A safety practice called "lock out, tag out" is used to make sure that dangerous machinery is correctly turned off and cannot be restarted until maintenance or repair work is finished. Before beginning work on the aforementioned equipment, dangerous energy sources must be "separated and rendered inoperative." The isolated power sources are then locked, and a tag identifying the worker and the explanation for the LOTO is attached to the lock. The employee then keeps the lock's key, making sure that only they can open the lock and turn on the machine. This stops equipment from accidentally starting up while it's in a dangerous state or when a worker is in close proximity to it.