I'm looking into mounting a TV on my patio on the exterior wall of my brick home. Only problem is, the best place for it is the exterior of a masonry fireplace/chimney, so I can't drill through the wall to run the power.

I've mounted TVs on interior fireplaces similarly by running armored cable into the attic with a surface mount box and then building a facade to hide the cable, so I'm picturing something similar on the outside with conduit going up through the soffit and a GFCI in a weatherproof box, and building a weather resistant enclosure with a locking door around the TV.

My question is, what kind of conduit can I run up through the soffit to the junction box in the attic? I live in Oklahoma where we regularly see 100+ degree days in the summer, so I'm guessing PVC conduit is out due to the 122 degree limitation? Picturing the wire running inside the soffit to the right and going around the right side of the chimney in the attic so I'm not sure EMT or rigid would be ideal, although I've read that NM-B can be run through EMT with a protective plastic cap to prevent chafing? What would you do in this situation? Thanks!

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  • I'd be worried about keeping the TV out in 100+ temperatures. Nov 24, 2021 at 15:25
  • 1
    That wall is shaded 100% of the year, so I don't expect it to get too terribly hot. It's also an old, inexpensive TV I don't care too terribly much about. Just something to watch the game on while BBQing.
    – ancapn8
    Nov 24, 2021 at 15:57
  • Note that the inside of a vented attic can get to 122degF in the middle of summer... Aug 21, 2022 at 19:54

1 Answer 1


You cannot use NM-B, because it's not rated for wet, and all exterior conduit is defined as a wet location.

You can use NM-B cable inside and transition in a junction box to a wet-rated wire type (THWN, etc.) in conduit before going outside.

Unless your 100+ is actually 122+, PVC conduit is probably fine, but EMT is suitable and easy enough if you prefer not to play close to that limit.

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