A cylindrical sleeve having annular flanges is formed of irradiated terpolymers of ethylene, propylene, and a diene monomer (EPDM) material. The sleeve is then expanded, but the irradiated EPDM material has a "memory" which tends to cause it to return to its original dimension when heated to a predetermined elevated temperature. The expanded sleeve is positioned over the body of a current limiting fuse and heated so that the sleeve shrinks back to tend to assume its original dimension thereby sealing the sleeve around the body of the fuse. The inside surface of the sleeve may be coated with a thermosetting plastic sealing coating which softens at the elevated temperature further aiding in sealing between the fuse body and the sleeve. The sleeve may be heated in a vacuum oven to ensure that air is not trapped between the body of the fuse and the sleeve.