The high-voltage (400kV and 275kV) electricity substations in the United Kingdom are listed in the following tables. The substations provide entry points to, and exit points from, the National Grid (GB) or Northern Ireland Electricity Network. Entry points include power stations, major wind farms and inter-connectors from other countries and regions. Exit points are to lower voltage (275kV, 132kV, 66kV and 33kV) transmission and distribution substations which are also shown in the tables.
The first high-voltage substations in Britain were built as part of the National Grid in 1927–1933 by the Central Electricity Board under the provisions of the Electricity (Supply) Act 1926. The substations and the grid operated at 132kV and provided local and regional inter-connections.[1] Higher voltage substations were built as part of the super-grid designed for the bulk transfer of electricity which began to operate from 1953, firstly at 275kV then from 1965 additionally at 400kV.[2] The first 400kV line was the 150 mile section between West Burton power station in Nottinghamshire and Sundon substation in Bedfordshire; the line had a capacity of 1,800 MVA per circuit.[3] The first 400kV substations in Scotland were commissioned in 1972 associated with the line from Hunterston, Ayrshire to Neilston, Renfrewshire.
From 1958 the super-grid and its substations were built by the Transmission Project Group within the Central Electricity Generating Board and included architects and landscape architects. The 400kV super-grid reduced the number of lines and substations and therefore the number of amenity objections.[4] Some substations in urban areas were installed in enclosed structures but the majority were in the open. The appearance of substations, and their visual impact, was improved using earth mounds and trees. Between 1968 and 1973, 725,000 tall trees, 915,400 smaller trees and 17,600 ground cover plants had been used to screen substations. The substation at Sundon, Bedfordshire adjacent to the M1 motorway was screened with a beech hedge, and at Bishop’s Wood in Worcestershire the substation was built within an existing wood. In 1972 a Mark II low profile 400kV substation was commissioned, the first was at Wymondley, Hertfordshire. The substation used lighter support structures and the height was reduced from 72 ft to 53 ft (21.9 m to 16.1 m).
The rapid development of the 400kV system is demonstrated in the numbers of new substations that were being built: in 1971 ten 400kV substations were commissioned by the CEGB, these were: Pheasant Farm, Abham, Didcot, Exeter, Hinkley Point, Indian Queens, Landulph, Melksham, Drax and Harker.[5] By 1973 there were sixty-one 400kV substations. In 1979 there were a total of 201 (275kV and 400kV) substations.[6] By the time of privatisation of the British electricity industry in 1990 there were 212 substations operating at 275kV and 400kV, and a total of 4069km (2,528miles) operating at 275kV, and 9822km (6,103miles) circuit at 400kV.[7] In 2020 there were 179 400kV substations and 137 275kV substations.
Centralised co-ordination of electricity supplies in Northern Ireland began with the establishment of the Electricity Board for Northern Ireland in 1931. The Northern Ireland Electricity Service was established on 1 April 1973 by the Electricity Supply (Northern Ireland) Order 1972. The integrated electricity network was built in the late 1960s and early 1970s.[8] In 1979, the system comprised 323km (201miles) of 275kV lines, 836km (519miles) of 110kV line, and 38875km (24,156miles) of distribution mains.
The 275/400kV grid and substations in England and Wales are owned and operated by National Grid Electricity Transmission. It also operates the grid and substations in Scotland although the systems are owned by ScottishPower and Scottish & Southern Energy. In Northern Ireland grid and substations are owned and operated by Northern Ireland Electricity Networks Limited (NIE Networks).
