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I am remodeling my bathroom and am bringing in a new 20 amp circuit.

I want the box on the bottom to contain the GFI outlet. The box on the top will house the connection for a hardwired lighted makeup mirror.

My issue is that I want to bypass the top box and bring the wire into the bottom box first and then into the top box. My issue is that I have very limited space. As you can see in the picture, the two boxes barely fit between the studs as it is.

I can't run the wire on the left stud and then bring it up because there will be a pocket door there. On the right stud it's the corner of the wall.

What are my options here?

Should I use a shallow box for the top box and run the wire behind it to the bottom box and then back up?

Can I run the sheathed wire through the top box down to the bottom box and then bring it back up to the top box?

Should I try running the wire down the adjoining wall and running it through the corner then bring it up?

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  • Why do you want to bypass the top box first?
    – Trevor_G
    Mar 2, 2017 at 19:52
  • Or are you saying you want to run the light from the GPI output line.
    – Trevor_G
    Mar 2, 2017 at 20:04
  • Yes, I'm saying I want to run the top box off of the GFI outlet. Mar 2, 2017 at 21:23

4 Answers 4

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The box must be large enough for the wire fill and device by code since you are installing a 20 amp circuit it should be #12 wire. #12 wire has a volume of 2.25 per conductor and 4.5 for the device so if you use a shallow box and only run the 3 wires into it the box volume would need to be 11.25 sq inch (listed value not measured) if there is enough room to put the wire to the back of the box and still have 1-1/4" to the face of the stud this would be legal. If you run through the box without a splice the volume would need to be 15.75. You only count 1 ground wire in the box. I did not add a clamp volume of 2.25 because these look like non clamp boxes. And the cables will need to be stapled within 8" of the box, 12" with clamps.

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Can I run the sheathed wire through the top box down to the bottom box and then bring it back up to the top box?

Yes.

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I would pigtail at the first (top) box and continue to the second box. Essentially wiring in parallel.

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  • I want to run the top box off of the GFI outlet though. Mar 2, 2017 at 21:23
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You have basically two choices.

  1. Route or chisel out a channel in the edge of the 2x4 beside the box so there is room to put the cable outside the box.

  2. Run the cable through the top box down to the bottom box and back up.

Or I guess door #3..Put the outlet above the light switch.

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  • You could use a shallower box for the top box and run the cable behind it down to the bottom box with the GFCI and then out the top of that box to the upper box. I don't know if code allows running cable behind a box and so close to the drywall on the back side. I can't see why this would be preferable to running the cable through the upper box except that to run it through you'd have to break off the two of the integral plastic tab clamps to avoid having a space hogging loop in the cable. Mar 2, 2017 at 22:13
  • Only issue would be if the switch filled the box to the extent that there was no room for the cable without over-cramming it. Which would be more of a problem with the GFI rather than the switch. @JimStewart Me.. I would go with #2 or #3.
    – Trevor_G
    Mar 2, 2017 at 22:22

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