ralpha494
Member
- Location
- Southeastern Wisconsin
New industrial manufacturing building in South Milwaukee, WI. We're still adding and changing things, working on punch list, finishing phase two. Cutler-Hammer gear, two switchboards, don't know what gfci was set at.
The word I got from our foreman:
5000 amp main for switchboard B tripped.
1200 amp feeder for panel that feeds the crane tripped. 480 volts, ground wire, but no neutral.
500 amp breaker for the crane rail locked off and tagged off. Also 480 volts, a ground wire, but no neutral.
Crane guys were working on batteries for magnets that can lift 10 tons.
They said 239 volts dc negative ground.
Accidentally grounded positive lead up on the overhead crane, a flash, and half of the building goes down, generator started, management begins chanting "When in danger,fear, or doubt; run in circles scream and shout."
How does grounding that battery positive take out the main?
What is the gfci sensing?
How lucky was I to be in the job trailer (fed from swbd A and unaware of any problems) for lunch when it happened?
The word I got from our foreman:
5000 amp main for switchboard B tripped.
1200 amp feeder for panel that feeds the crane tripped. 480 volts, ground wire, but no neutral.
500 amp breaker for the crane rail locked off and tagged off. Also 480 volts, a ground wire, but no neutral.
Crane guys were working on batteries for magnets that can lift 10 tons.
They said 239 volts dc negative ground.
Accidentally grounded positive lead up on the overhead crane, a flash, and half of the building goes down, generator started, management begins chanting "When in danger,fear, or doubt; run in circles scream and shout."
How does grounding that battery positive take out the main?
What is the gfci sensing?
How lucky was I to be in the job trailer (fed from swbd A and unaware of any problems) for lunch when it happened?