Who are SP Energy Networks?
SP Energy Networks is part of the ScottishPower Group. It is 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. Its role is to maintain, operate and invest in the network to secure a safe, reliable, and economic service for current and future consumers.
What statutory obligations does SP Energy Networks have?
Statutory obligations are set out in the Electricity Act 1989 and in the transmission licence. It includes a responsibility to develop and maintain an efficient, coordinated and economical transmission system in accordance with security and quality of supply standards. An obligation to connect new power generators to the system and, make sure any work carried out 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?
SP Energy Networks is regulated by Ofgem (Office of the Gas and Electricity Markets) the independent national regulatory body. Further information about Ofgem is available on:
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 new renewable generators replace older fossil-fuelled power stations.
Our planning work with the National Energy System Operator (NESO) has identified that, for the UK to meet its Net Zero carbon emissions targets, we need to reinforce the network between Denny and Wishaw so it has extra capacity to transmit additional green energy.
This reinforcement includes uprating some existing overhead lines from 275kV to 400kV to increase their capacity, and building the proposed new overhead transmission line between Bonnybridge and a point near Glenmavis, enabling the additional green electricity to flow into the wider transmission network.
Find more detailed information in our Need Case document.
What exactly are you proposing?
The Denny to Wishaw Network Upgrade Project includes new infrastructure and some changes and reinforcements to existing infrastructure. Please see The Proposal page on this website for full details.
How much will the project cost?
It is early days and at this point we are unable to cost the project fully. This will happen when we have a definite proposal.
Who will pay for this project?
The cost of investment in the electricity system is partly borne by consumers through electricity bills, so we work hard to be economic and efficient in the way we maintain and grow the network.
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. Find out more about Ofgem.
Who gives you permission to construct new overhead lines?
An application for consent under Section 37 of the Electricity Act 1989 to install the proposed overhead lines will be submitted to the Scottish Government Energy Consents Unit. As such, Scottish Ministers will make the final decision as to whether or not it is granted.
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 or enjoy leisure time in the area.
Established guidelines for routeing transmission overhead lines are in place, 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 the Approach to Routeing and Environmental Impact Assessment document, which is available to view on our Preferred Route page.
You can find detailed information specific to the routeing of the proposed new Bonnybridge to Glenmavis overhead line in the Routeing and Consultation Document, and the Preferred Route Option – Update Report which explains how the original proposals have been modified since 2021. Please see the Project Document page.
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.
A new ‘tee-in’ section will be created at this point, allowing the existing XX overhead line to move away from residential properties at Grantown Gardens and Eden Court.
Please see the Preferred Route map for more detail.
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 will become duller in appearance over time.
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 is the proven choice for the bulk transmission of electricity throughout the world based on economy and reliability.
SP Energy Networks (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.
What is involved in uprating overhead lines from 275kV to 400kV?
When uprating (increasing the capacity) overhead lines, we usually need to replace the conductors (wires), and the insulators from which they are suspended.
We do not usually need to replace the existing L8 steel towers (pylons) as they are designed to carry circuits up to 400kV. We survey the foundations of each tower to decide whether any work is required.
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. This will also be the method of lifting the new insulators into position.
Following commissioning of the overhead line, all equipment and temporary access/storage areas will be removed with the land being reinstated to its former use/condition.
How are you consulting local people?
We first consulted on our proposals in 2021. Since then we have updated the plans and during January and February 2025, we will consult on the revised proposals.
You can find full details on the Have Your Say page.
Are you consulting landowners?
Yes. Owners and occupiers of land that might be affected by the preferred route, overhead line uprating or substation extension proposals will be contacted. If you believe that your land may be affected and you have not yet heard from us, please get in touch.
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 still continues to seek greater clarity; however, the balance of scientific evidence to date suggests that EMFs do not cause disease.
For more information, please see the 'EMF - The Facts' leaflet available in the Project Documents page.