Abstract: The switch has two metal contact strips projecting upwardly from the bottom all of the housing and connected to two pins which extend out of the housing. A rectilinear slideway parallel to the end wall contains a slide of electrically insulating material which is movable in the slideway between a first position and a second position. The slideway has an aperture in the region of the contact strips and the slide has a cavity which contains a freely rotatable contact roller and has confronting lateral surfaces which urge the roller to a position for interconnecting the contact strips in said first position of the slide and an inoperative position of rest in said second position of the slide. A spring wire supported in the slide biases the roller out of the cavity toward the contact strips.