Abstract: An apparatus for electrically insulating and supporting a power supply wire relative to a substantially planar boundary, is disclosed. A translucent insulator is formed from a supercooled, nonporous igneous magma, such as glass, and includes a head and a shank extending from the head, the shank extendable through an opening in the boundary. The head and the shank form an annular passageway for receiving disposition of the wire. A shoulder surface limits the extension of the shank through the boundary opening and a retaining member, such as a nut, engages corresponding features of the shank to secure the insulator relative to the boundary. A seal can be additionally provided to engage the head and the wire to further seal the insulator.