National Grid Completes Major Overhead Line Upgrade North of Harker to Strengthen England-Scotland Power Link

National Grid Completes Major Overhead Line Upgrade North of Harker to Strengthen England-Scotland Power Link

(IN BRIEF) National Grid has completed a major upgrade of more than 90 kilometres of overhead transmission lines north of its Harker substation near Carlisle, replacing existing circuits with higher-capacity wires and installing an additional 12-kilometre line to reduce congestion and strengthen a key cross-border electricity link between England and Scotland the works, delivered with Morgan Sindall Infrastructure, form part of a wider Harker substation upgrade that includes new 400kV and 132kV facilities using SF6-free gas-insulated switchgear and the installation of six 184-tonne supergrid transformers which will improve resilience and support future renewable connections community engagement has accompanied the project, including support for Blackford Primary School, while National Grid confirmed that this scheme is separate from its proposed Cross Border Connection project

(PRESS RELEASE) LONDON, 10-Feb-2026 — /EuropaWire/ — National Grid has completed a major upgrade of overhead electricity transmission lines north of its Harker substation near Carlisle, reinforcing a vital cross-border connection that supplies power to homes and businesses across England and Scotland. The work strengthens the resilience of the network, increases capacity for cleaner energy flows, and reduces congestion on this strategically important part of the grid.

The project was delivered in collaboration with principal contractor Morgan Sindall Infrastructure and forms a key element of National Grid’s broader Harker substation upgrade programme. This wider scheme includes the construction of new 400kV and 132kV indoor substations adjacent to the existing facility, enabling additional network connections and helping to future-proof electricity infrastructure in the region.

As part of the overhead line (OHL) works, existing circuits on two separate routes between Harker and the Scottish border have been replaced with higher-capacity conductors. An additional 12-kilometre circuit has also been installed on existing pylons to further improve power flow and ease network bottlenecks. In total, more than 90 kilometres of overhead line have been upgraded or newly installed, equivalent to the distance between Carlisle and Newcastle.

To support the enhanced lines, existing pylons along both routes have been refurbished and reinforced. Three new towers have been erected where required, while two older structures are scheduled for removal as they are no longer needed.

At the substation itself, National Grid is installing six 184-tonne supergrid transformers to improve system resilience and support reliable electricity distribution across the region. Five of the six units have already been successfully delivered, with the final transformer expected to arrive in March.

The new 400kV and 132kV facilities at Harker will use gas-insulated switchgear (GIS) that does not rely on sulphur hexafluoride (SF6), aligning with National Grid’s commitment to reduce emissions of this potent greenhouse gas from its network by 50 percent by 2030.

Together with other infrastructure projects in the area, the upgraded substation and overhead lines will increase the amount of electricity that can be transferred between England and Scotland. This cross-border link is becoming increasingly important as more renewable energy generation connects to the grid in both countries.

Mark Brindley, Construction Director at National Grid Electricity Transmission, said that the upgrade represents a significant milestone in strengthening this critical part of the network. He highlighted the close cooperation with supply chain partners and the efforts made to minimise disruption to local communities while delivering a complex engineering programme that improves reliability today and creates capacity for cleaner energy in the future.

National Grid and Morgan Sindall Infrastructure have also engaged with the local community as part of the project. Pupils from Blackford Primary School were recently invited to tour the Harker substation, and the school has received donations from Morgan Sindall Infrastructure toward a new multi-use games area, as well as learning resources from transformer manufacturer HD Hyundai Electric.

Peter Kirk, Managing Director – Energy at Morgan Sindall Infrastructure, described the overhead line upgrade as a strong example of effective collaboration to deliver long-term benefits for local homes and businesses. He also emphasised the importance of supporting community wellbeing through investment in local facilities.

National Grid noted that the Harker substation and overhead line works are separate from its proposed Cross Border Connection project, which would create a new electricity link between the Scottish Borders near Lauder and the Carlisle area.

Media Contact:

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SOURCE: National Grid