A disk-shaped insulator contains a conductive block and an insulating body, wherein the conductive block is located in a central region of the disk-shaped insulator. The radial dimensions of the insulating body are adapted to those of a flange used for connecting. Multiple holes are distributed over an edge region of the disk-shaped insulator, and the edge region is covered by a conductive coating.

A fastener device for a gas-insulated substation (GIS) type installation comprising a threaded shank and a ring including a duct configured to receive the threaded shank, the ring being housed in a supporting insulator of the invention.

A conductor includes a pair of bus bars, and an exterior component attached to the pair of bus bars. Each of the pair of bus bars includes a conductor portion and an insulating sheath with which the conductor portion is covered, and at least partially includes an attached portion extending in a linear shape. The exterior component includes a pair of groove portions extending in a linear shape so as to be capable of accommodating the attached portions of the pair of bus bars, and a pair of cover portions capable of opening and closing opening portions of the pair of groove portions. The pair of cover portions are arranged such that one and the other of the pair of cover portions overlap each other when the opening portions of both of the pair of groove portions are closed.