Zigbee installation in 100y old house - Technical question on switches

Newbie to HA here, but looking to upgrade my (soon to be) house from the 1920’s with some smartness.

One dilemma I immediately face - We need switches, we’re a large family… But I cannot install modern plastic Zigbee switches in this house, my better half will tear them out.
So, I’m looking at switches like these… But I also want control from phones/other, using Philips hue or other smart bulbs all around.
So what I really want is to ‘short’ the lamp wires to always-ON, and connect the switch to an input module… So the bulb always has power, and the switch only activates the input module and sends a command to the bulb to turn on/off. This leaves me with questions:

  • I don’t see many input modules for this, it’s all relays & dimmers. Am I the only one thinking this?
  • Am I being optimistic, in relying only on Zigbee to turn lights on and off? An error could leave me in the dark, literally.
  • Does such an input module exist, without battery? That is, mains powered? I’d really prefer not to change batteries every few years…
  • The lamps would sometimes be operated from switch, sometimes from other devices… So they would have to ‘toggle’. Sometimes off will be down, sometimes it will be up. Would this drive you crazy? Or should i spring for retractive switches? And would such an input module even be able to handle a ‘transient’ switch?

So many questions - I appreciate any knowledge or recommendations you guys can share with me.

You can consider putting a zigbee relay module behind your existing switches and power those directly.

You have two choices:

  1. Use a regular powered relay that you’ll just use to detect the switch action - they generally act as routers too.
  2. Something not requiring a neutral like the Tuya/Moes MS-104ZL or SONOFF/ZBMINIL2 if it is small enough to fit - this can be useful for bulbs that are not smart, but it will not work as a repeater. They can switch you light without the need for extra wires. Mind the current (amperage) limitations.

There are manufacturer other than Tuya/Sonoff out there - have a look at Database of Zigbee devices compatible with ZHA, Tasmota, Zigbee2MQTT, deCONZ, ZiGate and ioBroker and look for relay .

This will be your issue with that older home unless you’ve redone the wiring. Thays said, if it hasn’t been rewired or you don’t have it I the plan - with it being that old, I’d prioritize the wiring over making it smart TBH…

If it has been rewired then a smart relay behind ths switch plate is the way to go.

Or just use Shelly’s They use wifi instead of zigbee though
They are small, and fit easily behind the (existing) switch, and will also work stand-alone.

You can even re-flash them with ESPhome, making them even more programmable :grin:

Ah, but you said ‘no neutral’….
You could also place them inside the ceiling box (or the base of the lamp) ofc, you do have neutral a available there :thinking:

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Yes, always overlooked. A Shelly install at the light source instead of the switch has all the wires you need to get it done right. And you can use the original switch to boot.

You’ld generally not have the power available at the switch because you’ll only have the two wires there to control the “live” or “phase” wire continuity. And you have to make that interconnect permanent where the switch is located.

Thanks a lot for all the replies!
Super good info - I hadn’t considered the possible lack of a neutral wire…
I know the wiring is not original, but I don’t know the age - I’ll have to dig into it. If there’s no neutral, I will probably rewire to get it…

And I’ll look into the relays - It could be a good solution, despite maybe not using the relay part!
I would much prefer Zigbee over Wifi, so staying away from Shelly at this point…
Putting relays near the light source won’t solve the problem, as the relay would be unpowered if you throw the switch - And thus not controllable from other devices.

Is there a consensus on the best powered relays for this sort of thing…?

Thanks again!

I think you will have to take a closer look at your wires before you make a final decision, whether there is a neutral wire at the switch or not. If it’s original or wired in the 1950’s or before it’s very likely you won’t have a neutral or ground at the switch. You will have a there-and-back wire that will only be the hot.

If that is the case, then you can install a relay at the point where the hot and neutral meet, usually at the light receptacle. In the receptacle box you will likely see two or three black hot wires and you’re neutral (or more if it continues on to a second receptacle). Inside there you have everything you need to install a ready-made relay like the Shelly 1 to install. There are 6 connections on the relays, hot and neutral in, hot and neutral out, and two for a switch.

You could use the switch you already have installed in the house, which your family will appreciate, it will only control the relay signal and not the live power to the receptacle. You will have full control of it both through the switch and HA, and can control how the switch behaves to boot. This would be the best method to control dumb bulbs you are asking about.

Shelly 1 is great, and I personally primarily use wifi as I am not concerned with overhead as I have very robust network on my property. I also understand that zigbee is a pretty flexible protocol. There are a lot of comparable products out there that are essential Shelly or Sonoff clones that have zigbee baked in. Here is one of them: Amazon Zigbee Relay

If you end up wanting to use smart bulbs like Hue instead, best option would be to use a cover plate over the switch and get a remote of some kind to use instead.

Obviously, if you don’t know know how to diagnose the wires in a receptacle call for some professional help.

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That will only work if you deal with a light loop circuit. In a typical older installation, there are no light loops. The hot terminal at the receptacle will be controlled by the switch, there is no permanent hot available. So your relay module will be unpowered when the switch is off. Which makes it unusable in practice.

He said that this was not an option due to aesthetics.

The best option is to pull a neutral to the switch from somewhere nearby, if possible (careful to pull one from the same circuit if using bipolar GFCI’s) or to find a no-neutral module and put it behind the switch.

That could be, I was going by what he said that it had been rewired at some point. If it had been rewired at all it most likely has sheathed cable or at minimum BX cable. The few rewiring jobs I have seen usually have light loops or dead end circuits as it’s the cheapest way to rewire. If he has true split hot and neutral leads like knob and tube wiring you are correct.

Although in that case I wouldn’t pull a neutral over, I would replace it all as quick as I can.

If the only thing that holds back smart bulbs is aesthetics, there are remote switches that look just like real switches. Zooz Zen34

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This very much depends on what country he is from. Light loops are mostly a US thing from my experience, they seem to be much less common in the EU (I have never seen them here). Neutral at the switch is the standard for new builds / rewirings though. The switch he linked to is a European switch. And the webstore seems to be in London (the UK has some super weird wiring standards)…

Edit: well apparently light loops are a UK thing says Google ! You learn something new everyday I guess. So if the OP is from the UK, you would be correct then.

But I agree, he should check what is available at the switch and at the receptacle and go from there.

Replacing can be a total nightmare in an old house. I replaced most of my wiring a few years ago. I live in a 400 year old house. I almost went insane. You wouldn’t imagine the weird ways wires ran in that place when it was electrified like 50 years ago :woozy_face:

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Ha, that does sound like a nightmare, we don’t have anything that’s is 400 years old over here in the states!

I missed the UK switch and I am pretty unfamiliar with their standards as well. It’s good to know though.

Wow, lots of comments here. Really appreciated.
I’m actually in Denmark, and light loops are not common here - But I will make sure to get neutral wiring at the switches, if at all possible.

I dug around a ton, and found some interesting products. I’d love to hear your comments on these:

Unfortunately, I can’t find a shop that will ship the Gewiss to Denmark, but I can find the sunricher.
This isn’t supported in ZHA, but in Zigbee2MQTT… Guess I’ll have to start there if I want it.
It also looks like the Philips Hue wall switch module might work, but it’s battery powered…