Boxfill for Non Metallic boxes

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Old 01-25-14, 03:47 PM
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Boxfill for Non Metallic boxes

I have a Cantex Non-Metallic box EZ14SO that says 14 square inches inside. It has the flapper door knockouts.
https://www.platt.com/platt-electric...px?zpid=471712

Do I have to add 1 count for the clamp in the boxfill calculation?
 
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Old 01-25-14, 04:34 PM
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It is considered an internal clamp. It counts.
 
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Old 01-25-14, 05:17 PM
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Most plastic boxes will have the wire counts embossed on the back of the box for handy reference.
 
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Old 01-25-14, 06:30 PM
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It does say 16cuin. And its 9/14 8/12 7/10. But if I do a boxfill calculation for 8 12 awg it equals 18 cu in? I want to put one 12/3 with ground(red,black,white and ground and one duplex receptacle. I figure that accounts for 7 #12 wires if I count the clamp which is under the 8/12 allowed in the writing in the box, but violates the 14 cu in box listing? Which do I follow the 14 cu in written in the box or the 8/12 written just under the 14 cu in?

Mod Note: the box shown in this post says 14 cubic inches.
 
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Last edited by pcboss; 01-31-14 at 12:39 PM.
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Old 01-25-14, 06:55 PM
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Weird. I have a different brand box marked with the same number of wires but says it is 18 cu in.
 
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Old 01-26-14, 09:15 AM
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You could contact the manufacture, but if it were me I would go by the wire count. 8/12
 
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Old 01-26-14, 10:21 AM
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A xx-3 cable is 3 + 2 for device + one for ground = six + clamp = seven total.

It will fit but you will not enjoy getting it in the box. I would use a deeper box.
 
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Old 01-31-14, 11:40 AM
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Yea. I'll try to find a deeper box or abandon the 12/3 idea. I can only go 2-3/4 deep with this wall. I wanted to be able to switch the top and bottom of a duplex receptacle seperately for accent lighting options. My only other option is to use a 2-3/4 deep 2 gang box and run each outlet from each switchleg of the 12/3 to make it fit easier.
 
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Old 01-31-14, 12:03 PM
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I can only go 2-3/4 deep with this wall.
Is the wall going to be finished when you're done? If so, it sounds like you have room to mount a deep 1900 or 11-b box and put a single-gang mud ring or surface cover on it. Either of those boxes should give you plenty of room.
 
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Old 01-31-14, 03:19 PM
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The wall is already finished. They are foam panels with a channel to fish a wire down the back. I can cut a wider hole but not deeper. I would have to add a trimring of wood or something to hide the box projection if I used a deeper box than 2-3/4.
 
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Old 01-31-14, 10:03 PM
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The boxes I referred to are shallower than 2-3/4" but they're wide. A 1900 box is 4" square; an 11B box is 4-11/16" square. That's how they supply more volume. If you can cut wider they might work:

1900 box with bracket
1900 box w/o bracket
SG mud-ring for 1900 box, 5/8" rise

11B box with stud bracket
11B box w/o bracket
SG mud-ring for 11B box, 1/2" rise

But I'm curious. If the factor for 12AWG is 2.25 -- and I don't think it's that large -- ant it applied to the device and the clamp as well as the wire, you'd only need 15.75 in.3 What's wrong with the box you have now?
 

Last edited by pcboss; 02-01-14 at 09:48 AM.
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Old 02-01-14, 09:08 AM
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ut I'm curious. If the factor for 12AWG is 1.5 -- and I don't think it's that large
According to the table in Wiring Simplified, 12 AWG is 2.25.
 
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Old 02-01-14, 10:36 AM
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According to the table in Wiring Simplified, 12 AWG is 2.25.
Du'oh! That's right. The factor for 14AWG is 2 and using 12AWG adds the 0.25.

So the seven units the OP has require 16in.[SUP]3[/SUP] of volume using 12AWG. Got it.

Note to self: Check the reference materials more often.
 
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Old 02-01-14, 07:39 PM
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One other question. When pushing wires back in the recptacle box. Does the Neutral and ground have to be pushed to the opposite side of the hot? If so, when using 12/3 with red and black hot. Do the red and black have to be pushed to one side and neutral and ground to the other?
 
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Old 02-01-14, 08:19 PM
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Do the red and black have to be pushed to one side and neutral and ground to the other?
They don't have to be, but it can repay you well to do it that way.
 
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