The UK Grid Investment Pipeline in 2026: What RIIO-T3 Actually Means

RIIO-T3 runs from April 2026 to March 2031 and commits up to £35 billion to UK electricity transmission infrastructure, a 70% increase on RIIO-T2 investment levels. National Grid Electricity Transmission is delivering 17 ASTI projects under the Great Grid Upgrade programme, including five HVDC offshore links and 12 major onshore schemes. LSP Renewables recruits project leadership and specialist engineering across the supply chains delivering this work; this is our read of the pipeline and what it means for T&D hiring.

Key Takeaways

• RIIO-T3 covers April 2026 to March 2031. National Grid has accepted Ofgem's Final Determination, published 4 December 2025, with a baseline total expenditure of £10.3 billion approved for electricity transmission networks.

• National Grid's RIIO-T3 business plan targets up to £35 billion of investment across the five-year period, including around £24 billion in pipeline projects and £15 billion specifically to increase network capacity.

• The Great Grid Upgrade comprises 17 ASTI projects, including Eastern Green Links 1 and 2 (both 2GW HVDC cables), Sea Link, and 12 major onshore overhead line and substation schemes across England and Wales.

• All six Wave 1 ASTI projects entered construction by the end of the 2024/25 financial year. The Great Grid Partnership has contracted seven supply chain partners covering the full Wave 2 onshore scope.

• UK government figures suggest investment in onshore network infrastructure could support up to 130,000 jobs and contribute an estimated £4 to £11 billion of gross value added to Great Britain's economy by 2050, according to National Grid's published partnership documentation.

What RIIO-T3 Is and Why It Matters Now

RIIO-T3 is Ofgem's price control framework for UK electricity transmission, governing allowed revenues, capital expenditure, and performance incentives for the period April 2026 to March 2031. The current RIIO-2 price control ended on 31 March 2026, and RIIO-T3 has now taken effect. Understanding the framework matters for anyone working in T&D project delivery, because it is the mechanism that releases funding for the projects driving current and near-term hiring demand. Ofgem

Ofgem approved a baseline total expenditure of £10.3 billion for electricity transmission networks, up from £8.8 billion in the July draft determination. That baseline figure represents only around 15% of the prospective total spend across RIIO-T3. The remainder is released progressively through in-period funding tools for major projects. The pipeline is not front-loaded - it builds as projects move from consenting to construction, which means hiring demand accelerates through 2027 and 2028 rather than peaking immediately. Morningstar

What did National Grid commit to under RIIO-T3?

National Grid's plan includes an unprecedented level of investment of up to £35 billion over the five years to March 2031. This represents a 70% increase in investment versus the prior five years, with roughly £31 billion allocated to UK Electricity Transmission. National Grid has formally accepted Ofgem's Final Determination, confirming the framework is live and supply chain delivery is underway. National GridStocktitan

What is Ofgem's allowed return for National Grid under RIIO-T3?

The regulatory package includes a real allowed cost of equity of 6.12% at 60% gearing for National Grid Electricity Transmission. That figure sits above the RIIO-T2 level of 4.3%, reflecting Ofgem's recognition of the scale of investment required. It remains below the 6.3% National Grid originally sought, and the company has signalled it will monitor whether the framework proves investable in practice over the period. Stocktitan

The Great Grid Upgrade: What Is Actually Being Built

The Great Grid Upgrade is National Grid's overarching programme label for the 17 ASTI projects it is delivering across England and Wales. The ASTI projects are building the significant new electricity network infrastructure required to reduce the UK's reliance on fossil fuels by connecting 50GW of offshore wind by 2030. These are the live programmes generating the largest share of specialist T&D project leadership demand in 2026. Read the broader definition and scope of transmission and distribution to understand how these projects sit within the wider grid structure. National Grid

What are the HVDC projects within the Great Grid Upgrade?

