Lockout of a Line With Stored Energy and Contractors
A bottling line must have its labeler gearbox replaced. The line is locked out by maintenance using a group lockbox. An outside contractor is doing the gearbox work. The line includes: a conveyor with a gravity-fed infeed that holds about 40 bottles on an incline, a pneumatic reject arm fed from a receiver that holds pressure after isolation, and a gearbox that can retain rotational energy. The contractor has their own lock but has not applied it. A production supervisor asks whether the line can be re-energized for a 20-minute trial run of an adjacent filler while the contractor continues working on the gearbox, since 'the gearbox is isolated from the drive.'
1. Evaluate the supervisor's request and identify the energy-control failures in the current setup.
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The request should be refused. A trial run of adjacent equipment on a line under group lockout re-energizes shared systems and defeats the purpose of the lockout. 'The gearbox is isolated from the drive' addresses only one energy source and ignores the rest.
Failures identified:
Contractor has not applied a personal lock. Under group lockout, every worker exposed to the hazard must have personal control - typically a personal lock on the group lockbox or a hasp. Without it, the contractor has no assurance the line will not be energized while they are inside it. This is the most serious failure.
Stored energy not addressed. Three sources are named: gravity (bottles on an incline), pneumatic pressure in the reject-arm receiver, and rotational energy in the gearbox. Isolation of the electrical drive does not release any of these. The incline must be cleared or blocked, the receiver must be bled and verified at zero, and the gearbox must be allowed to come to rest and be blocked against rotation.
Verification. There is no mention of try-out or zero-energy verification after isolation. Each source should be verified, not assumed.
Trial run during work. Re-energizing any part of the line while a person is working on it creates a path for unexpected startup, and it also erodes the discipline of the lockout. If a trial run is operationally necessary, the contractor must be clear of the equipment, the lockout must be formally suspended and re-applied, and the contractor must apply their own lock before resuming.
The supervisor's framing - 'the gearbox is isolated' - is the core error: isolation is per energy source, not per component.
2. What must happen before the contractor resumes work after any trial run, and how should the group lockout be structured?
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Before resuming:
- The contractor must be confirmed clear of the equipment and accounted for.
- The trial-run suspension must be formally closed: locks removed only by the persons who applied them, energy re-isolated, and all stored energy re-released and re-verified (incline cleared or blocked, receiver bled to zero, gearbox at rest and blocked).
- The contractor must then apply their personal lock to the group lockbox before re-entering the work area.
Group lockout structure:
- A primary lock and tag by the authorized employee who isolates the line.
- A group lockbox holding the keys or isolation devices, so the line cannot be restored until every personal lock is removed.
- Each exposed worker, including the contractor, applies a personal lock to the lockbox. The contractor's employer's procedure and the host's procedure must be reconciled in writing before work starts - this is a common gap when contractors bring their own program.
- A single accountable person coordinates the lockout and maintains the list of locks applied.
The test of the structure is simple: can any single person restore energy while another is exposed? If yes, the structure is wrong.