Distribution line isolation switch sheath and installation device

The invention relates to a power distribution line isolation switch sheath which is used for protecting an isolation switch, the isolation switch at least comprises a cross arm, an insulator and a knife switch, and the sheath comprises a translation side wall, a transverse contraction assembly, a clamping assembly, a rotation stopping assembly, a fixed plug lug and a shielding plate assembly. A pair of translation side walls is arranged; the transverse contraction assemblies are connected between the pair of translation side walls, the number of the transverse contraction assemblies is one front, the number of the transverse contraction assemblies is one back, and each transverse contraction assembly comprises a middle shaft, a hinge arm and a transverse contraction torsional spring; according to the sheath provided by the invention, the side surface of the knife switch is coated and protected through the pair of translation side walls, and the upper end of the knife switch is coated and protected through the