Rotary switch

A rotary switch comprising:

• a synthetic resin substrate;
• a plurality of fixed contacts arranged on the surface of said substrate;
• a holder mounted on said substrate and movable over said fixed contacts and a further portion of said substrate not covered by said fixed contacts;
• a movable conducting plate supported to said holder;
• contact elements formed on said movable conducting plate and in sliding engagement with said fixed contacts such that the rotary switch is switched on by rotating said holder and thereby contacting at least two movable contact elements with said fixed contacts;
• a rib projecting upwards from said substrate and positioned so that said movable conducting plate contacts said rib when the switch is in the off position, thereby raising said movable contact elements from the surface of said substrate;
• said fixed contacts formed with curved ends and said substrate formed with a groove whereby a substantially planar, hour glass shaped slit is formed between said fixed contacts to be narrowest coincident with the sliding locus of said contact elements and widest outside the sliding locus so that the wider portions of said slit act as reservoirs for conductive wearing powder, thereby delaying a short circuit due to wearing powder accumulation.