Has anyone heard of any bus disconnect switchgear failures and their general causes. I have a rebuilt Sylvania HCSHD365 bus bus disconnect switchgear that when fastened to a 480-3phase switchgear worked fine but when the switch was thrown to connect it exploded. so much damage I can't tell if the stabs somehow shorted to ground or phase to phase. There were no tools or loose bolts in the switchgear box when the door was closed. The rebuilder claims that min resistance in a meggar test from phase to ground or phase to phase was 400 megOhm. There was no load side cabling yet connected at the time of failure. Any thought or prior experiences on what may have occurred here?
Phil
Phil