Abstract: This invention is directed at a lock actuated switch which has a housing and a lock cylinder. The housing includes a terminal housing portion and a support portion. The support portion has a wall that defines a longitudinal bore and that has an inner surface with V shaped notches formed therein. The V shaped notches may be formed by three triangular surfaces which meet at their apices. The longitudinal bore extends through the terminal housing portion and the wall has means of retaining a series of fixed contacts that have arced terminal ends. The lock cylinder includes a terminal end, a longitudinal second bore and a body portion. Tumbler slots are formed in the body portion in spaced relation to each other. One of the tumbler slots has a spring loaded detent tumbler mounted therein. As the lock cylinder is moved axially into the housing, the detent tumbler rides over one of the V shaped notches compressing the spring until the detent tumbler passes over the V shaped notch and comes to rest.