Five HVDC offshore links sit within the ASTI portfolio. Eastern Green Link 1 is a 2GW HVDC electrical superhighway between the Torness area in East Lothian, Scotland, and Hawthorn Pit in County Durham, England. Eastern Green Link 2 is a 2GW HVDC cable link between Peterhead in Aberdeenshire, Scotland, and Drax in North Yorkshire, England. Eastern Green Link 3 is a 500km HVDC link bringing clean energy from Scotland to Lincolnshire. Sea Link is a 138km offshore cable connecting Suffolk to Kent, enabling a two-way flow of renewable power. These five HVDC programmes represent the most technically specialised hiring requirement in the entire pipeline, with converter station, protection, and HVDC cable package roles commanding the highest day rates in the T&D market. National GridNew Civil Engineer

What are the major onshore ASTI projects?

The 12 major onshore ASTI projects include more than 200km of new electricity transmission reinforcement in East Anglia, comprising overhead lines and underground cabling. In Lincolnshire, a reconfigured design to connect two offshore schemes to new substations will reinforce the network to enable 18GW of customer connection capacity in the region, up from 4.6GW in 2021. Twenty-five new substations are being delivered in RIIO-T3, with a further 15 new substations planned beyond RIIO-T3. Each new substation requires primary plant design, protection and control engineering, project management, and commissioning leadership - the roles LSP Renewables places across its transmission and distribution recruitment desk. New Civil EngineerRIIO-T3

How far advanced is delivery on the ground?

All six Wave 1 ASTI projects entered construction by the end of the 2024/25 financial year. National Grid has now contracted or has frameworks in place for all 17 ASTI projects, with the Great Grid Partnership and the HVDC framework both in place. Wave 2 onshore delivery is now contracted to a consortium of seven supply chain partners covering design, consent, and EPC scope. The pipeline is not theoretical - it is in the ground, and the hiring demand that follows from active construction programmes is live. National Grid

What the Pipeline Means for T&D Hiring

The investment scale creates a structural imbalance between programme demand and available talent. The most in-demand roles across the Great Grid Upgrade include Overhead Line Design Engineers, Protection and Control Engineers, HV Substation Engineers, Power Systems Engineers, Project Managers, Construction Managers, and Commissioning Engineers. PwC UK research cited in sector analysis notes that the energy transition risks being constrained by a skills shortage, driven by an insufficient pipeline of skilled workers and an ageing workforce, with many expected to retire by 2030. Advance TRS

The UK government suggests that investment in onshore network infrastructure could support up to 130,000 jobs and contribute an estimated £4 to £11 billion of gross value added to Great Britain's economy in 2050. That figure covers the full supply chain, but the specialist T&D engineering and project leadership cohort is the one proving hardest to fill. The question of how long high-voltage specialist hiring takes is one every client on a Great Grid Upgrade framework needs to answer before they need the person, not when. National Grid

What roles does RIIO-T3 create most urgently?

Project Directors and Senior Project Managers for substation and overhead line programmes are the acute shortage today. Protection and control engineers, HVDC converter station specialists, and commissioning managers are the hardest individual disciplines to fill. Wave 2 onshore delivery and the active HVDC cable programmes are running simultaneously, which means the same small pool of candidates is being approached by multiple framework contractors at once. Operators who move to pipeline recruitment six to twelve months before a role activates consistently outperform those who recruit reactively.

How does the EPC contract risk allocation affect hiring on ASTI programmes?

ASTI projects sit under NEC4 contract structures with output-based performance incentives. The commercial profile this creates demands project directors with demonstrable NEC4 delivery experience and the ability to manage supply chain performance at programme level, not just project level. Candidates who have worked within similar framework delivery models - ideally on RIIO-T2 close-out programmes - are prioritised by ASTI framework contractors over candidates with equivalent technical experience but no comparable commercial exposure.

How to Position for RIIO-T3 Opportunities

Whether you are a candidate looking to move into the ASTI supply chain or a contractor building out a delivery team, the timing of engagement matters as much as the quality of the candidate or the strength of the brief.

Step 1: Identify which Wave 2 projects are in the pre-construction phase in your specialism. Substation-heavy programmes in East Anglia and Lincolnshire are the most active hiring locations in 2026. HVDC converter station roles are concentrated around the Scottish-English border and the East Durham coast.

