Our website uses cookies to improve your experience and record usage statistics. By using our site you consent to cookies as described in our Privacy Policy. We take your privacy and data security very seriously and all information collected will be kept strictly confidential.
Copper vs Aluminum Busbars: How to Choose the Best Material？
2025-11-24
Copper and aluminum are the two main metals used for busbars. Copper busbars excel in electrical performance, as copper has an electrical conductivity of about 58 MS/m compared to 37 MS/m for aluminum. This means copper busbars carry more current with less loss. Copper also has higher tensile strength and mechanical stability, making copper busbars more durable under stress. Copper’s corrosion resistance is generally superior as well.
Aluminum busbars, on the other hand, are significantly lighter (about 70% lighter for the same cross-section) and usually less expensive. Aluminum’s lower density makes installation easier in large systems, and its cost advantage is important in budget-sensitive projects.
Comparison of Copper vs. Aluminum Busbars:
Electrical Conductivity: Copper (~58 MS/m) far exceeds aluminum (~37 MS/m), allowing copper busbars to carry higher currents with less resistance.
Ampacity: Copper’s higher conductivity means it can handle more current for the same bar size. In practice, a copper bar will carry more amps than an aluminum bar of the same cross-section.
Mechanical Strength: Copper is denser and stronger, making copper busbars more resistant to bending or deformation.
Corrosion Resistance: Copper exhibits better corrosion resistance than aluminum in most environments. Aluminum forms an oxide layer, but copper’s stability is higher.
Thermal Expansion: Copper expands less with heat than aluminum, leading to more stable connections under temperature fluctuations.
Weight: Aluminum is about 70% lighter than copper for equivalent dimensions, which can be crucial in weight-sensitive applications (e.g., aerospace or large panels).
Cost: Aluminum is generally less expensive. For large busbars (like in utility or building distribution), aluminum can offer cost savings despite being larger in size.
What is the best metal for a busbar?
For most demanding applications, copper is considered the best metal for a busbar due to its unmatched conductivity, strength, and reliability. Copper busbars are ideal for high-performance systems (such as industrial power distribution, renewable energy grids, or critical infrastructure) where efficiency and longevity are paramount.
However, aluminum busbars are chosen when weight or cost is the overriding concern. In settings where lightweight components or huge sizes are required (for example, certain overhead bus ducts or budget-limited installations), aluminum can be an appropriate choice.
In summary, engineers in Europe and Asia will often prefer copper for its superior electrical and thermal performance; still, they may opt for aluminum when reducing mass or saving on raw material costs. The choice depends on specific project requirements, budget, and performance targets.
How to choose the size of a copper busbar？
Determining the correct thickness (and width) of a copper busbar is critical for safe, efficient operation. The busbar’s cross-sectional area (thickness × width) must be large enough to carry the intended current (ampacity) without excessive heating. As a rule of thumb, designers use a conservative current density of about 4 A per mm² for copper busbars. In other words, each square millimeter of copper cross-section can safely carry roughly 4 amps.
Using this guideline, you can estimate thickness: Area (mm²) = Current (A) / 4 (A/mm²). For example, to carry 300 A, a busbar that is 25 mm wide would need a thickness of about 3 mm (since 25 mm × 3 mm = 75 mm², and 300/75 = 4 A/mm²). In practical terms, around 3 mm (≈1/8″) thickness of copper can handle a few hundred amps.
How thick should a busbar be?
The thickness of a busbar depends entirely on the current it must carry and its width. There is no one-size-fits-all thickness. A helpful approach is to use the current density method above: determine the needed cross-sectional area from the required current, then divide by the chosen width. As a practical guide, many medium-power busbars use thicknesses of a few millimeters. For example, carrying 300 A typically requires roughly 3 mm (1/8″) of copper when the bar is on the order of 1 inch wide.
The Copper Development Association notes that typical copper busbar thicknesses range from around 1.6 mm to 19 mm, depending on width. If you need a quick check, manufacturers often publish busbar rating tables. For precise design, calculate the cross-section and verify with an ampacity chart or engineering software.
In summary, pick a thickness (and width) that yields a cross-sectional area ≥ (Current/DesignCurrentDensity). In Europe and Asia, engineers follow IEC or local standards for busbar design and often allow safety margins. Using this method ensures the busbar will handle the electrical load safely without overheating.
