Why are the majority of wire electrical cables made of copper?
Copper is popular for residential applications because it has excellent conductivity and doesn’t have the limitations of aluminum. Aluminum is preferred for higher voltages and in industrial applications because it is much less expensive, lower in weight, and still has very good conductivity. Aluminum has two problems that discourage its use in residential applications. One is corrosion – the exposed surface of an aluminum conductor will form a layer of corrosion that is invisible to the naked eye, but that inhibits the ability to form a good electrical connection. That problem is addressed in industrial and high-voltage applications by using a grease on the connection – the grease contains fine particles of zinc that essentially penetrate the corrosion layer to make a good connection. The other problem with aluminum is cold-flow – as an aluminum conductor is squeezed in an electrical joint, over time the aluminum will conform to the joint, essentially flowing out of the joint, causing
