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Mixed cables and conductors in a raceway? #196980 11/03/10 04:29 PM
Joined: Jul 2004
Posts: 9,543
G
gfretwell Offline OP
Member
Is there a violation if you used a cable with another conductor or two in a raceway system?
(example a 12-3 w/g Romex and an additional THHN for the 4th ungrounded conductor in a 3/4" raceway).
It didn't sound right when I heard it but I am not sure what you would cite.


Greg Fretwell
2017 / 2014 NEC & Related Books and Study Guides
Re: Mixed cables and conductors in a raceway? [Re: gfretwell] #196981 11/03/10 07:00 PM
Joined: Apr 2002
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HotLine1 Offline
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That's interesting...
I must say none of the rocket scientists here thought that up....yet!
Time to ponder what (if anything) to cite.

FYI: another reason to add common sense to the NEC?



John
Re: Mixed cables and conductors in a raceway? [Re: gfretwell] #196982 11/03/10 07:34 PM
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Posts: 356
Niko Offline
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can you install NM cable in a complete raceway system? Or only in a piece of raceway just for physical protection?


Be kind to your neighbor, he knows where you live

Re: Mixed cables and conductors in a raceway? [Re: Niko] #196987 11/03/10 08:58 PM
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Posts: 9,543
G
gfretwell Offline OP
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I can't cite any rule that says you can't have NM cable in a raceway system. Since all circuit conductors come through the same connector there are no inductive heating problems. I know this is ugly but I am stumped to come up with a violation.


Greg Fretwell
Re: Mixed cables and conductors in a raceway? [Re: gfretwell] #196994 11/04/10 01:37 PM
Joined: Jun 2004
Posts: 1,273
T
Tesla Offline
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It's not a violation.

However, due to economics you'd not expect to see it.

It's generally impractical.


Tesla
Re: Mixed cables and conductors in a raceway? [Re: Tesla] #196996 11/04/10 02:09 PM
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Posts: 763
K
KJay Offline
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Iím wondering if 300.3[B] and 300.3[B],1 might apply if the conductors are all part of the same circuit, since both also state the same "cable or cord" as well.
Something else maybe, is that 334.15[B] is for exposed work, so not sure if this would preclude the NM from being run in a conduit that is concealed or partially concealed.

Re: Mixed cables and conductors in a raceway? [Re: KJay] #197000 11/04/10 05:26 PM
Joined: Jul 2004
Posts: 9,543
G
gfretwell Offline OP
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I suspect the RX was there first and the THHN was added.

KJay, this was all exposed in a garage/shop. A 240 2 pole was converted to 120/240 3 pole from what I could assume.
I see RX in pipe quite a bit, just because that is what resi guys have on the truck or what homeowners buy at the HD. I bet 99% of it is fed into the pipe as they build the system just because of how hard it is to pull RX in pipe.
I think part of it is you can buy RX cheaper than THHN if you don't want 500 feet.

I was not AHJ, just asked if it was legal as "gee whiz" info.


Greg Fretwell
Re: Mixed cables and conductors in a raceway? [Re: gfretwell] #197002 11/04/10 06:28 PM
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K
KJay Offline
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I guess technically you might be able to say that EMT fittings are not designed or listed for use with NM cables, since I see where 300.15 says that fittings and connectors shall be used only with the specific wiring method for which they are designed and listed.

IMO, I donít think the NEC allowing NM to be sleeved for protection was intended to allow unlimited use like that, but Iím also not sure exactly where to find a specific rule prohibiting it.

Re: Mixed cables and conductors in a raceway? [Re: KJay] #197004 11/04/10 06:46 PM
Joined: Apr 2002
Posts: 7,218
HotLine1 Offline
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Kjay:
The fittings you reference above are EMT, and used on the EMT, not the NM as I understand Gregs description. 300.15 would be a bad cite.

I tend to say there is nothing to directly cite, unless at the begining of the circuit, there is no 'from-to' connector.



John
Re: Mixed cables and conductors in a raceway? [Re: HotLine1] #197030 11/05/10 08:40 PM
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Posts: 763
K
KJay Offline
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Originally Posted by HotLine1
Kjay:
The fittings you reference above are EMT, and used on the EMT, not the NM as I understand Gregs description. 300.15 would be a bad cite.

I tend to say there is nothing to directly cite, unless at the begining of the circuit, there is no 'from-to' connector.



True. It was just something to mull over. My thought was that NM is a separate wiring method with its own installation requirements and listed connectors, etc.

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