A 14/3 GA Romex type wire is rated at 15 Amps, and by regulation can only be used in home applications. You can use 14/3 for a 240 V application, in which case it would be capable of carrying 3600...
Copper, although it is not 100 % pure, it is still copper. for larger cables you can still get aluminum, but it is much more brittle and you can only work with it so much till it becomes weak. They...