An appliance includes an appliance interface forming a plug connection with an appliance-side interface unit of a power cable. The appliance interface includes at least one power contact part forming a power connection with a power contact part of the appliance-side interface unit supplying the appliance with electrical energy from a supply grid. The appliance interface includes a first thermoelectric element contacting a second thermoelectric element of the appliance-side interface unit, when the power connection exists. The first thermoelectric element is coupled to a first measurement input of a control unit. The appliance interface includes a measurement contact part forming a measurement connection, between the second thermoelectric element and a second measurement input of the control unit, with a measurement contact part of the appliance-side interface unit. The control unit determines measurement data relating to a measurement voltage between the first and second measurement inputs.