Which bus is not affected when placing the Emergency Electrical Cutoff Switch to OFF?

• A. Battery Bus
• B. Avionics Bus
• C. Essential Bus
• D. Main Bus

Answer: (A)

The Emergency Electrical Cutoff Switch is meant to isolate the main electrical power sources from most distribution buses to reduce load during an electrical abnormality. When you set it to OFF, power to the Main Bus, Essential Bus, and Avionics Bus is cut from the primary power sources, reducing load and protecting the system. The Battery Bus, however, is not routed through this switch and remains connected directly to the battery, so it stays energized. This design ensures that while nonessential or dependent systems lose power, critical circuits on the Battery Bus can still operate.