1991 Pontiac Gran Prix SE 3.1 liter 6 cylinder.
Alternator positive red wire from starter grounded out and split apart. What happened and why?
How do I fix it?
Is it safe to drive again?
There's a 10ga fusible link on the cable from the alternator to starter. This needs to be replaced with a new cable or you can generally buy a new fusible link and crimp or solder it in place.
As to the why when a always hot cable shorts to ground it's basically a circuit with no load to limit the amount of amps. One of three things happen, a fuse blows if you're lucky or something in the circuit will melt or catch fire.
As long as the cable is properly repaired it's a non issue.