The utility model relates to an isolation switch device and a sensor installation assembly. Sensor mounting assembly, the device comprises a transition plate which is arranged in a gap between two fork arms on a crank arm of the isolation switch equipment, a sensor fixing structure for fixing a sensor is arranged on the transition plate; the sensor installation assembly further comprises a limiting piece used for backing on to one side of the fork arm, the sensor installation assembly further comprises screw rods used for being arranged on the two radial sides of the shaft sleeve, and the screw rods are used for being connected between the limiting piece and the transition plate so that the limiting piece and the transition plate can be clamped on the shaft sleeve and fixed relative to theshaft sleeve. Transition plates are arranged at intervals between two fork arms on a crank arm, and a sensor is fixed by a sensor fixing structure; and the screw and the limiting piece are matched and clamped with the transition plate to assist the transition plate to be firmly mounted on the shaft sleeve, so that the mounting stability of the sensor is also ensured. Therefore, the sensor is firmly installed on the crank arm without changing the structure of the crank arm and influencing the use of the crank arm.