As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED THAT DURING TAXI OUT FOR DEPARTURE THE RIGHT BUS TIE CIRCUIT BREAKER TRIPPED. THE FLIGHT CREW ELECTED TO RETURN TO BLOCKS FOR MAINTENANCE CONSIDERATIONS. THE MAINTENANCE VENDOR TROUBLESHOT AND DETERMINED THAT THE RIGHT BUS TIE REMOTE CONTROL CIRCUIT BREAKER (RCCB)HAD FAILED. THE RCCB WAS REMOVED AND A NEW UNIT WAS INSTALLED OPS CHECKS SATISFACTORY. THE AIRCRAFT WAS RETURN TO SERVICE.