But on reflection, you’re probably right — it acts as an impulse relay. That would explain why every other time nothing happens with the real impulse relay.
Well, since you don’t send a pulse to the impulse relay with the Sonoff it’s normal that you’re forced to do on off and then off on.
The impulse relay changes state on a rising edge, so when you go from off to on.
Since you put the Sonoff and then the impulse relay you can’t have state feedback.
The only way is to replace the impulse relay with the Sonoff.
You’re afraid it will
[quote=« _Will_71, post:22, topic:8647 »]
the latching relay (télérupteur) is just a relay so it pulls in and closes a circuit for a time defined by an RC circuit or with a mechanical toggle (older ones). when you press the pushbutton with the Sonoff, when you keep both the contact isn’t solid and it can generate bounces since it’s ‹ self-powered ›, by removing the latching relay no more problem, and regarding durability… it’s rated for a certain number of open/close cycles so unless you play day/night… 
Hello everyone,
I finally took the time to get back to the subject and to do what @_Will_71 had suggested, to replace the impulse relay with the sonoff. It’s done and it works very well. I kept all the wires that were connected to the impulse relay (except the neutral) and put them directly on the sonoff (using the Lout, Lin, and S2 connections).
And I, who didn’t want to remove the impulse relay to have better reliability, realize that
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What a nightmare for someone not familiar!
Hello everyone, I don’t know if a proper introduction is absolutely required before posting in a specific category, in which case I apologize and will do it later.
I just came across this discussion which gives me a possible solution or at least an explanation for my troubles.
I started recently to automate things at home and I’ve come to want to modify my existing installation to control lights with Alexa (among other things for now the 4 spotlights in my kitchen) and later my garage.
First mistake: I had bought modules requiring a neutral and they didn’t work and were too big for the boxes, so I bought these little zbminil2 gadgets (4).
After watching some tutorials I thought it would be easy — I have push-buttons in the kitchen (3) to turn on my spotlights so it should be simple.
And then, not at all: after wiring it, it works but indeed in three steps, so with voice control you turn off then turn on then turn off again to switch on, or vice versa — in short: failure.
I just found this thread and it apparently talks about impulse relays… so when I opened my panel (attached) I discovered that on 3 lines at the end there is one, so that corresponds well to the 3 zones where I have push-buttons.
According to what is written above, it is in place of this impulse relay that I must put the module, which already makes me less keen to intervene at that spot but why not since I understand the issue and the principle.
My questions:
Is that really what I should do? Disconnect the impulse relay and put a Sonoff module in its place and not place it in a box behind a push-button as originally planned?
Second question: rather than playing the mad scientist, with the attached photos can you tell me where to connect the 4 wires of the impulse relay to the Sonoff even though I have a rough idea for 2 or 3 of the 4 — I’d rather be sure than try at random.
Will my push-buttons in the house still work?
Thanks to everyone in advance.
Hello @Thomas02,
You can indeed place your Sonoff in the position of the impulse relay (télérupteur) in your electrical panel.
However, make sure you correctly identify the impulse relay concerned 
(for example, the relay you circled is not the one you enlarged ).
As for the wiring, normally, from what I’ve seen online regarding the Hager esp 510b, the red wire would go to Lin of the Sonoff, the purple wire to Lout, the white wire to S2. I say normally because I’m not an electrician, and the wiring of your impulse relay doesn’t seem to be done to standard (the blue wire is supposed to be on A2, and the white wire on A1). You need to check that the red wire is indeed coming from the circuit breaker, and if you can confirm that the purple wire goes to the lamp and the white wire to the switches you would be certain.
Otherwise, if someone else could confirm they think the same as me, that would be helpful.
For the blue wire, put a domino or Wago on the end for protection (you can also remove it but if you want to put your impulse relay back for some reason, this will save you from having to reinstall it).
Then you will need to configure your Sonoff so it is in push-button mode (by default it is in toggle switch mode).
@bab85 @cce66 Thank you for taking the time to reply to me so precisely and especially so quickly.
I haven’t had the chance to test the connections yet. I should be able to get to it tomorrow.
Indeed, I have correctly identified the latching relay concerned; the photo was just an example. However, it’s difficult to confirm that the purple wire goes to the lamp — you’d have to remove the spotlights, and even then. As for the white wire toward the switches, as you can see in my photo, it is not present behind the switches.
We agree that I shouldn’t leave any wires on the latching relay? I remove them to put them on the Sonoff? No jumper wires between them? I’m worried about the operation of the push buttons — will they still work or not.
I’ll keep you informed, thanks again.
Purchasing a multimeter with a continuity tester is worth considering! 
Hello everyone and happy to join this forum.
I just moved into a new house, which I’m trying to set up with home automation.
Thanks to you, I just replaced my entrance lighting impulse relay with a ZBMINI L2. It works perfectly, thanks!
Just to be clear: only the live (phase) is connected to L out, nothing on L in — is that normal?
Another thing: since the neutral used to arrive at the impulse relay, could I replace the module with another one, and keep the ZBMINI L2 for a switch that won’t have the neutral? Since my impulse relay is in a junction box where there is space, I don’t need such a small module.
Any model to recommend? A Sonoff would be great, if possible.
Thanks, I feel like I’m going to learn a lot here!
Hello,
As for replacing the ZBMINIL2 with another module that works with the neutral, yes you can do that. If you want to stick with Sonoff it seems to me that the ZBMINIR2 is suitable: https://www.domadoo.fr/fr/peripheriques/7474-sonoff-module-zigbee-commutateur-10a-zbminir2.html. I’ve never tried it.
On my side I use WHD02 modules found on AliExpress (cheaper). Be careful on that site, they freely mix Wi-Fi and Zigbee modules, you need to check carefully what you’re buying. However, it’s only been a year since I installed the first ones, so I don’t have hindsight on long-term operation. For the moment they satisfy me.
Regarding your wiring, I’m very surprised that everything works perfectly without putting anything on Lin. Normally, you put the live conductor coming from your circuit breaker on it. So here I’d let a qualified electrician explain why that works.
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Thanks for your help and your feedback. I didn’t realize that the phase had to go into L1. I thought that, since the module was designed to operate without a phase, I didn’t need it: I put it aside…
I wanted to send a video to show you, but I don’t have permission, I’m a newbie…
The zbminil2 is a no-neutral switch but not a no-live one! You’re confusing neutral and live!
Oh yes, sorry!