Definition
An electrical distribution arrangement in which the aircraft's main bus bar is divided into two or more separate sections, each able to be powered or isolated independently. The split allows essential equipment to be kept on a protected section while non-essential equipment can be shed or isolated, typically through a bus tie switch or relay that connects or separates the sections.
Plain English
A way of wiring the aircraft's main electrical supply so it is broken into two parts. The two parts can be joined together or kept separate, so that if one side has a problem the other side keeps working and powers the important equipment.
Context Anchor
Seen in aircraft electrical system descriptions, maintenance troubleshooting, and abnormal or emergency electrical procedures.
Derivation
Bus' in electrical work is short for 'busbar', a common conductor that distributes power to multiple circuits. 'Split' simply means divided into parts. So a split bus is a busbar that has been divided so each part can be controlled separately.
Why Pilots Care
Provides redundancy so a single electrical fault or generator loss does not disable the entire system, keeping essential instruments and equipment powered.
Analogy
It is like a house electrical panel divided into separate groups of breakers. A problem in one group does not automatically mean every circuit in the house has failed.
Intuition Check
“Bus” does not mean a vehicle here. In aircraft electrical systems, a bus is a shared point that sends electrical power to multiple pieces of equipment.
Example Sentence 1
After the generator failure, the crew opened the bus tie to operate on a split bus, keeping the essential instruments powered from the battery side.
Example Sentence 2
During the electrical system check, the mechanic confirmed both sides of the split bus remained powered with the tie relay open.