Here you’ll find answers to some of the most frequently asked questions about Bramford to Twinstead.
We hope they answer your questions and we will continue to update them as our work progresses. If your question is not listed below, get in touch with the team using the details provided on the Contact us page.
National Grid Electricity Transmission, owns, builds and maintains the high-voltage electricity transmission network in England and Wales. In England and Wales, the high voltage network operates primarily at 400,000 volts (400 kV) and 275,000 volts (275 kV).
National Grid Electricity Transmission is part of the National Grid plc, which is made up of separate legal entities. The other part of National Grid is:
- National Grid Ventures is the competitive division of National Grid plc. It develops, operates and invests in energy projects, technologies and partnerships to accelerate the development of our clean energy future.
Generators
Generators produce electricity that we use in our homes and businesses from renewable or more traditional fuel sources.
Electricity generators trade the electricity they make to electricity suppliers. Electricity is also traded between neighbouring countries using interconnectors.
Suppliers
Suppliers buy the electricity in the wholesale market from electricity generators and supply to homes and businesses (end customers). The electricity supplier is the company you pay your electricity bill to.
We are regulated by Ofgem, the energy regulator. Ofgem has established price control mechanisms to ensure that the investment required to maintain a reliable and secure network is delivered at a fair price for consumers.
Our shares are listed on the London Stock Exchange and as such, we are also regulated by the Financial Services Authority in the UK.
This is set by the government as a whole and specifically by the ministerial department with responsibility for energy and clean growth, the Department for Business, Energy & Industrial Strategy (BEIS).
In April 2022, the Government published the British Energy Security Strategy. A key part of that announcement was the ambition to reach 50GW of offshore wind by 2030. This follows other government policy announcements including the ‘Ten Point Plan for a Green Industrial Revolution’ in December 2020, and energy white paper entitled ‘Powering our Net Zero Future’.
Through these suites of documents, the government has set clear goals to deliver net zero by 2050 and 50GW of offshore wind by 2030.
Offshore wind power takes energy from the force of the winds out at sea and converts it into the energy we all use.
The growth in offshore wind is largely driven by government policy, which is to deliver 50GW of offshore wind by 2030, a significant uplift in the amount of offshore wind operating now. As a result, it will require major development of both the onshore and offshore electricity networks to accommodate it.
The National Energy System Operator, NESO, leads an annual process looking at how the electricity transmission network might need to adapt to likely changes to where the electricity we all use will come from. That starts with stakeholder discussions and analysis about potential Future Energy Scenarios which are published each summer.
The National Energy System Operator takes those different scenarios and looks at what they might mean for the transmission network over the next ten years, publishing an Electricity Ten Year Statement each November. The transmission network owners, including National Grid Electricity Transmission, respond to the issues outlined in the Electricity Ten Year Statement with suggestions as to how those can be addressed.
Then in January each year, the National Energy System Operator publishes a document known as the Network Options Assessment (NOA), which outlines their recommendations as to which reinforcement projects should be taken forward during the coming year to meet the future network requirements.
The Bramford to Twinstead reinforcement has been identified as a critical reinforcement in all future energy scenarios and has appeared consecutively in the NOA.
Before building any new electricity lines, we look first and foremost at whether we can deliver more capability by upgrading the existing network.
We have already upgraded the existing 400kV lines between Bramford and Twinstead to carry more electricity and will continue this work on the transmission network to Rayleigh. We will also be upgrading the lines between Pelham and Twinstead and Twinstead to Tilbury via Braintree and Rayleigh, and between Norwich and Bramford.
We will also be increasing the voltage of the electricity line running from Waltham Cross south into London to carry more electricity into the capital by that route. In addition, we will be installing new power control devices at Burwell, Pelham and Rye House to move more electricity to where it’s needed via that route.
These improvements will increase the transfer capability of the transmission network here in East Anglia from 3.5GW to just under 6GW, but that still doesn’t deliver the network capability that is needed in the region by the end of this decade.
The National System Operator,, has explained that the Bramford to Twinstead reinforcement is critical in all future energy scenarios. This is set out in the Network Options Assessment (NOA). In addition to Bramford to Twinstead there are also other reinforcements planned to increase the overall capacity of the network in East Anglia, this includes offshore cables between East Anglia and Kent.
The reinforcement between Bramford and Twinstead is designed to address a bottleneck on the network, which has to be addressed.
