Forgive this crude diagram

enter image description here

Is this allowed in the US?

Can I use the white and black wires of a ROMEX wire as the two ends of black wire to the switch and take the white (in red) wire to the terminal of the recessed light and in the metal junction box of the recessed light twist the black wires together using a wire twist on.

Otherwise, I would have to run 2 romex pairs to the switch and twist the white wires together there. This was would seem to save me some ROMEX.

  • 3
    You could buy 12-3 NM-B (aka Romex) instead (black, red, white, and bare copper) to accomplish what you want and still have a ground wire. A lot pf smart switches require a neutral wire if you're looking to future-proof. If you are doing a lot of switches, buying a roll of 12-3 to have on hand in addition isn't too much of a cost adder. Oct 9, 2017 at 23:46
  • 1
    You'll want to have /3 NM on hand anyway for 3-way switches and ceiling or bath fans...so yeah, don't try to skimp here Oct 9, 2017 at 23:51

1 Answer 1


Not any more. You are describing a two-wire switch loop that used to be allowed, but now is not.

First your diagram shows black and red wires. One of them should be white (neutral), the other black or red (hot).

Current code requires that switch boxes have a neutral wire, not just a hot and a switched hot. This is required, even if your switch doesn't currently need a neutral. The next device you put in that box might.

Standard practice now is to use 3-wire (black/red/white + ground) cable to the switch. Black and red are the active lines, and the white is capped off if not needed.

  • Thanks - I'll research it - If you know of a diagram, that would help. Having trouble picturing this now. PS - In my diagram, the red is the neutral. (White background so I chose to make it red -- poor choice of color)
    – Matt
    Oct 10, 2017 at 0:00
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    Oh - I think I get it - The black is the black and the red is the switched black return from the switch. Then you cap off the white in the switch junction box. because you're not using it on the switch ?
    – Matt
    Oct 10, 2017 at 0:10
  • Yes, you got it.
    – bib
    Oct 10, 2017 at 0:35
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    I started to formulate my idea for an answer and fhe first words were going to be "not any more" :) Oct 10, 2017 at 2:13
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    @Matt I use gray or light blue for neutral since gray is the other legal neutral color in North America, and light blue is neutral everywhere else. Red and black were correct for UK/AU/NZ, but red was hot. Oct 10, 2017 at 2:16

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