Busbar
A common electrical connection for several circuits.
The thick horizontal conductor is the common bus; the vertical connections represent attached circuits.
A busbar is a conductor, or set of conductors, that forms a common connection point. In a substation, it connects incoming and outgoing circuits through switching equipment.
Several circuits, one connection point
A busbar forms a common electrical connection. In a substation it can join multiple incoming and outgoing circuits, normally through breakers and other switching equipment. It may be a rigid metal bar or another conductor arrangement.
Actual substations use a variety of bus arrangements. Some have extra sections or parallel buses so that equipment can be maintained while more of the network stays energized. A single line on a network diagram hides that physical detail.
Why it matters
The bus arrangement affects both how circuits connect and what happens when equipment is isolated for a fault or maintenance.