# How many wires permitted in a 4 gang box?



## Speedy Petey (Feb 1, 2004)

Metal or plastic?
What size wire, #12 or #14?


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## InPhase277 (Feb 9, 2008)

ryanh said:


> Hello
> 
> My code book only shows up to a 3 gang. I have a 3 x 4 x 2.5" deep box that will hold 4 light switchs. How many wires and nuts a I allowed?


How many cubic inches is the box marked as? It is 30 cubic inches by just doing the math, but it may be listed differently.

2.00 cu. in. per #14.
2.25 cu. in. per #12
2.5 cu. in. per #10

All the grounds count only once. Switches and receptacles count as two conductors each, and wire nuts count as one each (in Canada only).


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## williswires (Jul 21, 2008)

ryanh said:


> I have a 3 x 4 x 2.5" deep box that will hold 4 light switchs


Are you sure on the dimensions? A 3x4 box wouldn't be a 4 gang...

What is the mfg/model of the box?


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## darren (Nov 25, 2005)

On the side of the box there will be a capacity in ml. Count your wires you have, the ground and any wire that starts and ends in the box(pigtails) do not count. For each pair of marretts you count one wire(i.e 4 marretts=2 conductors, 6 marrettes=3, etc,. Each device counts as 2 wires. Divide the box ML by the wire ML and see how many your allowed to use and always round down and not up with your final answer(12.75 conductors=12 conductors)

With a 4 gang box you will have lots of room for wires, unless your planning on putting a ton of wire in there you won't have to worry about box fill.


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## InPhase277 (Feb 9, 2008)

darren said:


> On the side of the box there will be a capacity in ml. Count your wires you have, the ground and any wire that starts and ends in the box(pigtails) do not count. For each pair of marretts you count one wire(i.e 4 marretts=2 conductors, 6 marrettes=3, etc,. Each device counts as 2 wires. Divide the box ML by the wire ML and see how many your allowed to use and always round down and not up with your final answer(12.75 conductors=12 conductors)
> 
> With a 4 gang box you will have lots of room for wires, unless your planning on putting a ton of wire in there you won't have to worry about box fill.


Oh, so it's two wire nuts to a count. Sorry, I posted wrong.


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## darren (Nov 25, 2005)

Just to add #14 take up 24.6ml, if you are useing #12(which is a waste since your lighting has to be on a 15A) your looking at 28.7ml


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## ryanh (Jul 23, 2008)

Its a Iberville(Metal) 2 1/2 deep says 50 cu. inch

I got 6 blacks, 6 whites, 3 reds. Can't have more than 5 wires in a red marrett so i have to slip my whites and blacks and then pigtail them? So that would be 15 wires + 1 ground and 4 marretts? 18 x 2 So 36cu inch i will be using space wise?


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## theatretch85 (May 17, 2008)

ryanh said:


> Its a Iberville(Metal) 2 1/2 deep says 50 cu. inch
> 
> I got 6 blacks, 6 whites, 3 reds. Can't have more than 5 wires in a red marrett so i have to slip my whites and blacks and then pigtail them? So that would be 15 wires + 1 ground and 4 marretts? 18 x 2 So 36cu inch i will be using space wise?


I calculated 36cu. in that is with #14 wire and no devices. Each switch counts as an addtional 2 wires (one switch would be 4cu. in). With 4 switches and the number of wires you have, you'd be right at 52cu. in; which is obviously more than the rated capacity of the box. I'd reccomend instead of pigtailing additonal wires to connect your white wires and grounds to use bigger wirenuts. If you can reduce the wirenuts to just 2 you'd be ok.

15 wires = 30cu. in
4 wire nuts/marretts = 4cu. in
All Ground wires = 2cu. in
4 switches = 16cu. in
Total = 52cu. in

Also, I just noticed this is a metal box; the wire clamps used for the wires also count as part of your box fill. I don't remember if its 1 count for all the connectors or 1 count for each connector, someone else can provide that information here (pretty sure its just like the ground wires, 1 count for all).


