How Plated Busbars Help Reduce Copper Costs and Allow Higher Operating Temperatures
Bare copper busbars remain common across low and medium voltage assemblies. However, exposure to oxidation and contamination over time can raise contact resistance at joints, leading to higher losses and temperature rise.
By contrast, plating busbars and connections with finishes such as tin, nickel, or silver helps maintain stable, low-resistance interfaces and enables higher allowable temperature rise limits under standards like IEEE C37.20.2.
This allows engineers to achieve the same current ratings with smaller copper sections, reducing both material use and component cost while improving long-term reliability.
Copper Busbar Usage
Bare (unplated) copper busbars and connections are still widely used and can fully meet industry standards when correctly designed, sized and maintained. They avoid an extra finishing step in manufacturing, which can reduce initial component cost.
In many low and medium voltage assemblies, the copper is often exposed at joints, breaker contact arms, cable terminations and primary contact assemblies. In clean, controlled indoor environments, bare copper can perform acceptably, but in harsher or long service conditions, oxidation and contamination can increase contact resistance at these points over time.
Standards such as IEEE allow unplated copper bus connections, but it permits lower allowable temperature rise limits to the unplated joints. To achieve the same continuous current rating within those limits, designs with bare joints can require larger copper sections, resulting in more copper being used in the end.
However, despite the widespread use, there are a few factors to consider:
Current carrying capacity
The current carrying capacity of a busbar is governed by its conductor material, cross section, permissible temperature rise and cooling conditions. Plating helps maintain low and stable contact resistance at joints by limiting oxidation and fretting.
By keeping joint resistance low, plated busbars can operate at a given current with less additional heating at connections, supporting higher practical temperature rise limits for those joints in some standards and OEM designs.
Material Usage
Where unplated copper joints are limited to lower temperature rise values, engineers may need more copper (larger cross sections or parallel bars) to keep within the same current and thermal limits. This increases total copper usage and weight for a given rating.
Weight
By using plated connections with higher allowable temperature rise limits in the relevant tables, it is often possible to meet the same rating with less copper, reducing both material cost and assembly weight while staying within the required verification criteria.
Why is plating important
One of the major advantages of plating busbar connections is that standards such as IEEE C37.20.2 permit higher allowable temperature rise limits for plated joints compared with unplated copper connections. This can allow designs to achieve the required continuous current rating with less total copper.
Common busbar electroplating processes include tin, nickel and silver plus combinations such as nickel underlayers with a tin or silver as a top layer. These finishes improve corrosion resistance and joint stability, and in the case of nickel and silver, support demanding high temperature or high reliability applications such as MV switchgear, data centres and renewable energy systems.