FAQs

Who are SP Energy Networks?

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

What statutory obligations does SP Energy Networks have?

Our statutory 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 any work we do keeps 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 on:

• www.ofgem.gov.uk
• Calling Ofgem's Consumer Affairs team on 020 7901 7295
• Emailing consumeraffairs@ofgem.gov.uk.

Why is the Denny to Wishaw Network Upgrade needed?

The UK is in the middle of a transformation, with the electricity we use increasingly coming from greener, cleaner sources, as many new renewable generators replace older fossil-fuelled power stations.

Our planning work with National Grid ESO (Electricity System Operator) has identified that, for the UK to meet its Net Zero carbon emissions targets, the transmission network in central Scotland needs to be capable of transporting more green electricity from Scotland to England and Wales.

To achieve this extra capacity, we need to reinforce the network between Denny and Wishaw. This includes a new north-south overhead transmission line between Bonnybridge and a point near Glenmavis, to link up existing overhead lines, allowing the additional green electricity to flow between them and on to the wider transmission network.

You can find more detailed information in our Need Case document on this website.

More information on the ESO Holistic Network Design (HND) strategic vision for the UK's electricity transmission network is available here.

What exactly are you proposing?

The Denny to Wishaw Network Upgrade Project includes new infrastructure, and some changes and reinforcements to existing infrastructure, including: 

• Construction of a new double circuit 275kV / 400kV overhead line, running north-south from Bonnybridge 275kV substation for approximately 17km to a point near Glenmavis in North Lanarkshire, where it will connect to the existing 275kV overhead line (known as XX Route) that runs between the Easterhouse and Newarthill 275kV substations;
• Uprating one side of the existing overhead line (known as ZG route) between Denny North and Bonnybridge substations from 275kV to 400kV; 
• Work at Bonnybridge 275kV Substation to terminate the new Bonnybridge to Glenmavis overhead line; and
• Moving the uprated 400kV circuit from the 275kV substation to the 400kV substation at Denny.

We will also need to uprate some other overhead lines in the region from 275kV to 400kV, but these will be subject to a separate consultation in due course.

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 definite 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.

Who gives you permission to construct new overhead lines?

We will be applying for consent under Section 37 of the Electricity Act 1989 to install the proposed overhead lines. As such, applications will be submitted to Scottish Ministers who make the final decision whether to grant or refuse it.

How will you determine the final route of the new overhead line?

The routeing of overhead lines is a complex process, requiring a balance to be struck between statutory obligations, engineering requirements, economic viability, the environment, and people who live, work, enjoy recreation and pass through it. 

We are following established guidelines for routeing transmission overhead lines, which combine in-depth environmental studies with technical and economic factors.  A key part of this is consultation with landowners, stakeholders and the public to inform the development of the project.

You can find out more about how we develop routes in our Approach to Routeing and Environmental Impact Assessment document, which is available on our website.

You can find detailed information specific to the routeing of the proposed new Bonnybridge to Glenmavis overhead line in our Routeing and Consultation Document, which is available here.

How and where will the proposed new Bonnybridge-Glenmavis overhead line connect to the existing Easterhouse-Newarthill overhead line (the XX route)?

The proposed new overhead line will connect to the existing Easterhouse-Newarthill overhead line near New Monkland cemetery. We will connect the lines using a junction tower, which has three sets of cross-arms to carry the different circuits (standard steel lattice towers have two sets of cross-arms). You can see a visualisation of how the connection might look by visiting our interactive map here and selecting ‘New Monkland cemetery’ from the dropdown menu.

The exact connection point will be identified at the next stage of project development, after we have received feedback from the first round of consultation and carried out further technical and environmental studies to determine a detailed route alignment for the proposed new overhead line.

What will the new overhead line look like and how high will it be?

The new overhead line will be carried on L8 lattice steel towers (pylons), similar to those already in place on the existing Denny to Bonnybridge overhead line. Each tower will have three arms on each side, and each arm will carry a set of conductors (wires). This is because there will be a circuit on each side of the towers, and each circuit has three sets of wires. The towers are made of galvanised steel. They are grey in colour and become duller in appearance after about 18 months.

The towers have a standard height of 46 metres, but can go up to 63 metres where required to ensure electrical safety clearance to the ground. They are placed approximately 300 metres apart, but the exact distance between them will vary depending on the landscape and any obstacles such as roads, rivers and railway lines.

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.

SPEN will consider undergrounding a 132kV, 275kV or 400kV overhead line, or section of that line, in particular circumstances where no suitable route for an overhead line can be identified. You can find out more about this in our Approach to Routeing and Environmental Impact Assessment document, which is available on our website.

The existing overhead line between Denny North and Bonnybridge substations was built in about 1975. We will need to replace the conductors (wires), and the insulators from which they are suspended.

We do not need to replace the existing L8 steel towers (pylons) as they are designed to carry circuits up to 400kV, but we may need to deviate the lines where they enter the substation sites. 

Prior to uprating the overhead line, we may need to create temporary accesses to the towers and laydown /storage areas for our equipment, usually mid-way along the route.

Linesmen will climb each tower and the existing insulators will be unbolted and lowered to the ground using a tractor and winch, which will then lift the new insulators into position.

Following commissioning of the overhead line, all equipment and temporary access of construction areas will be removed with the land being reinstated to its former use/condition.

What is involved in uprating the Denny to Bonnybridge line from 275kV to 400kV?

The existing overhead line between Denny North and Bonnybridge substations was built in about 1975. We will need to replace the conductors (wires), and the insulators from which they are suspended.

We do not need to replace the existing L8 steel towers (pylons) as they are designed to carry circuits up to 400kV, but we may need to deviate the lines where they enter the substation sites. 

Prior to uprating the overhead line, we may need to create temporary accesses to the towers and laydown /storage areas for our equipment, usually mid-way along the route.

Linesmen will climb each tower and the existing insulators will be unbolted and lowered to the ground using a tractor and winch, which will then lift the new insulators into position.

Following commissioning of the overhead line, all equipment and temporary access of construction areas will be removed with the land being reinstated to its former use/condition.

How are you consulting local people?

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

The first round of consultation, from May 26 2021 to June 21 2021, is to seek people’s views on our preferred route for the proposed new Bonnybridge to Glenmavis overhead line, and where the new line might go within that route. We are also seeking views on the proposed uprating of the existing Denny to Bonnybridge overhead line from 275kV to 400kV.

Following this first round of consultation we will develop a detailed design and alignment for the new overhead line, including locations for towers, 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 then hold a second round of public consultation, so that people can give us their views on the detailed route alignment. We will also carry out a detailed Environmental Impact Assessment at this stage.

After considering feedback received in the second round of consultation, we will finalise our proposals and submit applications for consent to the Scottish Ministers.

The Scottish Ministers will then hold a final round of statutory consultation before making any decision on our applications.

You can find out more about our consultation here

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 yet heard from us, please contact us.