I bought a SonOff pow R2 to work with my 220V A/C Unit . My electrician says it cant work because our 220 V system uses 2 input wires but the sonoff only uses 1. he said something about it being a europpean system being different. What can he do to work around it?
It should work ...but... Keep in mind that the start current (inrush) on that AC unit will be 3 to 8 times the running current so if it pulls 8 amps when running it might pull over 60 for a split second when it starts. Also keep in mind that the ringback voltage when the circuit is opened may be several times the line voltage and cause a great arc flash. HVAC contactors are designed to handle this. That tiny relay inside the Sonoff is not. So don't be surprised if your Sonoff relay contacts get vaporized after a few cycles. This is a highly inductive load you are switching.
My 2 cents worth, and I have said it before, If you are going to switch a 240V single phase motor load then do it right to start with. Use the Sonoff to operate the coil of a proper contactor. If you don't, you are going to be disappointed and potentially unsafe.