2wire system, smart light switch and dimmer (UK)?

(Paul) #1

Hi everyone, just wanted to clarify if what Im planning to do will work out…as if not, I will need to think of a different strategy and do my shopping accordingly…

I would like to change my light switches to smart ones, I am in UK and with an old house which has a 2 wire system. Will it work if i connect my 2wires to fibaro dimmer, and than 3 wires (including neutral) from dimmer to the smart switch?

(Robin) #2

You only need one or the other:

Fibaro Dimmer 2 will work on either 2 or 3 wire setups

Most smart switches will only work on 3 wires

The Fibaros connect to the two incoming wires behind the switch and then 2 additional wires between the Fibaro and a regular ‘dumb’ switch.

I’m in the UK and reccomend you just use Fibaros for everything, the smart switch choice in the UK is limited, has less functionality and always require 3 wires.

(Paul) #3

Thanks Robin for reply.

The thing is i still want to have a switch (which most likely will be used by my partner), which will have some functions i.e. dimming, scenes etc… i dont want to have a seperate battery controlled switch or remote next to the dumb switch as it would look awkward…plus some of the smart switches look really good…

Would I be able to imitate 3wire system by using fibaro dimmer?

(Robin) #4

You’re not getting it, the dumb switch effectively becomes a smart switch.

The dumb switch is wired to the fibaro which is wired to the lights.

If you choose a retractive switch (push to make / momentary) you can control at the wall as follows:

  • 1 click - toggle on/off
  • 2 clicks - turn on at 100%
  • press and hold (when off) - turn on at 1%
  • press and hold (when on) - phase brightness up / down (alternate holds)

You can add a second physical switch to each Dimmer 2 module, not for controlling a load but for sending scene ID’s to the hub which smartapps like webCoRE can use to trigger whatever you like.

(Robin) #5


or for 2-way:

Or in the ceiling:

(Bob) #6

I went down a different route than Robin.
I have used LightwaveRF dimmers and outlets.
You DO need to have their hub as they cannot connect directly with ST. You can then control them through ST on a cloud to cloud or via a Pi.
Not as straightforward to initially set up, but once you have you leave them alone.
The switches work manually or via ST.
The dimmers and outlets are a direct replacement for you existing ones.
Just another option that you might like to consider.
There isn’t too much in the UK I’m afraid.

(Paul) #7

Thanks Robin ‘I GET IT’, but some smart switches look really good, and I havent seen many decent looking retractive switches (or maybe i dont know where to look). But thanks anyway.

Hi bobbles, thanks for the reply… it seems like a good option which I need to look in to, the only thing that worries me at the moment is cloudTOcloud, the internet is still unreliable and my mrss would kill me if we would be left in the dark because of my gadgets :smiley:

It does look like I will have to use fibaro dimmers, and maybe set up a touchscreen for if Ill want any effects, or some other cool stuff…

(Bob) #8

If the internet is down I use my mechanical device. My finger…But that is the case for most home automation stuff.
With Robins’ option you can pick whatever standard switch you wish. The switch still works but you can also use ST to use automations.
It is a good option. Just a matter of which road you go down.

The one thing you need to be aware of with the Fibaro is if you fit them in the existing switch back box, you will need to make sure there is enough clearance. Some people fit them in the ceiling rose as per one of Robins screenshots.

(Paul) #9

WIth the LightwaveRF, do you have to fit like a dimmer behinde the switch? or does it support 2wire syst?

In case of no internet, when controlling mannualy, do you know how lightwave talks to its gadgets, is it wifi?

Im also trying to weigh the costs, with the fibaro dimmer if i want to change all the switches, that will be LOADS of ££ :slight_smile: … however still works out cheaper than rewiring the house

(Bob) #10

The dimmer is a direct replacement for your existing switch. Just turn off the power to the switch, remove existing switch, connect new switch. Simple as that.
It has its own built in dimmer as part of the switch.
No neutral required.

(Robin) #11

These are the switches I use (in white), but just search google for retractive / push-to-make / momentary switches and there is tonnes of choice.


Personally I’d always go for the direct Zwave integration, not something that needs a seperate bridge and indirect integration like lightwaveRF.


Can lightwaveRF dimmers trigger scenes seperately from the connected load?

(Paul) #12

Thanks Robin, these look really good!
I would prefer having most of my stuff on zwave, probably just need to open spreadsheet and work out the costs, to see if there would be a great saving by using lightwave for lighting…

Also some people mentioned delay when using smartthing and zwave sensors to turn on the lightwave controlled lights…

(Robin) #13

The lightwave integration, as far as I know, is cloud to cloud so it adds a step in the flow:

zwave sensor > ST hub > ST cloud > RF cloud > RF Bridge > RF Dimmer

or for two zwave:

zwave sensor > ST Hub > ST Cloud > ST Hub > Zwave switch

(Bob) #14

I don’t think LightwaveRF will work out as cheap as Fibaros and switches.
But when your starting point is a Lightwave RF hub and 4 switches and you then get into Smartthings I was already committed to the LightwaveRF product.

(Bob) #15

I use a Raspberry Pi.
So the ST hub talks directly to the LightwaveRF hub. Not cloud to cloud.
Sensor > ST Hub > ST Cloud > ST Hub > Ras Pi > LW Hub (via Ethernet cable) > LW Dimmer.

(Robin) #16

From what I understand, the Fibaro Dimer 2’s also now work at a basic level with a default, locally running handler. Combined with one of the many locally running sensors you can now achieve lightning fast responses:

local sensor > ST Hub > local switch

Fibaos, being zwave 5, also allow for direct integration with most other zwave 5 devices and sensors, so this is completely possible:

zwave 5 sensor > zwave 5 switch

(Robin) #17

so that would be:

zwave sensor > ST Hub > ST Cloud > ST Hub > RPi > RF bridge > RF Switch ???


(Paul) #18

I might be wrong but i think RPi would eliminate Cloud… so than:
zwave sensor>ST Hub>RPi>RF bridge>RF Switch

I think Cloud would be causing the longest delay, but if that is eliminated i wonder if there is still a substantial delay i.e. 3s plus

(Bob) #19

Not really. Walk in room, light comes on within 0.5 secs. Not an issue for us.
Your right about the ability for local processing though. This will be never be available with this set up.

Sounds like we are getting into a “Who’s got the biggest dxxk” scenario. :wink: (I don’t mean duck BTW). :smile:

(Paul) #20

Did you fit fibaro dimmer behind every switch?

To cut the cost, in some places im thinking to add just a smart light bulb and leave standard switch always on… not sure if it would be a good option? also, i understand that these sort of lights would not be dimmable?