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## InPhase277 (Feb 9, 2008)

theatretch85 said:


> I calculated 36cu. in that is with #14 wire and no devices. Each switch counts as an addtional 2 wires (one switch would be 4cu. in). With 4 switches and the number of wires you have, you'd be right at 52cu. in; which is obviously more than the rated capacity of the box. I'd reccomend instead of pigtailing additonal wires to connect your white wires and grounds to use bigger wirenuts. If you can reduce the wirenuts to just 2 you'd be ok.
> 
> 15 wires = 30cu. in
> 4 wire nuts/marretts = 4cu. in
> ...


It is one count for all the clamps, but it is only for internal clamps. External clamps (i.e. romex connectors) don't count.


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## darren (Nov 25, 2005)

Going by the canadian electrical code you would take 50cubicinches/.061=819ml Take 819ml/24.6ml=33 #14 in your box

Wire-15 Conductors
Devices-8 COnductors
Marrettes-2 Conductors

This gives you a total of 25 conductors so you should be good. I would second the notion to get bigger marretts for your whites and blacks, they are called bcaps or #35 which you can find at Home Depot or Rona.


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## InPhase277 (Feb 9, 2008)

So, Darren, the Canadian Code assigns less volume to a #14? I thought they were the same for both codes. Guess not. 24.6 mL is only 1.5 cubic inches. I guess they have to do something to allow room for the counted wire nuts!:laughing:

And, the volume you guys have for #12 is less than the volume we use for #14!


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## darren (Nov 25, 2005)

Thats what the people who sit in the nice cushy chairs who write the code book tell us to use. You would think that they would be the same size, the wire is probably all made in the same factory except ours gets a CSA stamp on it.


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## ryanh (Jul 23, 2008)

So in Canada its 1.5cu inch and 2.0cu inch in the US for #14 wire? Wierd

Im really pushing this box. So 3 way dimmer and a single pole switch all still count as 1 device?


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## darren (Nov 25, 2005)

No in Canada it is 24(whatever that number was in my previous post)ml. Were canadian and are suppose to use metric but you show me a electrician who uses metric on a daily basis and i will buy you a beer(J/K). But converted over it is 1.5".

A device is a device, doesn't matter how big it is.


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## InPhase277 (Feb 9, 2008)

darren said:


> No in Canada it is 24(whatever that number was in my previous post)ml. Were canadian and are suppose to use metric but you show me a electrician who uses metric on a daily basis and i will buy you a beer(J/K). But converted over it is 1.5".
> 
> A device is a device, doesn't matter how big it is.


If you want to be all technical about it, then the boxes should be marked in cubic centimeters instead of mL. While they are numerically the same size, milliliters are meant to be a measure of fluid. And while I agree that SI is a more consistent system, I also like the fact that my country has decided that they'll adopt the metric system when they are good and damn ready to. Not just because the international "community" has. I like our independence and sovernignty.

Also, some things just don't sound as good when you say them in metric:

"Teenagers! Give them a centimeter, they'll take a kilometer!"
"A half liter is 500 grams the world around."
"That inspector wore a 4.55 kg badge."
"Talking 1.61 kilometers a minute."
"We've reached a critical kilometer-stone"
"A gram of prevention is worth a kilogram of cure."
"15 milliliters of honey will catch more flies than a liter of vinegar."

Etc.


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## ryanh (Jul 23, 2008)

darren said:


> No in Canada it is 24(whatever that number was in my previous post)ml. Were canadian and are suppose to use metric but you show me a electrician who uses metric on a daily basis and i will buy you a beer(J/K). But converted over it is 1.5".
> 
> A device is a device, doesn't matter how big it is.


Makes sense. Hey darren my bathroom is small 5' x 7' with the door located on the 7' side. Code says outlet should be no less than 19.4" from edge of tub, is it the same rule for a light switch? My light switch at most is 16" from the tub(at the edge of where the door opening starts).


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