Little Horsted – we are building a new substation (electricity supply point)

We are carrying out this development to provide a new connection for UK Power Networks, who need to upgrade their electricity network to meet future growth in electricity demand and to replace UK Power networks overhead lines, which are due for renewal, along an 18km route between Ringmer and Polegate.

Establishing a new grid supply point near Little Horsted, connected to UK Power Networks’ Lewes substation via new underground electricity cables, will maintain the future reliability of the network and means that UK Power Networks can remove 72 pylons between in the Ringmer area of East Sussex, including 10 in the South Downs National Park.

Under the Electricity Act, National Grid has a licence obligation to connect customers like UK Power Networks to its high voltage network in order to ensure a safe and secure network and to meet local demand.

The site was selected as it’s near National Grid’s existing 400,000volt (400kV) overhead line. It’s also close to the strategic road network.

In choosing this site, we have avoided sensitive environmental areas such as those with nature conservation, heritage or landscape designations. The nature of the underlying topography and vegetation in the wider area also means that the site is generally well screened, with scope for additional visual screening in the form of landscape planting.

The connection is required by UK Power Networks in the Little Horsted area. It is not feasible to use our nearest existing substations at Bolney or Ninfield as they are not where the connection is needed.

Two new substations are being built on this site, a 400kv one for National Grid and a 132kv one for UK Power Networks.  

When a new substation is required, National Grid engineers and designers develop the electrical, civil and mechanical designs to maximise the use of the land so that the design is safe to construct, operate and maintain. These designs are currently underway following the appointment of our principal contractor, Balfour Beatty. The final design for the 24 acres site will ensure that any environmental issues and the impact on the surrounding area are fully considered. Working with the local authority we’ve agreed a screening design to make the project as sympathetic to the local environment as possible. Existing features will screen construction compounds where possible.

As work progresses, you’ll see:

1. Site establishment

Before construction work starts, we set up the site. This includes the establishment of welfare offices, toilets, parking and storage areas or containers to support the operation on a day-to-day basis.

Access for construction vehicles will be off Eastbourne Road using the entrance gate we created during our enabling works. This will be the main site entrance once the substation is built.  A second access for cars is via the existing A22 farm entrance and will be left turn only.

We aim to achieve voluntary agreements with landowners to purchase the land we need. If voluntary agreements cannot be reached we can compulsorily acquire any land and rights necessary to construct and operate the new substation. This is done through a Compulsory Purchase Order which was confirmed on 4 May 2023 by the Secretary of State for Energy Security and Net Zero without modifications.

Traffic management plans will be agreed with the local authority to outline construction traffic movements.

2. Civil build/groundworks

So the new equipment can be installed the ground across the site needs to be levelled to provide a flat and stable surface for the foundations.

Major earth movements will be required, given the site’s topography, as the substation will cover the whole area. We anticipate there’s 65,000m3 of earth to be removed to level the site. This will take approximately four months to complete.

We’re encouraging the contractor to maximise the re-use of and recycling of on-site material wherever possible. It’s likely that the earth movement programme will involve around 8,000 lorries transporting materials away from site over this period, which equates to 100 lorry loads a day.

This aspect will be covered in the contractor’s Traffic Management Plan and be done in consultation with the local authority, and neighbours informed.

Once the site is levelled the foundations are then excavated and then steel reinforcements or piles are installed, before concrete is poured. This forms the platform or building on which the equipment will be supported and/or housed. Other civil works, like internal roads, are also constructed.

Towards the end of the first year our Super Grid Transformers (SGTs) for the substation will be delivered to site, installed and commissioned.  The transformers are very large, heavy pieces of equipment (some 178 tonnes each) which are being made overseas shipped over. They’ll be transported to site by a specialist haulage contractor. This will be a big logistics exercise which is likely to involve the police and the local highways authority and a series of road closures to get them from A to B.

3. Mechanical and electrical build

Once the foundations have been built, the structures are assembled and fixed to the foundations. Due to the nature of electricity, the equipment installed is raised off the ground to provide electrical clearance. The electrical build process is set out methodically, building each part of the structure piece by piece, including cable connections to the automatic control and protection equipment.

