The MASTER POWER EMERGENCY OFF switch, normally guarded to the ON position, cuts electrical power to everything except which two buses?

• A. HOT bus
• B. Emergency Power bus
• C. HOT bus and Emergency Power bus
• D. Main bus and Essential Bus

Answer: (C)

The switch is designed to shed power to all nonessential electrical loads in an emergency, while keeping two critical power paths energized: the HOT bus and the Emergency Power bus. The HOT bus is tied directly to essential, always-available power (often from the battery) so vital functions remain powered even when main power is cut. The Emergency Power bus is connected to the aircraft’s emergency power source, ensuring that critical avionics and flight-control systems can continue to operate when normal power is out. Keeping these two buses energized allows the airplane to maintain essential capabilities and maintain control during an electrical emergency.