Busbar

The skin effect makes 50–60 Hz AC busbars more than about 8 millimetres (0.31 in) thickness inefficient, so hollow or flat shapes are prevalent in higher-current applications.

A hollow section also has higher stiffness than a solid rod of equivalent current-carrying capacity, which allows a greater span between busbar supports in outdoor electrical switchyards.

A busbar must be sufficiently rigid to support its own weight, and forces imposed by mechanical vibration and possibly earthquakes, as well as accumulated precipitation in outdoor exposures.

To address these concerns, flexible bus bars, typically a sandwich of thin conductor layers, were developed.

Joints between high-current bus sections often have precisely machined matching surfaces that are silver-plated to reduce contact resistance.