Help:How to integrate a 2 way light switch into home assistant keeping the offline functionality

Hi, fellow Home Assistant users.

I am slowly integrating all my light switches into Home Assistant using Sonoff Zibgee MiniL and MiniL2 devices.

Now I am on a disyuntive.

I wanted to put a MiniL2 behind one of the two switches that control a light (2 bulbs in different places, but technically one load). This was my plan:

The problem is, that L1 at the right does not exist. Behind that light switch, the only power sources are the grey and black cables.

On the switch at the left, I could get the L1 split in to feed the MiniL2, but then I could not react to the switch at the right. Or at least I do not see it how.

Does anyone have any idea how I could achieve this?

Thank in advance you for your recommendations!


Updated Diagram of existent Connection:

This is the device I want to use:说明书-ZBMINIL2-V1.0.pdf

hi, do you have the existing wiring diagram for the 2 way?

i believe that’s the left-bottom part, where the “escalera” switch’s L (brown) is “cut”, does currently goes to the “left” bulp

How the sonoff works however, i dont know

I doubt he can “power” this from another circuit , should be the same as the other switches are powered from

while having a wire diagram of existing solution would be perfect, i wanted to add couple of things;

  1. whichever device you want to control, its load should be handled by sonoff relay through.
  2. at the same place, you need a load to power the relay
    satisfying the first condition satisfies the second condition automatically because you can use the load wire.

in my new home, I am 50% of the time lucky and I can find a proper switch which satisfies the conditions and I can just replace the dumb switch with smart relay.

for the rest, the live is coming to switch1, goes through switch2 and switch 2 is feeding the lamp. in the cases, you need to use smart relays which allows to run 220 over S1 and S2 inputs. it means that, you do not have constant live on switch 2, which is directly accessing to the light, so you need to run a live from somewhere else to switch 2 location. I am lucky as there is usually live around, but it is not the always the case,

I heard that sonoff relays are compatible with both solutions with some configuration options (havent tried myself.) posting what I am using at home locally (they are zigbee/wifi and I am not affiliated :slight_smile: )

if none of these solutions are suitable for you, you need to use replace both switches with smart ones and set an automation to keep them in sync and let the switch 2 manage the light.

The current connection is this

There in Switch Escalera (to the right) I also have access to Neutral and Earth cables, but no Live/Power/L cable

I have the same “setup” at my stairs to 2nd floor, at 2nd floor L goes to the bulps … been trying to figure out howto “change” the Bottom switch( your keller ) with a build-in motion-sensor, but are “stuck”
No matter how i, twist and turn it.

Anyhow, how does the your Sonof actually function, any details on how it works inside , and can you place it behind the “keller” switch ) , or in what seems to be a “connection-box” , in the middle ( there you have the L1, from your “incoming Circuit”)

The Sonoff can handle high input on the S2. That is what I planned initially to use until I found out no Live cable was available (just N and Earth).

AFAIK (from the manual) the S1 just provides voltage to use it from a switch, but not as secondary control or similar.

I think I will need to go to the 2 relay option using one of the cross cables (gray or black) to pass the Live signal to the second relay on the right switch., put the lights there, and control it with the S1 to S2 signal.

On the Keller (left switch) I will just connect a relay whose only function is to toggle the right delay when it changes.

What I do not like about this solution is that in case of a network failure, the left switch will not have any functionality.

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The “connection box” in my diafragm is really just for organization, in real life it does not exist. I connect the sonoff inside the switch box like shown on the web

Since here in Germany those spaces are really small, the size of the MiniL2 is a gift from the gods.

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Ok, i had a similar problem, no extra live wire that goes L1 of the sonoff mini.
Since i don’t plan to add additional wiring, I ended using this no neutral hack with the older version of sonoff mini (or sonoff mini extreme) and it works

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Do you have any central physical place as you drew on the diagram that you have both traveler and live? If yes, it looks like a perfect place :slight_smile:

Edit: just noticed that it is just for organization purpose, nothing physically exists

I saw this video on my research, but to be honest, at this point of my DIY adventure, I feel uneasy adding that configuration to my light switches without a fully calificated electrician.

Also in Germany there are no boxes on the celling or wall lights. We just get the cables there directly from the wall :cry:


I tried that too, but it didn’t work. 2 switches also burned out)) I put in Shelly, which knows what you want.

Your schematic is still incomplete. Lights don’t work with just one wire. What is the X in the top box? And what is the box in the middle?

Show what wires go where. All of them.

(I am assuming “PE” is ground.)

Then I would recommend hiring an electrician to extend another live wire for the Lin.
My setup was a bit complicated because I had a 3 gang UK type switch (each on 2 way wiring) that was wired to different wall switches. Obviously no space behind the switch so I installed the mini on the light fixture

You can forget the the bulb images. The X is the load, and I was considering the second light as just controlled by the same switch (B) as the first one (more of this at the bottom)

I was getting this idea for how the cables are arranged in the switch boxes.

This is box A (Keller):

This is box B (escalera)

The brown cables from box B go each one to one light. Of course, each light N and PE (Earth/Ground) arrive, I assume one comes from box B and the other one from Box A.


Now that I have taken pictures and made this. I THINK, the second brown cable on box B is returning to box A from where it goes to the needed light (with that white Wago connector), although I think this changes nothing for my problem.

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For now, this will be outside of the possibilities, unless I am mistaken, that would require for us to tear apart the wall and part of the ceiling (everything is made of concrete).

The cables in Germany come directly from the wall like this:

And the cables do not travel through any special tube, just inside the wall.

Looks like a lot of work just to extend an additional cable.
You could try this wifi relay, should work with your existing 2 way wiring (just need to install a capacitor on one the bulb)

Wiring should look like this, sorry for the mspaint edit

That makes two of us. I am still confused, what is the box with six connection dots and where is it in relation to the switch and light boxes?

Turn off the breaker and use your VOM to trace each wire if you aren’t certain where they go.

It’s in Cosmos ! , he mentioned it was only to “illustrate”, it doesn’t exist … but confusing, Yes, and actually no point in( misleading) showing it in the diagram,
Also, after showing pics of the switches, it turns out there is both ground(PE) and “null” (N) , in his switch-boxes … ( which i btw, unfortunately dont have in my “upper” switch box, there i only have the 2 coming from switch-1, and the “Live” going to the bulp :frowning:

And the suggestions in regards to a Capacitor, on 2 wires coming out of the ceiling ( there is no connection-box, so it’s “complicated” if even allowed ) in my ceilings either, beside the rooms where i have lowered the ceiling, and “attached” a box aimed for ceiling light-connection/bypass )

Could you post your wire diagram ?, maybe i could use this in few places, as i also have “issues” fitting anything behind some of my switches