When selecting a copper busbar, engineers often focus on one question: how wide or how thick should it be?
Width and thickness both determine the cross-sectional area of a rectangular copper busbar, but they do not affect the complete design in exactly the same way. Changing the width can affect contact area, heat dissipation, clearances, and available installation space. Changing the thickness can affect stiffness, bending force, mechanical strength, and the space required through the thickness of the conductor.
This means two copper busbars with the same cross-sectional area are not necessarily interchangeable.
This guide explains the difference between copper busbar thickness and width and shows how to decide which dimension should be increased for a particular electrical connection.
Neither dimension is always more important.
Width and thickness should be selected together according to the electrical, thermal, mechanical, and installation requirements of the application.
For a rectangular copper busbar, the basic cross-sectional area is:
Cross-Sectional Area = Width × Thickness
For example:
50 mm × 10 mm = 500 mm²
The 500 mm² cross-sectional area provides a starting point for evaluating current carrying capability, but the dimensions themselves also affect the mechanical and thermal behavior of the finished busbar.
Increasing the width of a copper busbar can provide several advantages, depending on how the conductor is installed.
Increasing width increases the cross-sectional area when the thickness remains unchanged.
For example, changing a busbar from 50 mm × 10 mm to 60 mm × 10 mm increases the cross-sectional area from 500 mm² to 600 mm².
However, current capacity should not be determined from cross-sectional area alone. Temperature rise, ventilation, ambient conditions, conductor arrangement, and the applicable design requirements must also be considered.
A wider copper busbar can provide a broader connection surface for some bolted joints and terminals.
This can be useful when multiple mounting holes, terminals, or connection points need to fit within the same section of the conductor.
A wider connection area can also make it easier to arrange fasteners without placing them too close to the busbar edges.
Busbar thermal performance depends on several factors, including exposed surface area, current, installation conditions, and temperature rise requirements.
A wider conductor can increase the exposed surface area for a given thickness and length, which may help heat dissipation in some configurations.
This effect should be evaluated together with the actual mounting orientation and enclosure conditions rather than assuming that a wider busbar will always operate at a lower temperature.
The main limitation of increasing width is often available space.
A wide busbar may require more horizontal or lateral space inside a switchgear cabinet, battery enclosure, or electrical panel.
Clearance to adjacent conductors and components must also be considered when increasing width.
Increasing thickness also increases the cross-sectional area, but it changes the mechanical characteristics of the copper busbar in ways that are different from increasing width.
A thicker copper busbar can provide greater resistance to bending and deformation in the direction influenced by its thickness.
This can be useful for longer unsupported sections or applications where the conductor needs to maintain a defined position.
However, stiffness depends on the orientation and geometry of the complete busbar. A thicker bar is not automatically the best solution for every mechanical design.
Thickness has a significant effect on copper busbar bending.
A thicker busbar generally requires greater forming force and can be more difficult to bend into complex geometries.
The required bending radius, tooling, material condition, and forming direction must therefore be considered before increasing thickness.
This becomes particularly important for custom busbars with multiple bends or three-dimensional geometries.
Increasing thickness increases the space occupied by the conductor through its thickness.
This may become important in compact electrical equipment where components are positioned very close together.
A thicker busbar can also affect the position of adjacent components, terminals, covers, insulation, and mounting hardware.
Not necessarily.
Consider these two examples:
| Busbar Size | Cross-Sectional Area |
|---|---|
| 50 mm × 10 mm | 500 mm² |
| 25 mm × 20 mm | 500 mm² |
Both have the same nominal cross-sectional area, but their mechanical and installation characteristics are different.
The 50 mm × 10 mm busbar is wider and thinner, while the 25 mm × 20 mm busbar is narrower and thicker.
They may differ in:
Therefore, cross-sectional area should be treated as an important electrical starting point rather than the complete busbar specification.
A wider and thinner busbar may be worth considering when the design benefits from a larger connection surface or greater exposed conductor area.
Typical reasons include:
A wider busbar can also be useful when the connection interfaces with broad terminals or electrical devices.
A thicker and narrower busbar may be preferable when mechanical stiffness or limited width is more important.
Typical reasons include:
However, increasing thickness can make bending more difficult and may increase the required bend radius and forming force.
Width and thickness have different effects on bending because the orientation of the bend determines how the material is deformed.
For a custom copper busbar, the manufacturer should know:
A design that is easy to manufacture in a wide, thin configuration may become much more difficult to form if the same cross-sectional area is converted into a narrow, thick configuration.
This is why electrical design and copper busbar fabrication should be considered together.
Copper busbar dimensions also determine how the conductor can be connected to electrical equipment.
For bolted connections, engineers should consider:
A busbar that is electrically large enough may still be unsuitable if there is insufficient space for the required mounting holes or connection hardware.
This is one reason busbar sizing should consider the complete connection rather than selecting the cross-sectional area alone.
There is no universal answer.
Thermal performance depends on conductor resistance, exposed surface area, installation orientation, enclosure conditions, airflow, ambient temperature, and allowable temperature rise.
For the same cross-sectional area and length, changing the width-to-thickness ratio changes the surface exposed to the surrounding environment.
A wider and thinner conductor may provide greater exposed surface area in some arrangements, while a thicker conductor may offer different mechanical and installation advantages.
The thermal design should therefore evaluate the actual busbar geometry and installation conditions rather than assuming that width or thickness alone determines temperature rise.
Copper material cost is strongly related to the amount of copper used, but fabrication cost also depends on the geometry of the part.
For customized copper busbars, manufacturing complexity can be affected by:
A thicker busbar may require greater forming force or different tooling, while a very wide busbar may require more installation space or specialized handling.
The most economical design is therefore not necessarily the thinnest or narrowest option. It is the design that meets the electrical and mechanical requirements without unnecessary material or processing complexity.
Suppose an electrical connection requires a copper cross-sectional area of approximately 500 mm².
Two possible geometries are:
| Option | Width | Thickness | Area |
|---|---|---|---|
| A | 50 mm | 10 mm | 500 mm² |
| B | 25 mm | 20 mm | 500 mm² |
If the equipment has sufficient width but limited vertical space, Option A may be more suitable.
If lateral space is limited but greater thickness can be accommodated, Option B may be considered.
If the copper connection also requires several bends, Option A may have a manufacturing advantage because the thickness is lower. However, the final choice should still be evaluated for current capacity, temperature rise, mechanical strength, connection geometry, and fabrication requirements.
The best copper busbar dimension is not always the one with the largest cross-sectional area.
A good design balances:
This is particularly important for customized busbars used in switchgear, transformers, battery systems, power electronics, and other electrical distribution systems.
A professional custom copper busbar manufacturer can review the geometry and help identify potential problems before production, including difficult bends, limited hole edge distances, excessive thickness, or insufficient space around the connection.
Copper busbar width and thickness both contribute to electrical performance, but they affect the mechanical and physical design in different ways.
Increasing width can provide more contact area and exposed surface area, while increasing thickness can provide greater stiffness and may be useful where lateral space is limited. At the same time, greater thickness can make bending more demanding, while excessive width can create installation and clearance problems.
The right choice should therefore be based on the complete application rather than cross-sectional area alone.
GRL Copper provides customized copper busbar fabrication, including cutting, punching, drilling, bending, joining, surface treatment, and dimensional inspection for electrical connection applications.
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