3.4 Testing, group lockout, shift changes and contractors
One person, one machine, one lock is the easy case. Real maintenance work is four trades on a line at once, a job that runs across two shifts, a machine that has to be jogged to set a component, and a contractor crew who brought their own program. 1910.147(f) covers all four, and each one is a place where protection can quietly disappear at a handover.
1 Testing or positioning: taking the locks off on purpose
Sometimes the machine has to run to finish the job — jogging a conveyor to reach the next roller, cycling a press to set a die, spinning a shaft to align a coupling. 1910.147(f)(1) allows it, and prescribes the exact sequence of actions:
- 1Clear the machine of tools and materials, in accordance with (e)(1).
- 2Remove employees from the machine or equipment area, in accordance with (e)(2).
- 3Remove the lockout or tagout devices as specified in (e)(3) — each by the person who applied it.
- 4Energize and proceed with testing or positioning.
- 5Deenergize all systems and reapply energy control measures in accordance with paragraph (d) to continue the servicing.
Step 5 is the one that gets skipped. "Reapply in accordance with paragraph (d)" means the whole six-step sequence again — including stored energy and verification. Not "put the lock back on." The temptation to leave the locks off "because we're going to have to jog it again in a minute" is exactly what the paragraph forbids.
2 Group lockout: the four requirements
1910.147(f)(3)(i) sets the objective: when servicing is performed by a crew, craft, department or other group, they shall use a procedure that affords the employees "a level of protection equivalent to that provided by the implementation of a personal lockout or tagout device." (f)(3)(ii) then lists what such a procedure must include, and it is used in accordance with the written procedure requirements of (c)(4).
| Paragraph | Requirement |
|---|---|
| (A) | Primary responsibility is vested in an authorized employee for a set number of employees working under the protection of a group lockout or tagout device (such as an operations lock) |
| (B) | Provision for that authorized employee to ascertain the exposure status of individual group members with regard to the lockout or tagout of the machine |
| (C) | Where more than one crew, craft or department is involved, assignment of overall job-associated control responsibility to an authorized employee designated to coordinate the affected work forces and ensure continuity of protection |
| (D) | Each authorized employee affixes a personal lockout or tagout device to the group lockout device, group lockbox or comparable mechanism when he or she begins work, and removes it when he or she stops working on the machine |
Requirement (D) is the heart of it, and it is the one that preserves the promise of the personal lock: your own lock, applied by you, removed by you. The group lockbox is simply a way of giving you one place to put it. Requirement (B) — knowing each member's exposure status — is why the box usually sits with a sign-in board next to it.
3 How a group lockbox actually runs
The standard describes the requirements, not the mechanics. The arrangement that satisfies them in practice looks like this:
Two rules keep it honest. First, the lead's verification does not replace anyone else's judgement — a group member who arrives after the isolation was done is entitled to confirm the isolation before putting their lock on, and a good procedure invites them to. Second, a personal lock goes on before the person begins work and comes off when they stop, exactly as (f)(3)(ii)(D) says. Locking on at the start of the shift "for the day" and going to work somewhere else defeats the exposure-status requirement of (B).
4 Shift and personnel changes
1910.147(f)(4) is one sentence and it is the least well implemented paragraph in the standard: "Specific procedures shall be utilized during shift or personnel changes to ensure the continuity of lockout or tagout protection, including provision for the orderly transfer of lockout or tagout device protection between off-going and oncoming employees, to minimize exposure to hazards from the unexpected energization or start-up of the machine or equipment, or the release of stored energy."
The word is continuity. There must be no instant at which the machine has no protection on it. That rules out the arrangement almost every plant tries first — off-going shift removes its locks, oncoming shift applies theirs — because between those two acts the machine is unlocked and someone else's start button works.
The arrangement that satisfies (f)(4) is the reverse: the oncoming employee applies their lock first, then the off-going employee removes theirs. The isolation is never unprotected, the handover is a physical act rather than a conversation, and the oncoming employee verifies isolation for themselves as part of taking it over. On a group job, the same logic applies to the lockbox: incoming personal locks go on, outgoing ones come off.
5 Outside personnel and contractors
1910.147(f)(2)(i) requires that whenever outside servicing personnel are engaged in covered activities, "the on-site employer and the outside employer shall inform each other of their respective lockout or tagout procedures." (f)(2)(ii) then requires the on-site employer to ensure that its own employees "understand and comply with the restrictions and prohibitions of the outside employer's energy control program."
Read (f)(2)(ii) carefully, because it runs in the direction people do not expect. It is not only that the contractor must respect the host's rules — the host's employees must respect the contractor's. If the contractor's program says nobody touches a machine bearing their locks without their lead present, that binds your maintenance department.
Three practical questions settle almost every contractor lockout dispute before it starts, and they belong in the pre-job meeting:
- 1Whose procedure governs this machine? Usually the host's, because the host knows the isolation points — but it must be said out loud and the isolation-point list handed over.
- 2Whose locks go on, and how are they distinguished? Contractor locks in a different colour, with the company name, so nobody mistakes them for a stale plant lock.
- 3Who is called if a lock has to be removed? Names and phone numbers, agreed before the job, so that (e)(3)'s "all reasonable efforts to contact" is a phone call and not a shrug.
6 Where the four cases meet
A large shutdown hits all four at once: several crafts on one machine, an outside contractor on the next machine over, a night shift taking over at 7 p.m., and a test run at 3 a.m. to prove an alignment. That is not an exotic scenario — it is a normal outage weekend — and it is where a program that works on paper either holds or fails.
What holds it together is that all four requirements are, in the end, the same requirement written four times: nobody is ever exposed to a machine whose energy is not under the control of a device they applied themselves. Group lockout gives everyone a personal lock on a box. Shift change transfers the protection without a gap. Testing rebuilds the whole (d) sequence rather than leaving locks off. Contractor coordination makes sure two programs do not each assume the other is holding the machine.
Before an outage, one meeting covering those four points — with the isolation-point lists on the table and the lockbox arrangements agreed — is worth more than any amount of retraining afterwards. A written pre-task plan is a reasonable place to record it.
- Testing or positioning follows the five-step sequence of 1910.147(f)(1) and ends by reapplying energy control in accordance with the whole of paragraph (d) — not just putting the lock back.
- Group lockout requires primary responsibility in one authorized employee, a way to know each member's exposure status, coordination across multiple crews, and a personal device from every authorized employee on the group device or lockbox (1910.147(f)(3)(ii)(A)-(D)).
- A personal lock goes on before the person begins work and comes off when they stop working on that machine — not at the start and end of the shift.
- Shift changes require continuity: the oncoming employee's lock goes on before the off-going employee's comes off, so the machine is never unprotected (1910.147(f)(4)).
- Host and outside employers must inform each other of their procedures, and the host's employees must comply with the contractor's restrictions too (1910.147(f)(2)(i)-(ii)).
- Agree in advance whose procedure governs, whose locks go on and how they are marked, and who is called if a lock has to be removed.
Free educational content — not OSHA-authorized training, no certificate or card issued. Follow your employer's program and the standards cited.