The proximity switch has a capacitive sensor which comprises a metallic support mounted on a printed circuit board and supporting, on a surface parallel to said board but facing away from it, a layer made of electrically conductive foam material. The latter nestles against a cover plate made of glass which provides the dielectric of a capacitive sensor actuatable by the stray field of the mains. When this alternating stray field is concentrated by a part of a human body brought into the vicinity of the sensor, the latter will actuate an electronic switch connected to it.