UK certificate or universal procedure. The question is whether the equipment and system achieve safe isolation in the real circumstances. A warning tag communicates information; it does not prevent reconnection.
PUWER 1998: regulation 19 ↗ · PUWER 1998: regulation 22 ↗ · Related guide: PUWER inspection requirements →
Identify every source—and every stored condition
Start from the actual machine, task and boundary. Energy can be electrical, mechanical, hydraulic, pneumatic, thermal or chemical. It can also come from pressurised steam, water or product; gravity acting on raised parts; springs and flywheels; batteries, capacitors and generators; interconnected conveyors; or an automatic system that can issue a remote start.
Drawings, manuals and isolation schedules help, but confirm them against the plant. Modifications, temporary supplies and poorly labelled valves can make the document wrong. Walk the equipment with operators and maintainers, identify each isolation point and decide what must be drained, vented, discharged, restrained, blocked, cooled or decontaminated before hands enter the danger zone.
Assess the intervention itself. Clearing a minor jam is not automatically low risk: familiarity and short duration do not remove the need for a suitable safe system.
Build a repeatable isolation sequence
The sequence should be specific enough that a competent person can follow it without guessing. Normally that means notifying affected people, stopping the equipment in a controlled way, operating every required isolation device, securing each device against reconnection, dissipating or restraining stored energy and verifying that the expected safe state has been achieved.
Personal padlocks can give each person control of their own protection. Multi-person or multi-shift work may need a group lock box, recorded handover and a defined process for adding or removing people. Keys, duplicate keys and removal of an absent person's lock need strict rules; an improvised bolt-cutter decision can defeat the system when the person is still exposed.
Verification must test the relevant hazard, not merely repeat the paperwork. That may involve a correctly controlled start attempt, proving electrical conductors dead with suitable test equipment, checking pressure gauges and drains, confirming movement has ceased, and physically checking that props or restraints are correctly fitted. Restore controls to a safe position after any start attempt.
Treat electrical isolation as a competent technical task
HSE says equipment, machinery and installations should be prepared by isolating and releasing all sources of energy. Electrical isolation must be secure so energy cannot be inadvertently reintroduced. For work on electrical systems, identifying the correct circuit, locking off, proving the tester, testing for dead and re-proving the tester require suitable equipment and competence.
Do not turn “test for dead” into a casual instruction for untrained staff. Define who is authorised, the installation and voltage range they may work on, the test equipment they may use and when specialist electrical support is required. Work on or near live conductors is subject to the strict conditions in regulation 14 of the Electricity at Work Regulations 1989; production convenience is not a reason to default to live work.
HSE: work on electrical equipment and machinery ↗ · Electricity at Work Regulations 1989: regulation 14 ↗
Test the procedure against the actual machine and task.
HR + SAFETY can help North East SMEs map isolation points, review maintenance controls and turn findings into a usable safe system of work.
Discuss an isolation-procedure reviewCoordinate contractors, permits and handovers
For contractor maintenance, agree who stops production, defines the plant boundary, applies isolations, verifies the state and authorises return to service. Client and contractor retain their respective responsibilities; a permit does not transfer them.
A permit-to-work can document the equipment, task, isolation points, residual hazards, precautions, authorised people, time limits and handback. It does not create physical isolation. The permit and the lock-off system must match what exists at the machine. Shift changes, testing phases and partial reinstatement need an explicit handover so nobody relies on an isolation that has been altered.
Control testing and restart
Some maintenance needs temporary power for testing, fault-finding or movement. Treat each change of state as a planned step: clear people, account for tools, refit the guards needed for the test, remove only the isolations required, energise under controlled authority, then isolate and verify again before intrusive work resumes. Do not allow an informal “quick test” to bypass the procedure.
Before final restart, inspect the equipment and work area, replace guards and safety devices, remove tools and temporary restraints, account for everyone and notify operators. Each person should remove their own lock unless a documented exceptional-removal process confirms their location and safety. The person accepting handback should understand any limitations or further monitoring.
PUWER also requires start or restart to result from deliberate action where appropriate, and the operator should be able to ensure nobody is exposed—or a suitable warning and time to get clear must be provided. A completed repair does not justify an uncontrolled return to production.
Safe-isolation checklist for managers
HSE's HSG253 gives detailed isolation guidance for hazardous process plant and intrusive work. Its methodology can inform higher-consequence tasks, but it is scope-limited guidance—not legislation, a certificate or a substitute for an equipment-specific assessment and safe system of work.
Legal requirements and official guidance were checked on 2 October 2026. Equipment design, energy type and task risk differ, so the assessment must determine the controls and competence required for the particular intervention.
- List the equipment and maintenance, cleaning, adjustment and blockage-clearing tasks that require isolation.
- Identify every normal, alternative and stored energy source at the actual plant.
- Provide clearly labelled, readily accessible and lockable isolation points where appropriate.
- Write equipment-specific sequences for shutdown, isolation, dissipation, verification and restart.
- Define competence and authorisation for operators, maintainers, electricians and contractors.
- Use personal or group-locking arrangements that keep each exposed person in control.
- Control keys, duplicate keys, shift handovers and exceptional lock removal.
- Match permits and isolation records to the physical equipment and task boundary.
- Plan any powered testing as a controlled change of state, followed by re-isolation.
- Audit real interventions and act on unclear labels, damaged devices, workarounds and near misses.
Safe isolation is a controlled state, not a button press: identify every energy source, separate and secure it, neutralise stored energy, verify the result and control every test, handover and restart.
This guide provides general information for UK employers. It is not legal advice and should not replace advice based on the facts of a specific matter.