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mdshunk

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Right here.
FWIW, the only time I've seen NM cable having failed when used non-compliantly was due to UV breakdown (exposed to sunlight). I've come across an aweful lot of NM in pipe outdoors and underground (maybe I've even done that a time or three), and have never observed any of it as having failed.
 

peter d

Senior Member
Location
New England
mdshunk said:
FWIW, the only time I've seen NM cable having failed when used non-compliantly was due to UV breakdown (exposed to sunlight). I've come across an aweful lot of NM in pipe outdoors and underground (maybe I've even done that a time or three), and have never observed any of it as having failed.


Before I knew it was a violation I ran NM in conduit outdoors, and even used it for A/C whips (inside of seal tight of course.)
 

Dennis Alwon

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Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Try this....

300.5(B) Wet Locations. The interior of enclosures or raceways installed underground shall be considered to be a wet location. Insulated conductors and cables installed in these enclosures or raceways in underground installations shall be listed for use in wet locations and shall comply with 310.8(C). Any connections or splices in an underground installation shall be approved for wet locations.

Edit to add definition

Location, Wet. Installations underground 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.
 
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Dennis Alwon

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tryinghard said:
So you are saying the NM is exposed when installed in conduit?

NM is exposed to the moisture when installed in conduit. It is there in B & W.

If the nec would mandate that NM contain thwn wire and the jacket made of the same material it may not be an issue but I don't think the NEC would mandate the insulation to be used/ It does mandate 90C but I don't know if they would go further on this issue.
 

tryinghard

Senior Member
Location
California
If cable is installed in conduit it still needs to comply with Chapter 9 Table 1, note (9) and conduit fill Table 4.

1 multi conductor cable is 53% and over 1 cable is 40% fill, inch sq = cable diameter squared x (3.141/4)
 

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
tryinghard said:
These are underground locations, how about above ground? Indoors?

As stated earlier 300.9. Indoors you can install NM in conduit as long as you follow the fill as you suggested. Sleeves don't come under chapter 9 IMO. That is for raceways not sleeves.

I am not sure why indoors is being brought up I thought we were talking outdoors with romex inside conduit.
 
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