Alternator started sparking

Get yourself plenty of light & start inspecting the harness. If you shorted something bad enough, you might see the melted taped & plastic insulation. If it were mine, I'd strip all of the tape off & inspect each wire from end to end & any connections there within. We've had electrical shorts on the race car, due to vibration & hard use. Every year, I strip off the tape & look for potential problems. By doing this, we haven't had anymore short circuits in the past 10-11 years.