Lets see if I understand your proposal correctly. You want to remove the current wall switch and permanently wire the light to always be on. Then in the electrical box, add electronics to send a wifi message when it's switch is pressed. Correct?
Will your new device be battery powered? Will it work while enclosed on three sides by a steel box, or are your electrical boxes all plastic? Will your wifi connection work that close to the existing electrical wiring?
Hi Paul, thanks for such a quick reply.
A preference would actually be to produce a switch which I can screw in and fit directly over the front of the existing light switches using longer screws so when I move and sell the house i don't need to re-wire the whole houses light switches, and (not being particularly experienced in mains electrical work) means I'm not potentially setting up fire risks in every room. That said, I understand battery life may mean I don't have any choice but to wire into the light switches anyway.
Either way, whether I power the new switches from the light switch or not, it will likely all be housed inside a 3D printed case which slots onto the outside of the existing switches so won't be housed inside a metal case and wifi shouldn't be an issue.
If battery was an option, I was wondering if there was some way I could have the device completely powered off until the physical button is pressed. This powers it on, sends the signal, then powers down again, but I fear as this would require connecting to the wifi network etc that this may not be a realistic solution.