An invention proposes a switch comprising a lower casing in the bottom of which are placed two contact elements. A trip member is elastically deformable through the action of an actuating member. At least one light source is supported by a support plate which straddles the actuating member and has terminals for electrical connection of the light source. The lower face of the support plate rests on the lower casing. The electrical connection terminals of the light source extend outwards from the casing along the vertical lateral faces of the casing.