SMELLED SOMETHING BURNING, LIKE ELECTRICAL WIRING. VEHICLE STARTED TO SMOKE ON WAY HOME. AFTER PARKING VEHICLE, LIFTED HOOD & NOTICED SPARKS & THEN FLAMES. EXTINGUISHER DIDN'T PUT FLAMES OUT. UNHOOKED BATTERY CABLES AT PRIVATE MECHANIC & INFORMED WAS ALTERNATOR & WRONG WIRES USED. ALTERNATOR & WIRES WERE REPLACED. *AK