The 400kV substations in England and Wales and their interconnections are given in the following table. The identification codes (e.g. 4YF) for the interconnecting lines and the lower voltage transmission, if any, from the substation are also given.[9] [10] [11] [12] [13]
| Abham | Devon | Exeter | Code 4YF | |
| Landulph | ||||
| Alverdiscott | Devon | Taunton | ||
| Indian Queens | ||||
| Amersham Main | Buckinghamshire | Iver | 132kV | |
| East Claydon | ||||
| Aust | South Gloucestershire | Melksham | Cable sealing end compound for underground Severn-Wye cable tunnel | |
| Newhouse | ||||
| Axminster | Devon | Exeter | Code 4YA | |
| Chickerell | ||||
| Barking | Greater London | West Ham | 275kV, 132kV, 33kV | |
| West Thurrock | ||||
| Tilbury | Code YYJ | |||
| Beddington | Greater London | Rowdown | Beddington Cable Tunnel Code ZZT | 275kV, 132kV |
| Kingsnorth | Former ±266kV HVDC Kingsnorth circuit (operational 1974-86) | |||
| Willesden | ||||
| Bicker Fen | Lincolnshire | On Walpole–West Burton circuits | 132kV | |
| Blyth | Northumberland | Link to Stella West–Eccles circuits | ||
| North Sea Link HVDC convertor station | HVDC link to Norway | |||
| Bodelwyddan | Denbighshire | Feed from Burbo Bank wind farm | ||
| Link to Connahs Quay–Pentir circuits | ||||
| Bolney | West Sussex | Ninfield | Code 4VM Also feed from Rampion wind farm | 132kV, 33kV |
| Lovedean | Code 4VF | |||
| Botley Wood | Hampshire | Lovedean | Code 4YE | |
| Chilling | Code 4YE | |||
| Bradford West | West Yorkshire | Eggborough | 275kV, 132kV | |
| Elland | ||||
| Lower Shelf | ||||
| Braintree | Essex | Rayleigh Main | 132kV, 33kV | |
| Twinstead Tee | ||||
| Bramford | Suffolk | Stocking Pelham | 132kV | |
| Norwich Main | Code 4YM | |||
| Sizewell | 4 circuits | |||
| East Anglia ONE | 220kV feed from East Anglia ONE windfarm | |||
| Bramley | Hampshire | Fleet | 132kV | |
| West Weybridge | Code ZH | |||
| Melksham | Code YYM | |||
| Didcot | ||||
| Bredbury | Greater Manchester | Macclesfield | ||
| South Manchester | ||||
| Bridgwater | Somerset | Under construction (2020) | ||
| Brinsworth | South Yorkshire | Thorpe Marsh | 275kV | |
| Britned | Kent | Grain | ||
| Bull's Lodge | Essex | On Rayleigh Main–Braintree circuits | ||
| Burwell Main | Cambridgeshire | Pelham | 132kV | |
| Walpole | ||||
| Bustleholm | West Midlands | Substation | ||
| Link to Hams Hall–Draklow circuits | ||||
| Canterbury North | Kent | Kemsley | Code ZV | |
| Richborough | ||||
| Sellindge | Code ZY | |||
| Capenhurst | Cheshire West and Chester | Connahs Quay | ||
| Carrington | Greater Manchester | Daines | ||
| South Manchester | ||||
| Kearsley | ||||
| Cellarhead | Staffordshire | Drakelow | Code ZE | |
| Macclesfield | ||||
| Chafford Hundred | Essex | |||
| Chickerell | Dorset | Mannington | Code 4VN | |
| Axminster | ||||
| Chilling | Hampshire | Botley Wood | Code 4YE | |
| Fawley | ||||
| Cilfynydd | Rhondda | Imperial Park | 275kV | |
| Swansea North | ||||
| Seabank | ||||
| Rassau–Rhigos circuit | ||||
| City Road | Greater London | St. John’s Wood | Underground along Regent’s Canal | 132kV, 33kV |
| West Ham | Underground along Lea Navigation, Hertford Union and Regent’s Canals | |||
| Cleve Hill | Kent | On Kemsley–Canterbury North circuits | Feed from London Array | |
| Connahs Quay | Flintshire (Sir y Fflint) | Capenhurst | ||
| Daines | ||||
| Flintshire Bridge Convertor | Western HVDC Link | |||
| Treuddyn | ||||
| Pentir | ||||
| Coryton South | Essex | Spur on Tilbury–Rayleigh Main circuits | ||
| Cottham | Nottinghamshire | West Burton | 400kV link to Cottam Development Centre | |
