Put two superconducting fibers next to each other with a thin insulating layer, or many fibers in a bundle. Have the supercurrent in one direction matched by t

Put two superconducting fibers next to each other with a thin insulating layer, or many fibers in a bundle. Have the supercurrent in one direction matched by the same supercurrent in the other direction, alternations as closely spaced as possible. The magnetic field will be confined, at least. When the fiber breaks, join the entwined superconductors together (equivalently: have the insulator break down), and the current in the rest of the transmission line can continue flowing. Coaxial variant also available.