I'm designing a zigbee switch with additional capabilities in order to give it some flexibility. The main idea is to put this design in the interconection boxes that are in my walls.
So, this PCB will be in a constantly noisy environment because the 220V AC cables around the PCB.
I want to reuse my wall switches rewiring the common to the 5V power supply of the board in order to convert these switches in digital inputs for the microcontroller, so if somebody changes the switch, the microcontroller can read the new status and change the output relay that is controlling the lights, wall plugs or whatever.
The problem is that some wall switches could be around 30 meter from the wall interconection boxes and can be near of power cables with 220V AC.
The power supply of the control electronics is an in-board AC/DC converter whose output is 5V and 3.3V DC and this is the reason the digital signal have to be in that values.
I don't want to change the 2.5mm copper cables that connects the lights with the switches.
Can be reliable this circuit with these characteristics or should I change the design in some point?
I have read in other topics that it can be done with an optocoupler, some capacitors and zener/schotkky diodes but them can change the wires for twisted pair or whatever in their design but this is not my case.
Edit: Simplified Circuit for clearance: