A pair of fixed contacts is associated with a pair of movable contacts. All of the contacts have circular contact faces. A U-shaped stainless steel arc shield is provided adjacent each set of movable and fixed contacts. The semi-circular bight portion of the arc shield forms part of an imaginary circle having its center concentric with the centers of the contacts. Thus, the outer arcuate portions of the contacts are in constant spaced relationship with the arcuate portion of the adjacent arc shield. The actuator for the contacts provides for sequential opening of the sets of movable and fixed contacts.