So the 3 wires going to the 3-way switch (all of which are occasionally hot) would be black, black, and black (both travelers black and switched power black)? And then steady power to the 2-way switch black and switched power coming back from that switch black? So 5 blacks in the conduit? At the non-switch end wouldn't that be confusing for someone trying to figure out what they each are?

A thought: I could get some red single conductor. Then I could distinguish the 5 wires by:

1) red with black tape on the ends

2) just red

3) black with red tape on the ends

4) just black

5) black with 2 bands of red tape (or maybe get another color of tape--which?)

That avoids white and makes it easy to know which wire at one end of the conduit is connected to which wire at the other end. What do y'all think?

I would do what you suggested, but perhaps one step farther: red for switched lines, black for unswitched power, and, if you have more than one circuit in the same conduit, another dark color for unswitched power. I also use numbered tape wrapped around each wire.

Thanks, mtvhike! When you say "more than one circuit", you mean off of more than one circuit breaker, right? No, all the power in this conduit is off of the same circuit breaker.

I'll order up a roll of red wire and perhaps some blue tape so I have enough different color combinations.

What color wire for the travelers?

What I'm suggesting is perrsonal preference, not code. The only code requirement is that any wire carrying power must not be white or green. So all power carrying wires, switched or not, can be any color. Most people are using Romex or its generic equivalent and the only choices are black and white, or black, red, and white, plus ground. Since you're pulling individual wires, you can use whatever color you want (except for white or green). As I said above, I like black for all unswitched power and red for switched power. Other colors, when available, to distinguish other circuits. Could be on the same breaker (with different destination) or not, but I can't think of a reason for two circuits on the same breaker (except for switching). If you don't want to use more than one additional color (red, in your case), you can distinguish different circuits with colored tape or numbered tape (at both ends of each wire, of course).

Thanks, mtvhike. I appreciate hearing your personal preference since that may be the personal preference of someone years from now who needs to troubleshoot something of mine when I'm dead and gone.

I'm ordering some red and I'll use that for the travelers. And I'll order some blue tape so I have more choices of labeling.

You bring up a different topic: 2 circuits on one breaker:

I actually can think of a reason to have 2 unswitched hot wires from the same breaker to the same box. That's the situation I described above. The 12/3 has an unswitched hot wire and another 12/2 cable has an unswitched hot going to a receptacle. Both cables first make a stop at the same box. So you could in theory use 12/2 for the travelers since you have hot from the 12/2 romex for the receptacle going to same box. It would work.

But I know an inspector who would object. He would talk about magnetic field canceling. The 12/2 for the travelers would have a strong magnetic field around it and would induce currents in the box (if it were a metal box) where it entered the box. By instead using 12/3 with its own hot wire (and keeping that hot wire separate even inside the box from hot wire from the 12/2 for the receptacle), the current flowing down the hot wire in the 12/3 is exactly equal and opposite to the current flowing in the travelers. Thus this 12/3 cable entering the box would induce no currents in the metal. The same problem is solved for the 12/2 for the receptacle where it enters the box. (I don't know the code line that requires this, but that inspector probably does.)

I don't think magnetic fields have any effect. I'm not sure what you are proposing, could you post a sketch. In wiring my old house 25 years ago, I used 12 Ga for 20A circuits to receptacles and 14Ga for 15A circuits for lighting. They frequently ran through the same conduit for part of their journey. And, of course, they had separate breakers.

Hi, Mtvhike, I would have to learn to post a sketch, but here is a much simpler example that doesn't need a sketch: Suppose you had 2 parallel sticks of EMT and you ran the neutral through one of them and the hot through the other. My inspector would object for the same reason--the magnetic fields of the currents not canceling each other.

I think your inspector needs to better understand how electricity and magnetism work!!!

First, I do want to say that I am so grateful to all you guys for your good suggestions and guidance. So it is with good spirit that I am continuing this discussion:

I did find the code item that refers to the induced currents from the magnetic fields that my inspector was referring to:

300.20 "Induced Currents in Metal Enclosures or Metal Raceways". I also notice that my code textbook "Electrical Wiring Residential, 14th edition" p. 135 shows various legal and illegal ways of wiring: the legal are where the conductors are arranged so that the amount of current flowing in one direction is exactly equal and opposite to current flowing in the other direction.