No, the refreshed NOA (2021/22) published after initial HDN work shows Bramford to Twinstead (described as BTNO) needs to be in place by 2028 to address a bottleneck on the network.
Reinforcing this part of the network is needed to resolve a bottleneck. At present, there are three double circuit overhead lines carrying the electricity generated elsewhere into Bramford (one from Norwich to the north and two from Sizewell to the east), but only one overhead line carrying power west of Bramford out of the region.
With substantial new sources of electricity connecting in the region by the end of the decade, the existing overhead lines carrying current out of the region to the west would be overloaded without the reinforcement.
Installing a new line (two circuits) between Bramford and Twinstead, allows the network to be reconfigured to create two separate double circuit routes that will avoid overloading the existing circuits and will provide flexibility and agility in the way the network interacts.
The Bramford to Twinstead reinforcement is a new 400,000 volt (400kV) electricity double circuit between Bramford substation, west of Ipswich in Suffolk and Twinstead, south of Sudbury in Essex.
The route is shown on the overview map, but for more information, please see the detailed mapping on our project website: https://www.nationalgrid.com/electricity-transmission/network-and-infrastructure/bramford-twinstead
The Bramford to Twinstead reinforcement is a new 400,000 volt (400kV) electricity double circuit between Bramford substation, west of Ipswich in Suffolk and Twinstead, south of Sudbury in Essex.
The route is shown on the overview map, but for more information, please see the detailed mapping on our project website: https://www.nationalgrid.com/electricity-transmission/network-and-infrastructure/bramford-twinstead
The feedback received from our non-statutory consultation in spring 2021 has helped to shape and guide the development of the reinforcement. As a result of feedback, we made the following changes:
- confirming undergrounding in two sections of the draft alignment: in and near to the Dedham Vale Area of Outstanding Natural Beauty (AONB) and parts of the Stour Valley
- proposing a greater amount of undergrounding overall
- changing the route and configuration of pylons around Bramford Substation
- considering a potential option for routeing the overhead line at Hintlesham Woods
- proposing an alternative route of undergrounding in the Dedham Vale AONB at Dollops Wood, resulting in the reduction of transmission lines in the AONB by around 1km
- proposing an alternative route of undergrounding in the Stour Valley
- proposing new sites for three of the proposed cable sealing end compounds
- proposing to remove more of the existing 400kV overhead line running south from Twinstead Tee and the diamond crossing
- proposing to build more full tension gantries at cable sealing end compounds to reduce the overall number of terminal pylons along the route.
National Grid have carefully considered all consultation feedback received during statutory consultation. Full details of the consultation process, feedback received and outcomes will be reported on in our Consultation Report, which will form part of our submission for development consent.
In the Stour Valley, feedback received expressed concerns about the proximity of construction activities to Alphamstone, as well as concerns around the impact on sensitive parts of the environment and footpaths. As a result, we have looked again at our plans for the route of undergrounding and are proposing to change to the route of underground cables between Moat Lane and the Stour Valley West cable sealing end compound.
National Grid have since made changes to the Stour Valley section and have undertaken a further targeted consultation on these changes.
We are required under the Electricity Act 1989 to find a balance, developing proposals that are efficient, coordinated and economical, and which have regard to people and places. Each network upgrade must be considered on its individual merits, as required in planning policy.
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, for example, at particularly sensitive locations, where potential adverse landscape and visual impacts of an overhead line may make it unacceptable in planning terms, taking account of the specific local environment and context.
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.
Our proposals include underground cable within the Dedham Vale AONB, and an area of the Stour Valley.
We are required under the Electricity Act 1989 to find a balance, developing proposals that are efficient, coordinated and economical, and which have regard to people and places. We must also be guided by the national policy statement (NPS) (EN-5) which states that the Government expects that fulfilling this need through the development of overhead lines will often be appropriate.
The costs for different options are provided in the table below. It should be noted that market and material costs have changed since 2013 and are likely to do so again before we reach construction, but based on analysis undertaken 2021, the capital cost estimates rounded to the nearest £m, are provided and continue to offer a basis for comparative assessment.
These figures were prepared to support the non-statutory consultation, further information is available in the Project Development Options Report (2021) available in our document library.
Trenchless crossing, otherwise known as horizontal directional drilling (HDD), is a method of installing underground pipelines and cables without digging open trenches. It 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.
UK Power Networks (UKPN) owns and operates the regional distribution network which makes up the 132kV and lower voltage wires and cables that take power from National Grid’s substations and deliver it to homes and businesses in the region.
As part of this reinforcement, National Grid has agreed with UKPN that it will remove the 132 kV overhead line between Burstall Bridge and the diamond crossing near Twinstead Tee. The removal of the 132kV overhead line will allow the new 400kV overhead line to be aligned along this route for the most part.
The stretch of existing 132kV 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.
Our proposal provides for the use of standard steel lattice pylons which are approximately 50m in height. Taller pylons may be required in some locations depending on the local topography and also to avoid sensitive features.
The current proposal entails approximately 50 new pylons (18km of new overhead line). The current proposal also stipulates that approximately 27km of existing 132kV and 400kV overhead lines will be removed along the same route.
The current proposal entails approximately 50 new pylons (18km of new overhead line). The current proposal also stipulates that approximately 27km of existing 132kV and 400kV overhead lines will be removed along the same route.
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.
Bramford substation is already operational - supplying the local area and connecting existing generation to the electricity transmission network.
The proposed grid supply point substation at Butler’s Wood could become operational between 2025 and 2026, depending on the outcomes of the planning process.
We expect the operation life of the GSP substation to be at least 40 years.
The pylons are designed to have a minimum lifespan of 40 years, subject to annual inspection.
Refurbishment could extend the lifespan of pylons.
The Environmental Impact Assessment (EIA) for the Bramford to Twinstead reinforcement will include a cumulative effects assessment, which will consider the cumulative effects of the reinforcement and other proposed developments. The cumulative effects assessment will be presented as part of the Environmental Statement (ES).
The cumulative effects assessment will be undertaken based on information available on other developments at the time of assessment.
Further information on how we selected which developments to include within the cumulative effects assessment can be found in the Preliminary Environmental Information Report 2022.
We know that our responsibility as a business goes beyond safely building new energy infrastructure to enable a cleaner, fairer and affordable future. We want to leave a lasting positive impact where we build our projects to help those areas and communities thrive and to support a sustainable future.
There are four key areas where we believe we can bring benefit to local communities and stakeholder groups who are hosting the infrastructure that supports the green energy transition:
- Natural Environment – we will build partnerships with environmental groups and NGOs where we can support initiatives that enhance the landscape, biodiversity and availability of green space within the areas we are constructing our projects.
- Net Zero – we will work collaboratively with local authorities and partner organisations to offer our expertise and support in delivering the net zero priorities for that region.
- Skills and employment – we will extend our Grid for Good programme to deliver training and skills development in the region that will ultimately deliver employment opportunities in the net zero industry. In addition to this, we will work with our suppliers to develop opportunities for local employment and to bring benefit to the local economy through our projects. We also work with schools and local authorities to encourage the next generation of engineers and help the long term unemployed develop new skills.
- Community Grant Programme - through our Community Grant Programme, charities and not-for-profit organisations can apply for a grant towards community-based initiatives that deliver social, economic and environmental benefits.
We hope, therefore, that both the offshore and onshore development needed to support the transition to a cleaner, greener future, can deliver sustainable, green growth and an economic ‘ripple effect’ that will continue for years.
Yes, the Bramford to Twinstead connection is essential to support the 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.
National Grid included an assessment on socio-economics, recreation and tourism within the 2021 Scoping Report. This concluded that the project was unlikely to have a significant effect on socio-economics and tourism and that it would be scoped out of the assessment as a standalone topic. The Planning Inspectorate agreed with this conclusion in their Scoping Opinion. Tourism will be considered, where applicable, within the cumulative effects assessment. Further details can be found in the Preliminary Environmental Information Report 2022.
As the UK looks to accelerate its economic recovery following the coronavirus pandemic, strategic infrastructure solutions such as those proposed along the east coast can help ensure that the UK continues to deliver strong, sustainable growth.
The Bramford to Twinstead reinforcement is one of the essential network reinforcements needed to deliver on the UK’s net zero target – without it, cleaner, greener energy generated offshore would not be able to be transported to homes and businesses across the country.
We are undertaking an Environmental Impact Assessment (EIA) for the reinforcement. This started back in 2009 and helped influence the routing and alignment studies. The EIA includes a number of baseline studies which tell us about the baseline environment within the area and this factors into our design and decision-making process, so that we seek to avoid and reduce impacts on the environment.
The term biodiversity net gain means increasing the amount of biodiversity in an area than currently exists.
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 (BNG) on this reinforcement. 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.
