Murphy has been awarded a significant contract by National Grid Electricity Transmission (NGET) to deliver a new substation at Uxbridge Moor in Buckinghamshire. This multimillion-pound project, adjacent to the existing Iver substation, will expand the electricity network and support rising demand in the west of London.
The project will leverage Murphy’s in-house expertise and direct delivery approach to construct a new 400kV substation, a 132kV substation, ancillary facilities, and associated infrastructure. It also includes 1.2km of raised access road, a new bridge over the River Alder Bourne, and underground cabling works.
Uxbridge Moor Substation - Project Details
The new substation is a critical part of NGET’s strategy to connect new customers and address growing electricity demands in the region. The scope of work encompasses:
Construction of a new 400kV substation and a 132kV substation.
Underground cabling to link the substations and modifications to the 400kV overhead line network.
A 1.2km raised access road off the A412 and a new road bridge crossing the River Alder Bourne.
Ancillary civil infrastructure and facility upgrades.
A notable feature of this project is the use of gas-insulated switchgear, which reduces the substation’s footprint by around 70% compared to conventional designs. This approach limits the impact on the surrounding environment and enhances the long-term sustainability of the facility.
Gas-insulated switchgear in Substations
Gas-insulated switchgear (GIS) is a compact and sealed system that uses an insulating gas, such as sulfur hexafluoride (SF6) or emerging SF6-free alternatives, to safely house electrical switchgear and components.
Unlike traditional air-insulated switchgear, GIS encloses live components within grounded metal enclosures filled with gas, which significantly reduces the need for electrical clearances between phases and to earth. This design enables a much smaller installation footprint—often up to 70% less—making it particularly valuable in urban environments or sites with limited land availability, such as the Uxbridge Moor Substation.
While GIS offers high reliability and protection against environmental factors like moisture, dust, and pollution, it comes with higher initial costs and maintenance complexities. It is primarily used in dense urban areas, critical industrial sites, or environmentally sensitive locations where space constraints and operational reliability are top priorities. With evolving technology, GIS systems are increasingly incorporating SF6-free insulating alternatives to address environmental concerns associated with greenhouse gas emissions.
Leadership comments on the project
Murphy’s Managing Director of Energy, Liam Corr, stated:
“Since 1951, Murphy has been a leading provider of innovative and integrated energy solutions – today we support groundbreaking transmission and distribution projects across the four countries in which we work. We are proud to be delivering this project in the UK’s capital and building on our strong working relationship with National Grid to help to ensure energy security for decades to come.”
Laura Mulcahy, project director at National Grid Electricity Transmission, added:
“Our new Uxbridge Moor substation will provide vital access to power for data centres that are at the heart of Britain’s innovation and economic growth. It will enable new jobs and investment in Buckinghamshire, and will support the UK’s digital future. Alongside these significant benefits, we are working to keep the substation’s environmental impact to a minimum. By using the latest SF6-free gas-insulated switchgear, we’re reducing the size of this crucial site by around 70%, and ensuring its technology is sustainable and resilient long into the future.”
Contract Structure
While specific contract details have not been disclosed, it is understood that this project will be delivered under a Design and Construct (D&C) approach. This model, well-suited to leveraging Murphy’s integrated delivery capabilities, allows for close control over the programme and interfaces, reducing potential delays or misalignments common in multi-contractor delivery.
This direct approach also provides opportunities for innovation and value engineering, particularly in the integration of SF6-free technology and environmental considerations, offering lessons for future substation and transmission projects.
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