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over 250 volts to ground #100219
10/30/06 05:39 PM
10/30/06 05:39 PM
luckyshadow  Offline OP
Joined: Jan 2005
Posts: 315
Maryland USA
Question : Is a bonding bushing required when you have 277 volt wiring going through 1/2" liquidtight flexible metal conduit ( sealtight). This is terminated into a 4 square box that has concentric / eccentric knock outs. The knock outs are 1/2" to 3/4"
with only the 1/2" taken out.
I say yes a bonding bushing is required as per 250.97 another electrician say no you don't need them because its sealtight not a metal raceway like rigid conduit.

2017 / 2014 NEC & Related Books and Study Guides
Re: over 250 volts to ground #100220
10/30/06 05:58 PM
10/30/06 05:58 PM
ShockMe77  Offline
Joined: Jun 2005
Posts: 821
Rahway, New Jersey
But LFMC is a metal raceway and in some cases can be used as the EGC. I've read 250.97 and 350.60 and 250.118 (C) and my educated guess would be YES, a bonding bushing is needed if this run is more than 6.'

I look forward to reading more replies on this matter but I have to leave for school now.

Re: over 250 volts to ground #100221
10/30/06 05:59 PM
10/30/06 05:59 PM
George Little  Offline
Joined: Jan 2004
Posts: 1,493
Michigan USA
IMHO you win the beer. Unless the box is listed to provide the required bonding with only the 1/2" ko removed. Some of them are.

George Little
Re: over 250 volts to ground #100222
10/30/06 06:01 PM
10/30/06 06:01 PM
iwire  Offline
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
I see it the same as George.

Bob Badger
Construction & Maintenance Electrician
Re: over 250 volts to ground #100223
10/30/06 08:26 PM
10/30/06 08:26 PM
HotLine1  Offline

Joined: Apr 2002
Posts: 7,069
Brick, NJ USA
OK, add a another agreement


Re: over 250 volts to ground #100224
10/31/06 09:22 AM
10/31/06 09:22 AM
Ryan_J  Offline
Joined: Aug 2003
Posts: 1,374
West Jordan, Utah, USA
According to the UL white book, all outlet boxes (such as four inch) are suitable for bonding over 250 volts, without additional bonding, even with concentric.

Ryan Jackson,
Salt Lake City
Re: over 250 volts to ground #100225
10/31/06 03:27 PM
10/31/06 03:27 PM
George Little  Offline
Joined: Jan 2004
Posts: 1,493
Michigan USA
Thanks Ryan, I thought I'd read that somewhere but I wasn't sure so I appreciate that info as does everyone else on this BB.

George Little
Re: over 250 volts to ground #100226
11/03/06 08:27 AM
11/03/06 08:27 AM
Elec N Spec  Offline
Joined: Jul 2006
Posts: 33
Rochester Hills, MI USA
I was reading about the UL listing on the new MC/ap connectors and the fact that they are rated for use without a ground wire on boxes with both concentric and eccentric knock outs on UL listed boxes caught my eye. In some applications you do not have to bond as long as the box is approved


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