Copper-clad aluminum wire is made of solid aluminum cor […]
Copper-clad aluminum wire is made of solid aluminum core wrapped with copper skin to improve its performance in the field. The copper-clad aluminum wire consists of a solid aluminum core covered with a thin copper cladding. About 10% of the conductor cross-sectional area is copper clad, and the thickness is not specified.
Copper-clad aluminum wire reduces the risk of aluminum wire, copper clad aluminum wire has a thin copper outer skin and an aluminum core. So when installed and visible in the main electrical service panel, it looks like "thick" copper wire, and at the cut end, the copper skin appears to be "painted" over the aluminum core.
For technical reasons, it is useful to realize that the wire is copper-clad aluminum. For example, the wire gauge or diameter size of copper-clad aluminum wire will follow the same physical dimensions as solid aluminum wire. From the outside, if we don't pay attention to the printed labels and markings that may be present on the copper-clad aluminum wire, if we just look at the wire itself and strip off the insulation, the wire looks like copper.
Early wire coating work and later wire wrapping work addressed the effect of sulfur in vulcanized rubber insulation on copper wire. The idea of producing a wire of one metal over another by covering a copper core wire with one or more layers of other metals has been around since at least the 1920s, but interestingly, early wire coating attempts started with the use of aluminum Coated copper.