QUOTE
Most current is carried on the outer surface of a strand of wire.
That is not true except for high frequency AC current.
Solid wire would be much better in our cars, except stranded wire has better fatigue properties and is flexible.
For my whole harness rebuild I used:
4Ga on -
battery + to starter
battery - to chassis
battery to the front fuse panel.
10Ga from Alt to Battery (or to starter if you dont have a cutoff switch).
And I have much longer runs because my battery goes through a master kill switch.
I tried to use some of the tables that specify wire gauge vs rated current, and the wires were MUCH larger than the stock Porsche wiring harness.
You have to take into account - Is the current intermittent (Starter) or continuous (headlights).
If continuous, then the rating tables are closer, but: "what gauge is the wire that carries the current to the starter solenoid in the stock harness?"
If you figure that out you will see that the Porsche engineers didnt use those tables either.....
Stu