3-way switch replacement: puzzlement

So today I was planning on replacing the 3-way dimmers from the earlier project. This should be really simple, I obtained a GE 45857 (zigbee dimmer) and a GE 12723 (add-a-switch). Just need to pop the old ones out and replace me thinks.

So, trip the breaker, open them up and... WTF? There is only 3 wires in each box.

Now, how could this be? I need a neutral, traveller, hot, heading towards the light, and a neutral + hot coming from the supply.

So, power back on, meter out. On the upstairs switch we have: W-B: 110VAC, W-R: 0, R-B: 0. OK, makes sense, i have line/neutral and a traveller.

But, how would this work? Somehow the neutral arrives at the light some other way, and the traveller goes naked to the other switch? But no, the other switch has 3 wires too.

Anyone have any input? I asked the great hive-mind of reddit too.

2 comments on “3-way switch replacement: puzzlement
  1. db Mike says:

    I believe your light has the live. Figure out what wire is live by checking your meter against R/W/B wires against ground. I suspect one of the sides will show that white is actually live, which means neutral is provided at the light.

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