Here you’ll find answers to some of the most frequently asked questions about the Bramford to Twinstead Reinforcement. We hope they'll answer your questions and will continue to update them as our work progresses. If your question is not listed below, get in touch with the team by emailing [email protected], by calling 0808 196 1515, or by writing to Freepost B TO T REINFORCEMENT.
Bramford to Twinstead is a consented electricity transmission reinforcement between Bramford substation, which is to the west of Ipswich in Suffolk and Twinstead Tee, to the south of Sudbury in Essex.
The project will involve constructing approximately18 km of new 400 KV overhead line and approximately 11 km of 400 kV underground cable, along with a new substation at Butler’s Wood and associated works. Strengthening the network here is vital in order to transport more cleaner and greener power from where it is generated to where it is needed, supporting the UK’s drive towards Net Zero.
At present, there are three sets of 400 kV overhead line carrying electricity generated elsewhere in East Anglia into Bramford substation (one from Norwich and two from Sizewell). However, there is only one 400 kV overhead line carrying power west of Bramford and out of the region.
With new offshore wind and nuclear generation, plus greater interconnection with countries across the North Sea being proposed, there will be a huge increase in the amount of renewable and low carbon electricity generation connecting along the East Coast in the years ahead.
While the existing high voltage electricity network in East Anglia has been sufficient until today, it doesn’t have the capability needed to reliably transport all the new energy that will be connected by 2030.
Building a new overhead line and underground cable route between Bramford and Twinstead will resolve a capacity bottleneck, helping to connect more cleaner, greener electricity with homes and businesses across the country.
When developing proposals for new infrastructure projects, National Grid has a duty under the Electricity Act 1989 to do so in a manner that is efficient, coordinated and economical, whilst having regard to people and places.
The national policy statement (NPS) which covers building electricity networks infrastructure (EN-5) states that the Government expects overhead lines will often be appropriate. It does, however, recognise that there will be cases where this is not so, such as at particularly sensitive locations where potential adverse landscape and visual impacts of an overhead line may make it unacceptable in planning terms.
National Grid’s duties and obligations include balancing the need to be economic and efficient, which includes keeping costs down in the interests of the bill-paying consumers, with a duty to have regard to preserving amenity, which includes the natural environment, cultural heritage, landscape and visual quality.
This project will include the use of underground cables within the Dedham Vale National Landscape and an area of the Stour Valley.
We considered a range of options when developing our proposals, including both fully overhead and fully underground options. The cost of these different options (as calculated in 2021) is set out below. Since this information was prepared, market and material costs have changed.
| Option | Description | 2021 capital cost |
|---|---|---|
| Proposed option (predominantly overhead line with underground cables in Dedham Vale National Landscape and Stour Valley Project area) | Substations, overhead line, 2 x underground cable sections in Dedham Vale National Landscape and Stour Valley Project area, 4 x cable sealing end compounds | £363m |
| Predominantly overhead line with underground cables in Dedham Vale National Landscape only | As proposed option, apart from overhead line in Stour Valley Project area instead of underground cable and 2 x cable sealing end compounds | £245m |
| Predominantly overhead line with underground cables in Stour Valley Project area only | As proposed option, apart from overhead line in Dedham Vale National Landscape instead of underground cable and 2 x cable sealing end compounds | £256m |
| Entirely overhead line | Substations, overhead line for whole route | £142m |
| Entirely underground cable | Substations, underground cable for whole route | £694m |
For more information, please see the Project development options report (2021).
UK Power Networks (UKPN) owns and operates the regional distribution network, which makes up the 132 kV and lower voltage wires and cables that take power from National Grid’s substations and deliver it to homes and businesses, in the region.
National Grid has agreed with UKPN that it will remove the existing 132 kV overhead line between Burstall Bridge and the diamond crossing near Twinstead Tee. The removal of the 132 kV overhead line will allow the new 400 kV overhead line to be aligned along this route for the most part.
The stretch of existing 132 kV overhead line between the diamond crossing and the grid supply point substation is not owned or controlled by National Grid. It is owned and operated by UK Power Networks (UKPN). The removal of this section of overhead line is not required for the route of the new 400kV overhead line.
The grid supply point (GSP) substation at Butler’s Wood is expected to become operational between 2025 and 2026.
The pylons are designed to have a minimum lifespan of 40 years, subject to annual inspection. Refurbishment could extend the lifespan of pylons.
We appreciate the Government’s guidance on community benefits, as we believe communities should be rewarded for hosting new transmission infrastructure that supports cleaner and more affordable power. This guidance provides a clear framework for us to collaborate with communities and deliver meaningful social and economic benefits through strategic investment.
We are dedicated to working with Ofgem, industry partners, and local communities to ensure these benefits are delivered fairly, fostering positive change for those integral to our electricity network. Additionally, the Government has announced plans for a bill discount scheme for nearby households, and we will continue to engage with them as more details become available.
Government has announced plans for both ‘wider benefits’, in the form of community benefit funds, and direct benefits, in the form of a bill discount scheme.
The guidance for delivering community funds is designed to deliver for the communities and areas that are hosting new transmission infrastructure. In line with this, we will invest in community-led initiatives that focus on creating lasting social, environmental and economic benefits for local communities and wider regions.
Government has also announced its plans to introduce a bill discount scheme for households within 500 metres of new infrastructure, which it proposes to introduce through the Planning and Infrastructure Bill. This is evolving government policy. Government expects this scheme to be in place by 2026 and we will share further details as they emerge.
Yes, the Bramford to Twinstead Reinforcement is essential to supporting growth in clean, green energy from North Sea offshore wind. We will all benefit from that clean, green energy, and some will be consumed in East Anglia.
