How do I choose the right conductor material for cables and wires?
From copper to aluminium to optical fibres: Find out how the various conductor materials in cables and wires differ from one another.
Various materials can be used as electric conductors for transmitting energy, signals or data in cables and wires. The most well-known and commonly used one is copper (Cu) which is a very ductile metal with high conductivity. It is also flexible, high-tensile and comparatively cheap, making it the first choice for many applications. The conductor comprises either a single wire or multiple wires twisted together to form a so-called strand. Copper can be tin-plated, for example, to make it more corrosion-resistant, or nickel-plated to improve its temperature range.
Copper, aluminium - or fibre optics? Choosing the right conductor material is often not easy for cable and wire users.
Aluminium (Al) is another potential conductor material. Its major benefit over copper is a much lower density. But it has poorer conductivity which means a greater cross section is required to transmit the same current. In addition, aluminium wires are less flexible and hence more likely to break. This makes them unsuitable for moving applications. As a result, aluminium is mainly used for energy distribution cables and medium voltage cables where weight plays an important role.
The material with the best conductivity is silver (Ag) but it is many times more expensive than copper. For this reason, silver is normally only used in special applications where exceptional performance and efficiency is required – for example in high-end audio. Another possible conductor for audio cables is silver-plated copper wire which stands out for high conductivity and resistance to corrosion. The high price and poorer conductivity of gold (Au) compared to silver and copper rules this out as a conductor.
Another material which, at first glance, would also appear to be an unsuitable conductor is steel with a conductivity significantly worse than that of copper or aluminium. On the other hand, it is extremely strong and highly tensile. For this reason, steel is used in military applications as well as in aerospace, often in combination with other materials such as aluminium.
About the author: Christian Dettmer is Head of Technical Department at HELUKABEL
Alongside all these metal conductors are optical fibres, or so-called optical waveguides. These are ideal for transmitting signals at high speed using light. They consist of a quartz glass or plastic fibre core. The latter is more flexible and hence can be bent more easily. The core is surrounded by an optical jacket, known as the cladding. The light signals are reflected between the core and cladding and hence transmitted through the waveguide at high speed. Optical waveguides are used in a variety of applications, such as in telecommunications, medicine and aerospace. They cannot transmit current though.
The best conductor material thus depends heavily on the application in question and the prevailing conditions. These must be known precisley in order to be able to carefully consider the pros and cons of each material. Of course other characteristics of a cable such as stranding, cross section, insulation and sheathing material also play an important role. For this reason, it is always best to seek expert advice when choosing cables and wires to ensure compliance with all the requirements of everyday use.