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I'm trying to hook up an always-hot outlet coming from the 2nd 3-way switch, which that switch controls a light.

I'm thinking if I connect the black wire from the outlet cable to any of the 3 wires in the box (the red traveler, the black traveler, or the black switch leg), then the outlet will always be flipping on or off depending on the switch's state.

As an idea, I'm thinking of splicing the red and black travelers with the black from the outlet cable and that should provide power constantly, but I can't find anyone online doing this. Would this work? Is there a better way?

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    Without an always hot wire running to that point you can't. Joining the travelers together will completely defeat the 3-way switching and the result of that will be that your light becomes always on. – brhans Nov 1 '16 at 15:06
  • You're right that the travelers spliced would create an always-on state for the light. I guess there's not way to do this from the 2nd switch. I could see doing it from the 1st (left most) switch in my diagram, as there'd be an always-hot wire coming into that box. But the 2nd switch seems impossible to feed other circuits from? – Tony DiNitto Nov 1 '16 at 15:11
  • How much room do you have in the 2nd box? What you want to do is possible, if you're willing to blow some money on a relay and swap some wires around...\ – ThreePhaseEel Nov 1 '16 at 23:08
  • @ThreePhaseEel I'm interested to know what you have in mind. If there's not enough room in the box, I can always replace the box with a larger one, since ripping down the walls to run another power/line is not an option. – Tony DiNitto Nov 2 '16 at 1:26
  • One other thing -- how many watts of lighting does this switch setup control? – ThreePhaseEel Nov 2 '16 at 2:29
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Due to the way the three way switch is wired, you will not be able to do this. Either, your outlet will turn on and off with the switches, or you would essentially render the switches "Always On" (By connecting both travelers together in the outlet). Regardless, your best option is to run a new line to the outlet. See the diagram below:

3 Way Switch Diagram

You should be able to daisy chain off a nearby outlet so you don't have to go all the way back to the breaker box. Good Luck!

  • What, relays weren't invented in your world man? – ThreePhaseEel Nov 4 '16 at 1:46
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This isn't as impossible as it sounds -- boy, do relays sure come in handy!

Alright -- I need a bigger box at the 2nd location, to begin with. Plastic boxes don't generally have conduit knockouts, so we'll use a metal box here -- a 4 11/16 by 1 1/2" square box with a 1/2" single gang mud ring will do the job in all cases, or I could use a 4" by 1 1/2" square box with a 1/4" single gang mud ring if I had all 14AWG cables. I'll also need to use NM clamps that clamp the cable on the outside of the box as box fill is critical here. Finally, make sure to leave one side of the box completely open, with one of the 1/2" KOs on the ends pried out to fit the relay I'd then put in as the last step before installing the box into place -- I'd use a Functional Devices RIBU1C here as it's relatively inexpensive, easy to install and wire, and amply rated for the task at hand, as well as being fully UL listed, which most off-the-shelf relays are not.

Once the box/relay combo is installed and mounted, I'd then wire it up -- all grounds go together of course (box pigtail, switch pigtail, and all three cable grounds). From there, the black wire to the outlet goes to the black wire from the first switch as it will become the hot feed later, as well as the yellow wire from the RIBU1C. The blue and orange wires from the relay go to the traveler terminals on the 2nd 3-way switch, while the white neutral wires all nut together along with the white/yellow striped wire from the relay. Finally, the white/black wire from the relay goes to the red incoming wire from the first switch, the white/blue wire from the relay gets capped off with a nut, and the common terminal on the switch goes to the black wire going out to the light.

I'd then button up the first box (carefully, as it'll be quite stuffed) and move onto the other switch box, which needs a trifle bit of rewiring now to make everything work as intended. The wire to the common terminal of the switch gets removed and hooked to a pigtail which goes to the common terminal, and also is attached to the black wire going to the other switch box, which is also disconnected from the switch. The existing white and ground wires are left intact, and the red wire remains hooked to the switch.

Once everything is buttoned up and turned on -- the first switch should turn on and off the relay, which acts as a stand-in for the first switch, only located remotely off in the 2nd box, freeing up one wire to serve as a hot feed while the other switches the relay on and off.

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