| Wymondley | ||||
| High Marnham | ||||
| Cowley | Oxfordshire | Didcot | 132kV, 33kV | |
| Seven Springs | Code 4TE | |||
| East Claydon | ||||
| Crayford | Greater London | Hurst | Under construction | |
| Creyke Beck | East Yorkshire | Thornton | ||
| Keadby | ||||
| Culham JET | Oxfordshire | Spur on Didcot–Cowley circuits | ||
| Daines | Greater Manchester | Connahs Quay | ||
| Carrington | ||||
| South Manchester | ||||
| Macclesfield | ||||
| Damhead Creek | Kent | Kingsnorth | ||
| Deeside power station | Cheshire West | Connahs Quay | ||
| Didcot | Oxfordshire | Bramley | Code 4YG | 132kV, 33kV |
| Cowley | ||||
| Dinorwig | Gwynedd | Pentir | Underground | |
| Tee on Pentir-Trawsfynydd circuits | Underground | |||
| Drakelow | Derbyshire | Cellarhead | Code ZE | |
| Penn | Code ZN | |||
| Hams Hall | ||||
| Ratcliffe | ||||
| Drax | North Yorkshire | Thornton | Code 4VC | |
| Eggborough | Code 4VJ | |||
| Fenwick Tee | Code 4VH | |||
| Dungeness | Kent | Sellindge | Code 4VO | 275kV |
| Ninfield | Code 4ZJ | |||
| East Claydon | Buckinghamshire | Cowley | 132kV | |
| Amersham | ||||
| Sundon | ||||
| Enderby | ||||
| Eaton Socon | Cambridgeshire | On Wymondley–Cottam circuits | 132kV | |
| Eccles (Scotland) | Borders | Stella West | ||
| Eccleshill | West Yorkshire | Padiham | ||
| Penwortham | Code ZO | |||
| Kearsley | ||||
| Eggborough | North Yorkshire | Drax | Code 4VJ | |
| To trans-Pennine (Woodhead) circuits | ||||
| Monk Fryston | ||||
| Elland | West Yorkshire | Bradford West | ||
| Link to Ferrybridge–Rochdale circuits | ||||
| Elstree | Hertfordshire | St John’s Wood | Elstree to St. John’s Wood Deep Cable Tunnel | 275kV, 132kV |
| Sundon | ||||
| Enderby | Leicestershire | East Claydon | ||
| Ratcliffe | ||||
| Exeter | Devon | Taunton | Code ZZ | |
| Fawley | Hampshire | Nursling | Code 4YD | |
| Mannington | ||||
| Feckenham | Worcestershire | Seven Springs | 132kV | |
| Hams Hall | ||||
| Penn | ||||
| Fenwick Tee | North Yorkshire | Connection to Drax on the Thorpe Marsh to Keadby circuit | ||
| Ferrybridge | North Yorkshire | Drax | ||
| Rochdale | ||||
| Fleet | Hampshire | Lovedean | 132kV, 33kV | |
| Bramley | ||||
| Flintshire Bridge Convertor | Flintshire | Connahs Quay | ||
| Frodsham | Halton | Rocksavage power station | ||
| Capenhurst | ||||
| Grain | Kent | Kingsnorth | Code 4YN | |
| Kemsley | Code 4TL, includes River Medway Cable Tunnel | |||
| Grain CHP | ||||
| Grain Static Inverter Plant BritNed | 450 kV DC | |||
| Grain CHP | Kent | Grain | ||
| Grain Static Inverter | Kent | Grain | ||
| Grendon | Northamptonshire | Sundon | 132kV | |
| Staythorpe | ||||
| Grimsby West | North East Lincolnshire | Keadby | Feed from South Humber Bank, Killingholme B and Immingham power stations to Keadby–Grimsby West circuits | |
| Hackney | Greater London | Seven Sisters Road | London Power Tunnels | 275kV, 132kV, 66kV |
| West Ham | Lower Lea Valley Cable Tunnel | |||
| St. John’s Wood | London Power Tunnel, single circuit | |||
| Hambleton Tee | Lancashire | Heysham | ||
| Penwortham | ||||
| Stanah | ||||
| Hams Hall | Warwickshire | Feckenham | 275kV, 132kV | |
| Ratcliffe | ||||
| Drakelow | ||||
| Harker | Cumbria | Hutton | ||
| Gretna (Scotland) | ||||
| Hawthorn Pit | Durham | Norton | Code 4TF | |
| Heysham | Lancashire | Stanah (via Hambleton Tee) | ||
| Quernmore | ||||
| Highbury | Greater London | Spur Seven Sisters Road–St. John’s Wood circuit | Underground line | 11 kV |
| High Marnham | Nottinghamshire | Cottam | ||
| Staythorpe | ||||
| Hinckley Point | Somerset | Melksham | ||
