# 3 Gang Box & Box Fill



## macmikeman (Jan 23, 2007)

A Little Short said:


> What is the best way to wire (2) 3 gang boxes with (3) 3-way switches in each & using 12-3 NM?
> 
> Normal 3-gang box is 44 cu in. In the box with the load, if you bring (3) 12-3 cables along with (3) 12-2 load cables, then add the switches, you are over the 44 cu in.
> 
> Other than using 14AWG, what is the best way to wire this?


Depending on whether you are required to run a neutral into that box due to code cycle , you could feed the lights , and run one 3 wire cable for each end of the 3 ways from the switchboxe up to the light where everything gets spliced up. Why are you using #12 anyway, is it a spec?


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## Dennis Alwon (May 9, 2009)

Use the gangable deep metal boxes. I believe they arte 18 cu in. 18 x 3 = 54


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## MTW (Aug 28, 2013)

Allied makes deep 3 gangs. That's what I would use.


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## A Little Short (Nov 11, 2010)

macmikeman said:


> Depending on whether you are required to run a neutral into that box due to code cycle , you could feed the lights , and run one 3 wire cable for each end of the 3 ways from the switchboxe up to the light where everything gets spliced up. Why are you using #12 anyway, is it a spec?





Dennis Alwon said:


> Use the gangable deep metal boxes. I believe they arte 18 cu in. 18 x 3 = 54





MTW said:


> Allied makes deep 3 gangs. That's what I would use.


It would be hard to do a splice point because most of the lights are just 4' strip lights and no junction box. Not sure if there will be attic access either. Other lights are outside lights.

This is for a garage and most everything was 20A. Didn't want to buy #14 for just the lights. Change order for the (2) 3 gangs and the #12 put the fill over. They want this done quicker than I can order deeper boxes & get them in. So I'll just have to change to #14 for lights.


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## jw0445 (Oct 9, 2009)

I would use a deep three gang. This would work.

*EZ Box® Residential Boxes with Nails*

*three Gang, 74 Cubic Inch Residential Box with Nails*








Select part number for detailed information and technical drawing.
74 cubic inch box - The largest two gang box on the market. For installation on steel or wood studs.
Two gang nail on switch/outlet box with eight clamps. Use our divider to install a low voltage or communication device on one side of the box, in tandem with a switch or outlet on the other.
Suitable for masonry walls.


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## Dennis Alwon (May 9, 2009)

That is pretty incredible at 74 cu. in. The deepest pass and seymour box they have (3 gang) is only 54 cu.in. Not sure how they got 20 extra inches.

I guess that extra 7/8" inch in depth does it


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## Dennis Alwon (May 9, 2009)

I thought Bills 44 cu in box was not right. I always use the deepest boxes available from P&S and I have never had trouble. Bill, you must be using shallow 3 gangs


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## markbrady (Jun 2, 2014)

Home Depot sells Carlon 53 cubic inch new work 3 gang boxes and they are not special order and you don't have to buy the whole case or package. They are $2.84 each in my area.


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## Dennis Alwon (May 9, 2009)

markbrady said:


> Home Depot sells Carlon 53 cubic inch 3 gang boxes



Yeah 53 or 54 cu in is normal but 74 as stated above-- it would be nice to have a few of them for the rare occasion that one needs it


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## markbrady (Jun 2, 2014)

Yes it would be. I just did the box fill calculation for what the op stated and came up with 51.8 so all he needs is that box and he can worry about getting bigger boxes at a later date


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## A Little Short (Nov 11, 2010)

Dennis Alwon said:


> I thought Bills 44 cu in box was not right. I always use the deepest boxes available from P&S and I have never had trouble. Bill, you must be using shallow 3 gangs


I don't know if these are classifed as shallow or not, its what I always get. I asked the SH and they said it was the largest they carry.
*Cantex EZ44TN*


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## A Little Short (Nov 11, 2010)

markbrady said:


> Yes it would be. I just did the box fill calculation for what the op stated and came up with 51.8 so all he needs is that box and he can worry about getting bigger boxes at a later date


I got 49.50

(3) 12-3 = 9
(3) 12-2 = 6
1 EGC = 1
(3) devices @ 2 = 6

Total 22 x 2.25 = 49.50

But thanks for the link to the larger boxes. I may order some even if I don't ever fill them to the max. More room is always welcome!:thumbsup:


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## markbrady (Jun 2, 2014)

I got 49.50

You are correct, I used constructionmonkey and typed in 16 as i included the ground and the sight has the ground in another part so it did the math for 17 wires plus the 3 devices:bangin:


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## jw0445 (Oct 9, 2009)

I believe 14 gauge is 2", 12 gauge is 2 1/4"


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