There’s a very straightforward answer to this question: the person who locks a machine is the only one who should unlock it. But let's dive a little deeper into why that is the case and when an exception can be made.
LOTO in a Nutshell
Lockout/Tagout (LOTO) is a procedure for ensuring that a machine or tool of any sort is made impossible to use when the authorized operator is not around. This includes any machine or tool that uses some form of energy, such as electricity, fuel, or compressed air, as well as any device like a control panel or tool cabinet that gives access to other dangerous equipment.
Basically, the rule applies to any piece of equipment that has the potential to cause injury or death if left in a state where it could be used by an unauthorized individual or where it could re-engage by itself.
Only One Person Should Have the Authority to Unlock the Equipment
There should be just one person who has the authority to unlock or reconnect such a piece of equipment, and that’s the person who locked it up or disconnected it after it was last used. This could be a supervisor, but it is usually the operator, since they're the last one who had their hands on the device.
When leaving the scene, either for the day or just temporarily, it is vital th
at the machine is rendered inoperable until the operator returns.
When Can Someone Else Unlock the Equipment?
If – and only if – the authorized individual is not available to lock or unlock the device, a second person may be authorized to do it, but only by following a clear set of prepared steps that have been developed and incorporated into the company’s authorized health and safety program.
Why Authorization Matters
Once the machine is locked out (kept turned off by a lock, seal, or other device) and tagged out (placing a warning tag on the equipment), unauthorized use of it is forbidden.
Formalities like this might appear tedious, but they help ensure the safety of people and machinery by reducing the risks of accidental or unauthorized events in the workplace.
LOTO also makes it illegal for another person to unlock the machine. This is a regulation established and enforced by health and safety authorities like OSHA. Violations can result in hefty fines and severe punishments.