Why would you use a In-Wall Relay over a normal in-wall switch?

I understand what they do and I could see that maybe their size plays a roll since you can control two devices with one little relay but It seems that you’d have the “smart bulb” problem where if the switch is turned off the relay wouldn’t work. Is this true? What are the benefits of these relays over a normal switch?

No, I believe they basically turn the switch into a momentary push button and the in wall relays handle the load switching. I can’t attest to this being true of All of the in wall modules, but I think that this is true for most.

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Switch color was the reason that I used two of them. I needed a dark brown to match the reset of the kitchen switches and have them blend into the tile.

The switch then connects to the relay so there isn’t an issue of turning off the relay, etc.

They aren’t that small. There were enough other wires running into the 4 gang box that I couldn’t make them fit - well I only tried for an hour. Instead I mounted them in a different box (the wall was unfinished on the other side in the utility/furnace room) and moved the romex wires then just put the original switches in the main box with a simple wire running between the relay and switch.


I agree. I had problems fitting the relay in my 2 and 3 gang boxes. Seems like my 4 gang can support 1 with minimal effort.

I fit one aeon relay in a one gang box but can’t fit 2 in a 2 gang box. When wired correctly, the relay will have constant power and the wall switch is an auxiliary switch. What the actual switch does can usually be configured (e.g. momentary contact, on/off…). For lights I like the actual switches better though because you can use double functions (search for “double duty” app e.g. when light are off and you press off again - turn off additional lights…)

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You can also put them in the light fixture when the switch doesn’t have full time power (switch loop) to allow the light to be controlled by ST and still work from the wall switch (which is an improvement over using smart bulbs.)


Very good point! I did put one in a ceiling fan to control the light bulb of the fan (wired separately from the fan) because I only had space for the fan controller in the wall box and there is no light/fan zwave combo switch as far as I know.

Money is another reason. You can buy the Monoprice Dual Relay Module to extend z-wave functionality to two switches for the cost of one GE Switch.

One of the most common reasons for using the in wall relay is because there is no neutral at the light switch to power a network device. There still has to be a neutral on the circuit somewhere, typically at the ceiling fixture, so the micro relay can be placed there instead. Relays are very commonly used in European homes for this reason, or in Adobe or cement homes where “fishing up” a neutral is not possible.

Additionally, in US homes relays can be used to provide networked control of GFCI circuits in bathrooms and kitchen. There are no Z wave GFCI receptacles for technical reasons: the GFCI is intended to cut all power to the receptacle, while the Z wave has to remain always powered in order to work. So they have conflicting purposes. But the micro relay can be placed on the circuit upstream from the GFCI outlet and now you have the safety feature of the GFCI cutting the power at the outlet itself and the convenience factor of the upstream relay allowing for networked control.

Sometimes there’s The form factor issue: a single gang light box that includes two devices, such as a half receptacle and a light switch, probably won’t have an equivalent networked device just because it’s hard to fit two radios into a single gang box. Depending on the exact wiring, it may be possible to independently control the two devices using a dual relay. Or even to only network one of them with an in wall micro.

So in addition to the other reasons already mentioned above, quite often there are wiring set ups where a micro relay makes it possible to add network control when you can’t just swap out the existing device.


Does anyone have a current recommendation for an in-wall application of a relay, ideally relatively inexpensive? I’ve purchased an Aeon Labs in-wall micro, but at $31/ea, it’ll hurt to automate everything I want to. Also, I’m unsure if I have space in the gang boxes. I was going to buy a dual toggle from Aeon, but Amazon no longer carries them.

I’ve considered sonoff’s dual wifi relay, but I’m concerned installing in-wall would be a fire hazard.

I’ve looked for this information just about everywhere I can think of, and everything useful I find seems to be outdated or the product is no longer sold.

Any help is appreciated. Thanks!

The older Aeotec dualmicro has been discontinued in favor of their new nano line, but that line is more expensive.

The vision relay is still widely available and is probably the least expensive zwave model.


Also, shop around. Amazon is often more expensive than some of the specialty retailers, particularly for items which Amazon does not stock it self, because the specialty retailers have to pay a commission to Amazon for every sale so the same item may be cheaper from their own site. Also you may be able to find some of the discontinued models still in stock.

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Thank you! I’ll check those out.

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CAn I use the relay with no switch? I have a portrait light that I want to install to hard power but there is no switch and I don’t want to install one. Ideally this goes in the wall and we control via SmartThings programs to turn on and off at certain time/situations

As long as the relay is rated for line voltage then yes. It’s not the safest thing to do but that’s your decision

Is there a safe way or model to use for this?

have a means of disconnecting the power… ie: a switch and not rely on the breaker alone. If you need a quick means of disconnecting the power how would you do that? Running the breaker panel (unless its in the same room) isn’t really a feasible option.

in my country, the standard size of gangboxes and modular switches is smaller than the available in-wall smart switches. so to automate a particular switch the best option is an in-wall relay.

and as noted by someone else in this thread, these in-wall relays are fast disappearing (older models discontinued, newer models at ridiculous prices e.g. aeotec nano range)