A B747-400 Captain reported loss of an AC Bus that produced a large number of failure messages. Using his Captain's emergency authority; he re-set a circuit breaker and restored the affected systems.

Narrative

Approximately one hour into flight; got multiple EICAS messages; five pages of failures in the CMC of mostly right side navigation and datalink systems. It appeared we had lost an entire bus as all generators and bus ties showed normal; also lost ACARS. Checked Circuit Breaker (CB) panel and found AC 2; DIST P-7 popped. [We] called Dispatch and Maintenance for conference. Maintenance checked wiring schematics and said 3-phase breakers sometimes pop. Advised I could use Captain's emergency authority to try one reset. We reset the CB and all systems returned to normal operations. All EICAS messages cleared except No Land 3. [We] used CMC to clear all status messages at Maintenance direction. Maintenance suggested we turn off and re-engage autopilot to reset No Land 3 message and it worked as stated. [We] sent MRM code per Maintenance request. The help we received from Maintenance was superb! The following systems were lost: ATC RIGHT; STAB AUTO TRIM; RUDDER RATIO; DME; RIGHT ADF; RIGHT VOR; RIGHT ACARS; MU; RADIO ALT; RIGHT STAB; XFR SIG; ILS RIGHT; FLAP SYS MONITOR; FLAP CONT RIGHT; NO LAND 3; TRANSPONDER RIGHT; RUDDER RATIO; SNGL SATCOM; DATA DATALINK SYS. The use of Captain's Emergency Authority was warranted to prevent a diversion. Had the system not reset; we would probably have ended up diverting rather than risk an ocean crossing and possible subsequent failures.