Why not use copper-coated aluminum wire instead of solid copper

[Crazyhorse2882]

If electrons flow on the surface of a wire, why isn't copper coated aluminum wire used in electrical applications instead of solid copper wire? It would be more cost effective

 

[phinds]

Electrons only flow near the surface at very high frequencies and high frequency waveguides are hollow for that very reason.

 

[nsaspook]

If electrons flow on the surface of a wire, why isn't copper coated aluminum wire used in electrical applications instead of solid copper wire? It would be more cost effective

It is used but the required gauge is two sizes larger (possibly increasing the needed conduit size) than solid copper for the same utility power (60hz skin depth is about 9 mm so for most commercial and residential wiring it's unimportant) application. Fires in houses build in the 70's with Al wiring has made many people reluctant to save maybe 20% on wire when wire is a small percentage of cost on most projects. (a 10 million dollar machine in a multi-billion dollar factory with 20K wire costs is a typical example)
http://www.commscope.com/docs/cca_solutions_br.pdf

 

[meBigGuy]

I think *waveguides* are hollow because they are conducting electromagnetic radation within the internal area in TM or TE mode.