I have a 3 way switch that looks like it's wired like the illustration below. I would like to remove the switch shown on the left and replace the switch shown on the right with a Zwave switch that requires a neutral wire connection.

3 way switch wiring

In my configuration, there is a second switch in the box on the left (which I am leaving alone) and 4 white wires which seem to be neutral, all connected with a wire nut. There is also a second switch controlling a different load in the box on the right which is connected to a different breaker (and different breaker box) and which seems to be wired as shown in the photo below.

single switch wiring

Ideally, I would like to also eliminate the second switch on the right and control that load using the same Zwave switch which will be placed in the box on the right. The big problem in all this seems to be that the box on the right does not have a neutral wire. Can anyone think of a configuration that would allow:

  • BEST CASE: Both loads to be controlled by my Zwave switch in the box on the right.
  • PLAN B: Leaving the single pole switch and load alone and only replacing the two three way switches with my Zwave switch in the box on the right.

Any help is much appreciated.

2 Answers 2


If I understand your description, here is one way to alter your wiring:

suggested Zwave circuit

Basically you use the existing white wires to extend the neutral node everywhere. Use the black wires to extend the unswitched hot all the way to the Zwave. Use the red wire in the third leg to bring the switched hot back to the first two lamps, which have their hot sides connected with the other black wire in the second leg.

For the last lamp on the right, disconnect it from its breaker supply and cap off the supply cable. Then re-use its former switch cable as a switched loop now powered from the Zwave. Check the total load on the breaker that supplies the box on the left, as you are adding one lamp to it.

As you see, you have more wires than you need. Cap all abandoned wires with small wire nuts. Don't just clip them short, I did that once and got a rocket from the inspector.

I have omitted the ground wires (the bare copper) but of course you will not.

Please allow me to express my extreme gratitude to you for providing me with the opportunity to draw yet another wiring diagram.


If your wiring is connected as shown in the first picture then you will not be able to put the Zwave switch in the right hand box. The reason being that there is no neutral in that box. To be able to use the Zwave switch you would need to add another Romex cable run from the right switch box up to the light box where the neutral is present. You could either replace the existing 12-3 cable with 12-4 or run an additional 12-2. In either case I would swap the existing white wire that has the black tape markers and use that for the neutral connection and use the black or colored wire in the new cable run for the 3-way switch traveler.

If the independent light switch is really on a separate circuit as you describe then:

  1. The neutral of that circuit should NOT be connected to the neutral of the 3-way lighting circuit.
  2. You would NOT be able to convert that independent light for operation with the 3-way circuit without running more wires and sourcing the power for that light from the source that feeds the 3-way circuit.
  • OP plans to remove the switch on the left rather than retain 3-way operation. Feb 12, 2016 at 10:10

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