| Humber Refinery | North Lincolnshire | Immingham power station | ||
| Hurst | Greater London | New Cross | Under construction | 275kV, 132kV |
| Crayford | Under construction | |||
| Hutton | Cumbria | Harker | ||
| Quernmore | ||||
| Imperial Park | Newport | Melksham | ||
| Cilfynydd | ||||
| Indian Queens | Cornwall | Landulph | ||
| Alverdiscott | ||||
| Ironbridge | Telford and Wrekin | Penn | ||
| Drakelow–Penn circuits | ||||
| Shrewsbury | ||||
| Iver | Buckinghamshire | Amersham | 275kV, 132kV | |
| Keadby | North Lincolnshire | West Burton | 132kV | |
| Grimsby West | ||||
| Thorpe Marsh | ||||
| Kearsley | Greater Manchester | Carrington | ||
| Penwortham | ||||
| Kemsley | Kent | Grain | Code 4TL, includes River Medway Cable Tunnel | 132kV, 33kV |
| Northfleet West | Code TP | |||
| Canterbury North | Code ZV | |||
| Kensal Green | Greater London | St. John’s Wood | Underground, along Regent’s Canal and Grand Union Canal | |
| Willesden | Underground, along Grand Union Canal | |||
| Wimbledon | London Power Tunnels, single circuit | |||
| Killingholme | North Lincolnshire | On Keadby–Grimsby circuits | ||
| Kingsnorth | Kent | Northfleet East | Code 4YN | |
| Tilbury | Code 4VG | |||
| Grain | Code 4TK | |||
| Feed from Damhead Creek | ||||
| Beddington | Former ±266kV HVDC Kingsnorth circuit (operational 1974-86) | |||
| Lackenby | Redcar and Cleveland | Thornton | 275kV, 66kV | |
| Landulph | Cornwall | Indian Queens | ||
| Abham | ||||
| Langage power station | Devon | Abham–Landulph circuit | ||
| Legacy | Wrexham | Shrewsbury | 132kV, 33kV | |
| Treuddyn | ||||
| Leighton Buzzard | Bedfordshire | On East Claydon–Sundon circuits | ||
| Little Barford | Bedfordshire | On Wymondley–Cottam circuits | ||
| Littlebrook | Kent | Northfleet West | 275kV, 132kV | |
| West Thurrock | Dartford Cable Tunnel | |||
| Longfield | Kent | ? | ||
| Lovedean | Hampshire | Bolney | Code 4VF | 132kV |
| Fleet | Code VB | |||
| Nursling | Code 4YC | |||
| Botley Wood | Code 4YE | |||
| Lower Shelf | Blackburn with Darwen | Padiham | ||
| Bradford West | ||||
| Monk Fryston | ||||
| Macclesfield | Cheshire | Cellarhead | Code YV? | |
| Daines | ||||
| Stalybridge | ||||
| Mannington | Dorset | Chickerell | Code 4VN | |
| Nursling | ||||
| Marchwood | Hampshire | On Fawley–Nursling circuits | ||
| Medway power station | Kent | Grain | ||
| Melksham | Wiltshire | Hinkley Point | Code ZG | |
| Bramley | Code YYM | |||
| Minety | ||||
| Imperial Park | ||||
| Seabank | ||||
| 400kV feed to Whitson | ||||
| Middleton | Lancashire | Heysham | ||
| Link on Penwortham–Hutton circuit | ||||
| Minety | Wiltshire | Seven Springs | 132kV | |
| Melksham | ||||
| Monk Fryston | North Yorkshire | Eggborough | 275kV | |
| Lower Shelf | ||||
| Necton | Norfolk | On Norwich Main–Walpole circuits | 132kV | |
| Neepsend | Sheffield | Hunshelf | ||
| New Cross | Greater London | Wimbledon | Under construction | 275kV, 132kV, 66kV |
| Hurst | Under construction | |||
| Newhouse | Monmouthshire | Aust/Whitson | Cable sealing end compound for underground Severn crossing | |
| Ninfield | East Sussex | Dungeness | Code 4ZJ | 132kV, 33kV |
| Bolney | Code 4VM | |||
| Northfleet East | Kent | Northfleet West | 132kV | |
| West Thurrock | Includes overhead Thames Crossing | |||
| Singlewell | Code 4YN | |||
| Northfleet West | Kent | Rowdown | 132kV, 33kV | |
| Northfleet East | ||||
| Littlebrook | ||||
| Kemsley | Code TP | |||
| North Sea Link HVDC convertor station | Northumberland | Blyth | HVDC link to Norway | |
| Norton | Stockton on Tees | Hawthorn Pit | Code 4TF | |
| Spennymoor | ||||
| Teesside high voltage users | ||||
