Lockout/tagout (LOTO) is the procedure used to isolate hazardous energy sources before maintenance, repair or servicing work on plant and equipment. It prevents the unexpected start-up or release of stored energy that can cause serious injury or death. Every year in Australia and the US, workers are killed or permanently injured because energy isolation was skipped or done incorrectly.
This guide walks through the complete lockout/tagout process, from preparation to energy restoration. It applies to electrical, hydraulic, pneumatic, mechanical, thermal and gravitational energy sources and aligns with Australian WHS Regulations and US OSHA 29 CFR 1910.147.
Before you start
Gather your lockout padlocks, hasps, tags, and energy isolation devices (circuit breaker lockouts, valve lockouts, plug lockouts). You will also need a voltage tester for electrical isolations and the LOTO isolation checklist or LOTO procedure template for the specific machine.
Review the machine-specific energy isolation procedure before starting. Every machine should have a documented procedure that identifies all energy sources, isolation points and verification methods. If one does not exist, it must be developed by a competent person before the work begins.
Step-by-step lockout/tagout
1. Prepare and identify energy sources
Review the machine-specific isolation procedure. Identify every energy source: electrical, hydraulic, pneumatic, mechanical (springs, flywheels, counterweights), thermal and gravitational (elevated components). Many serious incidents occur because a secondary energy source was overlooked, so work from the documented procedure, not from memory.
2. Notify affected personnel
Inform all workers who operate or work near the equipment that a lockout/tagout is being applied. Tell them why (the work being performed), how long it will take, and who is authorised to remove the locks. This notification is a regulatory requirement, not a courtesy.
3. Shut down equipment
Shut down the equipment using its normal stopping procedure (stop button, control switch or shutdown sequence). Never pull a breaker or close a valve as the first step, as the machine may need to cycle down safely. Wait for all moving parts to come to a complete stop.
4. Isolate energy sources
Operate each energy isolation device to disconnect the machine from its energy sources. This includes opening circuit breakers, closing valves, disconnecting pneumatic lines, blocking mechanical movement and relieving stored energy (bleeding hydraulic pressure, discharging capacitors, releasing springs).
5. Apply locks and tags
Attach a personal lockout padlock to each isolation device. Each worker performing the maintenance applies their own lock. Attach a lockout tag that identifies the worker, date, time and reason for the lockout. Use hasps when multiple workers need to lock out the same isolation point.
6. Verify zero energy state
This is the most critical step. Test each energy source to confirm it is at zero energy. For electrical, use a calibrated voltage tester at the point of work. For hydraulic and pneumatic, verify pressure gauges read zero. For mechanical, confirm no movement is possible. Attempt to start the machine using normal controls to verify it will not operate, then return controls to the off position.
7. Perform the work
With zero energy verified, the maintenance or servicing work can begin. If the scope of work changes or new energy sources are discovered during the job, stop work and repeat the isolation and verification steps for the additional sources.
8. Restore energy (reverse order)
When work is complete, remove tools and materials from the machine. Confirm all guards and safety devices are reinstalled. Ensure all personnel are clear of the machine. Each worker removes only their own lock and tag. Re-energise in the reverse order of isolation. Test the machine before returning it to production.
Energy sources reference
| Energy type | Isolation method | Verification |
|---|---|---|
| Electrical | Circuit breaker, disconnect switch | Voltage tester at point of work |
| Hydraulic | Valve closure, line disconnection | Pressure gauge reads zero |
| Pneumatic | Valve closure, bleed valve | Pressure gauge reads zero |
| Mechanical | Blocking, pinning, restraining | No movement possible |
| Thermal | Cool-down period | Temperature check |
| Gravitational | Lowering, blocking, chaining | Component secured, no drop risk |
Group lockout procedures
When multiple workers are servicing the same equipment, a group lockout is used. An authorised person (typically the lead tradesperson or supervisor) applies the primary lock to each isolation point. Each worker then applies their personal lock to a group lockout box or hasp. The primary lock cannot be removed until every worker has removed their personal lock and confirmed they are clear.
Shift changes during a group lockout require a documented handover. The outgoing shift must not remove their locks until the incoming shift has applied theirs, ensuring continuous protection.
Regulatory requirements
In Australia, WHS Regulations Part 3.2 Division 5 covers the management of risks from plant, including isolation of energy sources. AS 4024.1603 provides detailed guidance on lockout/tagout procedures for machinery. Failure to isolate plant before maintenance is a high-consequence breach.
In the US, OSHA 29 CFR 1910.147 (The Control of Hazardous Energy) is the primary standard. It requires written machine-specific procedures, employee training, periodic inspections of procedures, and the use of standardised lockout/tagout devices. Penalties for non-compliance are among the highest OSHA issues.
Going digital with MapTrack
Paper-based LOTO permits are difficult to audit and easy to lose. With MapTrack, you can manage isolation procedures digitally using customisable forms that capture every isolation point, lock number, worker name and verification step. Each isolation device can carry a QR code that links to the machine-specific procedure.
Active lockouts are visible in real time, so supervisors and control room operators know which equipment is isolated and who holds the locks. Automated alerts notify relevant personnel when a lockout has been active beyond its expected duration, and all records are stored for compliance reporting.
