Fastening NM Boxes

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Re: Fastening NM Boxes

Originally posted by ryan_618:
314.23 gives you two ways of mounting a box with nails or screws:
1) Brackets on the outside, or
2) Nails and screw that "pass through the box" and meet the 1/4 rule.

I'm not saying I like what I am saying, but that is the way I read it. :(
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And I don't like that I have to agree with what you point out. :D

It's through the box or outside the box.
 
Re: Fastening NM Boxes

Bob, I use these boxes all the time With "Madisons" Wonder why those holes are there? Just to keep Electricians, Inspectors and NEC on their toes? It seems like they invite us to do something wrong don't they? Who are "They" any way?
 
Re: Fastening NM Boxes

Originally posted by iwire:

It's through the box or outside the box.
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And with that in mind, a literal reading of the code would not permit this installation:

:D )

[ January 16, 2006, 02:32 PM: Message edited by: ryan_618 ]
 
Re: Fastening NM Boxes

Can't disagree with you Ryan.

Well OK I can :D

314.23(B) only applies to an enclosure supported from a structural member of a building or from grade

314.23(A) covers surface mounted boxes and has no such restrictions. :

Actually the more I look at 314.23 the more I want to close my book and just do what I have always done. :D
 
Re: Fastening NM Boxes

Originally posted by ryan_618:
I used to KNOW that the picture above was a violation. Then I KNEW that it wasn't. Now I just don't care and I ignore it :D
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Well said, ditto. :cool:
 
Re: Fastening NM Boxes

Loophole? The "smart box" would be allowed as it uses internal brackets.

But, assuming the philosphy that screws "that start in the box and exit only one wall" are not allowed is valid. Then how do you mount a 4"sq to a cement block wall?

Also, other than the possibilty that the environment classification may be changed (i.e. UL/NEMA 12 becomes a UL/NEMA 1) and no specific instructions by the manufacturer, I can find no prohibition that says a listed box can not be mounted using field drilled holes. This is the same reasoning applied to field cut conduit entrances.

edit typos

[ January 16, 2006, 03:32 PM: Message edited by: jim dungar ]
 
Re: Fastening NM Boxes

314.43 Nonmetallic Boxes.
Provisions for supports or other mounting means for nonmetallic boxes shall be outside of the box, or the box shall be constructed so as to prevent contact between the conductors in the box and the supporting screws.
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Bill

[ January 16, 2006, 04:48 PM: Message edited by: bill addiss ]
 
Re: Fastening NM Boxes

314.43 Good catch. So only if the mounting screws are in a recess (like the smart boxes) are they allowed inside of non-metallic boxes. But what about cable clamp screws?

So then what is wrong with screws in side walls of metal boxes, or through the back of them into wood braces between two structural members?
 
Re: Fastening NM Boxes

Originally posted by iwire:
This next picture shows nails passing through the box that 314.23(B)(1) allows.

mountingbox3.jpg


And finally nails passing through a box that 314.23(B)(1) prohibits.

mountingbox2.jpg
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Bob, I believe both nail paths through the "gem" box are permissable; the upper has the nails against the back, and lhe lower has them against the ends.
 
Re: Fastening NM Boxes

Somebody needs to manufacture a little plastic wedge piece that simulates the recess of the smart boxes, so that we can screw on any box type we choose and be in compliance with 314.43.
 
Re: Fastening NM Boxes

Originally posted by triphase:
05' NEC 314.23(B)(1) Would it be allowable "Let's say" to fasten a Nonmetallic box (In a tight location where normal manufacturer installed fastening is not possible) with screws toward the front edge interior? I see this a lot and have done this before. What are your interpretations? Thanks.
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I suggest using a Carlon B1188-UPC, the third item down on the first page:

http://www.carlon.com/Brochures/2B1-ZipBoxes.pdf
 
Re: Fastening NM Boxes

Originally posted by LarryFine:
Bob, I believe both nail paths through the "gem" box are permissable; the upper has the nails against the back, and lhe lower has them against the ends.
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You have a good point. :)
 
Re: Fastening NM Boxes

Carlon's super blue boxes have two recesses in the back for mounting screws. I like the idea of the plastic wedges though.
 
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