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#100219 - 10/30/06 02:39 PM over 250 volts to ground
luckyshadow Offline

Registered: 01/04/05
Posts: 305
Loc: 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.

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#100220 - 10/30/06 02:58 PM Re: over 250 volts to ground
ShockMe77 Offline

Registered: 06/11/05
Posts: 823
Loc: 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.

#100221 - 10/30/06 02:59 PM Re: over 250 volts to ground
George Little Offline

Registered: 01/18/04
Posts: 1492
Loc: 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

#100222 - 10/30/06 03:01 PM Re: over 250 volts to ground
iwire Offline

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
I see it the same as George.
Bob Badger
Construction & Maintenance Electrician

#100223 - 10/30/06 05:26 PM Re: over 250 volts to ground
HotLine1 Offline


Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
OK, add a another agreement


#100224 - 10/31/06 06:22 AM Re: over 250 volts to ground
Ryan_J Offline

Registered: 08/19/03
Posts: 1355
Loc: 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

#100225 - 10/31/06 12:27 PM Re: over 250 volts to ground
George Little Offline

Registered: 01/18/04
Posts: 1492
Loc: 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

#100226 - 11/03/06 05:27 AM Re: over 250 volts to ground
Elec N Spec Offline

Registered: 07/06/06
Posts: 33
Loc: 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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