Patchwork built

The electricity industry does a remarkable job -considering it has to patch modern cabling into a 100-year-old network, says Allan Russell.

Despite all the issues that we encounter as engineers in our daily work, one of the single most important priorities for consumers is whether they can, or cannot, turn on a light and switch on their televisions. Essentially it’s up to us to ensure that demand for electricity is always matched by supply. However, too often the cable under our feet is overlooked in favour of the generation project of the moment.

The UK power network is constantly evolving, a patchwork of different cable types with its roots stretching back over 100 years. This results in the complexity of modern multicore polymeric cable having to be joined to fixed-core paper cable that has lain underground for the best part of a century. The scale of this patchwork is mindboggling — every factory, home or office requires a secondary cable to be ‘jointed’ off the main network cable and every network extension needs new cabling to be added to the existing infrastructure. Remarkably, this infrastructure continues to operate at near 100 per cent reliability, with power failures almost unheard of in many areas of the country.

However, this situation is becoming even more complicated. The trend towards using sustainable energy such as wind and wave power means that generation sources are now in some of the UK’s most remote, exposed and often prettiest regions. This places a great deal of pressure on our generation and distribution companies, since standard transmission methods, such as high-voltage overhead lines, often cannot be used. So engineers have to place long, expensive cable runs underground, often across areas of significant scientific interest and through difficult terrain. This raises significant servicing problems, since in the unlikely event of a joint failure special access permits may be needed to dig up cables, plus joints made.

These issues have led to a rise in the popularity of cold applied jointing and termination technologies. The challenge of joining paper to polymeric cabling has had a particular impact since the application of heat has a significant degenerative impact on the polymeric sheath. Furthermore, as joints and terminations are now being made in increasingly exposed environments, the consistent shrinkage that cold applied technology offers has made it the method of choice.

This migration needs to be implemented properly, however, with appropriate investment in training. Although mistakes are rare, when they do occur they are not only very public but also expensive (replacing a failed joint costs around £3,000). Not to mention the impact on supply and the expense of fines incurred. These failures are often completely needless — a recent one occurred simply because an engineer did not know about EC cable colour legislation, a rather explosive gap in his training knowledge!

That said, I’m constantly impressed with the quality of training that the utilities offer, and the calibre of some of the apprentices coming up into the industry is second to none. We just need to make sure that quality is not wasted, and that the industry can continue to deliver the quality of the past 100 years into the next century.

Allan Russell is technical services manager for 3M.