B737-700
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface
Aircraft Equipment Problem Critical
Flight Crew Diverted; Flight Crew Landed As Precaution; General Declared Emergency; General Maintenance Action
Human Factors; Aircraft
During cruise the Standby Power Off light illuminated. The QRH directed us to place the Standby Power switch in the BAT position; which we did. The First Officer then noticed that the C5 Bat Bus Sect 2 circuit breaker was popped on the P-6-5 Standby Power Control Unit and that the illumination of the Standby Power light may have been coincident with his retrieving his personal bag from the area in front of the P-6- 5 panel and possibly inadvertently pulling it out. We contacted Dispatch and advised Maintenance of the situation but they did not want us to reset the circuit breaker and directed us to divert for repairs. We advised ATC that we were diverting and declaring a precautionary emergency since we did not know if the breaker had popped on its own and the Battery Bus appeared to be unpowered although there was no drain on the ships batteries. Maintenance replaced the Standby Power system and we continued the flight without incident. It would be helpful if Maintenance Control had the ability to communicate to the flight crew the various systems that would be affected when a particular circuit breaker is open.
B737-700 Captain reports the Standby Power Off light illuminated in cruise. QRH procedures are complied with and it is discovered that a circuit breaker is tripped on the P-6-5 Standby Power Control panel. The First Officer may have inadvertently tripped it retrieving his bag from the area but Maintenance directs a diversion for repairs.