Art 334 NMC Cable In A Damp Environment

Ravenvalor

Senior Member
Hello,

For the past several years I have been using UF in outside conduit, residential garages and residential carports. I am currently looking at Article 334 and am not seeing anything that suggests that I cannot use NMC cable for these applications. Does anyone know of a code in the NEC where these applications are restricted for NMC cable?
I may have as usual been misinterpreting the code all these years. :)

Thanks for the great help.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
This explains both questions then. If manufacturers were producing NMC we would be able to use it in both garages and inside conduit outside.
I don't think that you could use it in conduit in a wet location. Isn't NMC listed only for damp locations?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Hello,

For the past several years I have been using UF in outside conduit, residential garages and residential carports. I am currently looking at Article 334 and am not seeing anything that suggests that I cannot use NMC cable for these applications. Does anyone know of a code in the NEC where these applications are restricted for NMC cable?
I may have as usual been misinterpreting the code all these years. :)

Thanks for the great help.
You do realize that NC has an amendment that allows nm outside in conduit for 6'. The exception was added to this section of the NEC

300.9 Raceways in Wet Locations Abovegrade. Where raceways are installed in wet locations abovegrade, the interior of these raceways shall be considered to be a wet location. Insulated conductors and cables installed in raceway in wet locations above grade shall comply with 310.10(C).

Exception: The raceway shall not be considered a wet location if:
(1) The section of raceway routed in a wet location above grade does not exceed 1.8 m (6 ft) in length;
(2) Any fittings or conduit bodies are watertight and listed for use in wet locations; and
(3) All termination points of the raceway are only open in any of the following: a. A dry location; b. Equipment suitable for outdoor use; or c. Equipment listed for use in a wet location.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
So the conduit outside only gets wet if longer than 6 foot?
LOL, no but it is great when you have an exterior panel and you are running cables thru the crawl space and come out thru an LB up to a panel. Otherwise you would need UF homeruns or splice the wires before exiting the crawl area.

I have worked here in NC for 40+ years and have seen many exterior panels with this type install and I have never seen moisture inside the conduit.
 
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