Lock out tag out (LOTO) is a maintenance procedure used in all mines, and originally developed by OSHA (Occupational Safety and Health Administration). The basic concept is that if any type of maintenance is being done on a piece of equipment, locks are physically placed on equipment along with tags identifying the personnel locking the equipment in order to prevent unexpected start-up or electrocution during the maintenance. LOTO programs require that the all personnel working on the equipment use their own locks and own tags; thus, only after each employee has removed their lock and associated tag can the equipment be put back into service.

An example of how LOTO can be used to ensure safety is: Suppose a conveyor belt is being worked on by a maintenance crew. Because the belt is so long, it is possible that an operator may not see the maintenance personnel. If that operator starts the belt, an accident may occur. Lock out will prevent the belt from starting. And tagging the equipment also shows which maintenance employees are working on the belt, so the operator knows who has the key for the lock and who to contact about the status of the machine.