My electrical panel is in the basement on the west end of the house and my garage is on the east end. I had planned to run a 6/3NM-B cable along the joists and through the rim joist to get into my garage to feed a 60 amp subpanel. That has proven to be a much bigger challenge than I expected, so now I'm thinking about running THHN from the main panel to the outside of the house and run it through PVC conduit along the north wall and then run it back into the garage wall to feed the subpanel. I would use #6 (red, black, and white) and a #10 green for ground. Does this sound like a reasonable approach? It feels a bit hacky to go outside and then back in, but it's going to be much easier than the other approach.

  • 1
    I take the conduit run extends from panel to panel as a contiguous run? May 25, 2017 at 2:11
  • I take it that means it NEEDS to be a contiguous run? May 25, 2017 at 2:13
  • 1
    Yes -- it does. You can't run single wires outside of a Chapter 3 wiring method (in practice, that means "no single wires outside of raceway or conduit") May 25, 2017 at 2:14
  • Good to know. I had planned on running it in conduit the entire way, but may have taken the easy way out and not gone the last 4 feet from the ceiling to the main box, but now I'll be sure to do so. Thanks. May 25, 2017 at 2:16

1 Answer 1


I learned here on the stackexchange that running wire outside is considered a wet location and THWN wire is needed, even if its in conduit.. The W is for wet locations.

  • 3
    It is extraordinarily rare to see THHN-only building wire -- just about all building wire made is dual-rated THHN/THWN-2. May 25, 2017 at 2:12
  • 3
    @ThreePhaseEel The new stuff, anyway. May 25, 2017 at 2:16

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.