Blown Alternator Wire

[CoachH]

I just replaced the generator in my daughters '54 chevy truck with a one-wire 100 amp alternator (Summit Racing® Alternators SUM-811001). It has the stock 235 motor in it. After installing it we tested the alternator and everything checked out fine. We took it for a ride today and it ran great. But when I pulled over to let her drive, it struggled to start when she turned the key over and before it kicked over it started smoking. I popped the hood and it fried the alternator wire. It was toast from the edge of the battery terminal half way up the wire towards the alternator. It was 8 gage wire as per the recommendation that came with the alternator. Anyone have ideas why it melted the wire? im guessing maybe something shorted it out by the battery? I saw a few sites online that recommend 6 gage wire for an 100 amp alternator, but the paper that came with it said 8 gage so i didnt think that could do it.

Anyone have any ideas?

Thanks