Hello! I would like to find a relay on z-wave or xiaomi/aqara which could control al electricity at home. In case of fire or water issue. Any advices how to manage that?
What is the current rating on your main switch?
I doubt you will find a zwave or xiaomi with a high enough rating (+100A) and with a fault current rating high enough to do this directly.
What you can do is trigger a circuit breaker that has a shunt trip with any mains rated zwave or xiaomi switch. Search for “shunt trip circuit breaker”.