Lighting Issue - Can you Trigger Lights from a Switch (Like a Button)? (UK)


I’ve done some searching in the community, but haven’t been able to find an answer.

We’re building a new home and the plan was always to have an element of “Smart Home” features with CAT6 to each room and neutral wire at all lights to allow the use of Fibaro modules with SmartThings where required - although for most areas we will just be using standard light switches etc.

Yesterday the electrician realised a mistake had been made! In our living room at the bottom of the stairs, which is also the entrance from a hallway - we have a two gang switch for two sets of lights in the living room (so far so good!), at the other side of the room where you enter from the kitchen SHOULD be a corresponding set of two way switches, they have completely forgotten to put the wires in and the room is plastered and painted!

We can easily get a power source to where the switch needs to be (neutral/live/earth), is there a way to put a switch in there which is simply triggering commands to the other switch/Fibaro module/SmartThings hub. Our plan is to use Click Micro Switches throughout.

Any solutions and if so are there downsides i.e. significant delay in switching or are we pulling walls apart!?


Sure, no problem. :sunglasses: This is called a “virtual two way” in the UK (and a “virtual three-way“ in the US), it is a very common way of adding additional wall controls that don’t require wiring.

You can use a mains powered device or if you prefer you can use a battery powered one. (There are even some new devices which are not wired to the means but are “battery free“ using the kinetic power from when you push the button.)

So there are many options.

There are two main ways of doing this. If you have only Z wave devices, you might choose to do it by having the button talk directly to the master device. This is called “Z wave direct association.”

Or, you could have the button talk to the hub and then the hub talk to the Master. This lets you use any device that the hub can communicate with, including devices of other protocols like zigbee. It also does a better job of keeping all the statuses in sync. So this is usually the preferred method, but some people do still like to use the older the wave direct association method because it will work even if the hub or smartthings cloud is not available.

See the following FAQ for some of the device options. Each entry is marked as being for the US or the UK, and indicate whether it is Mains powered or battery powered. The post should also have a link to a discussion thread about that specific device.

If you do have any questions about individual devices, please use the linked to discussion thread or come back here and ask them. Don’t put questions in the FAQ, it is just intended to be a poster or two about each individual device to keep it easy to read in the future.

( The topic title is a clickable link)

@anon36505037 May have more to add. He is in the UK and has done two full houses with Fibaro Kit.

Some US members may suggest a method that involves hotwiring a master switch so that it doesn’t control the load. My understanding is that method is not legal in the UK unless the switch is specifically designed for that purpose and the manufacturer provides a wiring diagram that matches what you are going to do. And in any case that approach is not necessary for the situation you describe.

One possibility that I used in a finished bathroom is to wire the second switch in with the neutral and line wires connected, but leave the load unconnected. It’s a switch that does nothing until you set up the Smart Lighting App. With the Smart Lighting App you create two rules, one to mirror the slave switch to the master switch and one to mirror the master switch to the slave switch. That way, you can flip either switch up to turn on the lights and flip either down to turn them off.
There is a slight delay as the mirror behavior works its way up to the cloud and back down, but it’s usually less than 2 seconds and often much quicker than that.
I don’t believe this violates any code (as the master switch is still wired into the actual light). It wouldn’t hurt to check with the electrician just to be sure. (I can’t imagine why it would, but hey, it’s code :slight_smile: )

Please check in future to see if you are replying to a post in the UK category. My understanding is that the method you describe is not legal there. Electrical devices connected to the Mains must be installed in a manner in conformance with the manufacturer’s instructions and wiring diagrams. The UK allows for much less DIY than the US, particularly when it comes to electrical systems. It just confuses everybody if you bring up wiring methods in UK threads other than those that the manufacturer has designed the device for.

Submitted with respect.

I will check on UKness in the future. The difference between this situation and the one that prompted our first exchange was that this was not bypassing the original switch in any way. It was only that a secondary/remote switch was wired into power. The electrical integrity of the primary circuit is unaffected. However, since “Electrical devices connected to the Mains must be installed in a manner in conformance with the manufacturer’s instructions and wiring diagrams.”, it might be at issue. (I suppose it depends on whether the manufacturer has a wiring diagram which has this option.)
I hope you’ll note that I did suggest that they check with the electrician about code as well. I thought that would be sufficient to forestall anything untoward.

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Yes, if the manufacturer has provided a wiring diagram that matches the no load suggestion, then it would be fine.

If in future you would like to suggest that they look for a device which has a wiring diagram with this option, then that would be fine in the UK category. There are some of these in the US, such as the GoControl WT00z auxiliary switch. I’m not sure if there’s one of this type in the UK, although there may well be.

UK directives want any sparky to be able to work on any project set up by another.

Just as one example of how different the approaches are in the US and the UK, in the UK wire colours are strictly mandated. In the US in most cases they are not, and anyone can use any colour for any purpose, typically just depending on what’s left in the toolbox at that point. (I’ve seen a US box that just had four black wires, none of which were the line in!)

In the UK, you can typically tell how old the wiring is just by looking at the colours used. That’s not possible in the US.

In addition, at the completion of any wiring job, the person doing it is supposed to issue a safety certificate saying that it complies with UK standards.

So in addition to having different voltage, different grounding methods, different zwave frequency, Different terminology, and different Switch shapes from the US, just the whole approach to DIY is quite different. Hence the creation of a separate UK section of the forum. :sunglasses::uk:

“different the approaches are in the US and the UK”.
Agreed. I can see the value to each approach, but you have to work with the rules where you are.
“in the UK wire colours are strictly mandated. In the US in most cases they are not, and anyone can use any colour for any purpose, typically just depending on what’s left in the toolbox at that point.”
Believe me, I quite understand. Having renovated two houses and worked on a few things in our current (no pun intended) home, I’ve seen all manner of cobbled electrical and plumbing work. I’ve done my best to get each one up to code. (Indiana code to be sure.) Such work often causes me to scratch my head and say “What were they thinking?” and occasionally utter a fervent appeal to deity especially when colour choices included swapping white and black wires (!!). There are times when I envy the UK sparkies.

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Really appreciate that link, currently ploughing through it and a lot of posts which are linked from it!

I understand now what I need a lot better, however what I haven’t yet come across, is a way to make a standard retractive switch into a virtual switch or a button, so that it will match with the switches in the rest of the room - unless I have missed something?

Appreciate the suggestion Russ and the following commentary, however, the challenge is getting any wire back to the master switch, otherwise would be able to wire in the normal fashion :frowning:

Hi Robin

I’ve read several of your posts and great to see someone with such experience in the UK - will definitely be seeking your advice at some point no doubt :smile:

Absolutely, the electrician is more than happy to rectify, however, due to the stage we are at it will mean remedial work to plastered and painted walls with switches which are 7 metres away from each other - was trying to avoid if possible :frowning:

If you want to use an existing switch, then you have to Wire it to something which has a radio so that it can communicate to the network.

Option 1: wire a battery operated radio device behind a regular dumb switch

There are people who do this with a battery operated sensor, but the problem is then they usually want to put it inside the wall, which is a bad idea and likely not firesafe.

Batteries can and do outgas. So battery operated switches are almost always designed for a “surface mount” where they just sit on top of the wall. That can work very well, But it means the battery operated switches will be elevated from the wall a bit and won’t exactly match the mains powered switches. But they will look the same other than the elevation, so it just depends on whether you are OK with that or not.

Option 2: use a Fibaro micro with a dummy switch

The other option is that you said you could get power with a neutral to the switch location. So you should be able to put a fibaro micro there that doesn’t turn anything important on and off. I’m not sure exactly what UK code would be for that, @anon36505037 might know. But it would essentially function as a Switch In a location Where an outlet might normally be. It turns that circuit branch on and off, but there isn’t any other device on the same branch.

( or perhaps have that switch control an outlet that you don’t intend to use. That should work as far as code goes, but it’s additional cost and in trouble for something that you actually don’t need.)

If there’s a way to do that legally to code ( or if you add the additional no unnecessary outlet) then you could have the micro with the dummy switch communicate to the micro for the master switch, Either using the hub for a virtual two-way or using Zwave direct association.

Again, Robin Would have a better idea of what’s practical in a UK home… Conceptually it’s not a problem, I just don’t know if UK safety code allows you to have a dummy switch of this type. If you have to add the additional outlet as well, The project should be doable, just more expensive and people in the home using your system have to know that the switch is going to be controlling the Master lights as well as that outlet.

This is what I meant by a “dummy switch.“ I suspected @anon36505037 Would know the answer. :sunglasses:

I would support everything he said, and would also prioritise solutions in the same way: first try to get the builder to provide what was promised, or alternatively, use the Fibaro method he suggested. (I’m not going to edit my post above because there may be some people who do want to look at the battery option, particularly if they are renting and are not allowed to change wiring, but in your particular situation, I like his recommendation very much.)

I was unaware of the staircase issue for the UK. In the US, there is a somewhat similar code issue but in most jurisdictions it only applies to lights for an attic.

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So here you go. The UK equivalent to the GoControl WT00z, that is, a device available in the UK that can be installed without connecting a load wire, effectively creating a dummy switch that can then communicate to a master in a “virtual two-way,“ is a Fibaro micro relay (not dimmer) when installed as described by @anon36505037 in his posts 13 and 14 below:

It would probably be best to refer people directly to that post, as there are a number of small details required to make it match UK safety codes. :sunglasses:

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Just wanted to thank everyone for their support - the electrician ran the wires as suggested by @anon36505037 so I now have an abundance of options :slight_smile: