1. A switch device comprising an electrically insulating housing having housing walls, at least one of the walls having an opening, a stationary contact structure within the housing, a movable contact structure within the housing and being movable rectilinearly between open and closed positions relative to the stationary contact structure, operating mechanism for the movable contact structure external of the housing and comprising an operating lever and a switch handle thereon for manually moving the operating lever, the operating mechanism also comprising an overcenter toggle operable by the operating lever to effect movement of the movable contact structure, a connecting member operatively connected between the movable contact structure and the overcenter toggle, the connecting member extending through said opening and comprising upper and lower toggle links and the lower toggle link being pivotally connected to the connecting member, the upper and lower toggle links being movable arcuately, the overcenter toggle also comprising spring means extending between the pivotal connection to the connecting member and the lever adjacent to the switch handle.

6. A switch device comprising an electrically insulating housing and an overcenter toggle structure, said housing comprising walls forming a chamber, a stationary contact structure within the housing, a movable contact structure within the housing and movable rectilinearly between open and closed positions relative to the stationary contact structure, the overcenter toggle structure being mounted externally on the housing and comprising a pair of links movable in arcuate paths and the connecting member being pivotally connected to one of the links to effect movement of the member rectilinearly, a connecting member, the overcenter toggle structure also comprising spring means for biasing the overcenter toggle structure in positions corresponding to the open and closed positions of the movable contact structure, the connecting member being pivotally connected between the pair of links and the movable contact structure, and opening means in the one wall communicating with the chamber for guiding movement of the connecting member.

9. A switch device comprising an electrically insulating housing and an overcenter toggle structure on the housing, a plurality of sets of contacts within the housing and comprising stationary contacts and movable contacts movable between open and closed positions with the stationary contacts, pivotal means for pivotally connecting the overcenter toggle structure to the set of movable contacts, the pivotal means comprising a connecting member, an opening in the housing, the connecting member extending through the opening and being slidably movable therein, the over-center toggle structure comprising upper and lower links and spring means, the lower link being pivotally connected to the connecting member, the spring means being operatively connected to the links for biasing the overcenter toggle structure in positions corresponding to the open and closed positions of the movable contacts, and the overcenter toggle structure comprising a handle movable laterally to effect longitudinal movement of the contacts in the direction of movement of the movable contacts.