I have existing 3-way switches controlling two LED bulbs (sockets). My initial attempt at using Z-wave switch was with a Enbrighton brand where I learned about the “Neutral wire required”. I obviously had to return the product as it wouldn’t work.
This is what I’m working with is pictured below, there is nothing else in the junction box.
I was asked not to replace the other switch. Looking for a suggestion for a switch that might work, or perhaps an alternative idea – would a relay be appropriate here or in the junction box with one of the lights? Unclear if they have a neutral wire requirement as well.
You would need to open the other switch box and find out what you are dealing with, exactly.
There are multiple ways to wire a 3-way (and some are now no longer to code) so you’d need more information. Depending on what you have, you MIGHT be able to put the smart switch in the other box, and leave the dumb 3-way switch in the box in the picture… but we’d need more information. Also what is the age of the house - it may help clue us into what you are up against.
The alternative, of course, is to use a relay like a ZEN51 at the light fixture. (There has to be a neutral at the fixture otherwise the bulb wouldn’t light up.). Although you said both “bulbs” and “sockets” - is this one light fixture, multiple, or are they outlets with lamps connected?
Thanks for the reply. The house was built in early 1980’s, but unclear when the basement was finished. I bought the house in Nov 2025 and have no working knowledge of what’s behind the walls or how its connected. I have 44 circuit-breakers in the box and pretty much nothing is labeled. It’s a discovery process.
The LED lights being controlled are two ceiling mounted units. One is a self-contained array of LEDs hard-wired with a cover. The other is a socket type with E26 based LED bulb screwed in it.
I tried the Enbrighten Z-wave switch here too, didn’t work. Exhibited the same behavior as when installed in the other box – the Z-wave switch LED backlight would turn ON or OFF when position toggled and the LED bulb in the socket would flash on for a fraction of a second and turn off.
My father is retired electrician from ConEd and we checked the voltage of each wire to ground in all the possible switch combinations. He pretty much said “That’s weird”, “that’s wrong”, but “but not unusual” (He felt who ever installed it, got it working and said ”good enough” without an understanding of how its supposed to work). I didn’t capture all the details, but he felt something else either feed or perhaps from the bulb was wired wrong and the black was acting as a possible neutral (didn’t have time to test/check all of that). But we did a quick re-wire with assumption black was neutral, had black/black in wire nut and two white wires to 3-way switch:
Turned power on and tested with both existing 3-way switches and it operated as expected, turning lights on/off using any combination of the switches. Replaced this switch with the Enbrighten Z-wave switch with a pigtail/jumper to the assumed neutral and it didn’t work – exact same behavior. Switch backlight turns on/off when operated, the room LED bulb flashed on for an instant on turns off. Removed that switch and sent it back.
You’re on the right track tracing out the wiring! It is amazing how do-it-yourself types don’t always know how to “do it right” or, as @getoffmylawn states, how the electrical code has changed over the years.
Once you know exactly how your lights are wired and have drawn diagrams, you have a great starting point to see what Zooz switches might work in your specific situation. Should all that not work out, using a relay at the light fixture end of the whole thing could be an option–but address the switch approach first!
Here are a couple of Zooz support articles that should provide you with food for thought…
Also, I have found the Zooz support folks to be very helpful, so don’t hesitate to contact them. @Sara is often here on the forum and may chime in with additional suggestions.
Yes, this is good info. And @Barkis 's diagrams are a huge help when thinking this through.
Studying your diagrams I think I have a theory on what you have - a modified double dead-end 3-way! No longer code compliant. Check out Backyard Maine for great videos on this stuff. Here’s a link to the dead end and double dead end three way: https://youtu.be/dg-4wj3JF3U?si=l6QU-DSNmqYJzer8
In your case, I think it is modified to put the power source to the light, and then the 14/2 to your switch #2, with a 14/3 between box 1 and 2. My guess is that this was a traditional one-way loop switch, which they modified later to be a three-way!
You should verify this of course. Here’s a diagram (sorry for my handwriting) of what I think you might have:
That makes sense. Thanks for the clear explanation. Researching the ZEN51, the sample wire diagrams don’t show it installed in a light fixture. Have one handy? If not I’ll reach out to support.
I attempted to draw this quickly and spare you more of my handwriting. Here’s an example of how the ZEN51 could play a role - this again assumes my guess at your wiring is correct. Please verify before following!
S - the switched 120v line from the two 3-way switches (this senses what the non-smart switches are doing)
OUT - the hot (120v) wire to the light fixture
IN - 120v from the power source (breaker)
L - 120v from the power source (breaker) (to power the relay itself)
N - Neutral from the power source (to power the relay itself)
I made a dashed box illustrating what could all be in the light fixture. Note your box will need ample room for all of this and the associated wire nuts/wagos, etc.
You’d also likely want to set Parameter 7 to value 0; so each time the input from the dumb switches change, the light state toggles to the other option. This will be the most natural assuming some zwave control happening as well. I hope this helps! ZEN51 Dry Contact Relay Advanced Settings - Zooz Support Center
In thinking about using the Z51, I look at each of the two lights controlled in the 3-way. This is the socket type with E26 based LED bulb screwed in it. It’s just a black and a white wire, the ground isn’t even hooked up. I assume this is not enough for the Z51 to work with.
The 2nd option is the LED light fixture. Much more going on, I assume the Z51 can work here, I’ll replace the wire twist caps with WAGO connectors to get more room.
Thank everyone for the help. Success! To help whoever else stumbles upon this thread, I made a drawing of what was in the Option 2 box. This is my before making modification reference so I could undo any mess I made.
I then decided to draw out what the changes needed to look like as a reference when installing it. For me this is an easier way to account for all the wire connections up front.
I apologize for the sloppy notes on the side… but needed to track things. I had an assumption that things would just work without configuring the ZEN51 Relay, I thought I could test switches and see lights come on/off before doing any Zwave work… that was not the case.
No lights worked initially.
Switches did not toggle lights ON.
ZEN51 had a green light flashing.
I pressed the Z-Wave button 3 times and the lights turned on (my first clue that it might not work without configuration) testing the toggle switches still would not turn the lights OFF.
I paired the device using Zwave-JS-UI and notice the firmware updates available. Upgraded firmware from 1.70.0 to 1.90.0.
While in Zwave-JS-UI I set Parameter 7 to 0 (zero) as suggested by @getoffmylawn.
Only after setting Parameter 7 the toggle switches start working. It was tight getting everything back in place:
