Frequently asked questions

Here you’ll find answers to some of the most frequently asked questions about Sea Link.

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.

About National Grid

Who is National Grid?

National Grid sits at the heart of Britain’s energy system, connecting millions of people and businesses to the energy they use every day. We bring energy to life – in the heat, light and power we bring to our customer’s homes and businesses; in the way that we support our communities and help them to grow; and in the way we show up in the world. It is our vision to be at the heart of a clean, fair and affordable energy future. 

Find out more about National Grid. 

Who is National Grid Electricity Transmission?

National Grid Electricity Transmission owns, builds and maintains the high-voltage electricity transmission network in England and Wales. This network operates primarily at 400,000 volts and 275,000 volts. 

It is NGET that is developing plans for Sea Link. 

Find out more about National Grid Electricity Transmission. 

Who is the ESO?

The ESO is the Electricity System Operator for Great Britain. The ESO makes sure we all have the essential energy we need by ensuring supply meets demand every second of every day. 

Generators of electricity apply to the ESO when they wish to connect to the high-voltage electricity network and the ESO leads the work to consider how the network may need to evolve to deliver a cleaner greener future. In April 2019, the ESO became a legally separate business within the National Grid Group and is regulated independently by Ofgem. 

Find out more about the ESO. 

Who is National Grid Ventures?

National Grid Ventures is a division of National Grid plc that operates outside of National Grid’s core regulated businesses in the UK and US. National Grid Ventures develops and operates energy projects, technologies, and partnerships to make energy cleaner, more secure and more affordable for consumers.    

National Grid Ventures’ diverse portfolio of low carbon and renewable energy businesses includes subsea electricity interconnectors in the UK, and transmission, battery storage, wind and solar power in the US. 

Find out more about National Grid Ventures. 

What is The Great Grid Upgrade?

The Great Grid Upgrade is the largest overhaul of the grid in generations – making sure that renewable energy can move from where it’s generated to where it’s needed, enabling us all to power the things we love with cleaner energy. Sea Link is one of several projects that is part of this upgrade. 

Find out more about The Great Grid Upgrade  

How does National Grid fund its projects, and how does it re-invest its profits? 

National Grid funds new projects such as power transmission lines through an agreement with Ofgem. They pay upfront costs, which are gradually passed to customers over 40 years, easing the burden on electricity bills. Investors support National Grid, expecting profits and eventual repayment. This spreads the investment cost over years, avoiding sudden bill spikes. 

If National Grid decides to build new infrastructure for a connection, does it pay for it or does the company wanting to make the connection pay or can it be a combination? 

National Grid charges generators and supply companies for system connection and usage, approved by Ofgem. National Grid covers initial connection costs, which are later passed to consumers. During construction, the cost burden is shared among generating companies benefiting from it. 

Are higher energy bills needed to pay for Sea Link, which features more expensive technology such as subsea cable rather than cheaper overhead lines?  

The bill you receive from your energy supplier is made up of a number of separate charges. Some of these charges are based on the different stages through which electricity makes its way from the producers to your home. In 2022/23, £19.70 of the annual household bill was for operating, maintaining and investing in the national electricity transmission system. This charge is set by the energy regulator Ofgem and is not affected by the price of energy. Around £100 of your annual household energy bill goes to the local distributor to build, maintain and invest in the local electricity network.   

Find out more about how your energy bill is calculated here. 


About Sea Link

What is Sea Link?

National Grid Electricity Transmission is proposing to reinforce the network between Suffolk and Kent via a new, primarily offshore, 2 gigawatt high voltage direct current link – known as Sea Link. Sea Link has been designed to increase the capability of the network to carry low-carbon and renewable energy from where it is generated to homes and businesses across the country. 

Why is Sea Link needed in Suffolk and Kent?

Much of the existing transmission network in East Anglia and the south east was built in the 1960s and does not have sufficient capacity to carry the renewable and low carbon power that is forecasted to connect to the network in the future. This includes offshore wind, interconnectors and nuclear power. 

The four main reasons we need to build Sea Link include:  

  1. the existing transmission network was not designed to transport electricity from where we increasingly now generate it (largely offshore) 

  2. the growth in offshore wind, interconnectors and nuclear power means that more electricity will be generated in the years ahead than the current network is able to securely and reliably transport 

  3. as a country, electricity demand is forecasted to at least double by 2050, increasing the amount of energy we need to transport to homes and businesses 

  4. upgrading the existing network as it is today (such as through replacing cables to carry more power) will not be enough to carry the amount of future power whilst operating to required standards. 

Sea Link is just one of several electricity network reinforcements that are needed to ensure the electricity transmission network is fit for the future. 

What's happened so far?

Between October and December 2022, we gathered feedback through a non-statutory consultation involving local communities and stakeholders. Following this consultation, we refined our project proposals based on this feedback, input from specialists, environmental and engineering surveys, and ongoing design development. 

Between 24 October and 18 December 2023 we presented our developed plans for Sea Link for your feedback. Following the close of this consultation, we are considering all of the consultation responses submitted.

What are you consulting on?

Between 24 October and 18 December we sought your  views on our developed plans for Sea Link, including: 

  • the proposed Friston substation 

  • the proposed route of the high voltage alternating current (HVAC) underground cable between the proposed Friston substation and the Saxmundham converter station 

  • the proposed Saxmunham converter station  

  • the proposed onshore route of the high voltage direct current (HVDC) underground cable, from converter station to landfall 

  • the proposed landfall location in Suffolk 

  • the proposed offshore route of the HVDC cable, from landfall to landfall 

  • the proposed landfall location in Kent 

  • the proposed route of the HVDC underground cable, from landfall to converter station 

  • the proposed Minster converter station and substation 

  • the proposed HVAC overhead line between the Minster converter station and substation, and the Canterbury to Richborough 400 kV overhead line 

  • our construction methodology 

  • the likely environmental effects arising from the proposed Project 

  • opportunities for biodiversity net gain and mitigation of potential environmental impacts.

Why have you not considered brownfield sites and/or other National Grid substations?

Sea Link is designed to meet a specific need to reinforce the electricity transmission network between East Anglia and the south-east of England. As we have developed our proposals, we have considered a number of strategic options that could provide the reinforcement required. Our work identified that a connection between East Anglia and Richborough in Kent provided this reinforcement, as it resolves capacity requirements within the electricity network.  

As part of the development of the plans for Sea Link, we assessed a variety of potential areas for infrastructure, including brownfield sites. The sites we assessed were within a 5 km radius of the connection onto the network to maximise efficiency, reduce energy loss and minimise additional electrical infrastructure (thereby lessening the potential impact on the local environment). 

Any brownfield sites within the search area are too small to accommodate the infrastructure we would need to deliver Sea Link.  We are however, able to connect into the proposed Friston substation in Suffolk, rather than building a new one. Clarifications on our decisions to discount brownfield sites will be outlined in our non-statutory feedback report, which will be publicly available as we begin our statutory consultation. 

Why is Sea Link not connecting to Bradwell?

As part of the development of our proposals, we have undertaken several studies to confirm where in East Anglia would be most suitable to connect into. These studies determined that connecting in the Sizewell area is the preferred solution for Sea Link. 

Connecting into Bradwell does not reinforce the electricity network in the place where it is needed. Notwithstanding that, there are other factors like the need for additional overhead line infrastructure, coupled with other technical and environmental constraints which make connecting into Bradwell unsuitable.   

Why is Sea Link not connecting to Bramford?

Under the Electricity Act 1989, National Grid has a duty to bring forward proposals that are ‘economic, efficient and coordinated’. Connecting into Bramford substation rather than at Friston would require building over 30 km of additional transmission network infrastructure. It would also provide additional capacity between Sizewell and Bramford substation where it is not currently required. 

What is the project timeline?
Timeline graphic explaining the progress of the Sea Link project. The project is at 'October - December 2023 - statutory consultation'
What stage is the project in now?

We have recently finished our statutory consultation, which took place between October and December 2023. We are now considering all of the feedback submitted to this consultation.

When will construction work start and finish?

We anticipate construction will start in 2026 and should be complete around 2030 to make sure the link is in place and connected to the rest of the network by the end of 2030. Some reinstatement and landscaping works would continue into 2031.  

Local communities and the environment

How will Sea Link benefit the community?

We're dedicated to creating a positive impact in communities through infrastructure projects, emphasising social responsibility and equity via our Community Benefit Plan. 

The Community Benefit Plan is split into four distinct pillars, each comprising several initiatives and schemes. These pillars are:   

  • Grid for Nature - Develop green space for local and deprived communities to use and enjoy. Consists of the Woodland Strategy & Great British Bee Project initiatives, several regional/national partnerships, and green leases.    

  • Net Zero Heroes - Form strong local partnerships with stakeholders close to our projects and through our in-house expertise, to help them realise their own climate ambitions.    

  • Skills/STEM - Seek regional partnerships with suppliers to part fund the establishment of training centres and flexible training programmes to help give the next generation the skills they need to be part of the Net Zero Energy Workforce. Additionally, we will engage with schools and colleges through site visits, grants, and innovative targeted programmes that are aligned to the curriculum.   

  • Community Benefit - Funds community projects that provide social, economic, and environmental benefits to local communities, ensuring we leave behind a positive legacy.    

NGET's Community Benefit Plan aligns with National Grid’s Responsible Business Charter, emphasising impact in environment, communities, people, economy, and governance, shaping our strategic priorities with a focus on responsibility.  

What will be the cumulative effects of all these projects on the East Suffolk communities, and what are you proposing to do to mitigate and compensate for those effects?

Our proposals in Suffolk have been developed for Sea Link as a standalone project, but also include opportunities to co-locate infrastructure for up to two further projects at the converter station, along the cable corridors and at the landfall location. We are also committed to exploring how we can coordinate our construction activity with other developers, like Scottish Power Renewables and EDF.  We are also considering and assessing the potential for cumulative impacts arising from other projects as part of our ongoing Environmental Impact Assessment and we are seeking your views on our approach.   

National Grid is committed to being a good neighbour and we fund projects run by charities and community groups that meet local community needs by providing a range of social, economic and environmental benefits.  

Why can’t all three projects (Sea Link, LionLink and Nautilus) be considered together in a combined examination process?

There are several key differences between these projects that restrict the ability of all applications to be brought forward as on single DCO.  

  1. Sea Link is part of The Great Grid Upgrade and is an essential network reinforcement and standalone project 

  2. The projects are being promoted by different companies, with different project teams covering several different geographical locations who are at different stages. Making coordination into a singular DCO or examination unworkable given the need to deliver Sea Link by 2030 

  3. The businesses are separate legal entities and have different statutory duties

Will the impacts on the local community be permanent, or temporary during the construction period?

We work closely with local communities to make sure we minimise construction impacts as much as we can and support community initiatives in areas where we are working to deliver social, economic or environmental benefits. During construction we will need to do a range of temporary activities such as creating equipment storage areas, site offices, and road and public rights of way diversions will need to be implemented. Before we do this, we will prepare a construction management plan that will set out controls and measures to reduce our impact on the local community. We might still need permanent access rights for maintenance.  

How will Sea Link reinforcement contribute to the Government’s 2050 net zero targets for a sustainable future?

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 Sea Link Reinforcement Project is one of the essential network reinforcements needed to deliver on the UK’s net zero target – without it, low carbon, renewable energy generated offshore would not be able to be transported to homes and businesses across the country.Sea Link would help connect renewable sources of energy to homes and businesses helping to deliver 50 GW of offshore wind by 2030 and ultimately net zero. 

What are EMFs?

EMFs are electric and magnetic fields. Electric fields 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. 

Where do EMFs occur?

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. 

Will EMF from the Sea Link project affect my health?

Some people worry that Electromagnetic fields (EMFs) may have negative health effects. 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 visit our website, 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]. 

Have you considered the environmental impact?

We are rigorously assessing Sea Link's impact on designated sites and the environment, adhering to the "mitigation hierarchy" by avoiding, minimising, restoring, and offsetting impacts. Our efforts include micro-siting cables, using non-intrusive methods, and ensuring a 10% Biodiversity Net Gain, which means that the local environment will be left in a demonstrably and measurably more biodiverse state than prior to the commencement of the Project. This will be achieved by a range of measures, such as habitat creation and enhancement for protected species.  

We'll conduct a comprehensive environmental impact assessment, meeting legal requirements under the EIA Regulations. Stakeholders can comment on our Preliminary Environmental Information Report (PEIR), and when we submit our application for development consent, we will include the full Environmental Statement accounting for expert and public feedback received during consultation.  

What are National Grid’s net gain commitments?

All construction schemes have a target of delivering 10% Environmental Net Gain (which must include a minimum of 10% Biodiversity Net Gain). 

What counts as Biodiversity Net gain (BNG)?

Green Infrastructure (GI) features can contribute to a project's BNG calculations and there are a range of GI features that can be included, such as:

  • green roofs, green walls and Sustainable Drainage Systems (SuDS);

  • landscaping included within the Post-Development Plans.

It is possible to use sites delivering nutrient neutrality/ a suitable alternative natural greenspace (SANG)/Great Crested Newt habitat to also deliver net gain, on the basis that:  

  • delivery of the non-BNG outcomes can contribute to a point equivalent to no net loss of BNG but NOT beyond  

  • additional habitat features created or enhanced on the same land beyond those delivered for non-BNG outcomes ( addition) could take you into positive BNG territory.   

What are the options for National Grid to deliver Net Gain?

Onsite: Within the project’s development area  


  • land owned by the client  

  • land leased by the client  

Offsite: Use a financial contribution to offset impacts  

  • through discussions / agreements with the Local Planning Authority /Local Wildlife Trust  

  • through a Habitat Banking / Biodiversity Unit Provider  

  • through the use of Government Statutory Units (last resort)  

National Grid’s non-operational land can be used for offsite mitigation. 

The ‘offsite’ locations could be either a wildlife site or nature reserve and would meet the ‘ecologically desirable’ criteria. National Grid will implement a range of strategies to protect and improve known wildlife sites and nature reserves as well as creating new habitats where appropriate.  


Infrastructure and construction methods

What is a converter station?

A converter station houses the technology that converts electricity between alternating current (AC) and direct current (DC) and enables it to be transmitted over long distances. AC current is used in each country’s transmission system to power homes and businesses, while DC is used for sending electricity more efficiently over long distances.

What is a substation?

Substations house electrical equipment which enables the system operator to control the flow of electricity. These substations come in many sizes and configurations depending on the need. Substations are also key in helping to isolate and fix faults and allow maintenance to be undertaken safely on the electricity network. 

What is a cable joint bay?

Cable joint bays are needed at intervals of approximately 500 metres to 1,000 metres when constructing underground cables, to allow for individual sections of cable to be joined together. In areas where a cable joint bay is needed, a wider cable corridor may be required. 

What is a cable duct?

Cable ducts are sections of tubing where electricity cables are placed. 

What is a link box?

A link box is an above ground kiosk which allows inspection and maintenance of the cables. 

What is a transition joint bay?

Transition joint bays are used to connect an onshore cable to an offshore cable. These are generally around 10 to 15 metres in length, 5 metres in width (dependent on design requirements) and are located near the coast. 

What sort of construction methods will you be using?

We are proposing to use a range of construction methods for Sea Link. These include underground cable installation, which requires an area beyond the corridor, accommodating site compounds and material storage. Trenchless crossing which minimises surface interaction, reducing impact on wildlife and communities. Subsea cable installation, which involves precise surveys and specialised cable-laying vessels.  

What would a new overhead line look like?

Overhead electricity transmission lines typically involve building new steel lattice pylons to support the wires (conductors). The size, height, and spacing of pylons are determined by safety, topographical, operational, and environmental considerations. A typical 400 kV pylon is around 50 metres tall. 

What are draft order limits?

Draft order limits form the current anticipated boundary of the entire area within which Sea Link could take place. 

What are limits of deviation?

Limits of Deviation lie within the Draft Order Limits, they give us flexibility when constructing the project in case of unforeseen circumstances (such as unexpected environmental constraints), they allow us to move infrastructure within the Draft Order Limits. We would not need all of the land within the draft order limits, but permanent infrastructure could be installed within the Limits of Deviation. 

Has National Grid considered the effects on Suffolk’ and Kent’s tourism industry?

Yes. Potential effects on tourism are being assessed as part of our Preliminary Environmental Impact Report. Measures have been considered throughout the construction phase of the project that would look to manage the impacts that could impact tourism such as footpath or road closures impacting journey times and travel patterns.   

What will you be doing to mitigate the impact of HGVs on the local road network during construction?

Within our outline code of construction practice, we are considering a range of measure that would help control the management of impacts on local traffic and transport. Our traffic management plan will set out how we plan to reduce route and journey mileage to and ensure considerate parking practices in local areas. We will work closely with the local authority and take guidance from them to further reduce our impact such keeping our movements to earlier in the day. 

What will be the working hours of construction?

Proposed working hours will be included within the environmental impact assessment. The exact timings will form a requirement of the Development consent order. We will do as much as we can to keep disturbance to the local community to a minimum.  

Will you be closing any public footpaths?

We don’t anticipate closing any public footpaths permanently, but we will need to redirect public rights of way during the construction phase and possibly permanently Our traffic management plan will set full details of where and when these will be implemented. We will keep the community informed at all times and provide as much notice as possible.  

Why can't you build an offshore grid?

The power needed is still required to come onshore and feed into the network at the right places, otherwise we wouldn’t be adding to capacity and resilience where it is needed. Even predominantly offshore projects need to come onshore and link into the network in order to take power from where it is generated to where it is needed up and down the country. 

To put this into perspective, successfully delivering the Government’s 50 GW of offshore wind ambition will require significant new onshore and new offshore electricity transmission network being consented and delivered within this decade across the east side of the country.  


When will you be engaging with landowners?

Engagement with landowners started in winter 2021 and we continue to do so. We've appointed TerraQuest, a land referencing firm, to contact individual landowners to verify the publicly available information and to ensure we have made diligent enquiry. We are also working with Dalcour Maclaren, a land agency, to assist with contacting landowners and occupiers and arranging access for non-intrusive and intrusive surveys to be carried out. 

If you own or occupy land where our works are proposed and wish to get in touch, please email us at [email protected]or call 0808 134 9569.  

What are the next steps?

We are currently in the process of analysing and considering all feedback submitted to our recent statutory consultation. We are also continuing with assessments and surveys, and continuing to engage with local authorities and other key stakeholders as we progress our design and prepare for submission. We will submit our application to the Planning Inspectorate, who will examine the proposal, gather stakeholder input, and present a report to the Secretary of State for a final decision.  

Visit the Planning Inspectorate website for more information about the Development Consent Order process.  

How can I find out more?

You can contact us by:  

Who to contact if you are a landowner or person with interest in land 

If you are a landowner and want to talk to our lands team, please email: [email protected]  

Alternatively, you can find out more information about land interests by visiting

Who to contact for a media enquiry 

If you are a journalist and would like to speak with a member of the National Grid media team, please call 01926 656 536. 

Sea Link

Contact us

Please get in touch if you have any questions or comments about Sea Link by emailing [email protected] or calling us on 0808 134 9569.

You can also write to us at Freepost SEA LINK, please note no stamp or further address details are required.

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