Electrical question

[Peter Stahl]

Do I need to use conduit to run a wire through the rim joist? Had a sun room put on my deck and I have to go under the deck then through the rim joist in to the basement. I live in New Jersey if that makes a difference.

[Jim Becker]

If it's exposed, most likely, yes. But I'd do that anyway even if it wasn't required.

[Charlie Velasquez]

To answer your specific question, the conductors must be protected up to the entrance of the building. The bored hole must be smooth and at least 1 1/4” from the edge, but structurally you want the hole to be in the center third (as it is a rim joist continuously supported by the foundation, probably not an issue with the center 1/3. If you are going through joist of the deck consider it).

If the deck is exterior it is considered a damp or wet location, depending on your ahj, and regular romex may not be allowed. Our inspector would not pass any romex anywhere on a deck, even stapled directly under a board and most certainly not along the side of a joist. If your inspector is similar you will need a junction box at each end anyway. Adding a stub piece of pvc conduit cost a buck.

Edit:NEC 334.12(B)(4) NM cable, uses not permitted damp or wet locations
Additionally, depending on you locale you may have a problem, especially in the winter, with condensation from air flow from the interior of the house to the exterior in the junction box. You should seal the hole or sleeve from air circulating. NEC 300.7(A) discusses this.

[Peter Stahl]

Thanks for the replies. I'm looking using at least flexible conduit if that's ok? I need to talk to the inspector. I'm allowed to do my own electric which I'm surprised being I can't do any plumbing.

[Charlie Velasquez]

... I'm looking using at least flexible conduit if that's ok? I need to talk to the inspector.

Talking to the inspector is always a good idea. Draw a detailed plan and present it. If he is like the inspectors I have dealt with he will not be allowed to give advice. He can answer yes or no to a specific question and direct you to specific passages in the code book.

If in our area, concealed under a deck would provide significant protection.
If I were to wire it I would use nm (romex) inside, then if running under the deck parallel to the deck joists, transition to uf (underground feeder) in a plastic junction box on the interior of the building, stubbing a piece of pvc sleeve through the drilled hole into the jb, and add a bushing at the end of the sleeve, staple (plastic insulated saddles, switch out the attaching nails to stainless steel brads or short treated deck screws) the uf to the rim joist running to the closest deck joist, and continue stapling, then transition back to nm back inside the sunroom.

Or b) if running perpendicular to the deck joist -transition to thwn in the inside jb with the pvc sleeve, add a couple of 45° elbows to get you level with the bottom of the joist and run the schedule 40 pvc conduit straight across attaching to the bottom of every other joist, transition back inside the sunroom to nm.

If you prefer you could also drill a 3/4” hole in each joist and run uf cable the whole way, no conduit under the deck at all. Check with your inspector. Some want more protection than that if going perpendicular.