I’m looking to automate some of my wall switches, but I’m unsure as to what I need to buy to achieve this. I was considering the sonoff switches, but having taken an existing switch off the wall I’m not sure they’ll work.
The above is the first one I’d like to replace, it’s a switch which triggers a relay which turns off all lighting circuits in the house. If the sonoffs won’t work, are there any other options for me?
How about a Z-Wave module?
Most modules will require a neutral wire, or to be a 2 wire compatible dimmer.
It might be better if you could explain the wiring that you have in there, as it’s “Non standard” for the UK.
A Sonoff will certainly NOT fit into the back box you have - they are quite large units. If you are prepared to replace the box - the world is your oyster as they say!
If you wish to retain the wall switch, as a mode of operation, that may not work with a Sonoff, which is designed to switch a permanently live supply on or off to the appliance/light. I’m not saying it can’t be done, somebody may have done something similar already - I just can’t get my head around how it might work.
Instead, you might be able to cobble something together with an ESP2866 (upon which the Sonoff is based) board and relay - you might even be able to use the existing relay.
As @Tinkerer states, a Z-wave module would probably fit, it can go at either end of the connection, so doesn’t have to go in the back box - although it is smaller than the Sonoff, and may fit. Obviously, there is a larger overhead involved with setting up Zwave if you don’t already have anything else - it may be something you want to look at.
Edit - Sorry, I didn’t realise that there was now a Sonoff Light switch - I thought you were talking of the original Sonoff wireless switches.
Hi,
All depend how much you want to spend, and which solution do you have in mind, and which one can be possible or not and also the visual design that you have implemented at home.
In case that you have places with switch and plug, maybe you don’t want to change the design, with 2 devices, and you want that all continue as you have, but behind the switch you have the smart electronic.
In my case i also want to make turn automate some switchs at home, but i don’t want chage the visual design, so i was testing with ESP8266 + relay and i will implement this solution. Here you have a little example with 2 relay, 2 lamps and 2 switched.
In that case, i’m using a ESPEasy firmware, and needed to make a little code, to synchronice the switch with relay, and how the state in home assistant.
I think a Sonoff basic will fit in a UK backbox if you trim the casing a bit.
For sure its a tight squeeze, but pretty sure it will work… in fact I’m banking on it for my project:
See the final photo - you can see the sonoff basic PCB fit with some mm to spare.
My trimmed sonoff case that you can see in the video is 2-3mm bigger than the pcb.
So 
Edit - actually comparing images I think maybe I benefited from the fact my backbox is 5+ mm deeper than the wall fact due to plaster thickness… mind you the switch plate gives a bit of additional leeway too as it probably 5mm proud of the wall.
Looks fairly normal to me, split live and no neutral but they used three core and earth cable you’d normally use for a two way circuit.
Could be wrong of course 
The trouble here is that unfortunately I’m no electrician. The house is only 18 months old but I’ve no idea what wiring standards are correct. Ideally I’d like to retain switch functionality for the odd time I may need it, but I’m assuming the Sonoff Touch won’t work in this case due to it not being wired the same as a normal lightswitch? (which would make sense as it’s not a lightswitch per se).
OK, so having done some more research I’m beginning to understand what is going on with the wiring in my photo above. The brown is the live feed, and the black (with the brown sleeve) is the switched live. In that case, what could the grey-sheathed one be?
If it helps, the switch for the extractor fan has the same setup (albeit the grey/black are swapped compared to the image above).
I did make a suggestion 
Did also read someone on here thought new regs permitted a neutral run to the switch but I couldn’t find any mention of it Googling. Would make sense given ‘smart’ switches are only going to become more prevalent and our normal wiring is holding us back.
My house was rewired in 2009 and the electrician wired N to the switch.
This IET discussion forum post (from 2007) suggests it’s now commonplace/best practice:
http://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=19209
If you want dimming and only have 2-wire then your only choice is the Fibaro Dimmer2 with the Bypass2 across the bulb. The Aeotec Nano Dimmer also supports 2-wire, but there’s no bypass available yet if you want to use LEDs…
The reason for this if you need an explanation is that the module itself needs to be powered (albeit a small amount). So If you only have two wires, there will be a small draw on it going through the bulb, which might be ok on a tungsten, but on an LED wouldn’t be that great. So the dimmer sits over the ± of the bulb to draw that bit of current away from the bulb.
If you had a 3-wire system with neutral, then the dimmer would just be powered through that.
You might possibly need deeper boxes depending on the switches you use, which should be pulse/retractive, ie, you click them down and they pop back when you release.
If you want dimming and only have 2-wire then your only choice is the Fibaro Dimmer2 with the Bypass2 across the bulb. The Aeotec Nano Dimmer also supports 2-wire, but there’s no bypass available yet if you want to use LEDs…
OK, people seem to be thinking this is a light switch, even though I’ve pointed out a couple of times that it’s not. It’s a switch which is connected to a relay which turns off all lighting circuits in the house. This switch is by the front door, the purpose of which is that you flick it off when you leave the house and all ceiling lights turn are turned off. By automating this I can carry out the same action based upon device trackers. There’s no dimming, just a straight on/off switch. I don’t want to lose the ability to use the switch, so replacing it with a Sonoff Touch makes sense (if it would work with it).
My Apologies, I scanned the thread at best.
its very cool, i will do the same, but i will use that button https://pt.aliexpress.com/item/Blue-Color-HTTM-Series-Capacitive-Touch-Switch-Button-Module-New/32470929982.html?spm=a2g0s.9042311.0.0.zdjMzn
I’ve got 2 POW modules monitoring total power on my lighting circuits, there is no reason why you couldn’t hook up a Sonoff POW to your lighting circuit (16a rated) and a basic to a standard mains outlet but not connect a load on it, and just use it;s button to signal the MQTT group for the main POW module which will flick off the power to the lighting circuit.
i have a similar setup for my 2-way switching so that one actually controls the power and the other just switches the POWER MQTT topic and does not actually cycle the relay.
I re-flashed mine so it uses Tasmota which does not rely on a web connection like the standard Sonoff firmware. it also allows different MQTT topics for the button and relay control
I’m currently in the UK but have full access to my setup in my home in Australia via VPN and all my switches have been flashed or are blocked form accessing the internet.
