Nuclear water lower limit switch

The invention provides a lower limit switch for nuclear water. The lower limit switch for the nuclear water comprises a main body shell, a connector shell, an outgoing line, a plurality of sets of redundant contact actuating mechanisms and an isolating component. The plurality of sets of redundant contact action mechanisms are respectively positioned in a plurality of independent cavities in a cavity enclosed by the main body shell and the joint shell, and are respectively configured to be disconnected from the outgoing line in an initial state and connected with the outgoing line in a detection state of detecting a detected object so as to output a contact signal. All cables in the multiple sets of redundant contact actuating mechanisms are connected with the outgoing line, so that contact signal transmission is carried out through the outgoing line. The isolation part is configured to isolate two adjacent sets of redundant contact action mechanisms, so that the multiple sets of redundant contact action mech