Zooz Zen51 and Zen52 - double relay & dry contact

Found these while taking a break from work.
I will be interested to learn how the switch inputs work (i.e. does a change in switch state always toggle the output?).


Nice find! Interesting these don't have an antenna tail ala similar offerings from qubino etc.

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It also doesn't list Hubitat under the "Works With" paragraph.

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Yet the install instructions include a QR code for accessing advanced settings on Hubitat.
Ready - FIRE - Aim ... that is pretty much how I launch products, too.


Ha, yep, that's kinda how Zooz rolls... I've learned to meter my new-Zooz-thing expecations accordingly and be patient in those early stages.


This looks like it would be super easy to make a custom driver for if I had one, probably could even do it without having one. The ZEN51 would probably even work with just a generic Zwave switch driver. Its just an on/off switch from the looks of it. The ZEN52 might need a child device if they are using endpoints for the two relays.


Was just looking at the zen51/52. Wondering if this is Zooz equivalent of the Aeotec nano?

I was really looking to see if it could be used as a dimmer, but looks like these may be a little new to the community. I didn't see dimmer functions mentioned on the Zooz site. But good breakdown of advanced settings.


My experience with double relays has been less than ideal - I've tried Aeotec Nano and Fibaro and have found them to be slow for physical switching especially if one switch is "no-load". It would be nice to find some that work better (for me).. but am now using "normal" smart switches.

Would love to hear how they work out!!

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Parameters 20, 21 are interesting to me (external switch behavior). Admittedly I am not sure if I have an application, but it is good to know the flexibility.

FYI, I just purchased a pair of Zen51. I was able to set them up as a "Generic Z-Wave Plus Switch" although I'm sure many other options would have worked.

FYI, I am using them to control my baseboard heaters. I asked Zooz and they said this should be ok for relatively low power devices like these (240VAC; 2A and 5A), They did not recommend them for continuous use at 240VAC 10A.

I am powering them off of 240VAC that is feeding the baseboard heaters by switching one the legs. So one of the hot legs is connected to the "L" and "IN" pins and the "OUT" pin is connected to my heater. The other hot leg is connected to the "N" pin.

After some thought, I decided to keep my old mechanical baseboard thermostat in series with the relay as kind of a thermal regulator that turns itself off after some time but I set them to max temperature. This is because there isn't much airflow in these rooms and I'm afraid the heater would be pointlessly working otherwise. I could be convinced to remove the mechanical thermostat though.

Just as an aside, I am using a virtual thermostat connected to a Sonoff Zigbee temperature sensor to regulate temperature.

Also, the radio didn't seem to be strongly affected by the metal junction box that is the baseboard heater.

If anyone has questions about it, please let me know and I'll try to answer... unless I burn my house down. It's 1AM and I literally just installed one in my bedroom before I'm going to sleep. So wish me luck.

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Just purchased a few of the Zen52s. The instructions for the Zen51s per Zooz is to use “Generic Z-Wave Plus Switch.” For the 52, they don’t have any specific instructions; the Generic Switch driver works for the 52, but fires both at once (this works for a couple of my installs, because I’m using them where 2 switches control ½ of the lights each in a basement room).

If you do happen to work on a custom driver anytime soon, I would be glad to provide any info you might need from my devices to assist. It’s working for my current setup, but wouldn’t mind being able to control the garage & driveway lights separately lol.

I have multiple switches in my house that are switch loops with no neutral installed so i bought a ZEN51 to try out. The default external switch setting (Parameter 7 for the ZEN51) is a little weird. It operates so that the switch needs to be in the on position for the relay to be turned on (which sounds reasonable at first) but if the light is on (switch up) and then you turn it off by Z-wave command and you try to turn it back on you need to flip the switch down and then up to turn it on (WAF would be way low on this) so i pulled it down and worked with Zooz support.

I used the basic Z-Wave tool to change the setting but I have to admit that I am spoiled by jtp10181's ZEN switch advanced drivers.

This thread is a little old but figured I'd tack on my experiences here. Not good first impressions with the Zen51. Have a stairwell with 2x two way (or three way, depending where you're from) switches: one at top, one at bottom. No neutral in either, so natural option is to install in the light fixture (at bottom of stairs). Single LED "100W" bulb.

Pairing and zwave control is fine (though I find it annoying it "works with Hubitat" yet the parameters have to be set manually as described above).

The issue is in use of the S1 input terminal. This is meant to toggle the Z51 output on and off by way of the original physical switch. It seems the Zen51 has zero tolerance for capacitively coupled / induced voltages on that input line. So when my switched conductor turns "off" there's either ~34, or 60-some Volts stray on that line (depending on the physical switch positions which changes the physical length of the conductors in question). It's simply induced from being in the same cable as the other live conductors. That S1 input is a high impedance input (apparently) because it does nothing to pull that ghost voltage as it's sometimes called, off the line.

