Can the white wire of 14/3 cable be used to supply power in a 3-way switch...

soup_sam

I have a typical single pole toggle switch controlling a set of under-counter LED lights in my kitchen. The power source cable runs to a wall box, connects to a switch, which is then connected to the LED load. I want to add a second switch for the lights on the other side of the room, but there is no available power near the new switch location. Typically, one would run 14/2 cable to the new switch location, and run 14/3 from the new switch...

Originally asked by Blaise on Stack Exchange (diy) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

You used to be able to do this, but now you probably can't. (Depends on which NEC code your local authority uses, so ultimately you'll have to ask them.) For a long time, the three wires in "/3" cable could handle the two travelers and the return power to an light control circuit being changed from single-switch to 3-way. Wrapping the white wire ends with black tape/marker was a legitimate way to do this. However, with the advent of smart switches that require neutral in the switch box, now NEC requires all light switch cables to provide neutral in the box, in case a smart switch is installed. So if your local authority uses the version of NEC that has this "neutral in the switch box"...

Full answer by Triplefault: https://diy.stackexchange.com/a/333596 (CC BY-SA 4.0).

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