An amperage wire size chart can be found on Blue Sea Systems or PowerStream. The former gives the chart at 30 degrees Celsius and other temperatures.
For American Wire Gauge, or AWG, 00, 000 and 0000, minus 1, minus 2 and minus 3 can be used respectively . The Maximum Amps for Chassis Wiring on PowerStream's chart refers to wiring in air. Whenever there is high frequency of alternate current or AC, there is bound to be current outside the wire or skin effect. Maximum frequency for 100 percent skin depth is meant to show the maximum frequency before the skin effect should be included for resistance.
Gold and silver are very good electrical conductors. If a wire is less conductive than another due to its material, a bigger size wire needs to be used for the same amperage.