You buy 2. Wire one smart switch to control the light and the other is powered up but does not switch the light. The light control wires are connected together so that there is always power to the light at this point.
Now you have two options.
group the two switches together using their built-in firmware or flashed firmware. Pretty sure Tasmota and most zwave switches can do this.
use home assistant to toggle the light (using switch 1) if either smart switch is operated.
The advantage of option 1 is that it continues to work if home assistant is offline.
All switches remain. Or are you walking through the house with your cell phone in your hand and switching? Add Sonoff mini can fit directly under one of them.
@tom_l : Ney, it is on the outside, just under the plastic switch cover
@francisp : haven’t seen that tasmota before.
I only know the QS-WiFi-D01/2-TRIAC Dimmers, and the 2channel has two switch inputs.
Which one is that???
The other option, if there is no neutral at the switch is to put the smart switch near the light fitting. Much easier to get a neutral there. The only issue with this is temperature in the roof space may exceed the devices’ environmental specifications.
Americans call it 3-way switching, the rest of world calls it the correct term: 2-way switching. It’s 2-way because you create 2 possible current paths with the switches, funnily enough using 2 switches… why they call it 3 way is just… American. (3 wire connections on a switch does not make it 3-way) Proper 3 way switching uses 3 switches where the one in the ‘middle’ is a special type, a changeover switch.
2-way switching (‘batten holder’ is a light fitting and the ‘L’ terminal on that fitting is just a looping point which doesn’t electrically connect to anything in the light itself. That terminal doesn’t exisint on most light fittings and would otherwise just be a wire connector)
All switches remain. Or are you walking through the house with your cell phone in your hand and switching? Add Sonoff mini can fit directly under one of them.
Thanks for the suggestions, everyone! I have learned a lot from your replies and now I have to consider if I want to do an in-wall solution like the sonoff or shelly 1, or if I want to go for switch replacements.
Re to tom_l I never changed the title of this post and I have no clue what you’re talking about.
Oh okay that makes sense
The title has not been edited that’s what I originally put in yesterday when I posted it
So I have no clue what czechlion is on about then heheh