Abstract: An insulating spacer 10 includes a molded insulator 11 having a central conductor 12. The molded insulator 11 part is disposed between the flanges 1A, 2A of metal containers 1, 2 and is coupled by through bolts 5. The peripheral dimension of the molded insulator 11 is smaller than the flanges 1A, 2A, and the insulating spacer 10 is provided with a thin section 11A, one lateral side of which is formed into a thin ring shape. A ring-shaped metal fitting 14 having a cross-sectional L-shape is fitted onto the thin section 11A of the molded insulator 11, the ring-shaped metal fitting 14 defining the dimensions of the space between the flanges 1A, 2A and forming a current path between the metal containers 1, 2. The ring-shaped metal fitting 14 is affixed to the thin section 11A of the molded insulator 11 by multiple tightening bolts 15.