National Grid Completes Key Overhead Line Upgrade Between Harker and Scotland
National Grid has completed an upgrade of overhead electricity transmission lines north of its Harker substation near Carlisle, reinforcing a key cross‑border link that supplies power to homes and businesses in England and Scotland.
Delivered in partnership with Morgan Sindall Infrastructure, the project is part of a wider Harker upgrade scheme, which also includes new 400kV and 132kV indoor substations. The upgrades allow for additional connections, future-proof the regional network, and support the integration of renewable energy.
The work involved replacing existing circuits on two routes with higher-capacity wires and installing an additional 12km of overhead line on existing pylons to improve power flow and reduce congestion. In total, more than 90km of line was replaced or added—enough to stretch from Carlisle to Newcastle. Existing pylons were refurbished and strengthened, three new towers were added, and two older towers removed.
As part of the substation works, six 184-tonne supergrid transformers are being installed, with five delivered and the final unit scheduled for March. The new GIS (gas-insulated switchgear) technology in the substations avoids the use of SF6, a potent greenhouse gas, supporting National Grid’s goal to cut emissions from its network by 50% by 2030.
Mark Brindley, construction director at National Grid Electricity Transmission, described the upgrade as a “significant step” in improving reliability and creating capacity for cleaner energy. Community engagement included school tours and donations from Morgan Sindall Infrastructure and HD Hyundai Electric to local educational and recreational facilities.
The Harker substation and overhead line works are separate from the Cross Border Connection project, which plans a new electricity link between Lauder in the Scottish Borders and the Carlisle area.
Source: nationalgrid.com