Step 2: Audit your NEC3 or NEC4 commercial exposure. Framework contractors on Great Grid Upgrade programmes require verifiable experience of contract management at programme level, not just project delivery. Candidates who can name the contract type, the incentive structure, and the commercial close-out process on prior roles consistently outperform those who cite project value alone.

Step 3: Register your candidacy with a specialist T&D recruiter at least six months before your intended move. The LSP Renewables transmission and distribution recruitment team holds active relationships with the seven Great Grid Partnership contractors and the HVDC framework holders, and places candidates into pre-construction roles before they reach open advertisement.

Step 4: For clients building delivery teams, brief specialist roles to a dedicated T&D recruiter at programme planning stage, not when the role becomes urgent. The average time-to-hire for a Protection and Control Engineer on a 275kV-plus programme runs 45 to 60 working days from brief to start. Building that into your programme plan is not optional on a time-critical ASTI delivery.

Frequently Asked Questions

What is RIIO-T3 and when does it start?

RIIO-T3 is Ofgem's price control framework for UK electricity transmission, covering April 2026 to March 2031. It replaced RIIO-T2, which ended on 31 March 2026. The framework sets the allowed revenues, capital expenditure, and performance incentives for National Grid Electricity Transmission and the Scottish transmission owners across the five-year period.

How much is being invested in UK electricity transmission under RIIO-T3?

National Grid's RIIO-T3 business plan targets up to £35 billion of total investment across the five years to March 2031. Ofgem's Final Determination approved a baseline total expenditure of £10.3 billion for electricity transmission networks, with the remainder to be released through in-period funding mechanisms as major projects progress from consenting to construction.

What is the Great Grid Upgrade?

The Great Grid Upgrade is National Grid's programme label for the 17 ASTI projects it is delivering under the RIIO-T3 framework. It includes five HVDC offshore links, including Eastern Green Links 1 and 2, and 12 major onshore schemes covering overhead line reinforcement, new substations, and underground cabling across England and Wales. Its goal is to connect 50GW of offshore wind to the UK grid by 2030.

How many substations are being built under RIIO-T3?

National Grid is delivering 25 new substations within RIIO-T3, with a further 15 new substations planned beyond the current period. Each substation programme generates sustained demand for primary plant engineers, protection and control specialists, project managers, and commissioning engineers across the design, construction, and energisation phases.

What jobs does the Great Grid Upgrade create for T&D specialists?

The most active roles across the Great Grid Upgrade in 2026 are Overhead Line Design Engineers, Protection and Control Engineers, HV Substation Engineers, Power Systems Engineers, Project Managers, Construction Managers, and Commissioning Engineers. Project Director and Senior Project Manager roles are the most acute shortage given the simultaneous running of Wave 2 onshore programmes and the active HVDC cable delivery programmes.

Will RIIO-T3 investment keep growing beyond 2031?

National Grid has identified a small number of high-value projects with current estimated costs totalling over £12 billion planned beyond 2030, with £1.9 billion of development and construction spend expected within RIIO-T3. The National Energy System Operator's connection reform process has identified 35 further schemes for development beyond the current period. The investment trajectory does not peak at 2031 - it continues into the following decade.

About the Author

John Martin is Divisional Manager for Onshore Renewables at LSP Renewables, with over 15 years in the staffing industry and more than a decade specialising in renewable energy recruitment. John has built lasting relationships with recognised brands across the energy sector, holding key leadership and strategy positions throughout a career that spans the rapid growth of the UK renewables market. His current focus covers grid, interconnectors, HVDC, and solar/storage recruitment across the onshore renewables sector. Connect with John on LinkedIn or reach him directly at john.martin@lsprenewables.com or on +44 (0) 203 905 6227.

Recruiting for RIIO-T3 and Great Grid Upgrade programmes? Talk to a specialist.

LSP Renewables places project directors, senior project managers, and specialist engineers across the Great Grid Partnership supply chain and the HVDC framework contractors. Permanent, contract, and interim cover across HV substations, overhead line, and HVDC packages. Brief a T&D vacancy with LSP or call the transmission desk directly.