Machines can start unexpectedly, release stored energy or move under gravity while someone is cleaning, clearing a jam or repairing them. Lockout/tagout (LOTO) is the discipline of isolating every energy source and keeping it isolated until the work is finished.
What is hazardous energy?
Electrical, mechanical, hydraulic, pneumatic, thermal, chemical and gravitational energy — plus stored energy in springs, capacitors and pressurised lines.
Lockout vs tagout
- Lockout uses a lock to hold an energy-isolating device (such as a breaker or valve) in the safe position.
- Tagout uses a warning tag to say the device must not be operated. A tag alone is a warning, not a physical barrier.
The seven steps of a LOTO procedure
- Prepare: identify the machine, its energy sources and the method of isolation.
- Notify affected workers that the machine will be shut down.
- Shut down using normal stopping procedures.
- Isolate every energy source — switches, breakers, valves, blocks.
- Apply locks and tags; each authorised worker uses a personal lock.
- Release or restrain stored energy — bleed pressure, discharge capacitors, block moving parts.
- Verify isolation by attempting to start the machine and checking zero energy, then return controls to off.
Removing the lock
Only the person who applied the lock removes it, after checking tools are cleared, guards are back and everyone is clear. Notify affected workers before re-energising.
Group and shift lockout
When several people work on one machine, use a group lock box so every worker attaches a personal lock. For shift changes, hand over the isolation formally so there is never a gap.
Training and periodic inspection
Authorised, affected and other employees need different training. Inspect the energy control procedures at least annually and correct any deviations.
Key takeaway: Isolate, lock, release stored energy, verify — and never remove someone else's lock.
Frequently asked questions
Can I use a tag without a lock?
Only if the device cannot be locked and your procedure shows equivalent protection.
Is LOTO needed for minor adjustments?
Not if safe alternative measures exist for routine, repetitive tasks integral to production — but servicing and maintenance almost always requires it. Learn more in our LOTO training.