Abstract: The invention provides an electrical conductor subassembly and a method of constructing an isolated electrical connection comprising a set of the connected electrical conductor subassemblies. Each subassembly is connectable with other of the subassemblies into a conductor string while being fed into an opening in a hole or pipe, thereby enabling an electrical connection along the conductor string that is electrically substantially isolated from external fluids in the hole or pipe. Each conductor subassembly comprises: a conductor segment with a conductor core surrounded by an insulating layer; two connectors attached to opposite ends of the conductor segment, having two respective conductor engagement elements attached to corresponding ends of the conductor core. The connectors of adjacent conductor subassemblies are connectable securely against forces in the hole or pipe and so as to electrically join their corresponding conductor engagement elements and seal them from contact with the external fluids.