Monoprice in-wall Z-Wave module uses only 2 wires? Old home savior?


I expect the answer is probably no, since I’ve learned not to get my hopes up about finding hard-wired Z-Wave switch modules to work without a hot neutral in the box. My home was built in 1929 so I’m in no neutral hell.

I found this Monoprice in-wall relay module and the wiring diagram seems to want only 2 wires to connect it up. Would this work with older wiring? Check out page 3 of the PDF here.

Would someone please let me know if this might work with older wiring?

Thank you,


Sure. Line and Neutral is all that’s required, as per the pdf. So yea, that would work.

Unfortunately zwave requires power to transmit/receive. It can get it from battery or from your 110. In order to get it from 110 it MUST have hot and neutral. There are a handful of older units that allow you to use the filament on an incandescent bulb as your neutral. Think intermatic c600.

As far as I can tell from that diagram, it does require a neutral even though it doesn’t specifically say it does. All diagrams show white connected to neutral.

I think you misunderstand. (or I do) He doesn’t have neutral in box.

You need a hot and a neutral in your switch box for that (and most other) zwave relay(switch) to work.

In general, if you don’t have both neutral and hot in the switch box, you cannot get a zwave device to work there. It cannot run through a light someplace first.

Right, it cannot go through the device first. It needs to be in the box you’re installing it first, THEN to the device. If power goes to the device first, then to the switch it’s not going to work, unless of course you installed this thing in the box w/ the light itself(which you could do, but you would lose control of the physical switch, and turning that off you’d lose control of your device entirely.

OK, thanks. That was the answer I was expecting (and afraid of). Oh well… :slightly_smiling:

Exactly. Ultimately, the only one I know of that would work without you pulling wire would be the intermatic ca600. I’ve had several of those and they work fairly well but have quirks others don’t seem to have. They also don’t make them anymore either. Oh and since they require incandescent… unless you stockpiled 60 watt bulbs 2 years ago, you may have trouble if you run out of bulbs.

I have pulled all but one out of my house and it is gonna go soon.

Try the New Fibaro Dimmer. It only needs two wires and works extremely well as a dimmer or a switch. I use them in all of my light switches (about 20 all up).

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This is the route I’m going to go.Quite a lot of my lights have two switches controlling them so I’m going to ignore them for now!

Cool stuff. I didn’t know that existed. I’m not sure how it operates without neutral AND supports LED. Perhaps it runs off of the one side of the AC cycle and stores it up with capacitors.

Are you using these with 110V wiring or 220/230V? The user manual online lists Supported Loads on page 5 as 230V and compatible loads in the 220-240V range in a table on page 6. I’m in the US where we’ve got predominantly 110V residential power, so looks like this might not work?

Manual shows 100-240v supply so it should work. I’m not an electrician but I commonly see double the wattage rating at the lower voltage so 500w resistive load max at 120v. Again, that’s just my limited assumption.

Im new to the openhab experience and this is exactly the type of thing i got into this for. I have started getting all my equipment for the NFC door striker and magnetic door lock. I am also looking to have motion and temperature sensor in every room. I have installed the baffles in the dock work for every room to make the house multi zoned without adding additional heating or cooling. My over all plan is to have every room have the ability to set its own temp with only using the central heating and cooling system. Also with the installed speakers I am working to have the bluetooth music from my phone to play in each room and stop as I walk around the house.