ECN Forum Forums General Topics of the Trade General Discussion Area Subpanel - Garage - THHN/NM

Doing a job wiring an unattached residential garage. I have to run the 100 amp subpanel feeders through the attic then down the outside wall to a underground trench then to the garage. Would like to run 2/3 NM through the attic but then when I get to the UG trench, I don't want to have to change to #2 THHN just to go through the ridgid pipe underground, that will require a splice. Can I run the 2/3 NM through the ridgid pipe?. Or I could run #2 THHN through flex in the attic then convert to emt down the wall, then to ridgid underground.
Any suggestions?

Conduit underground is considered a wet location...
Romex is not allowed in a wet location...
Change over to pipe with thhn/thwn conductors...

shortcircuit

With an emphasis on thwn

t is hard to find THHN that is not rated THWN

go pipe the hole way.

I agree with bucketman. You could use smurf in the attic and LB into RNC when you go outside if running the pipe in the attic is a problem.

Ya I agree, Prob the best way to go, I'll run pipe all the way.
Thanks,

aldav53...Jus noticed your in Arizona...gets real hot up there in those attics out there.

Be sure to apply the ambient temperature correction factors for the wiring up in that there attic. You could use a correction factor that would cut the ampacity of the wiring by 50%

Find this info below table 310.16 NEC...

You would be better off to run underground to that garage.

shortcircuit

"t is hard to find THHN that is not rated THWN"

Yes, As a matter of fact, I don't remember ever seeing any. You can bet, though, as soon as we say THHN is OK, that there will be some showing up for the first time. Accuracy is important, George

shortcircuit,
Have to run through the attic then down to the trench. Yes it is hot in attics here. I may have to go larger than #2 for 100 amps.