Fair enough, here goes then, two examples in fact:
As I'm no electrician I have no idea how these Volt and Amp ratings are defined. As a layman (with some ancient physics background) I'd assume the problem would be heat. So connecting a cable with larger conductor to a cable with smaller conductor could either a) cause smoke and flames or b) throttle the current to the lower standard.
I've been looking into all sorts of plugs and jacks lately, and there are all kinds of combinations possible. As I earlier mentioned the AC/DC converter I'm looking at is rated 13 A @ 12 V, yet I have not been able to find a jack that is rated high enough for current. There are jacks with 36 V rating and higher Amp ratings than 12 V jacks. Could I plug 13 A @ 12 V plug into a X A @ 36 V jack as long as the wattage is the same, as in
13 A * 12 V = 156 W = X A * 36 V
=> X A = 156 W / 36 V = 4,5 A (rounded up)
All I want is not to burn my home. This project has taught me quite a bit about wires and AWG stuff, but there is still so much to learn...