Electrical – How to run more than 2 circuits in conduit


My understanding of color coding allowed by NEC is:

  • Ground: Bare, Green or Yellow/Green
  • Neutral: White or grey
  • Hot: All other colors

If I need to run 3 distinct circuits in conduit, I might choose:

  • Ground: Green
    • Of course, if I'm using metal conduit & boxen, I can skip the ground wire entirely and use the conduit for the ground.
  • Hot: Black, Red, Blue
  • Neutral: White, Grey, and ???

I can pair the White/Black and the Grey/Red, but what do I pair with the Blue to provide a neutral for it?

In thinking about this, I believe that a MWBC could be a way around this, but I'm not certain if that technically only applies to cable (i.e NM-B/"Romex"), or if MWBCs can be used in conduit-based wiring as well. Additionally, from what I've been reading here, there's a strong trend away from them, especially for GFCI/AFCI protected circuits since handle-tied *FCI breakers are somewhat unobtanium.

Note: This is purely a theoretical question. I do not have an actual application for this at this time. I'm simply trying to learn ahead of a home addition/remodel that's coming up.

Best Answer

You can mark the white or gray neutral wires with colored tape. Unlike marking a switch loop wire in cable (where it changes white from neutral to hot), this does not change the function but is simply an identifier. Real simple:

  • Black + White or Black + White-with-black-tape
  • Red + White-with-red-tape
  • Yellow + White-with-yellow-tape
  • Blue + White-with-blue-tape

Of course, the colors don't have to match like that, but that would make it super easy to keep track of things.

With only two different circuits, yes white & gray as two different neutrals makes sense. Once you get to taping things, it is arguably easier to use white for all neutrals instead of having two different colors, but that depends on how much wiring you do.