35 Lock-Out / Tag-Out
Learning Objectives
Explain the process of lock-out / tag-out.
What is Lock Out/Tag Out?
Definition
It requires that hazardous energy sources be “isolated and rendered inoperative” before work is started on the equipment in question. Lockout–tagout is used across industries as a safe method of working on hazardous equipment.
Applying lockouts during maintenance is intended to avoid accidental energy release, whereas tagging them out keeps employees aware of what is going on with the machine. In spite of regulations, serious accidents continue to occur due to lapses during lockout and tagout (LOTO) applications
How Does it Work?
Regulations require that all powered machinery or equipment shut down for maintenance or repair must be secured against the possibility of the equipment being accidentally turned on while being worked on. To safeguard the person working on such equipment, lock-out procedures must be posted near the equipment, and the procedures listed must be followed before repairs or maintenance can start.
Locking out a machine usually means the power feeding the machine is disconnected either by pulling a plug, placing a switch in the off position, or turning a circuit breaker to the off position. The disconnected circuit is then secured in the inoperative position by the use of a padlock. The person doing the maintenance or repair keeps the key to this lock until the work on the machine has been completed. The worker then removes the lock and the machine is again operable.
Disconnecting or making safe the equipment involves the removal of all energy sources and is known as isolation. The steps necessary to isolate equipment are often documented in an isolation procedure or a lockout tagout procedure.
The isolation procedure generally includes the following tasks:
- Announce shut off
- Identify the energy sources
- Isolate the energy sources
- Lock and tag the energy sources
- Prove that the equipment isolation is effective
The locking and tagging of the isolation point lets others know not to de-isolate the device. To emphasize the last step above in addition to the others, the entire process can be referred to as lock, tag, and try (that is, trying to turn on the isolated equipment to confirm it has been de-energized and cannot operate).
Depending on the situation, the lock might be used to secure the power switch of the machine, or it might be used to lock shut the door to a circuit breaker panel where the thrown breaker is located.
If the machine is not wired into its own power circuit but simply plugs into the wall, the lock-out procedure may require that the machine be turned off with its power switch and unplugged from the power receptacle. The plug end of the machine must be kept in plain view of the repair person so no one can inadvertently restore power without the repair person’s knowledge.
In industrial processes it can be difficult to establish where the appropriate danger sources might be. For example