National Grid refurbishes 170km of UK transmission network

National Grid is delivering a £130 million ($163 million) project to refurbish and strengthen the existing overhead transmission line network between Lincoln and Stevenage in the UK.

The refurbishment will enable power to continue to feed into regional electricity networks, who distribute it to homes and businesses at lower, more usable voltages.

Once complete, the new line is hoped to strengthen the existing infrastructure from Lincolnshire through to Hertfordshire and ensure the network is able to continue to transport increasing volumes of renewable power.

The transmission project forms part of National Grid management of the high-voltage network in England and Wales, whereby 900 operational colleagues maintain the network, monitoring over 21,000 pylons, over 7,000km of overhead line (the same distance as London to Miami in the US) and 700km of underground cable.

Reinvigorating an aging power system

National Grid’s Operations teams and Morrison Energy Services, which repairs and refurbishes energy infrastructure, have been working at heights of up to 50m, installing 2,919km of new overhead line conductor to replace the original, which was installed in the 1960s and is now approaching the end of its scheduled working lifespan.

Three of four north-south circuits on the electricity transmission network have now been refurbished, allowing them to continue to function reliably, with completion of the fourth circuit expected in 2024.

Work on the transmission line, which runs from Cottam Power Station near Lincoln to Wymondley Substation near Stevenage, passing near Newark, Stamford, Peterborough and Hitchin, started in March 2022 and covers two project phases.

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The first phase of the works from Lincoln to Peterborough was completed last year and a further 1,479km of overhead line conductor has been installed so far in this year’s second phase, which runs from Stamford to Stevenage.

Each section of work has involved in depth planning around outages – when the system operator can afford to take a particular circuit off the live network.

The final circuit, which runs from Cambridgeshire to Hertfordshire, will be replaced to complete the project in 2024.

In addition to replacing the overhead lines, specialist teams climbed and surveyed 478 pylons along the 170km route and fitted around 80 tonnes of steel to reinforce the pylons to support the new line system.

National Grid invests more than £1 billion ($1.3 billion) a year to adapt and upgrade the transmission network, ensuring it is robust against severe weather, including storms and heatwaves and enabling the connection of more renewable power to help reduce emissions.

Edward Maddams, overhead line project manager for National Grid said: “These are some staggering statistics when reflecting on the amount of hard work that has gone into this job to date, and I would like to recognise the great teamwork, dedication, and skill of all involved in the project.

“I would also like to thank the local communities and landowners we continue to work with, for their cooperation in enabling us to make great progress in maintaining the health of our network and ensuring it continues to deliver safe and secure electricity.”