Also this could be possible (in german, sorry!):
You could be right, but as long as we do not know the current wiring it’s just a guess.
It could also be that the L to S1 loop is just a pure control line, with low voltage and amperage.
if the wiring is twin and earth method as many above, the simplest is add a openhab device that can operate a relay double pole crossover ( in the uk called a intermediate switch ) , it switches the strappers, but only inverts the state
Then you have two options
- 1 try to add more wires and use this
Help with a 2-way switch
Which will allow you to leave your current switches in place and add “smart” to the circuit, but I don’t think you’ll be able to have all wires between light and first switch.
or
- 2 you can just replace both of the switches with something like Sonoff Touch or Sonoff T1 and do it as master/dummy solution.
I personally did second option, as I do have L/N in every old switch I have. Some older buildings (pre 2005) were allowed to use only one wire, which obviously is not gonna work.
And I do like to have an option to literally put dummy switch anywhere I want and still be able to control various lights around the house with it (depends on my rules). This is huge advantage of this setup tho.
It has it’s own flaws, but so far I can somehow solve all of those 
I feel I haven’t given enough information to everyone who’s attempted to help here (all of which I’m grateful for, thank you very much indeed).
The downstairs switch which contains “switched live” for the light I would like to control, happens to contain a number of other light switches, which means that there is a “permanent live” available to power the Aerotec/Fibaro module at this switch, if necessary. I feel like an ass for not pointing this out earlier and I apologise. Does this information change anything at all?
there is always permanent L in switch box (otherwise it would not switch light on)
question is still same, if you want to use fibaro you literally need 6 (5 to be precise) wires in that very box which will be used as per diagram
I would have thought that on a 2-way switch, one of the switches would not have a permanent live, just a “switched live” . Have I got that wrong?
does not matter which kind of switch, all of them needs to have in L
switches have to have always L, which then is connected/disconnected further to the light and so closing the circuit.
some of them needs to have N as well, smart ones for sure
3way switch does exactly the same with difference that only one of them have to have permanent L which is then distributed to others from that switch, which results all of them have permanent L at their ends.
The point I was trying to make is this;
My 2 way switch has physical switches on the wall, 1 upstairs and 1 downstairs.
Permanent Live is on the upstairs switch.
Switched Live is on the downstairs switch.
The downstairs switch is part of a 6-gang unit, which means there are other switches on there that have a permanent live, some of these switches only control a single light, so are “always” live. I don’t know if that explains it any better, nor if it makes any difference.
Thank you
Your upstairs switch can be connected to downstairs as follows
L is switched to L1 which is connected to the light and at same time L is extended by L2 together with L1 to the downstairs switch.
This is standard connection which allows both switches toggle connected light. Basically you have three wires required at each end, live, switchable and lead. Thats why its called 3way switch
6gang will have more separated Ls but each one should be different circuit or can be one covered by one fuse, but upstairs should have own fuse eg different circuit.
What exactly you are trying to solve now?
Just dissaemble your wiring/switch boxes and see what you have, or if you are not comfortable with main ac lines, hire someone
I’m trying to solve the same thing as my original post. I just wanted to highlight that I did have “another” permanent live at the 6-gang switch, in case this was a limiting factor in trying to turn on / off the light using the aforementioned module(s)
ok, as I said, another L should be on another circuit. I don’t recommend to mix up circuits which are on different fuses for obvious reasons.
But then again, if you will be using one switch as dummy to control other via mqtt or whatever, it does not matter.
What you should not do is to physically connect L from downstairs with L from upstairs if they are on separate fuses
Sorry for dragging up an old thread but something I forgot to mention and it may help others when it comes to putting in a dimmer - style module behind a light switch because space can be tight in there. I bought a box of WAGO 2273 terminals. These really help
2 Likes
Indeed. There are other models to have 2/4/5 inputs, too (to connect multiple ground or neutral).
And there’s another product line that I use a lot, it’s the 221 series. Those are slightly larger but only slightly and they have levers to lock the wires. Very reliable fixation and those also work if you have those more flexible, drilled (right term ?) copper wires.
Although somewhat expensive at first sight, they’re effectively also faster to use thus ultimately cheaper if you have some electrician perform the works, and you avoid that annoying fiddling with the wires.
BTW I got to know these from my electrician who said to use them because those common left hand side shown lustre terminals (Lüsterklemmen for us Germans) are known to become loose after some years and these do not. Bad deal for him, now I don’t need him any more to get this done 
1 Like
Yep, I have plenty of those, too. 
Hey,
I’m new to OpenHab and never tried this way, but maybe you can use a two sonoff TX switches and configure it with a rule.
If you switch it ON: it will switch ON the 
bulb and set state to ON to the second switch.
AND
If you switch it OFF it will switch OFF the bulb and set state to OFF to the second switch.