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I'm finishing my basement, done the framing and starting wiring for lights. One wall runs parallel to the joists, and has a double joist (two 2x8) above the top plate (the wall is right next to the stairs, running between several existing posts).

I want to put the light switches on this wall, but I'm not sure how best to run the wires. I can't just bore a hole straight up through the top plate due to the joists.

Is it code to run the wires around the top plate? I am planning to install crown moldings, would those suffice to protect the wires? I could notch the top plate, but the wires will need to go around the joist face.

Alternatively I can run the wires to through the wall and then back to an adjacent wall and run to the ceiling from there. However, there is a 4x4 post in the corner between these two walls. Can I bore two perpendicular holes through that post to allow me to run the wire at the 90 degree angle?

Edit:

Here is a rough schematic of the situation. The two walls are shown, with red marking the existing posts. The wall that runs between the posts is the wall that has the double joists on the top header. The desired location for the switch is in blue:

Schematics

Edit 2:

Here are a couple of pictures. The joists are painted black, so they're kinda hard to see, but the wall with the box in it has the joists running on top of it:

Wall

And this is the corner (with the 4x4 post between the walls):

Corner

Edit 3:

Would it be possible to notch the first joist, drill through the top plate close to that joist, run the wire through the gap and protect it with a nail plate? As far as I can measure the joist is 15' long, and this falls just under 5' from the edge, so should be outside of the middle 1/3 span. Is there any requirement for the height of the wire on the side of the joist?

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  • Can you provide a diagram or some photos of the configuration?
    – ThreePhaseEel
    Jul 17, 2017 at 2:15
  • @ThreePhaseEel added
    – Eli Iser
    Jul 17, 2017 at 2:20
  • Hmm...where are the actual joists located relative to where you're putting the box?
    – ThreePhaseEel
    Jul 17, 2017 at 2:21
  • The double joist runs on top of the posts (marked in red). I'll take a picture later today and add it.
    – Eli Iser
    Jul 17, 2017 at 11:33
  • Where do you want to run this wire to? Is this a switch loop from the fixture, or do you have multiple cables going to this box?
    – ThreePhaseEel
    Jul 17, 2017 at 22:04

3 Answers 3

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Raceway exists for a reason

These types of problems are why we have raceway systems we can run on wall surfaces, or inside a wall for a ways then have pop out of the wall. So, instead of running NM and using a cheapie plastic NM-only box, run EMT or surface raceway for the switch loop (and just the switch loop, you can stop at the ceiling box and transition to NM for the rest of the circuit there) instead.

With the EMT option, some cleverness with a conduit bender could even get you to sweep 45deg out of the wall down a little ways from the molding then 45deg as it enters the ceiling finish. With some finish work, and some black paint appropriate for galvanized steel, I'm sure you can give it just that little industrial touch.

Of course, this means you need to use a metal box for the switches, but that's no big deal, right?

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  • Could I then use both an EMT and regular NM? Basically splice NM and THHN in a junction box? So this box will be metal with an EMT, and run it back to the other box which will be hooked up with regular NM cable? I wouldn't want to run EMT through all the circuit (with all the lights and switches) just to handle that single odd case.
    – Eli Iser
    Jul 17, 2017 at 23:02
  • @EliIser -- yes, you can do that.
    – ThreePhaseEel
    Jul 17, 2017 at 23:29
  • I just thought that perhaps notching the first joist would work. I update the question with the description, if you could have a look.
    – Eli Iser
    Jul 17, 2017 at 23:48
  • Ran a conduit at the back side of the wall (under the stairs), with bends to bring it in-line with the studs. NM in conduit with plastic bushings. This was suggested by the AHJ and passed rough electrical inspection today.
    – Eli Iser
    Sep 14, 2017 at 2:19
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After explaining this to the AHJ, he proposed running NM in conduit around the back side of the wall. This took some creative bending (me being a first time conduit bender, at least), but the end result is solid and passed rough electrical inspection:

Conduit exit Conduit run Conduit entrance

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Can the wires run on the opposite side of the joists than the finished wall? If not I think you are going to have to build a small "box" in the corner to bring the wires down into the wall.

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  • The other side are the stairs, so sadly, no. I also was thinking about framing a box around the wire, similar to framing around pipes or ducts.
    – Eli Iser
    Jul 17, 2017 at 19:59

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