How to design a busbar that matches its intended use?

06.08.2021 | 
Copper busbars
Examples of copper busbars.

What is a busbar?

Busbar is a key component used in the electricity and energy industries to conduct current between points A and B.

Examples of applications:

  • Distribution centres
  • Control centres
  • Transformers
  • Electric motors
  • Generators

The main material of the busbars is copper due to its good electrical conductivity.  Aluminium is also used as an alternative material, but its electrical conductivity is not as good as that of copper.

In many cases, as the price of copper rises, aluminium is considered as an alternative material. However, aluminium has to be used considerably more than copper, which increases the size and can no longer necessarily be adapted to the desired product.

Materials used:

  • Copper
  • Aluminium


Busbar is often flat in profile, making its lateral surface as large as possible in relation to the material used.

This is important for electrical conductivity, as electricity flows most efficiently on the surface of the material. Efficient utilization of the material also makes sense in terms of cost, as copper is known to be valuable.

On the other hand, when a strong electric current heats the busbar, the slab evaporates heat more efficiently than other shapes.

However, some products also use other shape solutions, such as round bars. In this case, it may be, for example, a solution that facilitates design. In these cases, however, the busbar will probably result in a fairly low amount of current.

Water-cut busbars
Water-cut products.

The shape affects the following:

  • Electrical conductivity efficiency in relation to the material used
  • The amount of material required / the price of the product
  • The ability to evaporate heat / cool

Please note! SOP-Metal has a comprehensive selection of copper slabs and bars of all sizes in stock.

Check the copper selection here.

Check the aluminium selection here.


Because electricity travels mainly along surfaces, the area of the busbar significantly affects its performance. In addition, many other factors affect the current conductivity.

When dimensioning according to the rated current of the busbar, at least the following factors must be taken into account:

  • Ambient temperature:
  • Permitted heating
  • Type of metal
  • Surfaces coefficient radiation
  • Position of the sub-bars of each phase in relation to each other
  • Ambient air velocity (ventilation)
  • Current type (DC or AC)


The products are manufactured both with and without insulation. Insulation should be considered if busbars are to be installed close to each other. 

Close-up installation without insulation can cause breakdown voltage and short circuit if current can jump from one busbar to another.

Insulated busbars
Insulated products.

Fixed busbar

A fixed busbar often consists of a piece of copper strip cut to a certain length and bent to a certain shape.  

The main purpose of bending is to save the space or to provide a load-bearing support structure in the product. In addition to bending, the manufacturing may involve many other work steps.

Products bent according to drawings.

Sub-contracted operations as part of manufacturing:

  • Bending
  • Punching, milling, drilling
  • Making joints (welding, soldering, screwing)
  • Cutting shapes
  • Assembly

Holes are utilized, for example, in connection and installation stages.


  • Can act as a load-bearing support structure in the product
  • In many cases material costs are smaller / cheaper option

Flexible busbar

SOP-Metal has its own patented manufacturing method for flexible busbars. Flexible products are made of tin-copper flat strip and are, as the name implies, flexible.

Flexibility is useful, for example, in installation. In addition, manufacturing tolerances can be slightly looser than those of conventional rigid busbar parts, and a flexible part is likely to be easier and faster to install.

Deformations in the structures due to thermal expansion do not cause any problems either.

Flexible busbars
Flexible busbars consist of several layers of material, which allows them to be flexible. The busbars in the picture are tinned.


  • The bar is easy to install
  • Withstands vibration
  • Withstands the movement of joints or busbar connection points

Study of the differences between fixed and flexible busbars

Early this year we commissioned a study at the Technology Research Institute VTT comparing the properties between flexible and fixed busbars manufactured by SOP-Metal. The study focused on comparing the products in terms of their power loss and heat evaporability. In practice, the study confirmed the theory, according to which there is no significant difference between the power loss of the two. Also, the heat is conducted in almost the same way away from both product types.

SOP-Metal Oy manufactures subcontracting products that require high material know-how for the electricity and energy industries. We are also experts in the management of electrical currents and their isolation, from design to component manufacture. In addition, we manufacture a wide range of structures from steel and stainless steel.

SOP-Metal Group consists also companies below:

UltraCut Oy is a company specialized in high-pressure water cutting and fiber laser cutting.

SOP-Metal Eesti Oü is a subcontracting company that serves companies in the electricity and energy industries in the Baltic countries. The company has an office in Jüri, Estonia, 15 kilometers from the center of Tallinn.

V-S Mikromekaniikka Oy specializes in the manufacture of aluminum and plastic precision mechanical products.

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