Interlocked actuator block prevents jamming by maintaining correct alignment. Uses an over-center actuator mechanism, which diminishes sparking and increases operating life in AC circuits. High-torque bushing construction prevents rotation or separation from frame during installation. Stainless-steel frame resists corrosion. High insulating barriers, formed in the molded diallyl phthalate case, increase isolation of circuits in multi-pole devices. Patented silver contacts of specially composed alloy for hardness. Prominent external insulating barriers increase insulation resistance and dielectric strength. Longer center solder lug terminal simplifies wiring and soldering. Epoxy-sealed terminals prevent entry of solder flux and other contaminants. Clinching frame to the case well above the base and terminals provides 1500V dielectric strength.