3-way switch in conduit

[dmcintosh]

I posted previously about my work project - finishing off a shipping container to be a portable aquapoincs lab. Working on running my conduit now (PVC). My lighting circuit will have a series of overhead 4' sealed fluorescent lights in series between two three-way switched (one at each door). Power will be fed from one end (i.e. from the panel) to the first switch, then to the lights, with the last switch at the opposite end. I've run 3-way switches before using NM 12-3 and 12-3 with success and easily found diagrams for how to wire that arrangement up. Does anyone know of a better diagram to reference when using conduit and THHN? I currently have access to white, black, green and blue wire, all 12-ga copper.

 

[walrus]

Its no different than doing it with 12/3 except the red in 12/3 is blue in your conduit

 

[dmcintosh]

In most of the diagrams they have an additional white wire they tape to mark as hot. Is it better to use the same color here and add tape or another blur or black wire?

 

[Terry D]

If all of this is going to be in conduit, there is no reason to use a white going to the switches. Use a black feeding power to your first 3-way common screw, use 2 blues to connect the travelers and a black on the 2nd 3-way common screw to go to the lights. The white will just be the neutral for the lights.

 

[dscheidt]

In most of the diagrams they have an additional white wire they tape to mark as hot. Is it better to use the same color here and add tape or another blur or black wire?

If this were wired by an electrician around here, you'd have a red or black feeding the first switch, a pair of purple, pink, or orange wires as travelers to the second switch, and a blue, brown, or yellow from that switch to the fixture. You can make those wires all the same color, it doesn't matter to the electrons. to someone trying to figure out what the last guy did, it's a lot clearer if they're color coded. (if there are multiple switches in the boxes, the second and third colors get used, if they're available. Again it's all about ease of hookup and future troubleshooting.)

The only reason wires get marked with tape is because they're using cable, and you're stuck with what the cable is made with. In conduit, there is no such limitation, and you may not re-identify a white conductor as something else. If you reidentify a white in a cable, it must be always hot, and not a switch leg.

 

[wyliesdiesels]

no need nor is it permitted to use white in conduit for anything other than neutral.