Standard for Copper Rods in Small Busbars

Copper rods for small busbars are typically made from high-purity copper (≥99.9% Cu) with excellent electrical conductivity, available in various tempers and sizes to meet electrical and mechanical requirements.

Material and Purity

Copper rods used in busbars are generally made from high-purity electrolytic copper (C10100) with a minimum copper content of 99.90% and electrical conductivity of 101% IACS (International Annealed Copper Standard) for optimal current flow . Deoxidized copper with phosphorus (DHP, C12200) is also used where welding or high-temperature brazing is required, though its conductivity is slightly lower at approximately 85% IACS . Alloyed variants, such as C11400 (with silver) or C14300 (with cadmium), are used to improve mechanical strength without significantly reducing conductivity .

Dimensions and Shape

Copper rods for small busbars are typically round or rectangular in cross-section, with diameters or widths chosen based on the current-carrying requirements and installation constraints . Standard rod diameters range from 6 mm to 25 mm for small busbars, but custom sizes are available. Rectangular rods are often preferred for compact installations due to better heat dissipation and ease of mounting .

Temper and Mechanical Properties

Copper rods are available in various tempers to balance machinability, bending, and strength:

• Soft annealed: Suitable for bending, forming, and deep drawing; ideal for small busbars requiring custom shapes .
• Hard or common hard temper: Provides higher strength for machining and structural stability but is less suitable for bending .
• Special hard tempers: Used for shallow forming or precise bends, ensuring minimal deformation during installation .

Electrical Performance

Copper rods are selected to ensure low resistivity and high current-carrying capacity. The admissible current depends on rod cross-section, ambient temperature, and final operating temperature, typically calculated according to DIN 43671 or equivalent standards . For small busbars, rods are often tin-plated to improve corrosion resistance, solderability, and long-term reliability .

Surface Finish and Coating

• Bare copper: Standard for indoor, dry environments.
• Tin-plated copper: Enhances corrosion resistance and facilitates soldering or welding.
• Other coatings: Silver or nickel plating may be used for specialized applications requiring higher conductivity or oxidation resistance .

Standards and Compliance

Copper rods for busbars generally comply with:

• ASTM B187: Standard specification for copper busbars and rods .
• IACS conductivity standards: Ensures consistent electrical performance .
• DIN 43671: Defines current-carrying capacity for copper bars at specified temperatures .

Summary

For small busbars, high-purity copper rods (≥99.9% Cu) with appropriate temper, diameter, and plating are used to ensure efficient current distribution, mechanical stability, and long-term reliability. Selection should consider current load, installation space, bending requirements, and environmental conditions to optimize performance .