4. Overhead line (OHL) works

There are three elements to this work to connect the new substation to the overhead line network.

• We’ll build the two new pylons and then restring/reconductor each side of the overhead wire and earth wire to the new pylons before dismantling the pylon which will no longer be used. This will require work to neighbouring pylons and the overhead wire either side of the new substation to connect it into the network
• The OHL work will be done during two electrical outages in late 2025 when the power will be switched off so the work can be done.
• When this happens people may see our workers, satellite compound areas, scaffolding over roads (to protect the wire) and overhead line activity near East Sussex National Hotel, Golf Resort & Spa (to the west) and the other side of Crockstead Farm (to the east).
• Once the line is restrung – the pylon towers on this section of the line will have new name plates and flags added for identification purposes all the way to the top on every level.  
• We’re already liaising with landowners and grantors about access and the work generally.

5. Commissioning

Once all the equipment is in place, we begin commissioning. The equipment is first commissioned off-line using test equipment to ensure it is connected correctly and it is then energised (made electrically live) at high voltage by connecting to the National Grid Transmission System.

6. Site demobilisation

After the equipment and substations are live operationally, the site is tidied up and screened through soft landscaping. The construction site is cleared and reinstated to its original condition and the site is demobilised of all construction workers.

We’ve purchased a parcel of land from one of our landowners which will be used as mitigation land to replace any ecological habitats that may have been lost through the works. It will be transformed into a meadow rich in flowers and fauna for the benefit of the local environment.

We’ll welcome school educational visits so if you’re interested in this element of the work, or to arrange a visit, please do get in contact.

Main construction began in March 2024 and the substations will be operational by late 2025.

Before work starts, we will brief all contractors to ensure they work responsibly and are considerate to the local community. This includes a briefing on considerate driving and minimising noise when entering and leaving site.

We will be keeping local people informed as the work progresses.

Our community relations team will keep the community informed by letter, information events and our website. There is also a dedicated free phone line and email address to contact if you have any questions or complaints about the works. See the 'further enquiries' information at the top right hand of this webpage for our contact details.

In the main our team will work from 7am to 7pm on weekdays (excluding Bank Holidays), 7am to 5pm on Saturdays and 8am to 3pm on Sundays. HGV deliveries are limited to 8am to 12pm. 

To complete the work in time we’ll work alternate weekends.

Any work on Bank Holidays will be agreed in writing by the local planning authority. 

No continuous 24-hour activities are envisaged.

The transformers will be delivered during the early hours of a Sunday morning.

The contract to build National Grid’s substation has been awarded to Balfour Beatty. This includes the detailed design and the work to the overhead power lines. Further contracts will be awarded for other elements of the project.

We’re committed to carrying out our works with minimal impact on the local community. We’ve completed an environmental assessment and before works begin Construction Environmental Management Plans and Construction Logistics Plans are shared and agreed with the relevant local authorities. We’ll monitor noise, dust, light, traffic movements and vibration throughout the construction programme.

There will be some construction traffic because of our work. This will be managed through an agreed Traffic Management Plan. We’ll do all we can to minimise any disruption associated with our construction traffic. This includes:

• Managing HGV movements and avoiding peak morning and evening times where possible.
• All construction related parking will be onsite to avoid any queuing or parking on neighbouring roads.
• We’ll use of a road sweeper at regular intervals to ensure site entrance and the adjacent highway is kept clean.
• Drivers to keep to A-roads and motorways and avoid villages.
• Promoting car share incentives.

During site establishment we’ll need to implement minor roadworks on the A22 (lane closure with traffic lights) while we connect the site to water, electricity and fibre optic cabling. There will also be minor roadworks on Eastbourne Road – for example to bring in plant and equipment. We’ll provide more information when able.

When the Super Grid Transformers are delivered to site (Autumn 2024), there will be a standalone Traffic Management Plan covering their journey from the port, likely from the Port of Shoreham (near Brighton), and their convoy to site. Again we’ll communicate more detailed plans and information when able.