What was found
AS A RESULT OF A MALFUNCTION OF THE ELECTRICAL BUSES, THE FLIGHT ELECTED TO RETURN WITH SUBSEQUENT OVERWEIGHT LANDING. REPEAT SNAG, L/R UTILITY BUSS OFF LIGHTS, EICAS MESSAGE, L/R RECIRC FANS OFF LIGHTS WITH LOSS OF GALLEY POWER AND PAX READING LIGHTS U/S. IFE WAS ALSO ERRATIC SINCE DEPARTURE. NO FAULTS STORED IN BPCU. DUE ELEC PANEL AND K10109 RELAY REPLACED PREVIOUSLY, BPCU REPLACED REF AMM 24-41-03. GND RUN BOTH ENGINES CARRIED OUT NO FAULTS.