Aluminium busbar trunking – not just a matter of cost



With busbar trunking systems continuing to gain favour across the UK electrical market – driven by increasing power demands from the nation’s industrial and commercial sectors – a wider debate surrounding conductor material choice has continued to rage in the background. Aluminium, often dismissed on the grounds of poor conductivity, has made considerable strides in recent years as the conductor of choice for busbar systems, in large part due to the cost of copper.

However, Steve Marr, an expert in power distribution systems at Legrand UK, puts forward the case that aluminium is much more than just a low cost alternative.

The UK busbar market – which in itself has steadily made ground on more traditional methods of power distribution such as cable or pre-fabricated modular wiring systems – has traditionally been dominated by copper; in part down to its availability as a raw material, and part down to the historic affinity and trust the UK electrical industry has towards it. However, copper’s high cost compared to aluminium has impacted its market share in recent years.

Prices from the London Metal Exchange demonstrate that the copper price has had a floor of circa £3,000 per metric tonne over the last five years and has, for much of this time, been above £4,000 per metric tonne.

The result has been the steadily growing influence of aluminium as the material of choice for busbar systems. Whilst hard figures are notoriously difficult to come by, I would estimate that aluminium now accounts for at least 40 per cent, if not more, of all busbar systems installed in the UK; although, largely down to the conservative nature of the electrical industry, much of its use has this far been limited to smaller projects under 3200A.

However, whilst cost has been the catalyst for change, once specified and used, many M&E contractors and installers have become aluminium evangelists, eagerly banging the drum for a material which they believe has many benefits over and above merely price.

So what are those benefits?

Whilst aluminium’s conductivity is roughly 62 per cent that of copper, as a material it is circa 70 per cent lighter; meaning that overall an aluminium system is likely to be around 30 per cent less heavy than an equivalent copper system. To put the issue into context, the Zucchini 4000A busbar is 62.7kg per metre in aluminium, whilst its copper counterpart is 101kg per metre. This weight difference will not only save money when it comes to transportation and logistics, but it will help to reduce time, effort and, of course, cost during installation.

There is still a lot of misinformation in the market about aluminium performance versus copper. The truth is that aluminium is now an exceptionally high performance product which offers outstanding characteristics, in terms of mechanical strength, heat stability and thermal conductivity.

In short, as long as you are specifying a busbar system that complies with BS EN 61439-6 then you should expect the same level of performance regardless of material choice.

Aluminium has also traditionally been criticised for its susceptibility to oxidisation which has the potential to affect the contact conductivity of the joint. However, manufacturers of busbar systems have been very adept at overcoming this issue by using electro-tin plating on the conductor bars to completely eradicate the problem.

Another major plus point. Unlike ferrous metals, aluminium does not generate sparks when used in combination with other metals, which makes it an ideal choice for use in safety critical applications, such as flammable or explosive environments. Also, due to the fact that aluminium is non-magnetic, it is ideal for use in applications that need minimal magnetic interference, such as high voltage applications and electronics.

Mechanical strength
Aluminium is an extremely strong material with a mechanical resistance of 60 to 530 Newton/mm2, which is more than sufficient for most applications and compares favourably with copper.

One of the key points to make about aluminium is that it has a much more stable commodity price than copper, protected from the vagaries of speculators, and political factors. Prices from the London Metal Exchange demonstrate this stability. In the five year period between 2010 and 2015 aluminium prices only fluctuated between a high of circa £1,650 per metric tonne and a low of just under £1,000 per metric tonne; significantly lower than its copper equivalent.

For M&E consultants, specifiers and installers price stability is a key issue. It can take months and years to bring major industrial and commercial projects to fruition. What is specified today, can jump in price tomorrow. Aluminium’s price stability is a major factor in its growth.

Finally, a word on sustainability. Aluminium’s stable, and ultimately lower, cost price is also largely attributable to its abundance as a naturally occurring resource when compared to copper. What’s more, when it comes to actually manufacturing and processing aluminium parts, 60% of the energy used comes from hydro-electric power, offering reduced carbon emissions compared to copper processing. One final point to also bear in mind is that aluminium can be fully recycled with only minimal impact on its quality, and it requires just 5% of initial energy to recycle; both of these factors are considerably favourable over its copper rival.

As such, aluminium is one of the most sustainable conductor materials available for use. In a world where material provenance is increasingly coming under the microscope throughout the supply chain, opting for an aluminium busbar system can go a long way to enhancing a project’s overall sustainability credentials.

Final thoughts
In short, aluminium busbar trunking has enjoyed great success in recent years, for all of the reasons outlined above. There are many consultants and specifiers who still go down the traditional route more often than not, especially when it comes to larger projects, and manufacturers such as Legrand are able to offer BS EN 61439-6 compliant systems which make use of either copper or aluminium.

However, the demand for copper busbar systems is declining and I firmly believe that aluminium is the busbar material of the future, and can offer direct benefits – from lower material cost and quicker install times to enhanced environmental credentials – there are advantages for choosing aluminium for stakeholders throughout the entirety of the supply chain.