Why does security alarm systems use cables with one conductor Aluminum and one Copper?
Some cables use a foil shield. The shield is mylar (polyester) coated with aluminum. The shield is not really one of the conductors, it is only used to drain away interfering signals before they reach the inner conductors, so it need not be a super good conductor. Aluminum is used for the foil shield partly because it is lightweight, but mostly because it’s much cheaper than copper.
