What was found
IAH - FLIGHT 3030 - DURING PREFLIGHT INSPECTION THE CREW REPORTED THAT APPROXIMATELY 5 MINUTES AFTER CONNECTING GROUND POWER, SMOKE WAS WITNESSED COMING FROM THE TOP OF THE GALLEY. MAINTENANCE PLACED THE GALLEY LIGHTING ON NEF-GL-01, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE. LATER THAT DAY THE AIRCRAFT RETURNED TO IAH WHERE MAINTENANCE REMOVED AND REPLACED THE LIGHTING BALLASTS ABOVE THE GALLEY CEILING, OPERATIONALLY TESTED WITH NO DEFECTS, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.