Work Boxes

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  #1  
Old 06-29-02, 09:11 PM
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Bugman70
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Work Boxes

I'm wiring a shop (separated from the house and totally independant) and I have a question.

I have bought some work boxes for outlets, etc... that are 2 1/8" x 4". How many #12 conductors can I run through or connect in these boxes? I ask this because I am running 1/2" EMT conduit for outlet/curcuit runs and would like to run other misc. circuits through the same conduit. It's not a problem (other than expense/time) to run new conduit, but I would like to use what I have as much as possible.

Thanks,
Bugman
 
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  #2  
Old 06-29-02, 09:32 PM
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The number of conductors is based on cubic inches of the box. However cubic inches is a three-dimensional measurement, and you only provided two dimensions.

If you are referring to a 4-inch square box that is 2-1/8" deep, most of these boxes have about 30 cubic inches. On the other hand, perhaps you mean a box that has an opening of 4x2-1/8. This is a much smaller box, but it depends on depth. Finally, you might be referring to a handy box with an opening that is 4x2-1/8. These boxes are only 10 to 14 cubic inches, depending on deptch.

Check the box to see if the box has some number of cubic inches marked on it. This is the best number to use. Otherwise, tell us all three dimensions of the box. Then we'll also need to know other information too, such as whether you are providing grounding with conduit or wire, whether the box has any internal cable clamps, and whether there will be a receptacle or switch in this box. The answer to your question will also depend on whether you will splice the wire in the box, or run it through without a splice.

Finally, be aware that as soon as you get more than 9 conductors in the same conduit, you'll need to reduce the sizes of all the breakers on all involved circuits.
 
  #3  
Old 06-30-02, 11:23 AM
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Bugman70
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Follow up

Sorry for the confusion. I realized last nite that I had left off an important piece of information. The boxes I have are 2.125" wide x4" tall x 1.5" deep for a total of 12.175 cubic inches.

I asked the quetion orginally beacause I am running outlets in the boxes and would like to run say two curcuits (six wires if running a separate ground) in one run of conduit. Also in one place I would like to pull off power to a switch for a fan in one box. So, in one box the most I would have three is uncut wires with an outlet or switch and their associated connections. I have calculated the loads and nothing is overloaded, but I want to be sure to stay under the box capacity for conductors/connections. Also in a couple of runs i have a dedicated circuit for various tools (table saw, radial arm saw, and other mobile 110v planers/shapers, etc..) and would like to run that through the conduit for the run on that wall. Working that way I might windup with nine wires in a conduit but I doubt that I'll try to put that much in the conduit.

The wire is #12 AWG and the conduit is 1/2".

Thanks,
Bugman
 
  #4  
Old 06-30-02, 12:56 PM
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These boxes are much, much too small. I recommend you return them and buy much, much larger boxes. 12.175 cubic inches is too small for most things you'd want to do with 14-gauge wire, let alone 12-gauge. My recommendation is to always buy the biggest box you can find -- for a few cents more it's well worth it.

12.175 cubic inch boxes are only good for one 12/2 cable plus a receptacle. You can't even daisy chain your receptacles with boxes this small!

What kind of 1/2" conduit do you have, and are you running THHN wire?
 
  #5  
Old 06-30-02, 06:46 PM
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Bugman70
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I also have some 4" x 4" x 1 1/2" boxes. Looks like thats what I will be using.

I got out today and looked at what I was about to do and you are right. The outlets won't hardly go into these smaller boxes by themselves, let alone wirenuts or any additional connections. I can't imagine trying to do anything elaborate or even adequate in the smaller boxes. I really appreciate your advice. It caused me to take a serious second look.

I am using # 12 THHN wire and 1/2" EMT conduit.

Any suggestions as to wire count in boxes, etc.. would be appreciated.

Where can I find a written source for this kind of info??

Thanks,
Bugman
 
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