5 Gang Box Wire Size And Cu? - Electrical - DIY Chatroom Home Improvement Forum

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10-12-2012, 11:13 PM   #1
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## 5 gang box wire size and cu?

I have 5 switches that i need to install. Looking at getting a 5 gang box. This will be installed in a 2x4 wall. What code is there about how many wires can be in the box? I plan on using 12/2 wire. There will be 2 circuits. 2 switches on one circuit and 3 switches on another circuit. Can i do this or do i need split out the boxes?

10-12-2012, 11:15 PM   #2

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You should be fine. To be sure we would need to know the dimensions of the box. You can have multiple circuits in the same box.

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 10-12-2012, 11:17 PM #3 Member   Join Date: Mar 2011 Location: Philadelphia Area Posts: 51 Rewards Points: 33 I thought so. Its all about the cubic in of the box? Any sizing i should be aware of?

 10-12-2012, 11:21 PM #4 Electrical Contractor     Join Date: Jun 2004 Location: Newnan GA Posts: 6,779 Rewards Points: 152 I came up with 56.25 cu with your cable and devices, so anything larger will be fine. __________________ "The problem isn't that Hillary Clinton lies. We all know she lies. The problem is that her supporters don't seem to care" Last edited by jbfan; 10-12-2012 at 11:41 PM. Reason: Math error and another math error, or maybe a drinking error
 10-12-2012, 11:26 PM #5 Licensed Electrician     Join Date: Mar 2012 Location: SE Wisconsin Posts: 4,352 Rewards Points: 2,006 Correct. Add up all the current carrying conductors and multiply that number by 2.5, then add 2.5 to that answer to account for the grounds. Next you have to account for the devices themselves. Each device counts as two CCC's, so that's 25 cubic inches. Add that to the running tab. So, if you have 2 12/2s feeding the 5 gang and 5 12/2s for the switch legs you get a total of 62.5 cubic inches. I am estimating here, the dimentions of a 5 gang is 3x8x3=72 cubic inches. __________________ __________________________________________________ ______________ Answers based on the National Electric Code. Always check local amendments.
 10-12-2012, 11:31 PM #6 Member   Join Date: Mar 2011 Location: Philadelphia Area Posts: 51 Rewards Points: 33 As always you guys rock. Thanks for the info.
 10-12-2012, 11:33 PM #7 Member   Join Date: Mar 2011 Location: Philadelphia Area Posts: 51 Rewards Points: 33 And the pigtails between switches don't count toward the needed CU right?
 10-12-2012, 11:36 PM #8 Licensed Electrician     Join Date: Mar 2012 Location: SE Wisconsin Posts: 4,352 Rewards Points: 2,006 Nope, only conductors that enter or exit the box. __________________ __________________________________________________ ______________ Answers based on the National Electric Code. Always check local amendments.
10-12-2012, 11:36 PM   #9
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Quote:
 Originally Posted by k_buz Correct. Add up all the current carrying conductors and multiply that number by 2.5, then add 2.5 to that answer to account for the grounds. Next you have to account for the devices themselves. Each device counts as two CCC's, so that's 25 cubic inches. Add that to the running tab. So, if you have 2 12/2s feeding the 5 gang and 5 12/2s for the switch legs you get a total of 62.5 cubic inches. I am estimating here, the dimentions of a 5 gang is 3x8x3=72 cubic inches.
I came up with 56.25. 12awg is 2.25 in^3. Either way there is still room.

10-12-2012, 11:38 PM   #10

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My bad, you are correct, I didn't look at my code book and for some reason was thinking 2.5 for a #12...my bad.

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