Copper for electrical applications
Copper is an indispensable raw material in our electrical society, where everything from homes to major infrastructure runs on electricity. And as we electrify everyday life, the demand for busbars and copper components for wind turbines, electric cars and batteries increases.
Choosing the right alloy
Copper is the second-best electrical conductor of all the periodic elements – second only to silver.
The purity of the metal is one of the most important factors for high conductivity. Even small, natural contaminants in the pure metal can cause a drastic drop in conductivity. This is why choosing the right alloy makes a big difference.
As an example, let us look at the difference between HCP and ETP, where a very small amount of phosphorus lowers conductivity by as much as 2%IACS:
|
Copper alloy |
Copper % |
Phosphorus % |
%IACS |
|
HCP |
99.95 |
0.02-0.07 |
98 |
|
ETP |
99.90 |
0.00 |
100 |
However, despite the superior conductivity, pure copper is not always the best choice: Production methods and the specific parts needed for the project will determine what is the most suitable alloy for a specific project.
You are always welcome to contact Alumeco for guidance on a specific project.
Solid busbars
Solid busbars are relatively cost-effective and easy to produce in large quantities, which makes them a standard product for electrical applications. They can be mass-produced, complete with bends and holes, using just a coil and a punching tool. In contrast, flexible busbars are produced individually and require braiding, welding or assembly of terminals.
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Solid bus bars are a great standard solution that allows you to define thickness and size. But if you need individually adaptable busbars, you will need flexible busbars.
Flexible busbars
Some installations require flexible busbars to make ends meet and keep the current flowing. In other cases, the flexible braids or lamels are chosen for their ability to absorb vibrations in large installations where the components move at different frequencies.
A flexible busbar consists of a braid or thin lamels connecting two solid contact areas. A braided connection piece provides all-directional flexibility, while lamels provide one-way flexibility.
We stock Isoflexx and Ultraflexx as standard flexible busbar options:
Isoflexx
Ultraflexx
Braided busbars
Braided copper parts consist of ultra-thin copper wires (o.2 mm) braided together into one large braid. A busbar with a cross-section of 50 mm2 consists of approximately 1600 single strands.
Braided busbars should be handled with care to minimize the risk of broken threads. Individual broken wires will not impact conductivity in any significant way, but they increase the risk of unwanted electrical contact with other components in the installation.
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Copper busbar with braided section. -
Tin plated busbar with 6 layers of braids. -
Stranded copper busbar. -
Small busbar with tin plated braided copper.
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Press-welded busbars
Press-welded busbars consist of thin copper lamels which are press-welded together at the ends. Press welding creates a seamless transition between the solid metal and the flexible lamels.
The lamels are typically 0.2 mm in thickness, and the outer lamels sometimes slightly thicker to avoid breakage. A broken lamel can cause unwanted electrical contact with other components and severely damage the installation.
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Flexible busbar with lamels and press-welded terminals. -
Flexible busbar with lamels and press-welded terminals. -
Tin plated flexible busbar with lamels and press-welded terminals. -
Tin plated flexible busbar with lamels and press-welded terminals.
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Aluminium as an alternative to copper
Copper is an expensive material, and we can expect demand and prices to rise as the green transition continues. In some cases, aluminium is a good alternative to keep cost down. Aluminium is a less efficient conductor than copper, but weight and price are significantly lower.
In terms of conductivity, gold and silver are the best alternatives to copper, but in terms of price and availability, aluminium is the best alternative:
|
|
Conductivity |
Conductivity |
Density |
Price level in relation to copper (2025) |
|
Silver (Ag) |
105 |
60.9 |
10.5 |
125 |
|
Copper (Cu) |
100 |
58.0 |
8.96 |
1 |
|
Gold (Au) |
70 |
40.6 |
19.3 |
11000 |
|
Aluminium (Al) |
61 |
35.48 |
2.7 |
0.3 |
As a rule of thumb, you will need around 50% more aluminium (by volume) to conduct the same amount of electricity, but the price and weight are about 30% compared to copper. With some rough math, that puts the price for an aluminium installation with the same electrical capacity at around 50 % compared to a copper installation. The specific cost will of course depend on the requirements for the specific installation.
Below you see a comparison of copper and aluminium busbars with the same conductivity (measured by resistance) but with different cross-sections:
|
Metal |
Alloy and temper |
Cross |
Conductivity |
Conductivity |
Ohm |
|
Copper |
CW004A |
80x10 = |
100 |
58 |
2,16 x 10-5 |
|
Aluminium |
EN AW 1050A |
80x15 = |
59,5 |
34,6 |
2,08 x 10-5 |
|
Aluminium |
EN AW 1070 |
90x15 = |
62 |
36 |
2,06 x 10-5 |
|
Aluminium |
EN AW 6101B |
100x15 = |
57 |
33,1 |
2,01 x 10-5 |
The table shows that you need a larger cross-section to achieve the same conductivity with aluminium as with copper. How much bigger the cross-section should be, depends on the requirements of the specific installation – consider the size difference between the aluminium alloys 1050A and 1070 as an example.
When deciding between the two, other properties such as strength will determine which alloy is the right choice.
Aluminium busbars
Busbars made from aluminium are solid, not flexible. Unlike copper, aluminium cannot be drawn into sufficiently thin threads, which makes braided or stranded busbars impossible. It is also not possible to press-weld aluminium because of the oxide layer, and the press-welded terminal is a significant feature of copper lamel busbars.