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's our vision to be at the heart of a clean, fair and affordable energy future. 

National Grid is a group of companies, and one of those companies, NGET, owns, builds and maintains the high voltage network in England and Wales. It is NGET who is leading the delivery of North London Reinforcement (NLR) project. 

Within the National Grid Group there are other distinctly separate legal entities, each with their individual responsibilities and roles. More information about National Grid can be found on the ‘about us’ section of National Grid’s website. 

NGET owns, builds and maintains the high-voltage electricity transmission network in England and Wales. It is NGET that is bringing forward NLRP.

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NGET owns more than 300 substations, where 275 kV and 400 kV overhead power lines or underground cables are switched and where electricity is transformed for distribution to surrounding areas.

The majority of the remaining 132 kV and smaller lower voltage substations are owned and maintained by local distribution companies.

The Great Grid Upgrade (TGGU) is the largest overhaul of the electricity grid in generations. Our infrastructure projects, including the NLR project, across England and Wales are helping to connect more renewable energy to your homes and businesses. It will help the UK switch to clean energy and make sure our electricity network is fit for the future; carrying more clean, secure energy from where it’s generated to where it is needed.  

TGGU will play a significant part in meeting the UK Government’s plans to power all homes and businesses with green energy by 2030, ensuring our electricity network is fit for the future.

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.

At National Grid, our priority in developing projects like the NLR project is to ensure energy security, support the transition to a cleaner energy system, and keep energy affordable for our customers. While we operate as a private company, our investment and project development decisions are made within a regulatory framework designed to balance the need for investment in the nation’s energy infrastructure with the interests of consumers and the wider public. Our profits are regulated by Ofgem, ensuring they are fair and aligned with efficient and necessary investments in the energy system.

The NLR project will see work being conducted on the existing overhead line between Pelham substation and Hackney substation.

The works will comprise of replacing the existing 275kV overhead line with a 400kV overhead line from Pelham substation, Hertfordshire to Waltham Cross substation in Epping Forest, through Enfield, to Tottenham substation in Haringey and then to Hackney Substation.

There will also be associated works to the substations at Pelham, Waltham Cross, Brimsdown, Tottenham and Hackney.

The NLR project will ensure London and the surrounding areas energy security by enabling the supply of energy into London to keep up with the capital’s increasing demand. The project will enable new and future renewable energy that is generated by offshore wind, solar and other sources around the country, to connect into the grid.

Without reinforcement, the current overhead lines would be overloaded by the amount of energy needed to meet demand. This would impact on the reliability and cost of energy. The NLR project is part of The Great Grid Upgrade (TGGU), the largest overhaul of the electricity grid in generations and will play a significant part in meeting the UK Government’s plans to power all homes and businesses with green energy by 2030.

The project involves expanding the substations at Pelham, Waltham Cross, Brimsdown, Tottenham and Hackney.  It will include replacing the existing 275KV overhead line with a 400kV overhead line that runs from Pelham to Hackney, this will include the removal of some towers and installation of new towers.

To prepare for the upcoming works, vegetation clearance took place at the Waltham Cross substation, which completed in February 2024. This included clearing trees and scrubland, which is crucial for allowing prompt commencement of work. The actual expansion work is set to commence in Q3 2024 and will continue until 2027.

Yes, the NLR project was approved in May 2014 by the Secretary of State and then subsequently put on hold by National Grid following a change in energy demand.

Given Government targets to connect 50GW of offshore wind by 2030, as well as increased demand across the network, the project has since been brought forward as part of the Accelerated Strategic Transmission Investment programme. A link to this project’s successful Development Consent Order (DCO) Application can be found on the Planning Inspectorate’s website.

National Grid has prepared an indicative timetable with an anticipated conclusion in 2027, see below:

Substations are integral features of the transmission and distribution networks and enable electricity to be transmitted at different voltages, securely and reliably. One of the main roles of substations is to convert electricity into different voltages. This is needed so the electricity can be transmitted throughout the country and then distributed throughout local neighbourhoods and into our homes, businesses and buildings.

NGET takes electricity generated from windfarms and other power sources and transports it through its network of pylons, overhead lines, cables, and substations. It then transmitted at a lower voltage via the local distribution networks to homes and businesses.

The planned substation upgrades include enhancements to capacity, reliability, and connectivity features to accommodate increasing amount of new energy sources coming online. By upgrading the substations, we aim to support the integration of renewable energy projects, improve overall grid stability, and ensure that local energy projects can connect and contribute to the energy supply.

Substation reinforcement will be provided in the form of uprating and refurbishment at the following existing substation sites:  

• Stocking Pelham (Bishop's Stortford, SG9)
• Rye House (Hoddesdon, EN11 0BW)
• Waltham Cross (Waltham Abbey EN10 6EY)
• Brimsdown (Mollison Ave, Enfield, EN3 7NJ)
• Tottenham (Tottenham, London, N17 0QJ)
• Hackney (Lower Clapton, London E5 0BU)

The substations across the route, like all substations across the country, enable electricity to be transmitted at different voltages, securely and reliably.

This process enables electricity to be transmitted throughout the country and then distributed throughout local neighbourhoods and into our homes and businesses. With increased demand and more renewable energy being connected to the grid than ever before, the substations need to be upgraded to support this growth in green energy.

To this end, the substation upgrades will perform a crucial role in enabling the effective delivery of net zero by ensuring new renewable energy generation makes its way from where it is generated to where it is needed.

All substations are designed to limit EMFs in line with independent safety guidelines, set to protect us all against exposure.Overhead lines, even at the highest voltages, are also designed to ensure EMFs remain below limits set out in the independent safety guidelines. After decades of research, the weight of evidence is against there being any health risks of EMFs below the guideline limits. Due to the design of the equipment that substations contain, substations do not produce a significant external electric field. However, they do generate a magnetic field.

There are carefully thought-out policies for protecting us all against Electro Magnetic Fields (EMFs), the main component of which is ‘exposure guidelines’. The UK guidelines are set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and have been adopted by the Government.

Such concerns are taken seriously and our priority is to keep the public, our contractors and employees safe.

Find out more about EMFs and substations

A supergrid transformer is a large adaptor for electricity. Just as you might use an adaptor to change the voltage when traveling abroad, a supergrid transformer changes the very high voltage used to transport electricity over long distances into a lower voltage that can be used in homes and businesses. It's a crucial piece of equipment that helps get power from where it's generated to where it's needed.

A quad booster is a special piece of equipment that helps control the flow of electricity in the power network. When power lines get too busy with electricity, the quad booster can redirect some of that power to less busy lines. This helps prevent overloading and ensures electricity can flow more efficiently to where it's needed most.

A cable sealing end compound is an area where overhead power lines connect to underground cables. It's like a transition point between two different types of electrical highways. The compound houses equipment that safely connects the overhead lines to the underground cables, protecting the connection from weather and other environmental factors. It is normally a small, fenced area with electrical equipment inside.

Stocking Pelham substation will be expanded in order to enable the delivery of two new quad booster units at the north east and south west of the site. Initial vegetation clearance has been undertaken to make way for the new quad boosters, with their arrival scheduled for Q1 2026.

To facilitate new connects, the substation will also see some diversions, relocations and removals of existing OHL and towers. This has the capacity to tidy the current tower configuration around the site and improve some visual impacts.

The arrival of the quad booster units in 2026 will require some road closures across a two-week period. The details of these will be agreed with the local highways authority and will seek to minimise day-to-day impacts as much as possible. The works undertaken fall within permitted development, rather than the remit of the consented 2014 DCO.

As part of the works, we are looking at where improvements can be made to the natural landscape to enhance walking routes and deliver a minimum 10% biodiversity net gain.

Waltham Cross substation will be expanded in order to enable the delivery of a new 10 bay substation extension. The eastern 275 kV substation will be demolished as part of the works. In addition, some new tower installations and some existing tower removals will be required. An OHL tower on the existing lake will be removed, improving the visual character of this area. As part of the works, we will also be making improvements to the car park that adjoins the site and is frequently used by anglers.

Initial vegetation clearance has been undertaken with lay down area construction anticipated to commence in Q3 2024. National Grid will look to best minimise any impacts on Lee Valley Park users and will work closely with the Lee Valley Regional Park Authority throughout the duration of the works.

At Brimsdown substation we will deliver the installation of a new cable sealing end compound at the existing OHL tower to the north east of the site, as well as the replacement of the two existing 275/132 kV transformers with two new 400/132 kV transformers (Q2 2026 and Q2 2027). The site will be accessed via a new access road adjacent to the current footpath. Pedestrian access along this path will still be enabled via a fenced off area.

Tottenham Hale substation will see minor OHL works carried out. These include the installation of a new cable sealing end compound, installation of a new tower and removal of existing tower, as well as the demolition of an existing building. The existing bus depot is being demolished to make way for new cabling to be routed underground. Works are scheduled to commence in Q1 2025.

For the OHL diversions to be carried out, some road closures on the A1055 will be required over a two-week period. These will take place during the night to best minimise impacts on road users.

At Hackney substation we will be removing two 400/275kV and two 275/66kV transformers, replacing them with two 400/66 kV transformers. These will be gas insulated and free of SF6, a highly potent greenhouse gas which is now being phased out of most substation builds. The new transformers will be quieter than the existing units, reducing noise impacts on surrounding residents and park users.

One transformer will be delivered in Q2 2026, with the second in Q2 2027. Additional minor works will be undertaken within the substation boundaries.

To bring the new transformers into the site, access will be provided via the existing park path, highlighted in the image below. A small laydown area will be required on the green space adjacent to the park for around 72hrs during the removal of the existing transformers and installation of the new transformers.

We are holding discussions with Hackney Council around how we could provide funding to improve the basketball area with additional outdoor facilities.

In partnership with our main works contractor; J Murphy Ltd; we are preparing to commence early enabling works in late 2024. This period of activity will provide necessary details for relevant authority approval, as part of the Development Consent Order (DCO).  

The substation works will begin with the Waltham Cross substation extension, located within Lee Valley Regional Park and continue North to Ryehouse and Pelham, and South to Brimsdown. 

We have carried out an Operational Noise Assessment and, a further Construction Noise Assessment will also be undertaken.

We always plan to complete any work with the minimum of disturbance for people living near to our sites. A clearly defined access route will ensure all traffic enters the site via one route, reducing impact on the wider area. We are aiming to only dispose of waste from the vegetation clearances during certain hours to reduce continuous noise and minimise construction traffic interactions.

We will liaise closely with local authorities and National Highways to develop construction management plans that seek to best limit impacts. We are committed to working with our neighbours to ensure that disruption and visual impact of our activity is kept to a minimum.

The final details of our working hours will be included within our Construction Management Plan, which will be agreed with each local authority ahead of works commencing. 

Our construction hours will typically be from 7:30am to 6pm, Monday through Friday. We might occasionally need to work on Saturdays, usually between 7:30am and 4pm. We'll try our best to avoid noisy work early in the morning or late in the evening. If we need to do any work outside these hours, perhaps for safety reasons or to minimise disruption to power supply, we'll let the local community know in advance. 

Some road closures will be required in order to transport the new infrastructure to the substation sites. These will take place at non-peak times and will be confirmed following consultation with National Highways, the relevant local authority and local police. Advanced notice will be given on these closures and we do not expect any of the works to require road closures longer than two days.

Some temporary closures may be required at public rights of way. These will not be required at all sites and will for short periods to enable the removal and delivery of transformer units.

Site access information to each substation is detailed in the “What works are being undertaken at the substation sites?” section of these FAQs. We will release further information on this in advance of works commencing.

The substation works carried out will modernise and upgrade the local energy infrastructure to increase the local capacity for new customer connections. Overhead line improvements in and around North London are also needed to connect customers to our substations.

From 2025 through to 2027, National Grid will be carrying out works to uprate and/or refurbish a number overhead line (OHL) routes. This will include:

• Reconductoring of the 4ZM overhead line between Pelham and Rye House 
• Replacing the existing 275 kV overhead line with a 400 kV overhead line (ZBD and ZBC routes) between Waltham Cross and Brimsdown 
• Reconductoring of the VC overhead line between Tottenham and Hackney 

The project will involve the replacement of overhead conductors on both circuits either side of the pylons, including the top earthwire conductor. It will also involve replacing fittings and furniture along the route of the pylons and some tower painting may be required to protect the steel structures.

The overhead line upgrades may cause some temporary changes in your area. You might see work crews and equipment along the power line routes and there could be some noise during construction hours. In some places, we might need to trim back vegetation near the power lines. Once the work is done, the lines might look a bit different – i.e., there could be slightly different support structures.

During construction we will need to carry out a range of temporary activities such as creating equipment storage areas and site offices. Road and public rights of way diversions will also need to be implemented. Before we do this, we will prepare a Construction Management Plan with each impacted local authority that will set out controls and measures to reduce our impact on the local community.  

We will work closely with the local community to minimise the impact of our project, where we can, and we will support community initiatives in areas where we are working to deliver social, economic or environmental benefits. We will write to local residents with more information on construction traffic routes and our working hours closer to construction starting. 

National Grid is committed to working with the public and our stakeholders to ensure that the North London Reinforcement project (NLR) is delivered in a manner that seeks to minimise any localised impacts and cause the least disruption possible.

Whilst we do not expect our construction works will cause any long term or major impacts, we are committed to ensuring that those affected are given advanced notice and are able to contact us via our community relations channels. We will issue letters to the public to inform on upcoming works, place posters and notices around sites undergoing work, as well as look arrange pop up sessions and community liaison groups where there is sufficient interest. Our website will remain up to date with the latest timeline and we will provide project updates detailing the progress of the works throughout construction.

People living near the infrastructure will not receive money off their bills or direct payments because of the project. It is our job to upgrade the network so people can continue to take for granted the energy they use every day.  

However, we are committed to engaging with communities to ensure the projects deliver other localised benefits via our Community Grant Programme and environmental benefits via biodiversity net gain (i.e. increasing biodiversity in the area we are operating in above what is currently there)

The Community Grant Programme is run by the NGET business. The programme is aimed at community organisations and charities in areas where our work is impacting local people through our operations and construction activities. 

Communities impacted by the maintenance of existing infrastructure (e.g. refurbishment of overhead lines or substations resulting in road closures and other impacts) can apply for grants of up to £20,000. 

To contact our community relations team, you may:

• Call our Freephone helpline number: 0800 279 3408 (lines open 9am to 5pm, Monday to Friday) 
• Email: [email protected]  
• Write to: FREEPOST NATIONAL GRID 

National Grid have set a 10% Biodiversity Net Gain (BNG) in environmental value target on all construction projects and is aiming to achieve 15% on this project. To reach this, we will work with ecologists and Lee Valley Park about how and where biodiversity net gains following this project will take place.

This upgrade aims to enhance electricity transmission capacity, addressing future energy demands. It plays a vital role in transmitting offshore wind power to residences and businesses, contributing to the UK's renewable energy and net zero objectives.

To reduce the impact on local wildlife and biodiversity, the vegetation work was carried out between January and March 2024. This is to protect breeding seasons along with taking into consideration the peak season of park users. Three ecology reports have been completed as well as a Habitats Regulations Assessment which has been accepted by Natural England in line with the clearance. We will also have an ecologist onsite for the works if required.

National Grid have set a 10% Biodiversity Net Gain (BNG) in environmental value target on all construction projects and is aiming to achieve 15% on this project. To reach this, we will work with ecologists and Lee Valley Park about how and where biodiversity net gains following this project will take place.