Panelboard under flood waters briefly

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brian john

Senior Member
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Leesburg, VA
I got a call from a contractor that had a busway 4000 amp 277/480 , due to a leaky roof water had entered the busway and tripped the ground fault protection (GFP). They did not want me to come to the site but asked for some direction as to what to do, I gave them a brief description of how to test (megger) the busway, possibly attempt to dry it aout and then to megger the busway at intervals to determine if the condition was improving.

I also explained the extreme risk in doing this and that they HAD TO BE VERY CAREFUL. Lastly I offered to come to the site, at no cost to verify what they were doing was safe. Their boss did not want this service as he felt his customer might question why I was not there in lieu of them.

Received a second call and their megger was causing problems, Well in my discussions I never mentioned the voltage range (I know the electrician and he knows enough to do this right). Well my buddy was not on site and he relayed what I said to his men. The guy on the job did not have a megger so they utilized a HI-POT, seems the 600 VAC busway resented the 50KV (that's 50,000 vdc I am assuming as their hi-pot is either 50 or 60 kv max) they used to test the busway. Now all the busway is bad not one or two sections.
 

mdshunk

Senior Member
Location
Right here.
brian john said:
Received a second call and their megger was causing problems, Well in my discussions I never mentioned the voltage range (I know the electrician and he knows enough to do this right). Well my buddy was not on site and he relayed what I said to his men. The guy on the job did not have a megger so they utilized a HI-POT, seems the 600 VAC busway resented the 50KV (that's 50,000 vdc I am assuming as their hi-pot is either 50 or 60 kv max) they used to test the busway. Now all the busway is bad not one or two sections.
Oh, my. Even a dry 277/480 bussway would have strange charred places at that voltage, I would expect. Hi-Pot, Megger... what's the difference? :roll: Twice operating voltage is the rule of thumb, is it not?
 
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