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ekstra   ara
 Post subject: Underground Manhole Systems
PostPosted: Fri Mar 20, 2009 9:10 am 

Joined: Fri Mar 20, 2009 9:07 am
Posts: 1
All -

What are you guys doing with respect to your UG manhole systems? Specifically, if you have calculated energies, what are you doing with PPE?


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PostPosted: Wed Apr 01, 2009 12:06 pm 
Arc Level

Joined: Tue Jan 13, 2009 5:00 pm
Posts: 576
http://standards.ieee.org/nesc/NESCIR557.pdf

Deenergize, mainly because of cable movement during a remote fault.


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PostPosted: Wed Apr 01, 2009 2:35 pm 
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Joined: Sun Dec 23, 2007 1:44 pm
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Location: Charlotte, NC
One other issue to consider. Years ago I was in a small vault checking on some equipment when I noticed a portion of cable had "blown out" at some point allowing an energized 7,200 volt aluminum cable to be exposed. Somehow it was still operating. Didn't hang around very long!


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PostPosted: Wed Apr 01, 2009 5:29 pm 
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Joined: Thu Jan 10, 2008 8:49 pm
Posts: 510
Location: New England
Enter manhole in HRC4. Check all cables with tic tracer. No live voltage found exit manhole and re-enter in HRC2.

De-energizing is often not practical. How many square miles of city is it acceptable to de-energize before inconvienence become infeasible?

Most manhole accidents to not occur because there was a conincidental fault on an adjacent cable. Most are from touch an energized conductor, by accident.


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