Electricity Transmission Design Principles (ETDP): Ministerial letter

To: Colleagues and Partners
From: Stephen Gethins MSP, Minister for Europe, External Affairs and Energy
Sent: 30 June 2026

Dear Colleagues and Partners,

This letter is being sent to mark Scottish Ministers' endorsement of the Electricity Transmission Design Principles (ETDP) which were published by NESO on 30 June 2026.

Background

The UK Government’s Electricity Networks Commissioner, Nick Winser, recommended the development of ETDP as a public document detailing the principles and methods used to design the electricity transmission system (Recommendation RD1). This recommendation was accepted by the UK Government in their Transmission Acceleration Action Plan as a means of agreeing some of the general principles associated with transmission design up front before specific projects come into development. 

NESO prepared the ETDP in collaboration with representatives from the Scottish Government, Welsh Government, DESNZ, Ofgem and Transmission Owners (TOs). The ETDP were subject to public consultation in Autumn 2025.

Applying the Electricity Transmission Design Principles (ETDP) in Scotland

The ETDP comprise overarching, strategic and project development principles for the design of electricity transmission infrastructure. They set the overall vision for good transmission design and offer detailed guidance on the selection, siting and design of specific technologies. 

As design guidance, the ETDP should be read and applied as a whole. They will sit alongside, rather than replace, existing policy for the design and delivery of electricity transmission infrastructure. This includes National Planning Framework 4 (NPF4) policy 11 (energy) part (e) which requires that project design and mitigation will demonstrate how impacts on a range of receptors are addressed and sets out that, in the case of proposals for grid infrastructure, consideration should be given to underground connections where possible. This also includes the Holford (1959) and Horlock (2003) Rules which provide guidance for the design of transmission lines and substations respectively. 

The Scottish Government does not expect that the ETDP will apply retrospectively to projects that are already at an advanced stage. It is not considered that the ETDP will require the design of projects to be revisited where, at the time of publication, strategic planning activities have already taken place, and broad parameters around the technology type, connection points to the existing network, and capacity requirements have already been established. 

As a statement of Scottish Ministers expectations, this updated policy position is a material consideration in the determination of relevant applications for planning permission and Section 37 consent.

Notwithstanding the above, Scottish Ministers consider that the ETDP must still be read and applied alongside the relevant sections of NPF4 as appropriate. NPF4 remains Scottish Ministers’ National Spatial Plan, as approved by the Scottish Parliament, and is expected to carry due weight in decision making.

Yours sincerely

Stephen Gethins MSP
Minister for Europe, External Affairs and Energy