Here is the reasoning behind using only a single 4 gauge fused power feed to the alternator. If you use the two 10 gauge black/orange wires in addition to the 4 gauge wire, you have two fused power feed paths. The total current capacity of the wiring is the sum of the fused paths. The 4 gauge path is fused for 125 amps, and the two 10 gages wires are fused for 60 amps. That is a total of 185 amps, which exceeds the capacity of the alternator. Overload can occur without the fuses blowing, damaging the alternator.
The worst case scenario is that the alternator develops an internal short to ground resulting in a catastrophic failure. The initial short circuit surge current is limited by the resistance of the wiring. The current in a parallel circuit divides up according to the resistance of the branches. If the 4 gauge fuse opens up first, the two 10 gauge black/orange wires will be carrying the short circuit surge current. Depending on the time lag of the fuse links, they may open up before a fire starts or they may not.
Stangnet 3G install sticky http://www.stangnet.com/mustang-forums/646825-3g-alternator-install-how.html#post6673702
The worst case scenario is that the alternator develops an internal short to ground resulting in a catastrophic failure. The initial short circuit surge current is limited by the resistance of the wiring. The current in a parallel circuit divides up according to the resistance of the branches. If the 4 gauge fuse opens up first, the two 10 gauge black/orange wires will be carrying the short circuit surge current. Depending on the time lag of the fuse links, they may open up before a fire starts or they may not.
Stangnet 3G install sticky http://www.stangnet.com/mustang-forums/646825-3g-alternator-install-how.html#post6673702
Correct. But I might add, do not remove the other end from the starter relay, because doing so, will disconnect the voltage sensing path to the voltage regulator. Trace is back through this pic.
3G alternators generally get warm or even slightly hot to the touch as you approach operating and high loaded conditions. If the alternator casing is chrome, or painted this will add to the resulting temperature as these surface treatments both thermally and electrically insulate. In this case ensuring you have a good ground to the alternator as this will help mitigate the issue.