Lower isolation insulation switch

The utility model discloses a lower isolation insulation switch, which comprises a three-position switch and a circuit breaker main loop, the three-position switch comprises an insulation cross beam and a three-position opening and closing mechanism, the three-position opening and closing mechanism comprises a closing contact seat, a moving knife assembly and a grounding contact seat, the closing contact seat is connected with the insulation cross beam, the circuit breaker main loop comprises an arc extinguish chamber contact seat, and the moving knife assembly is connected with the grounding contact seat. According to the utility model, the insulating cross beam, the transmission connecting lever and the insulating side plates are made of recyclable thermoplastic materials, so that the use of thermosetting materials is reduced, and the requirements of green, low carbon and environmental protection are met; a reinforcing structure is arranged on the side face of the insulating cross beam and used for reinforc