| Osbaldwick | ||||
| Norwich Main | Norfolk | Bramford | Code 4YM | 132kV |
| Walpole | Code 4VV | |||
| Nursling | Hampshire | Fawley | ||
| Lovedean | Code 4YC | |||
| Mannington | ||||
| Oldbury | West Midlands | Drakelow | ||
| 275kV substation | ||||
| Osbaldwick | York | Norton | 132kV | |
| Thornton | ||||
| Padiham | Lancashire | Lower Shelf | 132kV | |
| Eccleshill | ||||
| Patford Bridge | Northamptonshire | On East Claydon–Enderby circuit | ||
| Pembroke | Pembrokeshire | Swansea North | 132kV | |
| Penn | West Midlands | Feckenham | 132kV | |
| Ironbridge | ||||
| Drakelow | Code ZN | |||
| Pentir | Gwynedd | Trawsfynydd | Code 4ZC | |
| Dinorwig | ||||
| Connahs Quay | ||||
| Wylfa | ||||
| Penwortham | Lancashire | Kearsley | ||
| Stanah (via Hambleton Tee) | ||||
| Quernmore | ||||
| Eccleshill | Code ZO | |||
| Pudding Mill Lane | Greater London | Spur from West Ham–City Road line | Underground cable, main traction current supply to Elizabeth line, back up supply at Kensal Green/Westbourne Park[14] | 25 kV |
| Quernmore | Lancashire | Hutton | Code ZX | |
| Heysham | ||||
| Penwortham | ||||
| Rassau | Blaenau Gwent | Rhigos | 132kV | |
| Walham | ||||
| Ratcliffe | Leicestershire | Staythorpe | 132kV | |
| Enderby | ||||
| Coventry | ||||
| Drakelow | ||||
| Willington | ||||
| Rayleigh Main | Essex | Tilbury | 132kV | |
| Braintree | Code 4VB | |||
| Rhigos | Rhondda | Swansea North | ||
| Rassau | ||||
| Richborough | Kent | Canterbury North | Code ZID, feed to/from NEMO | 132kV, 33kV |
| Rochdale | Lancashire | Ferrybridge | 132kV | |
| Whitegate | ||||
| Rocksavage | Halton | Frodsham | ||
| Rowdown | Greater London | Beddington | Beddington Cable Tunnel Code ZZT | |
| Northfleet West | ||||
| Rugeley | Staffordshire | On Penn–Drakelow circuits | ||
| Rye House | Hertfordshire | Stocking Pelham | 132kV | |
| Waltham Cross | ||||
| St. John’s Wood | Greater London | Kensal Green | Underground, along Regent’s Canal and Grand Union Canal | 275kV, 132kV, 66kV, 22kV |
| City Road | Underground along Regent’s Canal | |||
| Hackney | London Power Tunnel, single circuit | |||
| Elstree | Elstree to St. John’s Wood Deep Cable Tunnel | |||
| Sandford | North Somerset | Under construction (2020) | ||
| Seabank | Bristol | Cilfynydd | ||
| Melksham | ||||
| Sellindge | Kent | Canterbury North | 132kV | |
| Dungeness | Code 4VO | |||
| Feed to/from France | 270 kV DC | |||
| Seven Sisters Road | Greater London | On Hackney–St John’s Wood circuits | ||
| Seven Springs | Gloucestershire | Cowley | ||
| Minety | ||||
| Walham | ||||
| Feckenham | Code ZF | |||
| Shotton Converter Station | Flintshire | Deeside power station | ||
| Woodland Conversion Station (Ireland) | 400kV DC East–West Interconnecter to Republic of Ireland, operated by EirGrid | |||
| Shrewsbury | Shropshire | Ironbridge | 132kV, 33kV | |
| Legacy | ||||
| Singlewell feeder | Kent | Spur on Northfleet East–Kingsnorth circuits (Code 4YN) | 25 kV | |
| Sizewell | Suffolk | Bramford | 4 circuits | |
| South Humber Bank power station | North Lincolnshire | On Keadby–Grimsby West circuits | ||
| South Manchester | Greater Manchester | Daines | ||
| Carrington | ||||
| Bredbury | ||||
| Spalding | Lincolnshire | On Walpole–West Burton circuits | ||
| Spennymoor | Durham | Stella West | ||
| To Norton–Hawthorn Pit circuits | ||||
| Stanah | Lancashire | Penwortham (via Hambleton Tee) | ||
| Heysham | ||||
| Stalybridge | Greater Manchester | Thorpe Marsh | Code 4ZO Trans-Pennine via Woodhead tunnel | 275kV |
| Stocksbridge | ||||
| Macclesfield | ||||
| Staythorpe | Nottinghamshire | Grendon | 132kV | |
