NM cable outside?

[bill@usps06492]

I know this question has most likley been asked before, and I know that in Art334.12(B) 4 states NMcable, cannot be used in damp or wet locations.
But I'm often asked if nm cable is ran from inside the house, outside, in pvc underground, to the inside of a garage, if it's okay, my short answer is NO, but I've been challenged on this a couple of times. My reasoning is that the paper that surrounds the wire attracts moisture, and the insulation on the wire is not rated for a wet enviroment(the inside of any conduit becomes wet over time because of condensation). I know that the article does state that there are types of NM that can be used in wet locations, but I'm talking about your run of the mill Home Cheapo boxed wire. Besides as anyone who has tried to run NM through pvc knows, it can be a real bear, because of the resistance of the plastic jacket and the pvc.

 

[Dennis Alwon]

If you pull wire in a conduit underground it must be marked wet location.
Since the wire inside NM cable is not marked as wet or damp location you may not use it in conduit outdoors.

 

[roger]

To expand on Dennis's post,

Location, Wet. Installations under ground or in concrete slabs or masonry in direct contact with the earth; in locations subject to saturation with water or other liquids, such as vehicle washing areas; and in unprotected locations exposed to weather.

The first three words of the definition is the key.

Roger

 

[kkwong]

I agree and I think the biggest problem is that people see NM and say..."I gotta pull this instead of the other stuff!" Part of it might be laziness on the part of the installer, but the majority of the time it is John Q. Homeowner who asks because they do not know. As a side question, at what point do we say enough with the education and higher someone to do the work for you?

 

[bill@usps06492]

You're right about this coming from Joe Homeowner, they want to use the same wire they bought to wire the plugs in the family room, somthing like that.. I have some business cards of friends of mine who are contractors, and when I start getting alot of questions, I start passing out their cards, that usally stops the questons.

 

[Brady Electric]

NM cable outside

NM cable outside

I agree with Dennis and Roger. People think that since you pull NM into PVC it is protected. They don't understand that even in PVC you can still get damp and sometimes even wet. Semper Fi. Buddy

 

[Twoskinsoneman]

You're right about this coming from Joe Homeowner, they want to use the same wire they bought to wire the plugs in the family room, somthing like that.. I have some business cards of friends of mine who are contractors, and when I start getting alot of questions, I start passing out their cards, that usally stops the questons.

Why is it so bothersome to answer questions? I absolutely don't condone someone performing electrical work when they don't know where they are doing (the average HO). However, IMO knowledge and education should be coveted like mad but never horded. In every job I've had there are always those people that are afraid to lose the "top dog" position, refusing to help anyone... It is not right.

 

[ryan_618]

Simply adding on to what others have said here, but 300.5(B) is the section I would cite.