Invisible, contactless switch device

The invention relates to a switch device for attaching behind an opaque wall (32) such that it is invisible from outside said wall and for controlling the connection of an electrical appliance (44), said device comprising a first module (10) and a second module (12) for carrying out the connection between the electrical appliance and a power supply source. The first module comprises a capacitive detector (16) provided with a capacitor on a printed circuit board which changes value when a user on the outside places their hand (34) close to the wall, at the site where the device is attached. The capacitor is contained within a metal frame, the function of which is to delimit the capacitive field created by the capacitor within the plane of the board and to maximise said field perpendicularly to the plane of the board.