Wiring for Fibaro Single Switch 2 not working

Hi, can anyone with experience of wiring Fibaro modules advise why the wiring in the photos isn’t working?

This is a Single Switch 2 module wired to a standard toggle on/off switch controlling 4 LED outdoor lights…


Honestly, I don’t understand your wiring. In the manual all options shows that the load (lights) connected to Q.

Where is your load connected? Where is your switch? Where is your power input?

Have you followed the manual?


And as you posted your question to the UK & Ireland section, I guess you are in the UK. This kind of (any electric) work, especially if you haven’t got any experience, should be done by a professional. It is just a comment for your safety.

Yeah, that’s not going to work. I suspect that before you installed the module the brown and blue went directly into the switch? You don’t have a neutral for the module and the Switch modules need a neutral.

UK wiring at the switch is typically a Live plus a Live return to the load(bulbs). All is not lost though. The Dimmer 2 would work in this scenario as it does not need a neutral.

Yes, correct.

I’m no electrician and this is being done by someone else, not me but this wiring has all just been run for a new extension and new lights so even in that case I wouldn’t have a neutral? How do you get a neutral to the switch?

Usually with some blue electrical cable, one end is attached to a Neutral wire on your circuit, and the other end is brought to the switch.

You don’t need a direct neutral with a Dimmer 2. The dimmer 2 finds neutral by draining though the load. The downside is that sometimes if you have LED bugs then one or more might continuously glow.

Hmm OK I’ll have to ask about that…

OK, my only sticking point is that I’m not sure I can return the Switch 2s I’ve bought and replace with Dimmer 2s now but worst case I’ll have to go on eBay…

Yes or try and pull a neutral.

IMO go with the dimmer 2 as they also run locally.

Can that be done? Sorry I’m a layman so just trying to understand.

OK but one thing I know about dimmer 2s is that they have a min load. Where I’m trying to wire this Switch 2 it’s to power 4 outdoor lights which have two 3W LED bulbs each in them. So total load will be 24W for the 4 lights - will the Dimmer 2 (assuming I go that way) be OK with that?

24W is on the cusp. I have two circuits around that value. One where I didn’t need the bypass and another where I did. You might need the bypass

Yea that’s the issue, that’s what I was trying to avoid really. OK well I think I’ll ask first if there is any way to get a neutral to the switch because that’ll solve it. If no, then I’ve got dimmer 2s wired at other switches so I can test one of those on these lights and see what happens before ordering either just a dimmer 2 or dimmer 2 and bypass. And I don’t even know if two modules will fit in my backbox - it’s deep but not sure it’s two modules deep!

The bypass is much smaller. It’s also connected across the load and neutral so would go up behind one of the lights.

Does the 1st gen relay have this same requirement for a neutral at switch?

So it wouldn’t go behind the switch? These are outdoor lights on my brick wall so not sure anything can be put directly behind them…

No, not behind the switch, just somewhere across the load. They are pretty small, so I am sure you could fit in in somewhere.

Only the Dimmer 2 can run without a neutral. All the other switches and relays need a neutral.

OK many thanks - I am at least a lot clearer on my options. I will report back here once I have developments for the benefit of those who may look at this in future.

OK so this is my mistake but I had planned to put Switch 2s in 4 places as part of the new extension work I’m having done but as I didn’t realise they need neutral I didn’t specifically ask the wiring to the switch to cater for that. And now they can’t get neutral to the switch. So the Switch 2s won’t work.

For the outdoor lights I will try a Dimmer 2 as the min load threshold may just work. The other three locations would have even less load so a Dimmer 2 definitely won’t work without a bypass. So, is there a smart module out there like the Switch 2 which can control low loads and work without neutral?

You said you have other Dimmer 2’s to test with. Why don’t you test first I don’t understand. Also I have a Dimmer 2 controlling a single 7W dimmable bulb quite happily without the Bypass 2. If you don’t test, you’ll never know.