INSULATOR

PURPOSE:To lessen the consumption of raw materials and make the products light and at the same time make the distance of side face and end face long by making the diameter of a trunk part thinner than the diameter of a holding part to be connected with a metal fitting. CONSTITUTION:A plurality of shades 2 and holding parts 3 are unitedly formed in the outer circumference of a trunk part 1 of an insulator main body G made of a ceramic and in both upper and lower ends of the trunk part 1, respectively. The diameter of the trunk part 1 at the center and that in the metal fitting sides, 4, 5 are different. More specifically, the diameter of the trunk part 1b of the center is made thinner than that of the trunk part 1b in the metal fitting sides 4, 5. The diameter of the holding part 3 is made to be the same as that of a holding part 52 of the insulator main body 50. That is, the diameter of the holding part 52 is wide enough to withstand prescribed shearing stress and tensile stress. In this way, raw material consumption is lessend and produced insulators are made light by making the diameter of the trunk parts 1a, 1b to which shearing stress is not applied be thinner than that of the holding part 3.