Which bus remains powered when the Emergency Electrical Cutoff Switch is OFF?

Which bus remains powered when the Emergency Electrical Cutoff Switch is OFF?

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

Answer: (C)

When electrical emergency power is considered, the system is designed to conserve power for what’s truly critical. The Emergency Electrical Cutoff switch is used to disconnect the feeders to the nonessential buses, so those loads go offline to save energy. The Battery Bus, however, is tied directly to the aircraft’s battery and does not depend on the normal feeder path controlled by that switch. Because of that direct connection, the Battery Bus remains powered even with the switch OFF, keeping essential or memory-critical systems alive while other buses lose power.

When electrical emergency power is considered, the system is designed to conserve power for what’s truly critical. The Emergency Electrical Cutoff switch is used to disconnect the feeders to the nonessential buses, so those loads go offline to save energy. The Battery Bus, however, is tied directly to the aircraft’s battery and does not depend on the normal feeder path controlled by that switch. Because of that direct connection, the Battery Bus remains powered even with the switch OFF, keeping essential or memory-critical systems alive while other buses lose power.