ghostbuster
Senior Member
- Location
- Great White North
http://s166.photobucket.com/albums/u91/ghostbuster7/?action=view¤t=1174620635.pbw
Location:Medium size data processing centre
Problem:On the PDU's (power distribution units) all the ground current sensing circuits were in alarm.On each PDU(4 in total) the indicated ground currents ranged from 20-60 amps.
Facts:
1.Found spring loaded metal clips on the back side of the front cover panels making contact with either the hot or neutral screws on the receptacles.
2.Contact with the hot tripped the breaker.The installation crew would then rotate the offending cover plate by 180 degrees and re-install, then reset the breaker.These clips would no longer line up with the hot screws and these breakers would no longer trip.
3.The crew finished their install with the breakers no longer tripping.They left the site,their job was finished (they did not tell anyone about these "little minor electrical flashovers" that had occured).
4.The crew did not realize they were now causing neutral to ground dead shorts on most of these receptacles.This was the cause of this very high ground current on each power system.
5.The mfr. was contacted and admitted he had changed his welding jig set up for the positioning of these clips.
6.All new "proper" plates and replacement damaged receptacles were installed at this site.Equipment had to be turned off during re-install . Computer Downtime approx. 4 days required, +++ lots of extra manhours
7.The local inspection agency was also brought into the loop.
Location:Medium size data processing centre
Problem:On the PDU's (power distribution units) all the ground current sensing circuits were in alarm.On each PDU(4 in total) the indicated ground currents ranged from 20-60 amps.
Facts:
1.Found spring loaded metal clips on the back side of the front cover panels making contact with either the hot or neutral screws on the receptacles.
2.Contact with the hot tripped the breaker.The installation crew would then rotate the offending cover plate by 180 degrees and re-install, then reset the breaker.These clips would no longer line up with the hot screws and these breakers would no longer trip.
3.The crew finished their install with the breakers no longer tripping.They left the site,their job was finished (they did not tell anyone about these "little minor electrical flashovers" that had occured).
4.The crew did not realize they were now causing neutral to ground dead shorts on most of these receptacles.This was the cause of this very high ground current on each power system.
5.The mfr. was contacted and admitted he had changed his welding jig set up for the positioning of these clips.
6.All new "proper" plates and replacement damaged receptacles were installed at this site.Equipment had to be turned off during re-install . Computer Downtime approx. 4 days required, +++ lots of extra manhours
7.The local inspection agency was also brought into the loop.