| Ratcliffe | ||||
| High Marnham | 4 circuits | |||
| Stella West | Tyne and Wear | Eccles | ||
| Spennymoor | Code 4TQ | |||
| Stocksbridge | South Yorkshire | Eggborough | ||
| Stalybridge | Code 4ZO Trans-Pennine via Woodhead tunnel | |||
| Stoke Bardolph | Nottinghamshire | Ratcliffe | ||
| High Marnham | ||||
| Stocking Pelham | Essex | Wymondley | 132kV | |
| Rye House | ||||
| Burwell Main | ||||
| Bramford | ||||
| Sundon | Central Bedfordshire | Elstree | 132kV | |
| East Claydon | ||||
| Grendon | ||||
| Wymondley | ||||
| Sutton Bridge power station | Lincolnshire | Walpole | ||
| Swansea North | Swansea | Cilfynydd | ||
| Rhigos | ||||
| Pembroke | ||||
| Taunton | Somerset | Alverdiscott | Code 4VW | |
| Exeter | ||||
| Hinkley Point | ||||
| Thornton | City of York | Drax | Code 4VC | |
| Lackenby | ||||
| Osbaldwick | ||||
| Thorpe Marsh | South Yorkshire | Keadby | ||
| Brinsworth | ||||
| Stalybridge | Code 4ZO Trans–Pennine via Woodhead tunnel | |||
| Tilbury | Essex | Kingsnorth | Includes Thames Cable Tunnel | 275kV, 132kV |
| Barking | ||||
| Rayleigh Main | ||||
| Tod Point | Redcar and Cleveland | Lackenby | ||
| Trawsfynydd | Gwynedd | Treuddyn | ||
| Pentir | Code 4ZC | |||
| Treuddyn | Flintshire | Connahs Quay | ||
| Trawsfynydd | ||||
| Legacy | ||||
| Twinstead Tee | Essex | On Bramford–Stocking Pelham circuits | ||
| Walham | Gloucestershire | Rassau | 132kV | |
| Seven Springs | ||||
| Walpole | Norfolk | Burwell Main | 220kV, 132kV | |
| Norwich Main | Code 4VV | |||
| West Burton | ||||
| Feed from Sutton Bridge Power Station | ||||
| Waltham Cross | Hertfordshire | Rye House | 275kV | |
| West Burton | Nottinghamshire | Walpole | 132kV | |
| Keadby | ||||
| Cottam | ||||
| West Ham | Greater London | Barking | 132kV, 66kV | |
| City Road | Underground, along Lea Navigation, Hertford Union Canal and Regent’s Canal | |||
| Hackney | Lower Lea Valley Cable Tunnel | |||
| West Thurrock | Essex | Barking | 275kV | |
| Northfleet East | Overhead Thames Crossing | |||
| Littlebrook | Includes Dartford Cable Tunnel | |||
| West Weybridge | Surrey | Bramley | Code ZH | 275kV, 132kV |
| Whitegate | Greater Manchester | Rochdale | 275kV, 132kV | |
| Whitson | Newport | Melksham | 275kV, 132kV | |
| Imperial Park | ||||
| Willesden | Greater London | Kensal Green | Underground, along Grand Union Canal | 275kV, 132kV, 66kV, 22 kV |
| Beddington | Former ±266kV HVDC Kingsnorth circuit (operational 1974-86) | |||
| Willington | Derbyshire | Ratcliffe | ||
| Wimbledon | Greater London | Kensal Green | London Power Tunnels, single circuit | 275kV, 132kV |
| New Cross | Under construction | |||
| Wylfa | Anglesey (Sir Ynys Mon) | Pentir | 132kV | |
| Wymondley | Hertfordshire | Sundon | 132kV | |
| Cottam Power Station | ||||
| Stocking Pelham | Code 4TB |
The 275kV substations in England and Wales and their interconnections are given in the following table. The lower voltage transmission, if any, from the substation is also given.
| Aberthaw | Cardiff | Pyle | ||
| Upper Boat | ||||
| Tremorfa | ||||
| Aldwarke | South Yorkshire | West Melton | ||
| Brinsworth | ||||
| Alpha Steel | Newport | Uskmouth | ||
| Baglan Bay | Neath | Margam | ||
| Swansea North | ||||
| Barking | Greater London | Redbridge | 132kV, 33kV | |
| Beddington | Greater London | Chessington | Code ZZU | 132kV |
| Wimbledon | ||||
| Berkswell | West Midlands | Coventry | ||
| Feckenham | ||||
| Ocker Hill | ||||
| Birkenhead | Merseyside | Capenhurst | ||
| Lister Drive | ||||
| Bishops Wood | Staffordshire | 2 links to Penn–Feckenham circuit | 132kV, 66kV | |
