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#189969 10/31/09 08:37 AM
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Is it clear that a bonding jumper is required between the green screw of a receptacle and a metal box when the receptacle is mounted on a 4 inch square raised cover?


George Little
2017 / 2014 NEC & Related Books and Study Guides
Joined: Jan 2005
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No, not clear at all.

In the latest edition, you still do not require such a bonding jumper if the cover has the 'dimpled' corners, or, IMO, for a metal cut-in box.

The 2008 NEC is where the distinction was made between the covers with the dimpled corners, and the nice, square-face covers. I'll see if I can find pics.

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OK, herre are the pics!

This one still does not require a bonding jumper:
[Linked Image from electrical-photos.com]

While this style cover does require a bonding jumper:
[Linked Image from electrical-photos.com]

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The receptacle also need to be permanently attached to the cover by rivets or screws with a thread locking means.

I would want to see the listing of that cover/receptacle combo ... or a bonding jumper.

If I really believed nobody would ever loosen the screws on that cover with the power on I might be a little more easy going wink


Greg Fretwell
Joined: Mar 2003
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2008 NEC Code handbook Page 254 ( 250.146 ).
Handbook has photos & Explaination.
Yoopersup

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Thanks Ernie- Looks like most installations will need a bonding jumper if the receptacle is field installed on a four square raised cover. Just followed your tip and looked in the '08 handbook.

You going to be in Ann Arbor 12/3-4/09?


George Little
Joined: Nov 2007
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Where 250.146,[A] references "a rivet or thread locking or screw locking means", would this include those little 6/32 nuts with the machined serrations or the serrated lock washers attached to them?

I've always just connected a pigtail to the device, but would be good to know the details.
Other than looking up the individual manufactures listing, is there any identifiable marking on these covers that would indicate they are listed for grounding?

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KJay, as I understand it, the supplied hardware does meet the code requirements for the 'screw locking means.'

Murphys' law being what it is, I next expect the folks who brought this on - remember all those rants against metal boxes on the ends of extension cords, with pictures of the assemblies missing screws and coming apart? - to start ranting anew when they find some place where "Loctite" was applied to the hardware.

Make no mistake about it; there are those who will find fault with everything. These are the folks who won't be happy until EVERY device has a pigtail and EVERY circuit has a gree wire.

No, there is no speciific marking on the packaging regarding the use of pigtails.

Which, of course, brings up another 'detail.' Virtually every cover of this type is made by one of two firms. The code change only impacts the one company's product; 'corners in' or 'corners out' was simply a style difference between the two firms.

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Unless they get the assembly listed as being suitable for grounding the corner style is academic. I am betting, when they do it will be stamped in the cover. I certainly expect to see a full page, glossy, ad in the IAEI magazine.

Yes I am one of those people who thinks every circuit should have a green (or bare) wire ground.
Fortunately, for me, that was the way all state RFPs were written so I didn't have to split hairs about it.
I am just a spectator now so it really doesn't matter too much what I think. wink


Greg Fretwell
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Presenting the opposing point of view:

1) I see no rewuirement for the cover to be specifically listed as a grounding means; just that there be some method used to prevent the screws from vibrating loose; and,

2) I have, nor has the NEC had, any problem with metal conduit being used as the ground conductor. If anything, this pronciple is reinforced with the new "MC smart,' that does away with the need to have a green wire in MC.

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