THIS VEHICLE WAS CONVERTED TO AN AMBULANCE BY WHEELD COACH. THE AMBULANCE CAUGHT FIRE AND SPREAD TO THE BUILDING IN WHICH IT WAS PARKED AND UNOCCUPIED. A PARAMEDIC SMELLED SOMETHING COMING FROM THE BAY, AND, WHEN HE WENT TO INVESTIGATE, HE SAW SMOKE AND FIRE DRIPPING FROM UNDERNEATH THE AMBULANCE. AN INVESTIGATOR DETERMINED THAT THE LUG CONNECTION AT THE ALTERNATOR WAS IMPROPERLY INSTALLED BY WHEELED COACH. THE CONNECTION PRODUCED A HIGH RESISTANCE CONNECTION, PRODUCING TEMPERATURES SUFFICIENT TO IGNITE A COMPETENT FUEL SOURCE AND/OR CAUSED THE BATTERY CABLE INSULATION TO FAIL, PRODUCING ELECTRICAL ARCING THAT PROVIDED A COMPETENT IGNITION SOURCE TO CAUSE THE FIRE. *TR