In aircraft electrical distribution, what is the purpose of a bus tie?

• A. To connect two batteries and share charge.
• B. To connect two buses and allow power transfer between them for redundancy.
• C. To isolate the buses.
• D. To measure bus voltage.

Answer: (B)

Connecting two electrical buses with a bus tie provides a crossfeed path that allows power transfer between them, enabling redundancy. In aircraft electrical distribution, power is split across multiple buses (essential, nonessential, standby) so systems can be protected if one line or generator fails. The bus tie lets a powered bus feed an unpowered one or share load between buses, maintaining critical electrical support and improving reliability when a fault or generator outage occurs. It’s not used to connect batteries, isolate buses, or measure bus voltage, which are handled by other components and controls.