Household appliance comprising: - first power supply lines which are connectable to an AC power supply source for receiving a main electric power (P1) from said AC power supply source and for providing a first AC voltage (V1) and a first AC current (I1), - at least a first load , - at least a second load operating by a second voltage (Vcc), - a master control circuit operating by said second voltage (Vcc), which is configured to generate control signals (SC) to selectively control said first load and second load , - an inverter device which is electrically connected to said first power supply lines for receiving said first AC voltage (V1), said household appliance being characterized in that : the second voltage (Vcc) is lower than said first AC voltage (V1); the master control unit further comprises a current measuring sensor configured to measure said first AC current (I1) and provide a first value (K1(I1) indicative of said first AC current (I1); the inverter device is connected to said master electronic control circuit to receive said control signal (SC), and is configured to control the voltage supplied to said first load based on said control signal (SC), said inverter device further comprises a voltage measurement circuit configured to measure said first AC voltage (V1) and provide a second value (K2(V1)) indicative of said first AC voltage (V1); wherein said inverter device is configured to provide said second value (K2(V1) to said master control circuit by opto-isolator electronic means , said master control circuit is configured to determine a third value (K3(P1)) indicative of said main electric power (P1) based on said first value (K1(I1)) and second value (K2(V1)). - first power supply lines which are connectable to an AC power supply source for receiving a main electric power (P1) from said AC power supply source and for providing a first AC voltage (V1) and a first AC current (I1), - at least a first load , - at least a second load operating by a second voltage (Vcc), - a master control circuit operating by said second voltage (Vcc), which is configured to generate control signals (SC) to selectively control said first load and second load , - an inverter device which is electrically connected to said first power supply lines for receiving said first AC voltage (V1), the second voltage (Vcc) is lower than said first AC voltage (V1); the master control unit further comprises a current measuring sensor configured to measure said first AC current (I1) and provide a first value (K1(I1) indicative of said first AC current (I1); the inverter device is connected to said master electronic control circuit to receive said control signal (SC), and is configured to control the voltage supplied to said first load based on said control signal (SC), said inverter device further comprises a voltage measurement circuit configured to measure said first AC voltage (V1) and provide a second value (K2(V1)) indicative of said first AC voltage (V1); wherein said inverter device is configured to provide said second value (K2(V1) to said master control circuit by opto-isolator electronic means , said master control circuit is configured to determine a third value (K3(P1)) indicative of said main electric power (P1) based on said first value (K1(I1)) and second value (K2(V1)). <EOS>