The blue wire goes from the alternator and voltage regulator (connects inside the relay board) to the alternator warning light. The other side of the light simply goes to switched power. That's probably the fuse that is blowing--the one supplying switched power. Which would mean that the blue wire is getting grounded.
At a guess, the alternator may be plugged in incorrectly, or it may be badly messed up, or the voltage regulator may be badly messed up.
--DD
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Pelican Parts 914 Tech Support
A few pics of my car:
http://www.pelicanparts.com/gallery/Dave_Darling