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 (52, 72) 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 (52, 72) 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.