# Ungrounded System, Maintenance



## Jlarson (Jun 28, 2009)

If there is it's location escapes me too. I've always just said it needs to be found ASAP but that's it.


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## HARRY304E (Sep 15, 2010)

Try this ...

http://ulstandardsinfonet.ul.com/scopes/scopes.asp?fn=0943.html


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## Rockyd (Apr 22, 2007)

The beauty of an ungrounded system is that it will continue to function normally when on of the legs goes to ground. With Qualified Personnel, it's normally a pretty easy gig to chase down a problem. However, when they are of limited capacity, is when the problems develop.

It's critical to isolate the ground before ANOTHER phase contacts ground, for whatever reason (rotating machinery, cords on floors, whatever) a second phase 

Four years on a ship with an ungrounded system. We used to check the lights every 8 hours when we were sailing, in port, not so much, for the aforementioned problems.


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## MDShunk (Jan 7, 2007)

HARRY304E said:


> Try this ...
> 
> http://ulstandardsinfonet.ul.com/scopes/scopes.asp?fn=0943.html


UL standards only apply to the equipment itself.


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## MDShunk (Jan 7, 2007)

Rockyd said:


> It's critical to isolate the ground before ANOTHER phase contacts ground, for whatever reason (rotating machinery, cords on floors, whatever) a second phase


I wouldn't necessarily say it's "critical", but maybe important. A breaker will trip. Woop dee doo. Granted, too many of these ungrounded and resistance grounded systems are installed to keep breakers from tripping because the self-important customer thinks their process is just so critical. :laughing:


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