Two light switches for the same light. how to install relay switch?

[maxdreamland 1]

Hi,

 

in our hallway we have two light switches, one on each end of the hallway, and both switches trigger the same ceiling light. So you can switch the light on and off from both switches. the german terminology for this is a "Wechselschaltung" and dict.cc proposes "two way connection" as a translation, though i'm not sure if this makes sense. but if you're an Electrician you probably know by now what i'm talking about

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I would like to install a Fibaro Relay Switch 1x2,5kW in one of these switches to remote control the light. But I'm not sure how to connect the relay to the switch.

 

I searched the internet for help and i found the circuit description I attached below. It describes how the light switches are connected and i opened my switches (see photo attached) and checked, and indeed each of the two switches has three wires (brown, black, gray) which is consistent with the circuit image. by the way the switches are on-off-switches, you flick it and it stays in the on position, you flick it back and it stays in the off position. they are not what i believe are called "momentary switches".

 

I even found a circuit description for doing this with a Fibaro Dimmer, which I also attached below. But i have very little experience with electrical installations and I can't really make sense of that circuit description and how to adapt it to my relay switch (instead of a dimmer).

 

Is it even possible to do this without laying new wires in between the two switch boxes?

 

maybe this would be easier if i install one relay in each switch?

 

Any help would be appreciated. Thanks in advance!

 

best regards

Max

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[Joacim 11]

First - in Sweden it would be illegal to install electrical equipment if you do not have enough knowledge.

Fibaro uk have some wiring diagrams. I believe this is what you have. (Without the switch in the middle) But I think it may be impossible to be surtain without closer examination.

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Edit: Wikipedia explain it quite well I believe.

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[morpheus75 77]

your lights contain all 'live' or 'switched live' wires which means a relay cannot be installed unless there is a 'neutral' wire hiding somewhere. (its not normal to have a neutral wire behind a switch).

the only option for a relay would be in the light it self as this has all all 3 types of wire ie 'live', 'switched live' and 'neutral'

[maxdreamland 1]

thank you for clearing this up for me. As I wrote above, I suspected as much but wasn't sure if I was reading the proposed circuit right. now i know for sure.

 

well, kinda sucks but i guess I'll find another use somewhere in the apartment for the relay.

 

thanks again for taking the time!

 

best regards

Max

[Joacim 11]

Well you do have a box in the ceiling above the light there is probably the place to put the relay. If you check my links you will se that it probably is possible.

[maxdreamland 1]

Well you do have a box in the ceiling above the light there is probably the place to put the relay. If you check my links you will se that it probably is possible.

 

in your linked diagram from the Fibaro Uk site, there is a "brown box" on the blue wire that goes into the S1 input of the relay. Any idea what that's supposed to represent? Is that a resistor? the same kind of "brown box" can be found on the L2 input of the "first switch"

[Joacim 11]

No that is not a resistor. It's just a wire marking to emphasise that the wire is a switched live wire.

[petergebruers 1,268]

No that is not a resistor. It's just a wire marking to emphasise that the wire is a switched live wire.

I agree. Put otherwise: that wire should have a brown or black color, not blue... but because you are reusing existing wiring that may be hard to fix. I am not sure that your local regulations allow for this... but you can put some brown (or black) tape on the wire ends of that blue cable. That way, if you or someone else, ever has to work on this circuit, it's clear that it is NOT a blue neutral wire! Please do not use this blue cable without brown tape. Also, please make sure (by testing) that this wire is not used by anything else. It's quite possible that a blue, neutral wire continues to another circuit (or splits somewhere). If you don't understand anything of this, I strongly advise you to ask assistance from qualified personnel. It is nothing to be ashamed of. I say that because if it's not done right, this can lead to personal injury or possibly pose a fire hazard.

[maxdreamland 1]

I'm taking the advice several people have made (or implied) and will leave this alone. I don't want to burn down the (rented) apartment

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thanks to anyone who took the time to explain it. It will be here for others to use who are more brave ... or knowledgable than me

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I'll stick to software for now.

 

regards

Max

[petergebruers 1,268]

Hi! I've been thinking about this "rented" thing... Maybe this is an idea... You could use these "Secure Wall Controller" modules from:

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And combine them with Wall Plugs so you have a minimal impact on the wiring. Or relay modules. You can stick these to the wall. Or you can use Aeon MiniMote, I have two of these.

I'm trying to think "out of the box".

Maybe you can connect the relay (you already own it?) to the first switch (following the instructions in the manual) and the light. And fix your second switch in the "on" position (with some PVC tape). Use one of those wall controllers at the other side, or in fact... anywhere you want. If that works, you can have a more permanent solution for the second switch. Remove the two wires that run to the "on" side of the switch. Then connect them with a WAGO connector:

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That's also straightforward to "undo".

Just some ideas...