I'm replacing the following:
enter image description hereenter image description here

With this one: enter image description here

But since there's not a white, I have no idea which is neutral. I tried hooking it up as pictured, but only the red wire had any power (and the switch wouldn't work).

This is a GFCI (I think) - its circuit powers the garage doors too. enter image description here

If I put the red in "line" and what was in "line" instead into "load", I at least get the led on the switch powered but the lights don't actually work.

I can confirm at least that (from the picture of the new outlet) the red and "line" wires are in the same sheathing from the wall.

Any guidance would be appreciated!

  • Can you post photos looking into the backs of the switch boxes in question? – ThreePhaseEel Jun 17 '18 at 1:43
  • Not sure how helpful it'll be, the spray painted everything in the boxes white :/ – ctote Jun 17 '18 at 1:47
  • you should be able to carefully peel the paint off the wires without harming the insulation too badly – ThreePhaseEel Jun 17 '18 at 3:08
  • This is a GFCI (I think) .... it has to be This is a GFCI (I am 100% sure) before you do any work – jsotola Jun 17 '18 at 6:03

We have to go by what people say and show us, but it seems like you're really stretching the limits of your knowledge to do this safely. That said, you have to start somewhere, so here goes.

First, the "old switch" is a 3-way switch. You surely know this light is controlled from 2+ locations. I suggest boning up on how these circuits work, so that you know what you're looking at and so you'll be able to reassign these wires to what the smart-switches need, since I have a feeling the other end will be involved too.

enter image description here

Traditional 3-ways have 2 travelers and 1 common. The 2 travelers are always in the same cable, so it's that red and the black that is with it. Clearly the other black is in a different cable since cables don't have 2 blacks.

They all have whites though, where are they? No doubt pushed into the back of the box and nutted together, these are your neutrals - probably. You'll need to pigtail off those to obtain your smart switch's neutral.

Traditional switches don't have neutral screws because they don't use neutral.

Note that wire color does not correspond to wire function. 3-way circuits especially. For instance your travelers are red-black; I prefer them yellow-yellow and will typically mark them that way with colored tape.

Hopefully armed with that knowledge you can fit what you have to the wiring diagrams in the instructions. You are required to obey the instructions when installing the product (that's in Code; NEC 110.3).

It may be worthwhile to go to the local library and get a book on wiring home electrical, and read a great bulk of it through. This will give you a well-rounded primer on the subject. Won't answer every question, but we're here.


Regarding the original 3-way mechanical switch. The energized (normally black) line wire connects to the dark screw, the traveller wires connect to the light-colored screws, and the ground (bare/green) wire to the green screw. The neutral (white/gray) wire is unswitched and and not connected to this passive device. You should expect to find two or more neutral wires bonded with a wire nut inside the switch box. If this switch is on the end of a switch loop it's possible that there is no neutral wire run to this switch box.

Your new smart switch draws power from the line wire and sinks to a neutral wire. This is why the NEC now requires a neutral wire in every new switch box even if it is unused.

If there is no neutral wire in this switch box you'll need to find another solution. Perhaps you can install the smart switch in the other 3-way switch location? Failing that, you may have to look for a suitable switch that draws less power and it approved to use the ground wire as a phantom neutral. There are some units like this (for example as timers and such) but I don't know if there are Z-wave switches of this kind as they may require more power.

  • I realized I was wiring the wrong outlet. The right one doesn't have a red. No matter which wire is in line and which is in neutral, I get power bleed (light remains on, but dim) when the switch is off (both black wires). Is this due to no nuetral? The house was just built last year. – ctote Jun 17 '18 at 0:58
  • Further, would I be safe to try one black in 'line' and one in 'load'? – ctote Jun 17 '18 at 1:01
  • 2
    Guessing and trying different combinations is dangerous. I suggest diagramming what you have, posting pictures of the inside of the boxes. If we can’t help sort it out remotely it may be best to hire a qualified electrician. – Stanwood Jun 17 '18 at 1:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.