Triple Gang light switch replacement (UK)

So here’s my plan for my first smartthings integration.

When someone approaches my front door I’d like to switch my porch lights on.

I know I can get an external motion sensor to work as a trigger but the porch lights are currently connected to a 3 gang switch in the hall. I’d like to keep a switch of some kind for the porch lights but also automate it on people approaching.

I’m thinking of using a smart relay switch or rewiring the porch light so it’s off the 3 gang switch but open to ideas.

In the UK and i have an aeotec hub.

That should be very doable, and there are several different ways to approach it. :sunglasses:

The first thing to mention is that these days many people do this with a smart video doorbell or a smart camera on the front porch, as these typically have a motion sensor built in. It is still possible to do it just with a plain motion sensor, but standalone motion sensors outdoors can be really tricky as far as avoiding false alerts. And you don’t want your lights going on and off all night long.

So you can do it, but if you think you might eventually want the video doorbell or the camera, I’d suggest going ahead and doing that. It’s just an easier technology to work with.

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As far as the light switch, it should be possible to replace that with a smart switch that will work. It’s a little trickier in the UK because of the integrated three gang design. There are some modular units where you can have two dumb lights and one smart light, but most people just go with the three gang smart light for the UK. Even if you aren’t planning to use automations for the other two lights, they will still work as a regular switch, so you don’t lose anything. sometimes it just comes down to aesthetics.

Can you post a photo of the current three gang switch so we know what we’re working with? Again, there tends to be more variation in these models in the UK than there is in the US.

Also, do you know if you have a neutral wire at that switch box location? That would make life a lot easier when it comes to smartening things up.

(For community members who live in the US and are not familiar with UK multi gang switches, they are quite different than US switches in this regard. The external dimensions are the same, there are just more toggles in the same area. Here’s an example.


So you can’t do the trick you would do in the US of just removing the faceplate and replacing just one of the underlying switches.)

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As @JDRoberts says you need to first thing about your sensing device. Be this motion sensor or doorbell.

Next think if you want to replace the 3 gang switch with a 3 gang smart switch (obviously making the additional 2 circuits smart). But this will depend on the 3 gang switch you already have. Is this 3 gang 1 way or 3 gang 2 way. (In other words do the other 2 switches only operate single lights or do either of them operate a light that can be turned off by another switch - like your landing light?) Sorry if I’m explaining something you already know. This option is tricky if it’s a 3 gang 2 way as your choice will be very very limited especially as in the UK there will most probably be no neutral at the switch.

The other option is to use something like a sonoff mini which can be wired behind your light rose with the existing 2 wires going to your switch connecting to the switch terminal of the sonoff mini. (This enables you to keep your existing 3 gang switch, making only this light smart).

So lots of things to think about, hope this helps with that.


Also, I forgot to ask, are the porch lights dimmable? The reason I ask is that the physics for dimmable lights are different than the physics for on/off relays, and sometimes it’s actually easier to use a dimmer for a switch which doesn’t have a neutral.

But there will still probably be some options no matter what configuration you have, it’s just that the more we know the better we can help. :sunglasses:

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Thank you both for the super helpful replies, it will teach me to just bash out a question whilst watching Eastenders without giving it enough thought. There is only so much Sharon Watts a man can bear but I digress…

So below is a picture of the current switch controlling multiple lights:

From left to right, the switches control:

Far left - On/off for just the lights in the porch. They are currently just spotlights within the porch ceiling, further picture below…
Middle - On/off for just an interior light inside the hall, not planning on making that smart just yet but if it’s easier to do then may well do so…
Far right - 2-way switch controlling the light at the top of the stairs. The light at the top of the stairs can also be controlled by a single switch outside one of the bedrooms. This might be trickier to convert as I guess I would have to do the same upstairs?

The house is a child of the 70’s so the wiring is slightly older than a modern home, I’ve taken a shot of the inside of the switch below:

These are the porch lights (there are actually three of them) as they currently stand, just spotlights. I haven’t removed the ceiling but I would imagine there is a transformer buried away up there but they could also be 240v lights. I don’t know without ripping out the ceiling (which is also planned)

Moving outside, we do have a crappy old mains spotlight that you can see in the shot below. I’m planning on replacing this with a smart floodlight instead so I’m now thinking maybe separating out these two ideas. Have the floodlight come on if the movement is detected around my car and have a second sensor for switching on the porch lights?

