Piped, outdoor, underground THHN installation?

[lunalilo]

Is this okay?

THHN in pipe underground like PVC or Rigid for a service application?

 

[480sparky]

No. THHN is not rated for wet/damp locations.

HOWEVER........ most THHN is dual rated as THWN, which is.

 

[roger]

Is this okay?

THHN in pipe underground like PVC or Rigid for a service application?

Yes as Sparky says since it would be dual rated.

Roger

 

[macmikeman]

And since you guys are always so customer friendly when I am searching desperately for ivory device plates in the every expanding almond isle, I would like to add this: When using dual rated thhn/thwn wire the use underground or other wet locations is rated for 75 deg before other de-rating but if it is used in a dry location that same conductor has a 90 deg rating before any other de-rating adjustments. So watch the ampacity of the intended use.

 

[iwire]

Mac, look for the '-2' after THHN / THWN, if the 2 is there the conductor is 90 wet or dry.

It's like they try to make the NEC difficult. :grin:

 

[macmikeman]

Mac, look for the '-2' after THHN / THWN, if the 2 is there the conductor is 90 wet or dry.

It's like they try to make the NEC difficult. :grin:

Dig. But I am assuming he is talking about #12 or #14 thwn and he works at the Home Depot. All the rolls of #12 and #14 at that particular Home Depot at least do not have -2 on the labeling. They are labeled Thwn. I checked this today while I was in there. Course I'm just guessing about the size

 

[LarryFine]

Course I'm just guessing about the size

Well, the OP did say " for a service application."