We are carrying out environmental surveys, including habitat surveys and protected species surveys. The results of these surveys will help inform the design and decision-making process as we finalise our plans for the reinforcement.
There are a number of designated and non-designated sites within the draft Order Limits. These include the nationally designated Hintlesham Woods, which is a Site of Special Scientific Interest. It is designated for its ancient semi-natural woodland habitat and associated bird communities. There are also county and local wildlife sites.
We have identified some protected and priority species within and adjacent to the Order Limits. These include bats; badger; brown hare; dormouse; water vole; otter; reptiles; amphibians, including great crested newts; European eel and a range of bird species.
The Environmental Impact Assessment will consider any potential impacts to habitats and species and any measures required to mitigate or reduce the effects. The results of the assessment will be presented within the Environmental Statement, which will be submitted with the application for development consent. The preliminary results of the assessment can be found in the Preliminary Environmental Information Report published as part of the statutory consultation material.
A suite of surveys were undertaken before the project was paused in 2013. We began to update these surveys in 2021 to get an up to date understanding of the baseline environment. The baseline surveys will continue into 2022 and we will continue to engage with environmental organisations such as Natural England and the Environment Agency. The results of the surveys will be presented within the Environmental Statement, which will be submitted with the application for development consent.
The preliminary results of the surveys to date can be found in the Preliminary Environmental Information Report published as part of the statutory consultation material. We have reviewed these again in light of the changes we have made which can be found in Appendix A of the Consultation Summary Document.
EMFs are electric and magnetic fields. Electric fields are voltage and magnetic fields produced 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.
All equipment that generates, distributes or uses electricity produces EMFs, and these also occur naturally. 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.
All overhead lines produce EMFs, and these tend to be highest directly under an overhead line and decrease to the sides at increasing distance. Underground cables produce no external electric fields, and the magnetic field falls more rapidly, falling to the levels typically found in UK homes within around 20m compared to around 150m for an overhead line. Substations and cable sealing end compounds do not produce significant EMFs outside their boundaries.
At National Grid, all of our equipment is designed to comply with the Government Guidelines and policies for Electromagnetic Fields (EMFs). 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.
As far as EMFs are concerned, we discharge that responsibility by ensuring that our network complies with any appropriate independent safety standards, i.e. the exposure limits advised by the HPA and adopted by Government. For further information visit www.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.
National Grid takes the issue of health very seriously. We believe it is right that the decision on what is acceptable or not is made independently of industry. Accordingly, we design all our equipment, overhead lines, cables and substations to comply with Public Health England’s recommended exposure guidelines. A vast amount of research has been done into the possibility of health effects, without establishing any risks below these levels.
The EIA includes an assessment on traffic and transport and the preliminary results are presented within the PEI Report. This shows that the project would not generate large numbers of vehicles during construction. We are also looking at creating a haul route along the Order Limits, which would mean construction vehicles could track along the working corridor which would reduce construction traffic and the number of access points required onto the local road network.
An Outline Construction Traffic Management Plan will be prepared as part of the application for Development Consent. This will set out the good practice measures proposed to further reduce impacts on the local road network and traffic. It will include measures to provide clear signage to make sure our construction traffic uses the agreed routes, with construction workers using public transport and car sharing where practicable. We 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.
The EIA will include a noise assessment, which will identify areas where there could be the potential for significant noise effects. In these areas, there may be the need for mitigation such as noise barriers to reduce noise during construction. Further details will be set out within the Outline Construction Environmental Management Plan submitted with the application for development consent.
A Construction Traffic Management Plan will be developed in consultation with the Highway Authorities along the route. It will set out which routes we are allowed to use and steps to minimise disruption to local communities. When it comes to construction, 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 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.
No. The work will have no impact on your electricity supply. The work that we need to carry out is on part of the national transmission system and will have no direct effect on homes, businesses, schools and other premises in the local area.
You would see our traffic management signs and vehicles on the roads where we need to access the works.
Our vehicles and equipment would be in the fields along the route of the new connection. There are likely to be excavators stripping soil and digging the trenches for the cables. There would also be cranes lifting the pylons and overhead lines in place. There would also be HGVs transporting materials around the working area.
Normal working hours are expected to be between 7am and 7pm Monday to Friday and between 8am and 5pm at weekends and on Bank Holidays. It's anticipated that the exact hours of construction will be specified and controlled through the Development Consent Order.
For the safety of members of the public and our contractors we may need to close some public rights of way and roads temporarily. We will seek to provide alternative diversions and to keep the closure as short as practicable. The closures and any required diversions will be agreed with the local authorities and clearly communicated to local people.
