Contributed by Frances Richards

It’s no secret that copper and aluminum are both effective conductors of electricity. Further, most engineers and system designers know that copper is a better conductor and easier to work with, while aluminum is lighter weight and less expensive. Beyond these widely known characteristics, let’s take a closer look at the key differences between copper and aluminum when it comes to industrial cable applications.

Copper has higher conductivity than aluminum, meaning it can carry electrical current more efficiently. While aluminum is still an effective conductor, aluminum cables must have a bigger diameter (50-60% larger) than copper cables to achieve the same conductivity. A related consideration involves ampacity, or current-carrying capacity. Copper cables typically have higher ampacity than aluminum cables of similar size, meaning that larger aluminum conductors are required to achieve the same ampacity as copper conductors. More specifically, an aluminum conductor has a roughly 40% lower current-carrying capacity than a copper conductor of equivalent size.

In addition, copper is both denser and heavier than aluminum, which can be an important consideration in applications where weight is a critical factor. Taking this a step further, because aluminum cables are lighter weight than copper cables of similar conductivity, aluminum’s weight savings advantage can be significant — especially in large-scale installations.

Cost is another variable to consider: Not only is copper more expensive than aluminum — often twice the price — the cost of copper tends to fluctuate more. Because aluminum is a more cost-effective option, aluminum cables are worthy of consideration for projects with budget constraints. Corrosion resistance is yet another variable to keep in mind. Copper is resistant to corrosion, making it well suited for a wide range of environments, including underground installations. Because aluminum is more susceptible to corrosion than copper, precautions must be taken in corrosive environments, such as special coatings or alloying.

Flexibility is another key difference between copper and aluminum cable. Copper is more flexible than aluminum, making it easier to work with regarding bending during the installation process. Because copper has higher ductility and malleability than aluminum, it can bend easily during installation and be maneuvered through tight corners and constricted areas without breaking or cracking. Further, aluminum cable is more prone to cracking and failure when subjected to vibration. This should be considered for industrial environments where machinery produces high quantities of low and high frequency vibration.

Another installation concern involves joints and terminations. Because copper is more malleable than aluminum, it is generally easier to terminate and join. When terminating aluminum cables, special precautions must be taken to prevent issues such as galvanic corrosion. A related concern involves tensile strength: Copper’s tensile strength is roughly 40% percent better than aluminum, meaning copper is less likely to break. Electrical wiring is often mounted by pulling it through various ports and it can become damaged during installation if it isn’t sturdy enough.

Thermal expansion must be considered as well. Because copper has a lower coefficient of thermal expansion than aluminum, it will expand and contract less with temperature changes. This is something that needs to be kept in mind for applications exposed to significant temperature swings.

One area where aluminum cable really shines is in high-voltage applications. Because aluminum is significantly less expensive than copper, cost becomes a key factor when specifying the large quantities required for long-distance power lines. In addition, aluminum’s lighter weight versus copper makes it easier and more cost-effective to transport and install over long distances.