Abstract: An electrical conductor has a copper base substrate coated with a tin base coating layer. To inhibit the formation of a copper/tin intermetallic and the resultant depletion of the free, unreacted, tin utilized as an oxidation and corrosion barrier, a barrier is interposed between the substrate and the coating. In a first embodiment, the barrier is formed from multiple constituent layers, at least one of which is copper. The thickness ("y") of the copper layer is dependent on the anticipated service temperature and satisfies the equation y=(-1.52+0.0871x+0.00859 t).+-.50% where t=anticipated time at the service temperature, x=anticipated service temperature (Celsius), and y=the thickness of the copper layer in microinches. In a second embodiment, the barrier layer is formed from one or more constituent layers, at least one of which is iron or iron base.