The pictures below are of the front of the house and a close up of the eaves over the front door. I’m also pondering an exterior light in the porch eaves but outside as we’re always struggling to see the lock when it’s dark…

So my ultimate goals here would be the following:

  1. Someone approaches the front door when it’s dark then the interior porch lights come on and a single spot under the eaves so we can see the door lock easily
  2. Retain the ability to switch the porch lights on and off (interior and exterior) via a “normal” switch. Thinking about the mother in law who is a technophobe.
  3. I work for a company that supplies a home smart alarm that has IFTTT and Smartthings integrations (I’m not going to say who they are as I don’t do name dropping) so maybe the floodlight should only come on when the system is armed and motion is detected. We have an IFTTT applet that can support that.

Hopefully, this is all helps and certainly sounds possible but I’d like to get this right as smart hardware is more expensive than a £4 light switch from B&Q.

Thanks in advance :slight_smile:

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You know you have some kind of wire hanging down from your drainpipe right? Needed to get that out the way first. I would come at this more elegantly than the other two posters trying to help, guess it comes down to experience. Your “crappy old mains spotlight” probably works very well, and is reliable right? Making something dumb smart I find preferable than spending more for something smart, “bespoke” but unreliable. Just get a micro relay module and stick it so the signal from the dumb motion sensor goes to it first before it goes to the floodlight, that way you’ll get notified and can automate when there’s motion outside, and you can control the floodlight from ST also. You could use the Sonoff Zigbee mini or a Fibaro relay.

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Aye the wire is on the list but I need some ladders. It got blown in the wind for the TV aerial that hasn’t been used in about 15 years :flushed:

The floodlight is gubbed though and needs replacing so might as well replace it with something more useful…

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Have a read, might inspire you in some way

Just don’t use a fibaro controler, a good option now is a magic home controler

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In the US as has already been mentioned you would replace each switch module with a smart one. (US switch modules are individually much bigger than UK/EU switches.)

In theory you could fit three smart micro modules behind the 3-gang face plate but in reality such modules are so big that fitting even one behind a standard UK/EU square face plate is hard work and more than one effectively impossible.

What you can do is fit the micro modules in the ceiling typically above the ceiling rose and from there link to the respective light switch circuit. These could be switch micro modules or dimmer micro modules depending on the light fixture. In the case of the outdoor light you would likely not want a dimmer. You could then link a motion detector via a rule so motion activates the switch. With the physical switch also wired in you would still be able to use it to manually control the light.

In terms of micro module brands since Aeotec now make the Smattthings hub their Z-Wave micro modules would be the logical choice but other brands may work. You might want to replace the light switch(es) with momentary ones - especially for dimmers but they would still look like your existing switch plate.

Another option would be LightWave-RF which is pretty much the only smart light switch available in the UK with 1, 2 and 3 gang variants. However it is only available in dimmer form.


What about the Yagusmart switches, I believe there is a no neutral version as well.

Otherwise there was a topic about Smart Switches in the UK:

@Phil_Williams, sorry for asking, but do you have a Hub or a Hub optional setup?


That might just do the trick, good find!

I have an Aeotec Smartthings hub so I’m flexible either way…

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I think I might just go for one of these you know as proof of concept. I can faff about with the motion sensors later

Worst case is I lose £18.99…

Very worst case is I electrocute myself :roll_eyes:

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Those have become quite popular, they are a rebrand of a Tuya model so you may also see the same device sold under other brand names.

Straight out of the box only one button will work, you may need custom code referred to in the other links you’ve already been given in order to get functionality of all three buttons. (This is typical of smartthings regardless of the brand, the base platform just doesn’t handle multi button devices very well.)

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Hmm yep that’s a consideration. Just reading @jelockwood post again I’m now flip-flopping and considering the micros switches instead.

I’m gonna have to sit down outside of work and plan this out I think…

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Custom code is easy, you basically just copy and paste code that somebody else has written into the cloud interface to your SmartThings account.

The following FAQ is old but will give you the terms, concepts, and basic approach. ( The topic title is a clickable link)

The problem is we have not yet been given any details about how custom code for Z wave or Zigbee devices (what smartthings calls “hub connected devices“) Will work once the transition to the new architecture is complete. so there is a risk in investing heavily in something which requires that kind of custom code at this time. :thinking:

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So I’m gonna ask a potentially stupid question here…

Say for arguments sake I got the yagusmart 3 gang switch but for the time being only set the first switch to be smart for the porch lights.

Would the othe two switches still behave in the same way as a dumb switch until I sort out the custom coding?

I think so, but I’m not 100% sure. Ask in one of the threads where people are using that model, they should know.

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Actually this appears to be worryingly simple.

No harm no foul, I’ll give it a try.

Really appreciate the advice :pray:

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Notice where that person says they only saw one parent and one child. That means only one of the buttons was working. :disappointed_relieved: If you read later on in that same thread you’ll see that people had to use custom code to get all three buttons working.

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