Thin Wall Conduit Question.

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  #1  
Old 06-29-05, 09:22 AM
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Thin Wall Conduit Question.

When working with thinwall (EMT) in interior exposed areas can I pass my 12/2 NM directly thru it if I use the proper diameter EMT? Or must I use individual conductors? I have a 250ft roll of 12/2 NM already, however If I must use the individual conductors can I use the smallest diameter EMT with #12 wires.

Sorry but one more question: I was planning this job originally with all WIREMOLD brand products and the prices were quite high. Is there a significant savings using the thinwall instead? I'm doing this strictly as a DIY.

Many thanks.
 
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Old 06-29-05, 10:54 AM
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My guess is that your plan is probably okay.
 
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Old 06-29-05, 11:34 AM
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I agree with John that your plan is probably okay...but I'd advise against it.

The proper size of conduit for running NM cable requires that you assume that the cable is _round_ with a diameter equal to the widest part of the cable assembly. Thus when you are figuring conduit size, you essentially have to dedicate the same area as 10-12 12ga wires for each single NM cable. For a single cable, this doesn't much matter, but as soon as you want two circuits in the same conduit, you will end up needing much larger, more expensive conduit.

Additionally, 12ga NM cable is made with solid wire, made stiffer by the fact that it is bundled together. Not much of a problem for 'straight shots', but a bear if your conduit run has any bends in it. Remember that you are not permitted to push the wires in and assemble the conduit in pieces; you need to assemble the entire run and then pull the conductors in.

Net result: the aggravation cost of trying to use the NM cable is far greater than the materials cost savings. IMHO you will be much happier if you run individual wires in the conduit rather than using the NM cable.

-Jon
 
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Old 06-29-05, 12:38 PM
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Individual wires

Thank you John & Winnie. I purchased 3 rolls, black, white , green. Maybe the green is not needed, But I feel safer with it , rather than counting on all my connections to the conduit connectors for my grounds. I hope this is ok to use the green also.
 
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Old 06-29-05, 12:51 PM
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It is okay to use an insulated green wire for ground in conduit. IMHO this is a better installation than simply relying on the conduit for ground.

One requirement, however, is that at any junction box all grounds must be be bonded together. Generally this is taken to mean that at any point where your circuit conductors are spliced, you must also splice your grounds and run a ground wire to the box. The only exception to this is for 'isolate ground' systems, which you shouldn't be installing.

-Jon
 
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Old 06-29-05, 01:45 PM
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Thanks so much, I be putting ground pig tails on all the boxes with a green grounding screw. thank you all for the help.
 
  #7  
Old 06-29-05, 04:00 PM
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Romex in emt

I was told by two AHJs in our area that I could not run NM cable inside of EMT except under circumstances where I was using EMT as a raceway (open both ends) and then they wouldn't allow any length over 10 feet. These authorities were from two different municipalities so I took their word for it.
 
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