Electrical Box in Shallow Wall


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Old 03-31-07, 02:07 PM
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Electrical Box in Shallow Wall

I am still working in my basement and am going to run new wire with ground to outlet boxes and install GFCI's (concrete floor). The walls have 1/4" paneling on furring strips (1-1/2") over concrete blocks. Existing boxes are the smallest I have ever seen - maybe 1960's variety handy-boxes.

Given that with the furring strips and paneling, I have a maximum of 1-3/4" clearance to mount a box, I have been racking my brain trying to come up with a code-compliant solution. Most boxes will have two 12-2 w/ ground cables, some will have only one - none will have more than two.

I thought of using a 4x4 box with a cover but I think all of the covers extend out as mud rings and these are probably 1/2" at least - is this correct?

Another thought was to cut rectangular/square wooden blocks, chamfer the edges, stain to match the paneling, mount them to the wall with construction adhesive and gain an additional 3/4" that way. I'd rather not do it this way because of the protrusion, but will if that is the best way.

Any ideas/suggestions from you folks will be appreciated.

JimC
 
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Old 03-31-07, 03:36 PM
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There are boxes that have a double box width but only one box opens to the room. Not sure how deep they are, so you need to check an electrical supply house. Big box might even have them.
 
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Old 03-31-07, 04:16 PM
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Yes, I know I've seen "low profile" boxes at "the depot".

Here is a Carlon box that is only 1 3/16" deep:
http://www.usahardware.com/inet/shop/item/30060/icn/20-127431/carlon/b108r_u.htm

That is the old work box (B108-R), they also make a new work (B108-R).

I think I've seen it at Depot or Lowes...but I feel like they had something else too that has a curved back to give more wiring room (takes up the width of a two-gang, but only one side is usable).

Thanks,
Guy
 
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Old 03-31-07, 07:07 PM
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Have you considered surface mounted boxes. Usually most will be behind furniture anyway. The ones made to work with surface race such as Wiremold look ok IMHO. (Not suggesting using surface race, just the boxes. The wires could still be run through the walls.)
 
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Old 03-31-07, 07:22 PM
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Electrical Box for Furred Wall

(ray2047) Yes, I had given some thought to the surface raceway boxes. Would prefer another method but they would work!

(4thisguy) The Carlon box you mentioned has a capacity of 8 cu in. That wouldn't meet code with 2 12/2 cable plus a gfci (2x2.25 for cables, 2.25 for device, 2.25 for grounds = 9.0). Appreciate the information, though.

(Just Bill) Haven't seen one of these boxes where only one side is open but will certainly check - that would be perfect!

Thanks.

JimC
 
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Old 03-31-07, 09:17 PM
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First, don't try to put a GFCI in a small box. Put the GFCI upstream in some place where you have more room.

Next, consider using 15-amp circuits so you can use #14 wire. I hardly ever recommend this, but it may be right for you.

Third, you didn't do the fill calculation correctly. Two 12/2 cables plus a device count as 7x2.25, or 15.75, not 9. You failed to count the black and white wires separately, and you must count two for the device. Even with 14/2, you'd need 14 cubic inches.

You might have to go back to your idea of the wood stained to match the paneling.

All of this trouble is why most basement finishes today are using standard 2x4 stud walls around the perimeter. You could always do likewise.
 
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Old 04-01-07, 03:57 AM
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4 in sq and 4 11/16 box to single and two gang mud rings come in Flat (no raise) 1/4, 1/2, 5/8, 3/4, 1 1/4

You can use a 4 sq by 1 1/2 box with 1/4 raised mud ring and have plenty of room for two number 12 cables and any device.
 
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Old 04-01-07, 10:37 AM
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Here is something I came across. Old work box, 17cu, 2" deep.
Page 6 of this pdf. #b117rsw

http://carlon.com/Master%20Catalog/Zip%20Boxes_2B1.pdf
 
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Old 04-01-07, 11:47 AM
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Originally Posted by jbfan
Here is something I came across. Old work box, 17cu, 2" deep.
Page 6 of this pdf. #b117rsw

http://carlon.com/Master%20Catalog/Zip%20Boxes_2B1.pdf
how will a 2 inch deep box help someone who has 1 1/2 inch of stud and 1/4 inch laminate?
[unecessary comment removed.]
 

Last edited by racraft; 04-01-07 at 11:57 AM.
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Old 04-01-07, 01:05 PM
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Yes, the B117RSW is what I was thinking of (I saw it last night at Lowes)...but again, 2" depth won't help unless you just want to build it out less.

Good luck,
Guy
 
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Old 04-01-07, 02:43 PM
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In retrospect, firring the walls this way saved 2" in the room but made it difficult to wire the space easily. Something to keep in mind for next time. I like your idea of building a cover ring for mounting on the wall surface but I have a question for the pros on this thread. Is it permissable to have the device partly in a space that is combustible (the sides of the ring)?
 
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Old 04-01-07, 06:00 PM
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Electrical Box for Furred Wall

RockPro - why would it be any different to add a 3/4" rectangular piece of wood to insert the box into than it would to install the box in a 1/2" or 3/4" wood paneled wall?

I think (and mind, I'm certainly no expert - everything I say on here seems to be corrected) that as long as you keep the front edge of the box flush with the front edge of the added wood piece, it would be ok. But we'll let the xperts decide on that!

Jim Crockett
 
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Old 04-01-07, 06:36 PM
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Yes, it is permissible to surround the box with combustible materials, as long as the box is not recessed (not by any amount whatsoever) behind the face of the combustible material.
 
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Old 04-01-07, 06:38 PM
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You are right. I had a mental image of this project that was different from yours. Installing the ring with the front of the box flush with it certainly solves the problem.
 
 

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