| Blyth | Northumberland | Stella West | Code XF | 132kV, 66kV |
| Bradford West | West Yorkshire | Padiham | ||
| Elland | ||||
| Kirkstall | ||||
| Monk Fryston | ||||
| Bredbury | Greater Manchester | Staylybridge | ||
| Macclesfield | ||||
| South Manchester | ||||
| Brimsdown | Greater London | Waltham Cross | 132kV | |
| Tottenham | ||||
| Brinsworth | South Yorkshire | Thurcroft | ||
| Templeborough | ||||
| BOC operations centre Brinsworth | ||||
| Chesterfield | ||||
| Tinsley Park | ||||
| Neeps End | ||||
| Bridgwater | Somerset | Hinkley Point | 132kV, 33kV | |
| Bushbury | West Midlands | link to Drakelow–Penn circuit | 132kV | |
| Bustleholme | West Midlands | Nechells | 132kV | |
| Drakelow | ||||
| Capenhurst | Cheshire West and Chester | Frodsham | 132kV | |
| Birkenhead | ||||
| Cardiff East | Cardiff | Pyle-Aberthaw circuit | ||
| Whitson | ||||
| Chessington | Surrey | West Weybridge | Code ZM | 132kV |
| Beddington | Code ZZU | |||
| Chesterfield | Derbyshire | High Marnham | 132kV | |
| Brinsworth | ||||
| Cilfynnyd | Rhondda | Upper Boat | 132kV | |
| Coventry | West Midlands | Ratcliffe | 132kV, 33kV | |
| Nechells | ||||
| Berkswell | ||||
| Cowbridge Tee | Cardiff | On Aberthaw, Cardiff East, Pyle circuits | ||
| Creyke Beck | East Yorkshire | Saltend North | ||
| Daines | Greater Manchester | South Manchester | ||
| 400kV substation | ||||
| Drakelow | Worcestershire | Bustleholm | 132kV | |
| Penn | ||||
| Dungeness | Kent | Power station 275kV to 400kV step-up transformer | ||
| Ealing | Greater London | Laleham | ||
| Willesden | ||||
| Elland | West Yorkshire | Ferrybridge | ||
| Stalybridge | ||||
| Bradford West | ||||
| Kirkstall | ||||
| Elstree | Hertfordshire | Waltham Cross | 132kV | |
| Watford | ||||
| Mill Hill | ||||
| Feckenham | Worcestershire | Bishops Wood | ||
| Berkswell | ||||
| Ferrybridge | North Yorkshire | Monk Fryston | ||
| Skelton Grange | ||||
| Elland | ||||
| Ffestiniog | Gwynedd | Trawsfynydd | ||
| Fiddlers Ferry | Warrington | Rainhill | 132kV | |
| Frodsham | ||||
| Fourstones | Northumberland | Stella West | ||
| Harker | Code XB | |||
| Frodsham | Halton | Fiddlers Ferry | 132kV | |
| Capenhurst | ||||
| Grangetown | Redcar and Cleveland | Feed from Lackenby | Underground cable | |
| Greystones | Redcar and Cleveland | Lackenby (400kV) | ||
| Tod Point | ||||
| Hackney | Greater London | Tottenham | 132kV, 66kV | |
| Hams Hall | Warwickshire | Coventry | 132kV | |
| Bustleholm | ||||
| Nechells | ||||
| Harker | Cumbria | Fourstones | Code XB | 132kV |
| Hartmoor | Durham | Hartlepool power station | Code 4TH | |
| Hawthorn Pit | ||||
| Hartlepool power station | Hartlepool | Saltholme | Code 4TG | |
| Hartmoor | Code 4TH | |||
| Hawthorne Pit | Durham | Hartmoor | 66kV | |
| Norton | Code 4TF | |||
| Offerton | ||||
| Hedon | East Yorkshire | Creyke Beck | ||
| Saltend | ||||
| High Marnham | Nottinghamshire | Chesterfield | ||
| Thurcroft-West Melton circuit | ||||
| Hinkley Point | Somerset | Bridgwater | ||
| Hurst | Greater London | New Cross | 132kV | |
| Littlebrook | ||||
| Iron Acton | South Gloucestershire | Melksham | 132kV, 33kV | |
| Whitson | ||||
| Iver | Buckinghamshire | Watford | 132kV | |
| Laleham | Code VW | |||
| North Hyde | ||||
| Jordanthorpe | South Yorkshire | Brinsworth | ||
| Pitsmoor | ||||
| Kearsley | Greater Manchester | Whitegate | 132kV | |
| Kirkby | Merseyside | Washway Farm | 132kV | |
| Rainhill | ||||
| Kirkstall | West Yorkshire | Elland | ||
| Bradford West | ||||
| Skelton Grange | ||||
| Kitwell | West Midlands | Bishops Wood | ||
| Ocker Hill | ||||