We will contact landowners and occupiers to arrange access for environmental surveys to help inform how we develop our proposals.
Wherever we need to carry out surveys on private land, a member of our Land team or our agents will contact landowners and occupiers to discuss the type of surveys, the timing and duration before we start.
At our last consultation, feedback highlighted concerns about the suitability of the local road network for large construction vehicles. Alongside this, several changes, modifications or restrictions may be required to the local road network to accommodate larger construction vehicles. A haul road may reduce the need to change and modify existing roads.
Although we are now considering building a temporary construction haul road, smaller construction traffic will still use local roads as part of the construction of the reinforcement.
We expect the haul road to be in place for up to 3 years to facilitate the construction of this part of the reinforcement.
The new temporary haul road would use existing gaps in field boundaries and hedgerows where practicable, in order to reduce effects. The construction of a temporary haul road would cause some temporary loss to habitats. However it has been designed to minimise this where possible and all habitats would be reinstated post construction.
The new temporary haul road occupies mostly arable land which will be reinstated to its existing use post construction.
Feedback received from stakeholders expressed concerns about the proximity of construction activities to Alphamstone, as well as concerns around the impact on sensitive parts of the environment and footpaths.
As a result, we looked again at the route of undergrounding and undertook further technical assessments of other options, which highlighted the opportunity to in install cables on a different route of undergrounding, using a different construction method.
We would like to hear what you think about this change and encourage you to give your feedback.
A number of different scenarios for construction phasing of the project are currently under consideration. Certain components of the project that could fall under alternative planning regimes may be consented and constructed earlier than would be the case if those parts of the project were only within the application for development consent.
We expect the construction period to be up to six years between 2022 and 2030, with differing potential start dates, depending on the different consenting approaches currently under consideration.
While the phasing of the programme is yet to be confirmed, one of the first phases would be the construction of the GSP substation. This would need to occur prior to the removal of the existing 132kV overhead line. The duration of the civil construction activities associated with the GSP substation would take approximately six to eight months within an 18-month period allowing for works that can only be undertaken in planned electrical outages. The phases that follow construction and commissioning of the GSP substation would take approximately four years.
Nationally Significant Infrastructure Projects (NSIPs) are major infrastructure developments in England and Wales. These include projects such as power plants, large renewable energy projects, new airports, airport extensions and major road projects.
A Development Consent Order (DCO) application to undertake an NSIP is made to the Planning Inspectorate, who will consider the application and make a recommendation to the Secretary of State. The minister will decide on whether development consent should be granted for the proposed project.
In addition to development consent, a DCO can contain powers for compulsory acquisition, the need for which will be considered as part of the examination of the DCO.
The process has six key stages:
- pre-application
- acceptance
- pre-examination
- examination
- decision
- post-decision
On receipt of an application for development consent, the Planning Inspectorate has 28 days to decide whether to accept it or not. There is then usually a period of around 3-4 months before the examination starts, and then a period of six months for the Planning Inspectorate to examine an application and three months for the Planning Inspectorate to make its recommendation to the Secretary of State. The Secretary of State has a further period of three months in which to issue a decision. The whole process from the date of application should take about 16 months. For more information visit the Planning Inspectorate website.
Under the process to apply for a Development Consent Order (DCO), we are required to consult with people with an interest in the land within the draft Order Limits, people and stakeholders living in the vicinity of the development as well as other prescribed groups of consultees.
Residents can sign-up to receive project information via the consultation website. Alternatively, they can contact us via our community relations helpline or via email.
Our recent targeted consultation on changes to our plans for the Bramford to Twinstead Reinforcement has now closed.
In September 2024, the Secretary of State for Energy Security and Net Zero granted development consent for the Bramford to Twinstead Reinforcement.
In anticipation of the Secretary of State’s decision, pre-construction survey work is already underway at various locations along the project route, prior to the planned start of major construction activity in the first half of 2025.
We will share more information on our approach to construction works, including how we will communicate such activity, in the coming months. Meanwhile, construction work is continuing at the grid supply point (GSP) substation site between Butler’s Wood and Waldegrave Wood, which already has planning permission via a separate application made under the Town and Country Planning Act.
Contact the team
If you have any questions or comments about Bramford to Twinstead, please get in touch by emailing [email protected], by calling 0808 196 1515, or by writing Freepost B TO T Reinforcement.
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