Why are bus bars in indoor switchgear usually plated with silver or tin?

Bus bars in indoor switchgear are typically plated with silver or tin primarily to prevent galvanic corrosion between different materials. When various metals are in contact with each other, particularly in the presence of moisture, galvanic corrosion can occur, leading to deterioration of the metal components. By applying a layer of a compatible metal, such as tin or silver, to the bus bars, it creates a protective barrier that reduces the risk of corrosion, thereby enhancing the longevity and reliability of the switchgear.

While enhancing the appearance, reducing failures, and increasing short-circuit current capacity are significant considerations in electrical design, the primary function of the plating in this context centers around protecting against corrosion, which is a crucial factor in ensuring the performance and durability of electrical components.