Date: 202202
Local time of day: 0601-1200
Flight conditions: VMC
Light: Daylight
Aircraft: B737-900
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Circuit Breaker / Fuse / Thermocouple
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Troubleshooting; Workload
Second reporter function: Captain; Pilot Flying
Anomaly: Aircraft Equipment Problem Critical; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Landed As Precaution; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Overcame Equipment Problem; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: At cruise flight FL330; a pop sound was heard followed by a Master Caution 'Electric' and Master Caution 'Air Condition' indication. Upon inspection of the overhead panel; the 'Standby Power Off' light; both 'Pack Lights'; and all three 'Zone Temp' lights were illuminated. QRH procedures were completed but all the lights remained illuminated. Then an observation of zero indication was noticed on the brake pressure gauge and PA comms/intercoms with the flight attendants were lost. Communications and intentions were (and had to be) completed in person with the Purser and to all the passengers. [Priority handling was requested] by the Captain and out of precaution (Concern of pressurization loss) a descent to FL250 was initiated. After communication/coordination between the flight deck crew; Dispatch and Company Maintenance; it was established that circuit breaker 'Bat Bus Sect 2' behind the First Officer seat had popped. With further discussion between Dispatch and Maintenance; a diversion to ZZZ was decided as best course of action. At about 20NM North of the ZZZZZ fix the diversion to ZZZ was initiated. Landed in ZZZ uneventfully.


Second narrative: During cruise flt at FL 330 we heard a pop and noticed that the mode control panel ELEC for the Standby Pwr Off and Air Cond light for both Pack lights and all three Zone Temp lights were illuminated. All appropriate checklists and procedures were accomplished. We then talked to ATC; Dispatch; Maintenance Control and the Purser. The Batt Bus Sect # 2 circuit breaker had tripped. Both the cockpit and the cabin PA systems were now also inoperative so our discussion with the Purser was in person and he had to relay my  briefing to the Passengers. Also our break pressure gauge was now reading 0 PSI but Maintenance said is do to the tripped circuit breaker and also that on landing one of our reverses may not deploy. As Captain; I [requested priority handling] and descended from FL 330 to FL 250 for a possible divert and pressurization issue and to burn fuel for landing weight considerations. After our discussions with Dispatch and Maintenance Control we thought it was best to divert. Our diversion and landing in ZZZ was uneventful.


Synopsis: First Officer reported a tripped circuit breaker caused a diversion and precautionary landing.