Strategic Wider Works

Delivery of large onshore electricity transmission projects

Our role is to ensure that new large onshore electricity transmission projects that are needed are delivered efficiently.

We do this through:

  • regulating the delivery of these projects by incumbent Transmission Owners (TOs), via our Strategic Wider Works (SWW) mechanism; or
  • introducing competition into the delivery of these projects.

We have recently published an update to our plans to introduce competitive tendering for onshore electricity transmission, available here.

We expect to consult on the needs case and our competition assessment for the Hinkley to Seabank SWW project later this summer. In that consultation we will also set out further thinking around options for introducing competition into the delivery of other new, separable and high value (£100m or over) projects.

SWW Mechanism

As part of the RIIO-T1 price control we put in place a mechanism to allow Transmission Owners to bring forward large investment projects – known as Strategic Wider Works (SWW) – where funding had not been awarded as part of the price control settlement.

SWW allows us to consider the need and funding for these projects during the price control period, so that delivery of these outputs can be brought forward in a timely manner.

Transmission Owners have identified in their business plans a number of projects that they consider are suitable for future consideration under the SWW arrangements.

Other projects which meet the eligibility criteria set as part of the price control, may also be brought forward.

SWW projects may meet our criteria for competitive tendering, so we decide on a case by case basis whether those projects should be delivered under the SWW mechanism or via competition.

Onshore competition

During RIIO-T1 we have the option to competitively tender SWW projects if they meet our criteria for tendering (new, separable, high value).

Approved SWW projects

Since April 2013 we have approved funding for three SWW projects:

Current and future potential SWW projects

The annual Network Options Assessment (NOA) report, most recently published by the GB System Operator (SO) in January 2017, identified several network reinforcement options as potential SWW projects in future. The potential SWW projects listed in the table below are existing SWW projects or those with a ‘proceed’ recommendation in this year’s NOA. We have also included in the table existing SWW projects proposed by TOs that have not yet reached the stage of being approved for funding.

In the January 2017 NOA the SO also provided its assessment of current and potential future SWW projects against our criteria for tendering - we have added the outcomes of that analysis to the table below.

Project name


Earliest in service date

Ofgem status NOA Onshore competition analysis

Western Isles link

Either a 450MW or 600MW HVDC link between the Isle of Lewis and Beauly, comprising 80km of land cable and 76km of subsea cable.


Possible future submission Suitable

Orkney Islands link

An AC subsea cable rated at around 200MW between Orkney and northern Scotland.


Possible future submission Suitable

Shetland Islands link

A 450MW of 600MW HVDC Link between Kergord on Shetland and Caithness, or alternatively landing in Morayshire.


Possible future submission Suitable

Torness to North East England AC reinforcement

A new double circuit from a new 400 kV substation in the Torness area to a suitable connection point in North East England.


Possible future submission Suitable

Eastern link

A subsea 2000MW HVDC cable. Options for link with vary with different combinations of cable drop off and landing points between Peterhead, Torness, Hawthorn Pit and Lackenby .


Possible future submission Suitable

Hinkley Seabank Connection Project

A new 400kV double circuit overhead line between Hinkley Point and Seabank.


Reviewing Final Needs Case Suitable

North West Coast Connections

A new 400kV double circuit connection for a proposed new nuclear power plant in Moorside.


Reviewing Initial Needs Case Suitable

Need help?

This page sets out information on the policy and processes around delivery of large onshore electricity transmission projects. If you're looking for information on other aspects of onshore electricity transmission, please refer to the transmission networks page.

If you can’t find the information you’re looking for, email us.


    Publications and updates

    • Published: 19th Dec 2013
    • Factsheets
    • 1 Associated documents
    This factsheet provides an overview of the SWW arrangements for our wider stakeholders.  If you would like any further information on the SWW arrangements please see our latest

    • Published: 21st Oct 2013
    • Guidance
    • 1 Associated documents
    This provides an overview of the SWW arrangements for stakeholders.  It gives detailed guidance to Transmission Owners (TOs) on how to prepare submissions under SWW.  It also encourages TOs to make complete and timely submissions to inform our assessment...

    • Published: 28th Jun 2013
    • Decisions, Other
    • 1 Associated documents
    SHE Transmission submitted a proposal for a new transmission link between the Western Isles and the mainland. This letter explains our decision to send it back for further relevant information that we need to conduct an SWW Needs Case assessment.