An electrically insulated conductor for carrying signals or current includes a solid or stranded copper core of various geometries with only a single electrically insulating and thermally conductive layer of anodized aluminum (aluminum oxide). The device is made by forming a uniform thickness thin sheet or foil of aluminum to envelop the copper or copper alloy core. The aluminum has its outer surface partially anodized either before or after forming to the core in an electrolytic process to form a single layer of aluminum oxide.