Millmoor Rig Wind Farm Overhead Line Grid Connection

Who is SP Energy Networks?

SP Energy Networks is part of the ScottishPower Group. SP Transmission sits within SP Energy Networks and are responsible for the transmission of electricity in central and southern Scotland and the distribution network in parts of North West England and North Wales. Our role is to maintain, operate and invest in our network to secure a safe, reliable, and economic service for current and future consumers.

As a regulated utility provider, SP Energy Networks is obliged under the Electricity Act of 1989 to provide grid connection for electricity generated from power stations, windfarms, and various other utilities into our transmission network, which comprises over 4,000km of overhead lines and 320km of underground cable.

What statutory obligations does SP Energy Networks have?

Our statutory legal obligations are set out in the Electricity Act 1989 and in our transmission licence.

We must develop and maintain an efficient coordinated and economical transmission system in accordance with security and quality of supply standards. We must offer to connect new power generators to the system and, make sure we keep disturbance to the natural and built environment and the people who live in it, work in it or enjoy it to a minimum.

Who regulates SP Energy Networks?

We are regulated by Ofgem (Office of the Gas and Electricity Markets). Further information about Ofgem is available:

• At https://www.ofgem.gov.uk/
• By calling Ofgem’s Consumer Affairs team on 020 7901 7295; or
• By emailing consumeraffairs@ofgem.gov.uk

Why is this project needed?

SP Energy Networks received a request to connect the proposed wind farm (Millmoor Rig Wind Farn) to the transmission grid in southern Scotland.

To comply with its statutory and license obligations, SP Energy Networks must provide such a connection. As with all the grid connections of this type, the initial premise is that these will be provided through OHLs.

What exactly are you proposing?

We are proposing to construct a new c. 18km 132kV overhead line (OHL) to connect the proposed Millmoor Rig Wind Farm to the electricity transmission system via existing Hawick substation in Scottish Borders.  

The OHL is proposed to be supported by wooden trident poles with galvanised steekwork cross arms supporting aluminium conductors on insulators. These are suitable for supporting single circuit lines operating at 132kV.

Wood poles have a standard height above ground of approximately 11-16m, but these can be increased or reduced as required when circumstances dictate, e.g. over elevated land, structures or features.

The distance between wood poles will average between 80m and 100m but can be increased if there is requirement to span a larger landscape feature etc.

How much will the project cost?

It is early days and we won’t be able to cost the project fully until we have a defined proposal.

Who will pay for this project?

Ultimately, the cost of our investment in the electricity system is partly borne by consumers through electricity bills, so we are obliged to be economic and efficient. We recover our costs through transmission charges levied by National Grid.

The amount we invest in our networks and the amount we are able to recover is agreed with Ofgem, which is committed to working with industry, governments and consumer groups to deliver a net zero economy at the lowest cost to consumers. You can find out about Ofgem.

Who gives you permission to construct new overhead lines?

We will apply for consent under Section 37 of the Electricity Act 1989 to install the proposed overhead line. As such, applications will be submitted to the Scottish Government’s Energy Consents Unit, and Scottish Ministers will make the final decision whether to grant or refuse it.

When is the project needed by?

We plan to have the project in operation by 2030, but there is a lot to do before then, such as environmental studies, designing the project, obtaining the necessary development consent, and building it.

How will the overhead line be constructed?

The construction of OHLs requires additional temporary infrastructure accesses to poles location and construction compounds to store materials. All have limited maintenance requirements and are subject to well-established procedures for dismantling/decommissioning.

Following site preparation, small excavations are required to install each pole leg and its foundations which requires no concrete. The poles are then erected in sections before the conductors are ‘strung’ between them.

You can find more information about the construction process in our Routeing and Consultation Report.

Can the new line go underground?

Under the Electricity Act 1989, SPEN is required to consider technical, economic and environmental matters, and reach a balance between them.

High voltage, high-capacity overhead lines are the proven economic and reliable choice for the bulk transmission of electricity throughout the world. Nevertheless, a section of underground cable is proposed as part of this connection due to technical constraints surrounding Hawick substation.

Section 9 of the Act places a duty on SPEN (as licence holder) to ‘develop and maintain and efficient, co-ordinated and economic system of electricity transmission/distribution’. In practice this means an overhead line will almost always be promoted ahead of an underground cable connection due to the higher cost of underground cabling for the relative voltages.

How are we consulting local people?

We are planning two rounds of public consultation before we submit our consent application to the Scottish Government.

The first round of consultation, from Tuesday 19^th August to Tuesday 30^th September 2025 is to seek people’s views on our preferred route for the proposed Millmoor Rig Wind Farm Grid Connection project, and where the new line might go within that route.

Following this first round of consultation, we will develop a detailed design and alignment for the new connection overhead line, including locations for poles, access routes and working areas. We will publish a report summarising the feedback received in this first round of consultation and how this has influenced our proposals.

We will carry out environmental surveys and reports, and hold a second round of public consultation, so that people can give us their views on the detailed route alignment.

After considering the feedback received in the second round of consultation, we will finalise our project proposals and submit consent applications to the Scottish Government’s Energy Consents Unit, for consideration by Scottish Ministers. The Scottish Ministers will then undertake a final round of statutory consultation before making any decision on our applications.

Are you consulting landowners?

Yes, we will be talking to owners and occupiers of land that might be affected by our preferred route. If you believe that your land may be affected and you have not heard from us, please contact us.

Can you tell me more about Electric and Magnetic Fields (EMFs)?

Wherever electricity is used there will also be electric and magnetic fields. This is inherent in the laws of physics – we can modify the fields to some extent, but if we are going to use electricity, then EMFs are inevitable. Like many other things that we encounter in nature, EMFs can be harmful at high-enough levels. But the fields required, for example, to start interfering with the body’s nervous system are much greater than those produced by the UK electricity system. Hundreds of millions of pounds have been spent investigating this issue around the world. Research continues to seek greater clarity; however, the balance of scientific evidence to date suggests that EMFs do not cause disease.

‘Electric and Magnetic fields – The Facts' is a document produced by the UK electricity industry.

How do we provide feedback without a physical public consultation?

In the same way as a normal consultation event, you are able to provide feedback via email or post. The addresses can be found below:

If your question is not answered within these FAQs, you can email the mailbox at: MillmoorRigProject@spenergynetworks.co.uk

Alternatively, you can write to:

Millmoor Rig WF project manager
Land and Planning Team,
SP Energy Networks
55 Fullarton Drive
Glasgow
G32 8FA