What was found
FLT 204 - WHEN PREPARING TO LAND, EN ROUTE, WITH GEAR LOWERED, HAD NO GEAR DOWN INDICATION. FOUND GROUND AIR CIRCUIT BREAKER TRIPPED; RESET CIRCUIT BREAKER AND DECLARED EMERGENCY. FUEL INDICATIONS WERE NORMAL, FLEW BY TOWER TO VERIFY LANDING GEAR WAS DOWN; LANDED WITHOUT FURTHER EVENT. CONTRACT MAINTENANCE INSPECTED THE LANDING GEAR AND CIRCUIT BREAKERS, ALL CHECKED NORMAL.