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United Kingdom
High- & Extra-High-Voltage Networks
2021-2023
275 kV Transmission Line Refurbishment
Circet delivered a large‑scale refurbishment of a 275 kV transmission line between Coolkeeragh and Magherafelt in Northern Ireland. Spanning 56 km, the project focused on upgrading critical infrastructure while maintaining network continuity on one live circuit, an essential constraint that shaped every phase of delivery.
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PROJECT SNAPSHOT
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Customer
NIE Networks
Location
Northern Ireland, United Kingdom
Solution
High- & Extra-High-Voltage Networks
Circet Energy's Role
double‑circuit transmission line refurbishment, including tower works, conductor and OPGW replacement, and live‑line operations
180
Towers upgraded
56 km
Transmission line refurbished
1
Live circuit
THE CHALLENGE
Delivering a full transmission refurbishment on a major 275 kV line while keeping one circuit live demanded precise operational control, stringent safety management, and large‑scale coordination across multiple specialist teams.
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Our approach
Managing complex refurbishment under live‑line conditions
Planning and live‑line preparation
The project began with detailed planning to structure works around live‑line constraints. Sequencing was carefully designed to allow refurbishment activities to progress while maintaining power transmission on one circuit throughout the program.
Upgrading and strengthening existing assets
We refurbished 180 towers along the route, carrying out foundation strengthening, steelwork refurbishment, tower painting, and conductor and Optical Ground Wires (OPGW) replacement. Four new towers were erected where required to reinforce network performance.
Executing works at scale with safety at the core
Acting as Principal Contractor, Circet coordinated multiple specialist crews to deliver works safely and efficiently across the 56 km corridor, maintaining strong safety performance while managing interfaces, logistics, and live‑line operations.