Whilst the existing transmission network can accommodate the current levels of energy generated in the east of England, in the future the network between Bramford and Twinstead will start to act as a bottleneck. If we don’t reinforce the network, this will restrict the amount of low carbon and renewable energy that can be transported across the country. Upgrading the network in this area is therefore vital to the delivery of cleaner, greener electricity and maintaining a reliable grid.
During the pre-application process, we undertook an Environmental Impact Assessment (EIA) and produced a detailed Environmental Statement (ES) which we submitted to the Planning Inspectorate with our application for development consent. This work started back in 2009 and helped to influence the routing and alignment of the route. Both the EIA and ES included a number of baseline studies which told us about the baseline environment within the area and this factored into our design and decision making process, in order to avoid and reduce impacts on the environment.
Once the new overhead line infrastructure has been constructed, we will carry out any additional work required to reinstate the work area. This includes landscaping works and planting in new areas to help screen the new infrastructure from sensitive receptors. To read more about this, please see our Construction environmental management plan (CEMP) on the Planning Inspectorate website here.
The term biodiversity net gain means an overall increase in natural habitats and wildlife, benefiting the environment.
National Grid will value nature and will protect and enhance it where possible using ‘natural capital’ and ‘net gain’ principles. National Grid has made a commitment to deliver a 10% biodiversity net gain on this project. This means that the habitat value for wildlife will be increased by around 10 per cent once the reinforcement is complete, compared to what currently exists. National Grid is working with appointed technical specialists, environmental organisations and landowners to identify potential opportunities for delivering environmental gains.
Electromagnetic fields (EMFs) are produced by voltage and magnetic fields by current flowing through a conductor. Overhead lines are a source of two fields: the electric field (produced by the voltage) and the magnetic field (produced by the current). Underground cables eliminate the electric field altogether as it is screened out by the sheath around the cable, but they still produce magnetic fields.
Background EMFs are present in most homes. They come from the house wiring, electrical appliances and the low-voltage distribution cables that carry electricity along streets.
We take these concerns seriously and want to keep the public, our contractors and employees safe. We ensure all of our existing and proposed equipment, including those on this project, comply with independent safety guidelines set to protect us all against EMF exposure. After decades of research, the weight of evidence is against there being any health risks of EMFs below the guideline limits.
For further information on EMFs, emfs.info. If you would prefer to talk about your concerns, please do not hesitate to call the EMF helpline on 0845 702 3270 or email [email protected].
At National Grid, all of our equipment is designed to comply with the Government guidelines and policies for electromagnetic fields. National Grid fully recognises people’s concerns and takes this issue very seriously. National Grid relies on authoritative and independent scientific organisations such as the World Health Organization (WHO) and the UK Health Protection Agency (HPA) to review the worldwide body of scientific evidence on EMFs and health.
We ensure our network meets independent safety standards for EMFs, including the exposure limits set by the HPA and adopted by the Government. For more information, visit emfs.info.
High-voltage underground cables produce magnetic fields in the same way that overhead lines do, although the fields produced by cables fall more quickly with distance as you move away than for overhead lines. Directly above an underground cable there will often be a higher magnetic field than will be found under an equivalent overhead line. Irrespective of the technology used, National Grid will always ensure that all of its equipment is designed to comply with any appropriate safety standards i.e. the exposure limits advised by Public Health England and adopted by Government.
A Construction Traffic Management Plan was developed during our pre-application consultation with the highway authorities along the route. It sets out which routes we are allowed to use and steps to minimise disruption to local communities.
We will provide clear signage to make sure our construction traffic uses the agreed route and stays within the speed limit for construction traffic. We will emphasise to our employees and contractors the special care that they need to take when driving to and from the areas we are working in.
As part of our Environmental Statement (ES), we investigated the likely noise impact to local residents during construction.
This assessment identified areas where there could be the potential for significant noise affects. In these areas, we will ensure that there is additional mitigation in place such as noise barriers to reduce noise during construction.
Further details of this mitigation are set out in the Outline Construction Environmental Management Plan submitted with the application. We will continue to work with local residents in areas with significant noise impact to mitigate against this.
To read more about this topic, please see Chapter 14 of our Environmental Statement on the Planning Inspectorate's website here.
For the safety of members of the public and our contractors we will need to close some public rights of way and roads temporarily to ensure that construction works can take place safely. We will always seek to provide diversions and keep any closures as short as possible. The closures and any required diversions will be agreed with the local authorities and will be clearly communicated to local people.
A trenchless crossing is a method of installing underground pipelines and cables without digging open trenches. One example of a trenchless crossing is horizontal directional drilling, which involves the use of a directional drilling machine to accurately drill along the chosen bore path and install the required cable without impacting above ground features.
Cable sealing end compounds are where high-voltage underground cables join onto an overhead line. The transition from one to the other requires termination points, known as sealing end compounds.
Normal working hours are between 7am and 7pm Monday to Friday, and between 8am and 5pm at weekends and on public holidays.
The core working hours exclude start up and close down activities, which can take place up to one hour either side of the core working hours.
Construction of the Bramford to Twinstead Reinforcement is expected to commence in mid-2025. Our main works contractor, Balfour Beatty, is currently completing some pre-construction and enabling works such as surveys and archaeology assessments.
We expect construction to be completed by 2029, with reinstatement works continuing into 2030.
In October 2022, National Grid’s planning application for a new grid supply point (GSP) substation at Butler’s Wood was approved by Braintree District Council. As a result, construction of the GSP substation commenced in 2024.
Contact the team
If you have any questions or comments about the Bramford to Twinstead Reinforcement, you can get in touch by emailing [email protected], by calling 0808 196 1515, or by writing to Freepost B TO T REINFORCEMENT.
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