Awl--
I seem to remember that current flow (or current density) on a solid conductor resides *exclusively* on it's surface, ie, looking at the wire cross-sectionally, you would see *only one* layer of electrons--not even two, no matter how high you cranked up the voltage across the conductor. This was explained on the basis of Coulombic repulsion, and something of Gauss' law, which I can't quite remember.
This would mean that the current-carrying capacity of a wire is *strictly* proportional to its circumference, not to its cross-sectional area.
But it seems to me that if the current density were high enough, and thus the very outer layer of electron flow sufficiently crowded, indeed an "inner layer" of electron flow should be forced, and that then the current carrying capacity of a wire would be proportional to its cross-sectional area.
Or is it that before the electrons could be forced into an inner layer, the repulsive forces of the electrons would be so strong as to force them to arc into air, or across an insulating covering??
Any idears?
Thanks.
---------------------------- Mr. P.V.'d formerly Droll Troll