Abstract: A thermally responsive electric switch including two dimensionally identical, bimetallic, snap-over, part-spherical, thermally responsive actuating elements 9, 11, arranged in a nesting, contacting relationship within the end portion 7 of a housing. The first element 9 changes from a first to a second curvature when its temperature rises above a first predetermined temperature, returning to its first curvature if its temperature falls below a second, lower, predetermined temperature. The second element 11 changes from a first to a second curvature when its temperature rises above a third predetermined temperature higher than the first temperature, and thereafter remains in that curvature. A common force transmitting rod 13 bearing on the uppermost element 11 transmits the movement of both elements to a pair of contacts 3 at the other end of the housing, the contacts being in one condition when both plates have the first curvature, and otherwise being in a second condition.