B747-400
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Time Pressure; Troubleshooting
Aircraft Equipment Problem Less Severe
Aircraft Aircraft Damaged; Flight Crew Overcame Equipment Problem; Flight Crew Returned To Departure Airport
Aircraft
At about one hour into our flight; I had begun my rest in the bunk when I heard a bang similar to someone dropping something in the cockpit additionally the light in the crew rest momentarily went out and back on. The Captain alerted me; and I return to the cockpit to find numerous EICAS messages. The other FO [First Officer] was flying without autopilot or auto throttle. The Captain and I evaluated the messages and began to work the QRH for those messages. We discovered that the AC Number 3 and Number 4 DIST circuit breaker (35 amp) had tripped we did not reset. After completion of the QRH items we made the decision to return to ZZZZ. The other FO and I swap seats and I resumed duties as pilot flying. The flight was then vectored to a holding point to dump fuel to achieve our landing weight. We landed at ZZZZ without further incident. Crew executed good CRM and no recommendations could prevent in the future.
B747-400 First Officer reported an AC electrical system malfunction which resulted in a return to the departure airport.