A dust proof electric switch is provided for use in a dynamoelectric machine employing a centrifugal acuator having a terminal board with a cup formed therein in which a fixed contact point and terminal are mounted. A pivotable switch arm having a contact point attached thereto is mounted to the arm and extends above and cantilevered across the terminal board so that pressure on the switch arm from the centrifugal acuator causes the contact points to touch thereby closing the circuit. An open ended, resilient, flexible boot is affixed to the cup and extends upward between the terminal board to snuggly abut the switch arm and completely enclose the contact points when they are touching and when they are apart thereby protecting the contact area from dust and debris as well as containing sparks within the boot. The terminal board contains stops which serve to maintain alignment of the switch arm.