An electrical switch arranged to be mounted on the rear wall of a switch box and having a base open at the front and rear with a partition wall between the front and rear. A blade-operating rotor is installable in the base from the rear and held in operating position behind the partition wall initially by a snap spring detent to facilitate installation of the base on the rear wall. Once installed, a flange on the rotor cooperates with the rear wall to retain the rotor in operating position should the spring fail. The load and line connectors are mounted on the front face of the partition wall for ready access when the front of the switch box is open. The switch blades and companion stationary contact jaws are carried by the base at the rear of the partition wall, and are drivingly engaged by the rotor. The blades are arranged relative to the contact jaws, rotor, and base so as to provide a wider contact separation upon opening of the switch than is usual in switches of comparable size.