by Callum Benton
Project Manager
Fleet-Aldershot upgrade
“When the demand for power went down; we climbed up.”
If you were to sum up one aspect which made the recently-completed upgrade to our overhead network between Fleet and Aldershot in east Hampshire both exhilarating and challenging, the sentence above might fit the bill.
We have a network of 132kV overhead lines in our central southern England distribution network area. Working on them needs a specialised skills-set and a different operational approach.
The dramatic photo above may have caught your eye; it shows our engineers working away high in the sky in the middle of the night, to upgrade a critical part of the network that keeps the lights on for more than 60,000 customers.
Why did we do some of this work under the cover of darkness? When renewing this line, we were only able to work on one circuit at a time – due to the particular loadings and back feed options available to us on this part of the network. This is to keep power flowing through the other circuit that hangs on each tower, thus keeping customers connected.
Running all the power through the other circuit that remains operational puts extra load on these wires, so a solution can be to sometimes carry out parts of the required works when there's less demand – and that’s when most of us are asleep. In the middle of the night at weekends, demand dropped to such an extent, that we were able to turn off both circuits, while still keeping our customers’ lights on via other routes.
Looking at the picture above, you’ll see the extensive scaffolding we had to erect for this project.
The scaffolding's necessary where the network passes over a road. It protects its users in the unlikely event of a conductor snapping whist it's being changed, as the nets suspended from the scaffolds would catch it.
The height of the conductors on some parts of this stretch of network meant a standard scaffolding design would have infringed upon minimum safety clearances in some cases.
So, we changed our approach. We had scaffolding partly built in advance – but only up to a safe distance.
With demand for power being lower on Saturday and Sunday evenings, there was an opportunity to turn both circuits off. So overnight during some weekends, we built the scaffolding up to full height for works to proceed.
Turning off both circuits is inherently safer when replacing protective earth wires, as it removes the risk of the earth wire striking a live conductor in the unlikely event of it breaking.
The scaffolding was then taken back down to a lower level before the sun came up on Monday morning, when the single circuit was restored in time for electricity demand ramping up again.
Working at heights of up to 100 feet, our teams swapped out the ageing existing Twin Lynx conductors, and fitted larger single Rubus replacements. Meanwhile at ground level, foundations were upgraded. And beneath our feet at one particular location, we undergrounded two stretches of 11kV network to allow us to more safely upgrade the 132kV lines flying high above.
When you realise there are 37 separate towers on this Fleet to Aldershot route, you get a better idea of the scale of this project.
We’ve invested £8.7m in this upgrade, and we finished works ahead of schedule. Now it’s complete, tens of thousands of households are benefitting from an even more resilient, even more reliable, electricity supply in time for the start of winter. And these upgrades are also future-proofing the network, so it’ll be able to provide more capacity for homes and businesses as they move over to heat pumps and EVs, or if they wish to install solar panels and export their own clean power to the grid.
We designed and led the delivery of this project in-house, using SSEN Distribution’s own expertise.
ABOVE: The local town crier visited the project during the construction phase to give his seal of approval.
With the volume of network investment underway, contract partners do play a huge, vital role in delivery across the UK, but we’re also proud that we retain the skills and capacity necessary for a project like this one within the SSEN Distribution family.
For example, our own lines people were critical in the successful delivery of this scheme; they responded to the challenges presented to them with common sense, a can-do attitude, enthusiasm, and most importantly, an absolute commitment to safety.
The sites were managed expertly by our own internal projects team, and the smooth running of the project’s delivery is one key reason why works finished ahead of schedule.
And a big shout out is also due to our Control Room team, led by Andrew Linkie. Their seamless management of the network as we switched circuits in and out to let us carry out our work safely and without delay was also invaluable.
And we’re grateful too for the support we received from Voltage Solutions, OCU Nettworx, Brand Energy, Energyline, A&I Engineering, OCS Security, and Sunbelt.
This project is one of the largest we’ve delivered in-house over the past few years. Now it’s been completed, this stretch of network is back to ‘business as usual’, discreetly, reliably delivering large volumes of electricity to the homes and businesses which need it.
And thanks to this investment – and the teams who delivered it – it will do so for decades to come.