After engine start, which electrical buses are normally active on the 737?

Prepare for the Delta 737 PA-LOD Exam with flashcards and multiple choice questions. Each question includes hints and explanations, ensuring you're ready for exam day!

The aircraft’s electrical system is arranged so essential systems stay powered while the rest of the system comes up. After start, the essential/standby bus is supplied by either the APU or external power, keeping critical instruments and controls energized. The main buses come online as the power sources (engine generators or APU) establish electrical power, so they power up “as power is established.” This sequencing ensures you have essential systems available during start and taxi, even before the main buses are fully energized.