Trisha's Blog on Ofgem's Draft Determination of RIIO-T3 - August 2025

The ISG Response to Ofgem’s RIIO-T3 Draft Determination consultation

As Chair of the National Grid Electricity Transmission Independent Stakeholder Group (NGET ISG), I am pleased to present our response to Ofgem’s RIIO-3 Draft Determination. Our group, comprised of senior cross-sectoral experts, operates independently to scrutinise and challenge NGET’s business planning and delivery, ensuring stakeholder and consumer interests are at the heart of decision-making.

We broadly welcome Ofgem’s strategic direction and ambition, particularly its commitment to enabling timely investment to support net zero and long-term consumer value. However, we raise concerns about the complexity of the regulatory package, the clarity of incentive mechanisms, and the lack of a cohesive strategic “guiding mind” across the determination.

Our response highlights areas requiring further clarity, including project maturity assessments, funding routes for T2/T3 crossover projects, and the logic behind fast-tracking load reopeners. We challenge the robustness of the proposed stakeholder engagement survey and urge Ofgem to better recognise NGET’s strong engagement practices.

We also call for greater emphasis on regional planning, stakeholder-led asset management, and environmental ambition—particularly around biodiversity and low-carbon opportunities. Additionally, we stress the importance of workforce development and supply chain resilience, urging reconsideration of rejected investments like the Eakring Training Centre.

Finally, we advocate for a strengthened and enduring role for ISGs throughout RIIO-T3, ensuring transparency, accountability, and stakeholder voice in shaping the energy transition. Please do take the time to read through our response.

— Trisha McAuley OBE, Chair, NGET ISG