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1 members (Scott35),
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Joined: Aug 2001
Posts: 466 Likes: 1
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I suppose the AHJ makes the rules but article 100 says wet locations are "... unprotected locations exposed to weather".
In 2008 they also removed the confusion about above grade wet location raceways I can think of one place near here that interpreted NM outside as ok in a conduit sleeve. Seems that changed the "unprotected" into "protected" and made everything OK. Sure that wasn't the intent but I can see how they came up with that.
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Joined: Jul 2004
Posts: 9,931 Likes: 34
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From what I read the problem is the paper packing in the NM. It can wick water. I am not sure why they still have the paper in there in the first place. I suppose it is just so they can sell UF for more money and make you carry two products. That is really 3 products if you include "damp" rated NM-c but I have never seen that. When you look for NM-c on the web sites for the manufacturers you get routed to UF
Greg Fretwell
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Joined: Aug 2006
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Does anyone know what type of insulation the individual conductors have?
I will contact southwire tomorrow.
Be kind to your neighbor, he knows where you live
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Joined: Apr 2002
Posts: 7,382 Likes: 7
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Can't say that I ever seen an insulation ID on the conductors within NM cable. IMHO, appears to be THHN, without the outer clear nylon.
John
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Joined: Aug 2006
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From Southwire application engineer
"The conductors inside of our Romex products are listed as THHN only. You are correct in the statement that most conductors are multi rated. Romex is listed as a complete product and the conductors SHALL NOT be used with out the outer jacket. It can only be used as Romex and where Romex is approved for use by the NEC."
Be kind to your neighbor, he knows where you live
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Joined: Jul 2004
Posts: 9,931 Likes: 34
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I do think the practice is incongruous in the way it applies "wet" and "dry" at the face of an exterior wall. It is OK to terminate RX in the canopy of an exterior light if the box is recessed in the wall but if you extend this wire through a short sleeve on the exterior wall it is "wet/damp".
I have seen differing opinions about a surface mounted box fed directly through the wall.
It doesn't really matter if this is an insulation issue or a "paper in the jacket" issue, it will still be present in the canopy of that outside light but everyone says the RX is OK there.
I don't understand it but that is the accepted interpretation.
Greg Fretwell
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Joined: Jan 2004
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Contrary to the statement by the Southwire Engineer, there is nothing in the files that says that the conductors inside NM cable are THHN. It only says that the conductors are rated for 90°
Greg I agree with you on your attitude on wet locations and feeding the fixtures etc. that have the stub out directly into the boxes.
George Little
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Joined: Aug 2001
Posts: 466 Likes: 1
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George, are you saying that you believe that UF should be run from the switch to the fixture box or just that there seems to be a potential conflict with the Code when using NM into the back of the box?
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Joined: Mar 2005
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I agree Reno, romex also has seen a wider privilege of use. So which is it good enough or hazardous? Here in my jurisdiction most inspectors will allow minimal footage of romex in damp/wet locations (just don't push the limit i.e. half the distance of total run).
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Joined: Jul 2004
Posts: 9,931 Likes: 34
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From what see, the criteria is you can't have the RX jacket on the wet side of the wall. IE you can have a pancake on the wall with the conductors sticking out and it is OK. Just don't come out the wall with RX and go somewhere.
Greg Fretwell
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Posts: 57
Joined: August 2003
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