box capacity

Old 06-18-03, 06:41 PM
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box capacity

In replacing some knob & tube wiring in the garage, I selected a 2-gang box (with two receptacles) for the first box in the run. The box is 4x4x2 inches, the two cables are 12/2G Nm-B. So far, I'm really struggling to get this all into the box. Am I correct to have put pig tails on all the receptacle terminals to make up the respective line, load, and ground connections w/wire nuts? When calculating box size, do pig tails get counted just like the other conductors?


Old 06-18-03, 08:08 PM
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Pigtails don't count in the official computation of box volume, but they obviously take up space. You can find deeper boxes to give you more room. Are one or more of these receptacles GFCI?
Old 06-18-03, 09:26 PM
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Thanks for your response, John. Whoops! ("Garage...I guess I SHOULD have a GFCI out there.") One of this box's receptacles is for a door opener, the other I added for occasional use of a vacuum or tools. The box fed by this box (at the end of the circuit) has one receptacle & is for another door opener.

Old 06-19-03, 08:34 PM
P Michael
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Sounds like you have a 4" by 4" by 2 1/8" box which officially amounts to 30.3 cubic inches.
According to the official rules of this game, you have
2 devices = 2 X 2. 25 = 4.5
2 #12 hots = 2 X 2.25 = 4.5
2 #12 "neutrals = 2 X 2.25 = 4.5
ground = 2.25
uncertain about whether internal clamps are present so = 0?
TOTAL = 15.75
Therefore you have plenty of theoretical room.
Your problem is like packing a suitcase: if you just toss stuff into it, it will fill up rapidly; if you carefully stuff your socks around your machine gun, you can get a lot more in.
So what you do is make up your pigtails first and pack them into the back of the box with only the pigtails sticking out. There is some advertised gimmick that is supposed to enable you to squash everything into the box. Don't bother. Instead of your 3 pigtails [or 6 with 2 receptacles] sticking straight out, what you do is PRE-BEND them in a Z shape and then pull them out and make your connections. This way, the wires are already pre-bent and will return to the positions when you push the recepacles into place.
[Note: you arrange these prebends directly behind their respective connections. For instance, in the usual configuration with the ground side sown, you would place the white and green wires on the left and the black wire on the right.]
Try to tuck the wirenuts especially into the corners or at least out of the way of where the recptacles will reside.

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