11.3 Lock-Out/Tag-Out & Safety Tag System
Key Takeaways
- Safety tags warn and identify isolation status; locks physically prevent re-energisation—use both as the system requires
- Personal locks and multi-lock hasps ensure each worker’s isolation is under their own control until they remove their lock
- Danger tags and out-of-service tags serve different communication roles—do not treat them as interchangeable
- Typically only the person who placed a tag/lock (or an authorised process) may remove it
- Supervisors must ensure trainees understand LOTO before they work under isolation
Purpose of the Safety Tag System
Safe isolation is incomplete if someone else can close the isolator while you are inside the equipment. The safety tag system and lock-out practices exist to:
- Communicate that equipment is isolated or unsafe to operate
- Identify who applied the control and why
- Deter casual re-energisation
- Work with physical locks so re-energisation requires a deliberate, authorised act
Tags without locks can be ignored or removed. Locks without clear tags can leave operators guessing. Competent practice uses lock + tag (or the site-equivalent system) at the isolation point that actually controls energy to the work.
Placement and removal rules (core principles)
| Principle | Expectation |
|---|---|
| Place at the isolation point | Tag/lock on the switch, breaker, or device that prevents re-energisation—not on a random door across the room |
| Clear information | Who, when, why; contact details where the system requires |
| One person, one control | Each exposed worker’s personal lock remains until that worker is clear |
| Removal authority | Generally only the person who applied the tag/lock removes it; emergency override follows a documented authorised process |
| Never operate tagged gear | Do not close an isolator that carries another person’s danger/isolation control |
Exam stems often punish “someone else removed my tag to restore power faster.” That is a serious safety breach, not efficient site management.
Lock-Off Devices, Personal Locks, and Multi-Lock Hasps
Lock-off devices
Isolators, circuit-breakers, and switchgear may accept lock-off attachments (padlock hasps, toggle locks, MCB lockouts, valve lockouts, etc.). The lock-off must actually prevent the handle or mechanism from restoring supply. A lock on a cover that still allows the breaker to be closed is not effective isolation security.
Personal locks
A personal lock is under the control of the individual worker. The key stays with that person. The purpose is simple: you cannot be re-energised by someone else’s decision while your lock is on. Sharing personal lock keys defeats the system.
Multi-lock hasps
When several people work on the same isolated equipment, a multi-lock hasp (or multi-lock scissor device) lets each worker apply their own padlock. Supply cannot be restored until every personal lock is removed. That protects the last person still inside the risk zone—not only the first person who applied a tag.
| Device | Role |
|---|---|
| Lock-off attachment | Makes the isolator lockable |
| Personal padlock | Individual control of isolation |
| Multi-lock hasp | Multiple workers, all must clear before restore |
| Tag | Communication of status and ownership |
Danger Tags vs Out-of-Service Tags
Sites and employers use tagging vocabularies that can vary, but candidates should hold the concepts:
Danger / personal danger / do-not-operate style tags
- Signal that people are at risk if the equipment is operated
- Typically applied during active work under isolation
- Linked to personal control and immediate life-safety
Out-of-service / caution / equipment-status tags
- Signal that equipment is not available for normal use (faulty, incomplete, awaiting parts, not yet verified)
- Protect against use of defective or incomplete equipment
- May not by themselves prove that a live work party is clear—still need isolation LOTO when people are exposed to energy
Do not conflate “out of service for repair” with “I am working inside this board.” Both may be needed: equipment status communication and personal lock-out for the workers doing the job.
If a stem asks which tag prevents re-energisation while a person is exposed, prefer the answer that combines positive lock-out with a danger/do-not-operate style communication—not a vague status label alone.
Who May Remove a Tag
The default rule taught across electrical safety systems:
The person who placed the tag and personal lock removes them—after they have finished work and are clear of the hazard.
Exceptions exist only under a formal authorised process (e.g. the original person cannot be contacted and a supervisor follows a written check that the person is not on site and the equipment is safe to restore). Unilateral removal because “the job is late” is unacceptable.
Related rules candidates should defend:
- Do not cut off another worker’s lock without the authorised process
- Do not borrow tags as generic “room decorations”
- Restore power only after all personal locks are clear and tests/permits allow
Supervisor Duties: Trainees and LOTO Competence
Supervisors and persons in control of PEW must ensure workers under their control—including trainees—understand isolation and LOTO before they rely on it:
- Explain why lock and tag exist (re-energisation kills)
- Demonstrate isolation points, personal locks, multi-lock hasps, and tag placement
- Confirm the trainee can prove–test–prove and knows not to remove others’ controls
- Provide oversight appropriate to competence; do not assume a first-year worker “knows LOTO from somewhere”
Under the broader Health and Safety at Work Act (HSWA) culture and electrical worker duties, inadequate supervision of isolation is a governance failure, not a minor admin miss. EWRB competence expectations align with keeping people alive during PEW—not only with filling forms.
Exam habits
- Prefer personal lock + tag at the real isolation point over “tag on the door only.”
- Multi-worker jobs → multi-lock hasp; restore only when all locks clear.
- Removal = placer (or authorised emergency process)—never casual third-party removal.
Study note
Link LOTO to prove–test–prove: lock and tag secure the isolation; testing proves the isolation worked. One without the other is incomplete personal safety.
What is the primary purpose of applying a personal lock on a lock-off device during electrical isolation?
Three electricians are working on the same isolated board. Which LOTO arrangement best protects all three?
Who may normally remove a personal danger tag and lock from an isolator?