An electrical apparatus (2; 50; 70) for installation in an electrical cabinet, said electrical apparatus comprising - a device for managing an electric current; - an electronic control unit comprising a communication interface provided with an internal antenna housed inside a first housing of the electrical apparatus; the internal antenna being a planar antenna with a first radiating element , the electrical apparatus (2; 50; 70) further comprising a removable coupling element connectable to an external radio antenna , the coupling element being provided with a second radiating element connectable to the external radio antenna and being movable between a position connected with the first housing of the electrical apparatus and a position disconnected from the first housing, and in the connected position, the coupling element is disposed in front of the internal antenna and separated therefrom by an electrically insulating element , the second radiating element being coupled to the first radiating element so as to receive electromagnetic radiation emitted by the first radiating element; the electrical apparatus (2; 50; 70) being characterised in that the communication interface is a radio communication interface and in that the internal antenna is a radio antenna which comprises a dielectric substrate and a ground plane , the first radiating element and the ground plane being formed on opposite sides of the dielectric substrate , and in that the coupling element comprises a second dielectric substrate and a second ground plane , the second radiating element and the second ground plane being formed on opposite sides of the second dielectric substrate . - a device for managing an electric current; - an electronic control unit comprising a communication interface provided with an internal antenna housed inside a first housing of the electrical apparatus; the internal antenna being a planar antenna with a first radiating element , the electrical apparatus (2; 50; 70) further comprising a removable coupling element connectable to an external radio antenna , the coupling element being provided with a second radiating element connectable to the external radio antenna and being movable between a position connected with the first housing of the electrical apparatus and a position disconnected from the first housing, and in the connected position, the coupling element is disposed in front of the internal antenna and separated therefrom by an electrically insulating element , the second radiating element being coupled to the first radiating element so as to receive electromagnetic radiation emitted by the first radiating element; the electrical apparatus (2; 50; 70) being characterised in that the communication interface is a radio communication interface and in that the internal antenna is a radio antenna which comprises a dielectric substrate and a ground plane , the first radiating element and the ground plane being formed on opposite sides of the dielectric substrate , and in that the coupling element comprises a second dielectric substrate and a second ground plane , the second radiating element and the second ground plane being formed on opposite sides of the second dielectric substrate . <EOS>