Fibaro 2 Dimmer (212 not 211)

Thanks, I’ll have a look into that. I’ve re-calibrated so many times though it probably doesn’t need that again.

I’m just at a loss as to how it works manually but fails on z-wave. In the log I see an on event followed by an off event, and I have no idea where that off is coming from. I’d have assumed if it was a surge or something then there wouldn’t be an off being sent, but I don’t really know.

I’m hoping the Qubino modules fix this; if not then I’ll have to start delving even deeper. Or give up!

Just curious, why are you guys putting the dimmers into ceiling roses instead behind the switches? Is it simply because you dont have enough room behind the switch?

I’m doing it because the way my house is wired, I’ve only got the common wire and the two strappers available there. Evidently the person who wired it connected the strappers to the live and switched live somewhere in the ceiling which is inaccessible. It’s under a tiled bathroom so I can’t even lift the floorboards to get to this junction. Either way, it means I don’t think I can wire it behind the switch according to the Fibaro diagrams.

Does that make sense?

Typically it’s because there’s a neutral wire at the Rose and no neutral wire at the switch box. This is pretty common in UK construction. It also gets done in older houses in the United States.

Ok that makes sense, but I guess you can also install Fibaros without the neutral, is it somehow inferior method?

No, but it often requires splitting the core wire open, and not everyone wants to do that or is allowed to do that by the property owner. It really just depends on the individual wiring and what the person doing the replacement is comfortable doing.

There is also one old form of wiring (in the United States we call it knob and tube) where the wiring is sealed together and partially enclosed in ceramic pieces and you have to find a place where there is an existing neutral already split out.

There Has to be a neutral on the circuit somewhere, but in older homes it often starts at the Rose.

1 Like

None of my switches have a neutral and the Fibaros are absolutely fine their, with N tied to Sx (if I remember correctly).

This issue I have in this one room is that there is no way I can get the module between the physical switches’ wires and the live/switched-live. If I attach at the switch, the control wires will be live (courtesy of the hidden junction box) and it’ll be bye-bye Fibaro, I suspect. Up at the rose it should just look like a standard one-way switch is connected to the live/switched-live cable. However I’m guessing a surge is creeping in. I’ve used a suppressor which helps the manual switch work more reliably, if not 100%, but the z-wave part never properly works now.

I will draw a diagram and upload that because I know my setup is fairly convoluted and folk on here may spot an obvious error on my part.

Hi Giles,

I know we have spoke about this already but just as it was exactly the same issue as mine that being that the lights would turn and off immediately when using zwave not the physical switch, can you confirm if this issue occurs if the switch is configured as on off only (no dim) and does the issue go away. If this is the case which I suspect it is you can “potentially” resolve this changing the dimming parameters.

Has anyone here got experience of the Dimmer 2 installed in 2-wire installations with 3-way (or greater) circuits and toggle switches?

I have put together a test circuit and the switching all works fine manually (single toggles required), and the Dimmer 2s work fine remotely, but I have an unusual behaviour when mixing on and offs between physical and remote.

For reference I’ve used the wiring from the Vesternet site ( but not bridged the Sx and N contacts (as this resulted in a red overload led on the module) and switched the light off after about 1s.

If I switch on physically, then switch off remotely, the next physical switch on will require 2 toggles to turn on. Equally, when I turn on remotely, and then turn off physically, I need another 2 toggles. Even more unusually I’ve noticed that in some states, the final switch in the circuit will work with 1 toggle (i.e. as expected). Can anyone confirm if the behaviour I’m seeing is what should be expected or is it indicative of a wiring anomaly somewhere? If it’s by design it’s a bit disappointing as it prevents me transparently installing into existing circuits - not keen on replacing switches.


Unfortunately yes, the issue still occurs. I tested it again today. I’ve tried so many wiring setups now that I’ve decided to pull out the Fibaros and abandon this one. Feels like I’ve spent hours lately fidding around with this ceiling rose and the switches.

I have a couple of Qubino units to try, but to be honest I might just leave it for now and come back fresh in a couple of months.

It’s unfortunate that this has all happened at the same time that SmartThings has been so useless with timed events failing routinely. It’s making me question the whole HA thing at the moment. Or at the very least, I’ve been having a serious look at the Vera Edge. I know these issues aren’t related, but I’m craving reliability at this point.


Can I just check something. The Fibaro dimmer 2 works in standard situations with SmartThings right? i.e fitting to behind the switch itself and with two way lighting?


Yes, especially well with momentary switches.

Thanks for that. I am wavering on returning my vera and replacing it with smarterthings (before my time to return runs out!).

I have been postponing buying this since the bypass is still not available for this never unit.

Anyone happen to know if I can use this as simple on/off switch for LED light with less than 50W draw?
Normally you need the bypass to dim the load below 50W, but since its outside light and I don´t actually want to dim it, just control on/off state I am perfectly happy if the dimming doesnt work.

Why dimmer for on/off and not simple smart switch you ask? Only reason is that I have 2 wire system and this is only unit that I know off that works with 2-wire system, other options are more than welcome.

This is how I have one of my circuits at current until I update some of my LED bulbs to dimmable ones.

No, you can’t use this as an on/off relay, for this you’d need a different module.

Dimmers are never truly off, whereas relays require a neutral wire to give enough power to move the switch (as the current is truly off when off).

I’ve heard elsewhere that the bypass 1 will probably work fine (and why shouldn’t it, it’s only a resistor), the two apparently has some ‘smart’ tech built into it.

If I were in your shoes (and if it were easy enough) I’d change out one of the bulbs for something with a higher draw until the bypass 2 became available.

The Bypass 2 is available. I bought 4 a couple of weeks ago from Vesternet.

For me, it didn’t help with a flickering LED on low dim (could be the LED at fault) but works brilliantly with compact fluorescent bulbs. I can even din these now, which I didn’t even realise was possible as they are old bulbs!

This doesn’t echo my findings, I current have about a circuit with around 4 x 4w bulbs configured as on/off and it works fine. It also mentions in the manual greater support when configured in this mode. I’ll dig it out when I get a chance.

I wonder if its because you have high enough load on the circuit.
I´m guessing when you have enough load, the dimming works and it can dim the circuit to 0%, effectively turning lights off. But if I were to have just one 11W LED on the circuit, dimming to 0% would not work and light would never turn off since apparently this device cant turn completely off, just dim?

Not sure if I´m right, but that would explain the varier reports above.

Can anyone recommend a switch that I could use in two wire system? Dimmer+bypass is kinda expensive for circuit that only needs on/off.

From the manual, suggests turning dimmer on or off and this is what I have done:

As a dimmer it operates under the following loads:
• 230V operated conventional incandescent and halogen light sources
• 12V operated ELV halogen lamps and dimmable LED bulbs (with electronic transformers)
• 12V operated MLV halogen lamps (with ferromagnetic transformers)
• dimmable LED bulbs
• dimmable compact fluorescent CFL tube lamps
• supported dimmable light sources (power factor > 0.5) with minimal power of 5VA using FIBARO Bypass 2 (depending on the type of load)

Without dimming function it may work with:
• compact fluorescent CFL tube lamps with electronic ballast
• fluorescent tube lamps with electronic ballast
• LED bulbs (power factor > 0.7)
• supported light sources (power factor > 0.5) with minimal power of 5VA using FIBARO Bypass 2 (depending on the type of load)

For one bulb could you not go with a smart bulb, you have probably missed it but Amazon on their Cyber Monday deals are having some great offers, v1 hue kit was £84.99 for 3 bulbs.