New Build - Lighting (UK)


We are in the UK and are in the process of building a house after knocking the old one down so are currently looking at ST as a solution for automating the house.

I am new to ST but am a coder by trade so not too concerned about having to code the odd thing here and there but are struggling with the light switches option.

I am also quite old school in that if I go into a room and want to dim the lights or turn on the bedside lamps I don’t want to have to use my phone or find a remote. Don’t get me wrong I also want all the cool app control stuff and the ability to control the house from your phone and turn on lights when you approach the house etc. However a switch(es) by the door should be able to control the room

I can see there are a minimum of 2 requirements I need

  1. A physical on/off switch on each circuit (this is a new build so nothing exists)
  2. A device that connects that circuit to ST

I see this can be achieved by
1- Micro relays behind standard off the shelf switches. I don’t particularly like this option because
-I need to pay for both a switch and the relay
-How does a physical dimmer work?
-I would need another device to do anything interesting like activate wall sockets

2- Use a battery powered switch such as the Popp described in the thread below. However, this would still require a physical on/off switch on the circuit. Great solution for beside the bed.
([Release], Popp, & Devolo Wireless wall Controller & Key Fob (EU), with button controller dimming apps and CoRE integration)

3- Somehow merge the 2 together. Something like the TKB Dual paddle wall switch would be ideal because the 1 st switch is the physical dimmer and the 2nd switch can be used to do whatever eg control bedside lamps. However

  • It requires a 3 wire circuit. Probably not a problem on a new build (just need to specify now)
  • A quick trawl of the forums says the 2nd switch is not picked up by ST according toa 2014 forum. Or can this be done now?

If you were starting from scratch with no constraints how would you be doing this?

Thanks any ideas really appreciated


If I was starting from scratch with no constraints then I would wire each room with CAT6e cable.This needs to go to all light switches and sockets and to anywhere you need an internet connection.
I would also take a decent CSA (cross sectional area) cable to any room where you need an audio feed - for speakers

Kind regards


  1. 3 wire everywhere. Once you have a neutral at the switchbox you will have a lot more choices in terms of devices. (Many networked devices use the third wire to power the switch when the lights are off so that the switch can hear the next “on” command from the network.)

  2. Deep back boxes, 47mm deep. This gives you much more room for the network devices for each switch. The switches will be standard width, but the depth varies a lot.

  3. SmartThings is better with multiple endpoint devices than it used to be (although not great). The change came in the summer of 2015, if I recall correctly. So you might have better luck now than in 2014. That said, if the device is using direct association to control other devices, it may not work well with SmartThings. So it really depends on the exact details of the device you’re considering. But again, if you have 3 wire, you’ll have a lot more device options to choose from. @adamclark_dev or @AdamV might know more about this.

  4. Ideally, and if you can afford it, plan on two mains-powered devices for Zwave plus per room if you will be using Zwave. With both zwave and ZigBee the more devices you have, the stronger the network will be, meaning the more alternative pathways each message will be able to use. This will make things faster and smoother as these devices can act as repeaters. Battery-powered devices do not repeat, nor do emergency system devices like smoke sensors. Don’t get single purpose repeaters–those were needed through zwave generation 3, but we’re now up to 5 you’ll get more value from a dual purpose device like a pocket socket, wired outlet, light switch, or relay. At this point all these devices will act as repeaters.

Zwave only repeats zwave and ZigBee only repeats ZigBee, so if you know what protocols you’ll be using you’ll know where to put repeaters.

If you intend to have a zwave doorlock you will need a repeater that supports “beaming” within 4 or 5 meters of the lock. ZigBee devices don’t use beaming, so if you’re thinking of a ZigBee lock this is not an issue.

Oh, and Zwave has a maximum of 232 devices per network, so just in case you’re moving into a castle, 2 mains powered devices per room might be too many. :grin:

  1. Put your SmartThings hub in the center of your home, both horizontally and vertically. Plan on at least 3 meters of space between your WiFi router and your SmartThings hub. Sometimes that affects where you’ll hide cable.

  2. Although most people use battery-powered motion sensors, some people prefer mains-powered ones. (In which case they’ll also act as repeaters.) Consider whether you may want to put some outlets high on the wall to allow for cameras, motion sensors, LED light strips, or other devices that might be located much higher than your typical wall outlet.

  3. Physical dimmers should not be used to control smart bulbs, whether the switch is networked or not. The two different devices confuse each other. (This is also true for micro relay dimmers.) But as long as the bulb is not smart, a physical dimmer normally works by literally changing the amount of current fed to the light fitting. The exact method is somewhat different for incandescents and dimmable (but dumb) LEDs, which is why you sometimes get flicker and buzz. So physical dimmer switches will indicate whether they can be used to control LEDs as well as incandescents or not.

As to how a physical dimmer works with an in the wall relay, it doesn’t. You put in a rocker switch and depress the rocker (either multiple times or for a longer hold, depending on the relay chosen) and that controls the dimming.

@Navat604 is one of the electrical experts in the community. I don’t think he’s worked with UK wiring, but he may have some additional suggestions about planning a networked lighting installation.

@JDRoberts - thanks for that. Great introduction to it all!

OK - doing some more research and it looks like the best thing to do is have switches and a relay/module behind it. It

My question now is on having multiple switches to control the 1 circuit. For example, if I have a room that has 2 entrances and I want dimmable led spots in that room what is the best solution? I have got as far as

-Have a Fibaro dimming module with a retractive wall switch on one wall that is connected to the load.
-I could then put the same type/look retractive wall switch on the other wall
-I am guessing here and any input would be appreciated
I am presuming the 2nd switch doe not have to be attached to the load? If this is the case what sort of device is needed to send the signal to the hub as I dont really want to have to pay the £50 for another dimming module.

Ok- Now doing some more research. Looking at the fibaro website the correct way to wire this would just have the one dimmer module and then have a series of connected retractive switches.


Starting to make sense now.

If I want to have a wall switch by the door that controls one of the plug in dimmer sockets what do I need in the wall switch? I am guessing some sort of relay?

If you have a plug-in pocket socket which is networked, then you don’t need to do anything more with the wiring to be able to control it with a separate switch. That’s one of the advantages of SmartThings. The control switch will talk to the hub, and the hub will talk to the pocket socket and tell it to turn itself off. The control switch does not have to be on the same circuit as the pocket socket; in fact it can be battery-operated. It just has to be able to talk to SmartThings.

The only issue here is that if your home automation system goes down, but your power is still on, then the switch will not work. But presumably that’s a temporary situation, and many of the pocket sockets have a button on them which allows them to be turned off.

So if you assume that you’ll handle emergency downtime in some other fashion, I would think the battery-operated pop switches which @adamv has created a device handler for, would be a good choice for most UK homes.

Again because the way these are used with SmartThings is to have the switch talk to the hub and then the hub talk to the pocket socket, you’d be able to use them to control either a zigbee pocket socket or a zwave pocket socket. Or a group controlling multiple devices of multiple protocols, such as a couple of lights around the room plus a fan plus even Devices in other rooms as well.

Here is a link to Adam’s topic:

And this is one of the devices, but there are a number of choices that can use the same device handler. :sunglasses:

Thanks for the reply. It is the control switch that I am interested in creating. I want to add a second switch in the wall switch that looks the same as the rooms primary switch. However this second switch would just be a control switch that talks to the hub which in turn takes to the wall socket as you describe.

I presume I attach a relay such as this to the switch but have no load?
If this is the case and the wall socket is dimmable does the relay need to be dimmable too or can an on/off relay work

Also another related question can a dimmer module be used to trigger an event such as the lights it controls are now at 80% send an on message to the wall socket that has a bed side lamp on it

You don’t need the relay to control a networked socket, you can get a noload switch that already has a radio in it. The battery-powered Popp, devolo, or devices all work this way.

You use a relay to add wireless control to a circuit. So for example to control a ceiling fitting.

But once you’ve added a networked device to the outlet, you don’t need a second relay for the switch. The switch already has its own radio.

You add a relay to a dumb wall switch so that that specific switch is now controllable by the network.

In the same way, you can add a relay to an in wall dumb receptacle so that it can be controlled by the network.

But if you’re using a smart switch or a smart receptacle then you don’t need to add a relay to them because The original device already has a network radio.

Don’t mix two networked dimmable devices on the same load. They’ll confuse each other.

Probably yes. It depends on the exact devices being used.

Actually the Fibaro dimmer module has a second switch input that can be used for exactly this. Happy days, I think I am all sorted now. Thanks for all your input

Correct, but that is still one relay with two switches. Also note that those set ups require that all three devices be on the same circuit.

If you use one of the battery powered switches, you have the advantage that it doesn’t have to be on any circuit, so you can place it anywhere, even in another room. Or you can use a mains-powered smart switch on a different circuit to communicate wirelessly to the hub and then have the hub send a message to the relay. But those have the disadvantage that they won’t work if your home automation system is down, while the ones that are on the same circuit will.

So if you just want to set up a two-way on the same circuit, then the second switch input to the Fibaro relay will work fine. But if you want to locate a switch that’s not on the same circuit, then you can’t use the second switch input on the Fibaro and you have to look at the other possibilities.

So just comes down to the exact wiring details for each location.

The best thing to do with wiring is to run power (line hot, neutral) and load ( load and load neutral) to the same gangbox in a U.K 2 ways. Try installing extra deep gangbox if possible. Of course I am not familiar with U.K code so asking your electrician and explain to him why would be the best.
Don’t forget about wiring for blinds, motion sensors and thermostats as well. It doesn’t cost much if anything for a new install.

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I’m not sure you’ve understood what @kiwiInLondon is saying (with respect), we’re not talking about two way switching here, we’re talking about a second switch on the module.

Parameters can be set to either:

  • Have this do nothing at all
  • Have this act as a down dimmer/off switch (so if you have an up/down momentary switch, up can be on/bright, down can be dim/off)
  • Have this do something else entirely.

IIRC if you enable parameter 28 on the Dimmer 2 it will start sending Z-Wave commands on button presses (switch 1 as well in case you wanted to turn other stuff on/off at the same time). I’m very interested in using S2 to do something else (like turn a smart bulb in a lamp on/off). I’m positive this hasn’t been done yet, but I’m fairly sure that it can be done.

It’s entirely possible that I’ve misunderstood, we began by talking about lamps and a battery operated switch (the following is from the original poster):

2- Use a battery powered switch such as the Popp described in the thread below. However, this would still require a physical on/off switch on the circuit. Great solution for beside the bed.

And then wandered through various discussions about the Fibaro relay, but with regard to a room with two entrances needing two switches.

My question now is on having multiple switches to control the 1 circuit. For example, if I have a room that has 2 entrances and I want dimmable led spots in that room what is the best solution? I have got as far as

But as long as the OP has found a solution that will work, that’s what matters. :sunglasses:

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Thanks - yes I am sorted. It was at @John_Crighton described what I was trying to do. I did not really want to use one of the stand alone battery powered switches as I wanted all the switches to match

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To be fair, as you mention, two way (or multiple way) switching is also covered here! I’ve got a house full of dimmer 2s and quite a few have multiple switches, this isn’t a problem, and can be done as JDR describes.

I haven’t used S2 on any of my modules, and would love dearly to be able to use it as a smart switch (as described) much like the Popp controller.

@kiwiInLondon, do you have a working solution for this, or are you just building it into your plan?

No, I have nothing working, I don’t even own a hub yet. I am just making sure all the pieces are in place and I understand what is needed so I can communicate to the electrician what is needed.

Vesternet has some good articles on all this. Here is the one on utilising the 2nd switch Email them too they are really helpful

Which version do you have?

My understanding, which may be wrong, is that the use of S2 changed a little bit between the first version of the Fibaro dimmer and the second version.

With the second version, you have a couple of options.

  1. You can use it in a regular two-way where there are two dumb physical switches both on the same circuit.

Or 2) you can use it so that S1 controls the load on the same circuit that the dimmer module is on. And you can use S2 with the same switch via Z wave association in association groups four and five to send “basic” (that’s a Z wave term) commands to other zwave devices that support association. Those devices have to be within one hop of the dimmer module, but they don’t have to be on the same circuit. The SmartThings hub will not know that those commands were sent, which can cause the status to get out of sync.

But I don’t think anyone has 3) created a device handler to use this as what smartthings calls a “button controller” where instead of sending Z wave commands directly to the other devices, the dimmer module would send the command to the hub who could then send it to any smartthings-controlled device, regardless of protocol or how far away it was from the dimmer module.

So using the second of the three choices you should be able to use it to control a smart bulb but only a Z wave smart bulb within about 20 meters of the dimmer module. You wouldn’t be able to use it to control, for example, a Phillips hue bulb or a bulb that was on the other side of the house.

But I haven’t followed all the details of what people have been doing in UK with custom device handlers, maybe somebody has solved the third option. :sunglasses:

You may well be right. Creating Option 3 is not so much of a problem for me as all I want to do is control a besdside light from a wall switch. For a lot of situations you probably would want the light in sight of the switch

I guess one situation that you may want to talk to the hub is if you wanted a single switch to turn off all the downstairs lights