Conventional to smart switch conversion

Hi everyone,

I am fairly new to smart things.

I recently built a house and the main issue I am having, is the quantity of lights and lights switches that don’t necessarly make sense in terms of which light come on, grouping of light and switch location.

My question is if you have as current set up :(conventional switches and conventional lights)

  • Switch 1 turning on light A
  • Switch 2 turning on light B
  • Swith 3 turning on light C

Is it possible to make it so that by replacing conventional to smart switches in all instances, switch 1 would turn on switches (1, 2 and 3 ) and therefore creating almost like a group.

To give an example, just in the kitchen alone there are 3 switches and 3 different lights which would work well switch on together…

Is it better to replace switches, lights, relays?

Thank you in advance

Depending on the proximity of the switches to each other, I’d start with looking to see if all three lights can be wired to a single switch. Much cheaper than home automation :slight_smile:

If you want a Wi-Fi only solution, it’s possible to write Routines to make devices mirror each other’s behaviors. You have to be sure to include conditions that check if a light is already on/off to prevent race conditions that can cause looping. With 3 switches, you’ll need six Routines to handle both on and off. You might also be able to use the Smartlighting app in ST to get the synchronization you want. Another choice might be to buy a separate smart on/off button or scene controller and use Routines to turn on/off the lights based on that.

If you want a hub based solution, Z-Wave devices have something called Association Groups that allow the actions of a device to be mirrored to other devices. I use this for two separate lights in my bathroom. Downside is that ST has removed Z-Wave from their latest hub and smart appliances that can act as a hub. It’s making some of us question ST’s commitment to Z-Wave in the future.

I’m not as versed on options for Zigbee but I believe the Edge drivers from @Mariano_Colmenarejo provide a mirroring capability. He’ll correct me if I’m wrong :slight_smile:

Personally, if I was starting over at this point, I’d probably lean towards Wi-Fi switches that support Matter (new home automation interoperability standard). If you need support for devices that support either Zigbee or Matter over Thread (another type of mesh network) and want to be in the ST ecosystem, you can add an inexpensive Smart Station or even a Samsung sound bar.

That’s my take. @JDRoberts and others might have a different set of suggestions.

I would give a much simpler answer to this and say that almost all home automation these days is based on a radio frequency (RF) protocol. There are a bunch of different options, including Wi-Fi, but the point is that on almost all platforms switch A can send a message telling switch B and C to turn on. Alternatively, on some platforms, you can actually group the switches together, again, utilizing the radio messages, so whenever any of them turn on the others turn on.

There are typically several different ways to do this depending on the exact home automation platform that you’ve selected, but it should be very doable. :sunglasses:

The exact details would depend on the specific home automation platform that you end up selecting, but I do feel quite confident that it can be done.

The one thing to be aware of is that some platforms have more of a delay in handling these messages than others, which means that there might be as much as two seconds “latency” from when switch A turns on before switch B turns on. That’s not usually a problem if the lights are in different rooms, but it can be quite annoying if they’re all in the same room and you get what is called a “popcorn effect“ as the different light pass the messages around and then turn on. So if you think it’s important to avoid that particular issue, that will limit the candidates you can use. But you should still be able to find something.

Have fun – – it sounds like quite an exciting project.

Also, I definitely agree with the following:

If you know that you always want the lights to come on together, then wiring together, or adding a fourth hardwired master switch to turn on the group, will eliminate any delay issues, and again be less expensive. And you can still add voice control and other automations to the master switch if you want. But it all comes down to the details.

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You already have received some great suggestions. Personally I like to keep all (or at least as many as possible) my HA devices off of WiFi. You may want to use Zigbee or Matter devices instead. I personally use a combination of Zigbee and Z-Wave devices but Z-Wave seems to be loosing support on some platforms.


I also try to avoid Wi-Fi for most simple home automation devices, and leave it for audio and video and real time energy reporting. The high bandwidth stuff.

My personal preference for lighting in North America is Lutron. Great engineering. In this specific case, you could put in a smart switch for each of the existing three switches, but leave the circuit wiring as it is and then add a fourth “Lutron pico remote” which is a battery powered remote in the Lutron system. It can be paired to multiple mains powered Lutron switches. So the pico, which can be placed anywhere on the wall, including right next to the other three, becomes the group control, and you have definitely under 1/2 second latency. And since all the other switches receive the command at the same time, they should work pretty much at the same time. But that’s just me. :sunglasses:

You could do something similar with Z wave or some Zigbee devices, but you would probably have somewhat higher latency.

Like I said, there are a lot of different options available, and there will be different ways to group the switches depending on which platform you pick, but there definitely should be a way to do it.

Which reminds me, we should ask what country you are in, as the device selections do vary. For example, Lutron, as I mentioned, is available in North America, but not for the DIY model lines in Europe or the UK.

This is great advice, thank you everyone.

Will try to physically wire where possible as some are pretty close.

The remaining will try some of these suggested options :grinning:

For reference I already purchased and installed the smarthings hub along with Alexa echo dot and echoshow 15.

Thanks everyone


Since this is a recent build you should have neutral wires at every switch. They are normally white wires and in multi-gang boxes on the same circuit they will all be twisted together. Having them expands your options for smart switches significantly.

I will add my voice to @wags1 in suggesting you avoid Z-wave. For now at least Z-wave is excluded from Matter and SmartThings is not including Z-wave in their hubs-in-devices or the Station.

Using Matter just now can be complicated and its usability will depend on which hub you bought. But we’re all hoping and expecting it to be the best long-term bet.

:point_up: 100% this! My Lutron Caseta devices have proven to be my most reliable and robust smart home devices. And, they work with all of the major home automation platforms (SmartThings, Hubitat, Home Assistant, Amazon Alexa, Google Home, Apple HomeKit, Logitech Harmony Hub, etc…)

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