If we had a dime for each time we get pushback on the most fundamental aspect of Lockout/Tagout (LOTO), we could all retire! NEVER is an authorized employee allowed to work under someone else lock – PERIOD! When servicing and maintenance that requires LOTO is performed, then EACH authorized worker MUST HAVE EXCLUSIVE CONTROL of ALL the isolation device(s) protecting them.
If there are three isolation devices and three workers doing the task, then EACH of the three workers MUST have EXCLUSIVE CONTROL of EACH of the three isolation devices. This is accomplished by either group lockout using a lockbox to have each worker secure the keys to the locks by placing their PERSONAL LO lock on the box and their key in their pocket or each worker using three locks to control the three isolation devices and the keys to their three locks go into their own pockets. If we take shortcuts to this fundamental practice, we end up with this (and it happens way more often than most safety professionals think):