I wired my DMM between the S1 input and Neutral, in the light fixture, and used the DMM's "LoZ" mode, which effectively places a 3k resistive load across the terminals to avoid these false readings. Voltage when switches are OFF is now reduced to 2-3V. Still, the Zen51 won't toggle the output. Of course if I physically disconnect the S1 input in the light fixture, I can toggle the output on/off by manually connecting/disconnecting. This is not a parameter 7 setting issue.

I have a support ticket in with Zooz, but I'm not really seeing a way around this as it stands. Pretty big bummer because the whole point was to keep existing (low cost) dumb switches. $26 Zen51 < $50-60 Casetta switch (which would require a neutral) or dimmer. Both of which have minimum load requirements. The dry contact and low cost was the appeal here for a single bulb.

Yes! I have the same exact experience with 3-way implementation. I installed in a 3-way light in my kitchen and it would only work via Hubitat. I pulled it out and put in a ticket with Zooz. They asked some questions about wiring and I told them I’d get back to them. Then I built a mock-up 3-way switch and installed the Zen51 and it worked like a champ. Went back to the actual light fixture with the same problem. Next I did exactly what you did and came to the exact conclusions. I was touching the S1 wire to the switched input to the fixture with less than 1 volt showing on my cheapo meter and it switched every time. I replied back to Zooz but said that I was going to try and figure it out. The said to let them know and I just haven’t gotten back to them. I don’t know what setting 3 is for parameter 7 but it says 3-way impulse control for select 3-way scenarios. The Zen51 works in a single switch configuration that I have but it would be a big problem solver for me if could make it work.

I've been going back and forth with Zooz support for days now... I don't see an easy solution other than a different product - in my case the walls are open so I can get a neutral in one of the switch boxes easily. At this point I need to cut my losses on a $26 device.

I did install the another Zen51 in place of a (<1A) fan switch. Kept the dumb switch as S input, local to that box, and it works fine. Seems Zooz has some issues to work out (interestingly it's listed as 'Beta' or something like that on their website... I don't like the idea of being someone's Beta tester for electrical devices behind my walls.....

Also a note for conciseness/clarity: those voltages of 30/60Volts were the unloaded switched leg, not connected to the Zen51. When connected I get like 116/120V. If I add the DMM in it's LoZ mode it realizably switches from 120V to ~2V.

I have just updated my list of in-wall relays, and Zen52 is the smallest of all the ones surveyed:


@slip1n1fall (or @nibyak) just seeing if you ever figured anything out for the 3-way setup? I was just trying to install a ZEN51 in a 3-way EXACTLY the same as @slip1n1fall right down to the stairwell with a single bulb. My traveler wire is around 15ft. While I do have more than average knowledge of electricity, you seem to be more advanced than me. How are you getting the stray voltage reading? Thinking maybe with the S yellow disconnected and then check voltage from the end of the switch leg I disconnected across to the neutral with the switch leg off (on should obviously read ~120v)?

The only testing I did was I found that even if ONLY the L/N are connected to a hot feed, I am registering 120v across the S/N which I though was odd since it is a switch input not an output. Testing the Ohms set to 20M across S/L I was able to register around 7-8 which... is a lot of resistance but not a fully open circuit.

At one point I was getting an odd lower voltage reading that was slowly climbing, I think I may have been accidentally picking up the stray voltage on the switch leg but don't remember what I had going on at the time.

ZEN51 is updated to FW 1.40

@jtp10181 my solution was to abandon the Zooz and install a Lutron Casetta. :laughing: Sorry not sorry (to Zooz) but I spent enough time troubleshooting for their sake, and don't care to act as hardware beta tester for something that gets installed behind my walls. The workaround could be installing a minimum load on that switch line. Something like an AC LED panel indicator would likely be enough. It's unfortunate because they are a good 'hidden' repeater solution.

I am successfully using one inside a wall switch box, with a local 'dumb' switch wired to S input, for a ceiling fan. Works just fine.

I measured the 3-way switched voltage as you described: disconnected from the S input, and measured relative to the neutral in the light fixture. You'll see 120 when on, and likely somewhere between 30-80V when "off". This is completely normal, and present on every three way circuit in America. Wire up a light bulb and it will function normally. It's the zooz that can't cope.

And yes I saw the same 120V on the S input with no input actually wired, and the zooz powered.

Good luck!

Ok thanks for the tips. I was also thinking if I re-wire the 3-way to use the impulse control setup that it should work, I just shouldn't have to according to their documents. I sent in a ticket yesterday and asked if that might work better.

I also could just drop a new 3-wire, to replace the 2-wire, from the light to the basement switch box, getting me a neutral and do what you have done. Its only about 10ft but dang romex is expensive these days.

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