Zooz ZEN21 and 3 Way Switch

My building is almost 30 years old, and it have neutral wiring, and I thought wiring these are straight forward. I have no issues installing the switch on the single pole in the kitchen. But the 3 way switch wiring is odd and doesn’t look like anything in the manual: I have 2x red, 1x black on the switch. Let me explain the 2 switch boxes:

Main box - It has two white wires capped together (i think this is neutral), two black wires capped together, two bare wire capped together. I do not know what are the capped wires connected to. On that 3-way switch, there is a red wire to the black screw, white and red wires on each brass screw.

Remote box - It has 4 wires (white, black, red, bare) coming out of the box. There are no capped wires. On that 3 way switch, black wire connected to black screw, red and white wires connected to brass screw.

The ZEN21 is installed on the Main Box, I have noticed the following: If I connect the red wire to LINE, white wire to TRAVELER, red wire to LOAD and white to NEUTRAL, the blue LED does not lit. If I swap the wires between LOAD and LINE, the blue LED comes on. The switch will operate, if I turn off the remote switch, it literally cuts power to the ZEN21. If I alternate between LOAD and TRAVELLER, the remote switch will cut power and the ZEN21 is cannot turn the lights on.

Now I revert everything back to the manual Leviton swithces, I want to know what you think. What makes the manual switches work but not the ZEN21? I am under the assumption the LOAD/TRAVELLER can alternate like their manual counterpart?

Do I need to hire someone to rewire the place up?

The “literally cuts power” to the master switch is how many nonnetworked three way switches are wired. It’s a sort of figure 8 on its side and when one Switch completes its side of the circuit the other switch is dropped out of the circuit.

Obviously, this will not work for network switches where the master needs to have power all the time so that the radio can hear the next on switch.

For this reason, network switches off and have to be wired somewhat differently then the switches that they are replacing.

Why don’t you take a look at the GE wiring FAQ and see if that answers any of your questions. Although I think the Zooz does allow for the possibility of using a dumb auxiliary switch, which the GE does not, the basic wiring concept is still the same.


Thanks, I will review the diagram.

You are correct that when I turn the lights on, usually light close to the main turns on, then half a second later the other one will turn on.

I got a reply from Zooz with this diagram but it seems that option 3 is close to what I have. 3 Way Diagram

There is another thing is that one breaker controls all the lights in the bedroom, I think the capped black wires are connecting to washroom lights and the light fixtures. I think if I have to re-do the wiring between the switch and the light fixture, I will get an electrician to look at it. That will be my last options of course because I want to learn something new.

something is weird with two red wires on one switch. Can you take pictures?

I agree this is odd, I have 3 sets of these 3-way switches that are installed in similar manner. I’ve done some testing myself, disconnected all the wires on the main switch and check of voltage (i left the remote untouched). The red wire with masking tape always carry a voltage. The white and other red wire will carry voltage alternately, meaning if I flick the remote switch on and off, the voltage will alternate to either red or white. At any time I will have 2 wires that has current.

Does the switch control one light fixture only or is there a fan with a light on that circuit?

Is it possible that this used to be a 4-way circuit with 3 switches (not 2) controlling the same light?

I don’t recall seeing a third switch to control any of the following lights.

Hallway - 2 sets of light fixtures
Bedroom - 2 sets of light fixtures
Den - 1 set of light fixture

My contractor put the new switches in before I moved in, I have no idea what they were before. I know for sure all the power in the bedroom (receptacles, lights, washroom light) are going to one breaker. I suspect the reason why there is a bunch of black wires capped together is because of all the things running on the same circuit.

If I can’t figure it out by myself, I will call someone in to have a look. If I have to retrofit the wiring (no budget at this time) then I guess I will have to return them to you.

EDIT: Would it hurt to test if I wire the diagram here to disconnect the remote switch like option 2: capped the black wire, connect neutral to common and leave traveler intact?

Please don’t attempt wiring the switches if you can’t match your wiring 100% to the diagrams provided, this is unsafe and may also damage the switch. If you send us wiring images from both switch boxes with all wires pulled out, we’ll have our technicians take a look at it and help you identify the wires. But please do not experiment!

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I did some more research and found THIS that looks exactly as my setup (2x red, 1x white on main; 3 wires on the remote).

Since the black wires are all capped together on the main, assuming if I tap onto it to LINE (now powers stays on always) and capped off the black wire on the remote, technically this make sense.

Is my logic false here?

You should have a line at one of the switches already. Turn off the breaker, pull both switches out of the box, but leave connected, turn breaker back on, and find the wire that has 110V no matter what position the two switches are in.

Are these switches for the light or fan in a ceiling fan?

There are no fans, just lights.

The pictures I uploaded, the red wire that I labeled temporary with green masking tape is the wire that has voltage running constantly, it is also connected to the black screw. If you look at the box, the one with the masking tape is going to the middle opening.

The white and red wire will carry voltage alternately if I toggle the remote switch. They are going to the right opening of the box.

In the main box, all the black wires from all 4 openings are capped.

My question is… why does the red wire (green taped) carry a voltage? Isn’t the black wire the hot wire?

On the remote box, black goes to black screw, red goes on the brass screw above the black screw, the white goes to the other brass screw. There is just one opening and that’s where the romex comes in with 3 wires.

I will try to take some more picture of the single gang switch in the den and pull the wires out, just without lights and the it gets dark early, I will have to do it when no one is around.

Problem solved. I used this instructions and the three ways are working, confirmed the wiring on the light fixtures first.

How the 3 way were wired is that the HOT/LINE is connected directly from main box to remote box, then the main switch is the red wire (black screw), white and red are the traveler and load.

By following the above wiring diagram and capped off the HOT wire between main and remote, I am able to get this to work.

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