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At the top and bottom of some stairs are two connected light switches (a 3-way switch).

The top switch has:

  • bare copper ground
  • unused white neutral (in back of box; two wires in a wire nut)
  • 2x black wires
  • red wire

the bottom switch has:

  • bare copper ground
  • black wire
  • white wire
  • red wire

My goal is to remove the bottom switch and replace the top switch with a new switch which requires a neutral connection.

(My original plan was to replace the existing switches with a brand of smart switches that require a neutral for both the main and secondary switch. Since the bottom switch doesn't have a neutral, I've decided to instead hard-wire and plate over the bottom switch, then surface-mount a battery-powered smart touch switch in that location.)

So far...

In both switches: I'm assuming the red wire is the traveler wire, and have capped it off in both switches.

In the bottom switch: I used a wire nut to hard-wire the black and white wire together. The copper ground is just hanging loose in the box.

As-is, the top switch operates the light as expected.

The problem:

When I replace the top switch the switch is unresponsive and the light is hard-wired either on or off (depending on wiring).

If it matters, the switch is:

GE Z-Wave Plus Wireless Smart Lighting Control Smart Dimmer (model # 14294 )

(and in my defense I've put in 4 of these exact switches elsewhere without issue.)

The important part of the switch, I think, is that it requires, and is wired as:

  • ground (connected to bare copper)
  • neutral (connected by adding a short wire into the existing wire nut in the box where the white lines were connected to each other)
  • load (one of the black wires)
  • line (the other black wire)

I'm not sure which black line is which, so I took a guess, then flipped them when that didn't work.

In one position, the switch is non-responsive (and its LED is off) and the ceiling light is on. In the other position, the switch is still non-responsive (and LED off) and the light is off.

(In the meantime, I've put the old switch back in at the top and it works as a normal 2-way switch.)

Photo of original top switch wiring: added: photo of original top switch wiring

  • Can you post a photo of the inside of the box for the light that these switches control? – ThreePhaseEel Dec 28 '17 at 1:11
  • Also how old is this construction? (Thinking California 3-way for those wondering why I’d ask) – Tyson Dec 28 '17 at 1:51
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    I don't think that white is neutral in this case. In your top picture the screw on the right side showing appears to be the common terminal. The black feeding it should be always hot, regardless of switch positions. The remaining red/black form a pair of travellers going downstairs. If that is true, it makes the white in this case the load, not the neutral. If this were done today the white would be marked black by wrapping it with tape, that convention was not well established in the late 80's tho. – Tyson Dec 28 '17 at 3:55
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    @ThreePhaseEel that's possible, but if thats case it would be fed from above typically, not here. It seems like this was wired as an upstairs single pole switch loop, then turned into a 3-way with a /3 from the top to downstairs. – Tyson Dec 28 '17 at 4:03
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    With the light (load) turned ON measure voltage between the black screw of the switch, and the white to white wire nut. If you get zero my theory is correct. – Tyson Dec 28 '17 at 4:43

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