Wet Location Conductors

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jflynn

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Does anyone see a problem using type THWN-2 insulation in a wet location?The reason I ask is we had trouble finding the wire size we needed in XHHW and looking @ article 310.8 (c) type THWN-2 is listed for wet locations.We found the size we needed with THWN-2 insulation and it is more cost effective.
 
jflynn said:
Does anyone see a problem using type THWN-2 insulation in a wet location?

type THWN-2 is listed for wet locations.
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You've answered your own question.:smile:

steve
 
While they are both suitable conductors per the code, XHHW is often specified for underground and other harsh conditions. It is a tougher insulation and will last longer.
 
While the code permits both in wet locations THWN-2 is rated for 90 degree C while XHHW is only rated for 75 degrees C in wet locations. If derating is involved that could be a factor is choosing one over the other.
 
On this subject, but off on a slight tangent, how does one evaluate components to determine if they are intended for wet (in my case, outside roof top) locations.

Cases in point: Fluorescent fixture behind a fabric canopy sign - totally exposed at the top to the elements (1st photo below).

Cable directly on the roof (nice use of a paint can for ballast, eh?).

http://i15.photobucket.com/albums/a352/TonyPE/IMGP0242_edited-1.jpg
http://i15.photobucket.com/albums/a352/TonyPE/IMGP0241_edited-1.jpg
 
If it is in a wet location it must be listed for wet locations.

If it is in a damp location it must be listed for damp or wet locations.
 
Just by looking at the pictures I can tell you that the junction boxes and EMT fitttings are not rated for wet location.

As far as the conductors, you could open a JB and see what type conductors were used.

All in all a pretty crappy installation, and definitely not code compliant.

Just my opinion
steve
 
iwire said:
If it is in a wet location it must be listed for wet locations.

If it is in a damp location it must be listed for damp or wet locations.
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Is there any way to make this determination on items in service for maybe 20 years or more?
 
tonype said:
Is there any way to make this determination on items in service for maybe 20 years or more?
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You need to look in Article 100 for the definitions of location, wet and location, damp.
 
infinity said:
While the code permits both in wet locations THWN-2 is rated for 90 degree C while XHHW is only rated for 75 degrees C in wet locations. If derating is involved that could be a factor is choosing one over the other.
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Good point,do you know if AL. wire is made with THWN-2?We seem to only be able to find it in XHHW.We had the exact issue you mention about derating with XHHW...
 
jflynn said:
Good point,do you know if AL. wire is made with THWN-2?We seem to only be able to find it in XHHW.We had the exact issue you mention about derating with XHHW...
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If you can use XHHW-2 it rated for 90 degrees C in wet locations.
 
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