A maintenance team were tasked with "fabricating a new grid for bag shredding extraction". The work involved working inside of the machine and so a complex Isolation procedure was required. The isolation procedure involved applying 6 locks.
The isolation was applied as per the isolation procedure. It was put on by a responsible person and another responsible person verified that all locks were on as per procedure.
The working party applied their personal locks to the isolation box and signed on to the permit. The job was completed.
During the task, a spanner was dropped down towards the Burst Bag Return Screw. The spanner was retrieved by removing a door below where the work had been carried out. After the door was refitted, the screw started up. Note, the isolation was still in place.
Isolation was insufficient for internal work as the screw had not been identified as part of the procedure.
It was discovered that an admin error had occurred several years previously when the isolation procedure had been transferred from the packing plant to the main plant and the screw accidently omitted from the procedure.