| Oldbury | ||||
| Knaresborough | North Yorkshire | Monk Fryston | ||
| Poppleton | ||||
| Lackenby | Redcar and Cleveland | Tod Point | 66kV | |
| Laleham | Surrey | Iver | Code VW | 132kV |
| Ealing | ||||
| West Weybridge | ||||
| Lister Drive | Merseyside | Kirkby | ||
| Birkenhead | ||||
| Littlebrook | Kent | Hurst | Code VN | |
| Macclesfield | Cheshire | Bredbury | ||
| Margam | Neath | Pyle | ||
| Baglan Bay | ||||
| Melksham | Wiltshire | Iron Acton | 132kV | |
| Mill Hill | Greater London | Elstree | 132kV | |
| Monk Fryston | North Yorkshire | Ferrybridge | ||
| Poppleton | ||||
| Knaresborough | ||||
| Bradford West | ||||
| Nechells | West Midlands | Hams Hall | ||
| Bustleholm | ||||
| Neepsend | South Yorkshire | Brinsworth | ||
| New Cross | Greater London | Wimbledon | 132kV, 66kV | |
| Hurst | ||||
| North Hyde | Greater London | Iver | 66kV, 11 kV | |
| Norton Lees | South Yorkshire | Pitsmoor | ||
| Sheffield City | ||||
| Jordanthorpe | ||||
| Brinsworth | ||||
| Norton | Stockton | Hawthorn Pit | ||
| Saltholme | ||||
| Ocker Hill | West Midlands | Willenhall | ||
| Berkswell | ||||
| Kitwell | ||||
| Offerton | Tyne and Wear | Hawthorn Pit | ||
| West Boldon | ||||
| Oldbury | West Midlands | Kitwell | ||
| 400kV from Drakelow | ||||
| Penn | West Midlands | Bustleholm | 132kV | |
| Feckenham | ||||
| Penwortham | Lancashire | Washway Farm | 132kV | |
| Pitsmoor | South Yorkshire | Sheffield City | ||
| Wincobank | ||||
| Neepsend | ||||
| Jordanthorpe | ||||
| Templeborough | ||||
| Poppleton | North Yorkshire | Knaresborough | ||
| Monk Fryston | ||||
| Pyle | Swansea | Aberthaw | ||
| Margam | ||||
| Rainhill | Merseyside | Kirkby | 132kV | |
| Fiddlers Ferry | ||||
| Ratcliffe | Leicestershire | Coventry | 132kV | |
| Redbridge | Greater London | Tottenham | ||
| Barking | ||||
| Rochdale | Lancashire | 400kV from Eggborough | ||
| Stalybridge | ||||
| Whitegate | ||||
| Saltend North | East Yorkshire | Saltend South | 132kV, 33kV | |
| Creyke Beck | ||||
| Saltend South | East Yorkshire | Saltend North | ||
| Saltholme | Redcar and Cleveland | Sabic Chemicals | ||
| Hartlepool power station | Code ZZA | |||
| Sellinge | Kent | Sellinge Converter | 270 kV DC to/from France | |
| Sheffield City | Sheffield | Brinsworth | ||
| Neepsend | ||||
| St. John’s Wood | Greater London | Tottenham | ||
| Skelton Grange | Leeds | Ferrybridge | ||
| Kirkstall | ||||
| South Manchester | Greater Manchester | Bredbury | ||
| Daines | ||||
| South Shields | Tyne and Wear | Tynemouth | ||
| West Boldon | ||||
| Spennymoor | Durham | 400kV? | ||
| Stalybridge | Greater Manchester | 400kV feed | ||
| Bredbury | ||||
| Rochdale | ||||
| Elland | ||||
| Stella West | Tyne and Wear | Blyth | Code XF | |
| Fourstones | ||||
| Swansea North | Swansea | 400kV feed | ||
| Baglan Bay | ||||
| Templeborough | South Yorkshire | Brinsworth | ||
| Pitsmoor | ||||
| Thorpe Marsh | South Yorkshire | West Melton | 66kV | |
| Thurcroft | South Yorkshire | Link from High Marnham–? circuit | 66kV, 11 kV | |
| Brinsworth | ||||
| Tilbury | Essex | Warley | Code Z3B | |
| Tinsley Park | South Yorkshire | Brinsworth | ||
| Tod Point | Redcar and Cleveland | Greystones | ||
| Hartlepool | ||||
| Tottenham | Greater London | Brimsdown | ||
| St. John's Wood | ||||
| Redbridge | ||||
| Hackney | ||||
| Trawsfynydd | Gwynedd | Ffestiniog | ||
| Tremorfa | Cardiff | Aberthaw | ||
| Whitson | ||||
| Tynemouth | Tyne and Wear | West Boldon | ||
| Blyth | ||||
| Upper Boat | Rhondda | Cilfynnyd | 132kV | |
| Aberthaw | ||||
| Uskmouth | Newport | Whitson | ||
| Alpha Steel | ||||
| Waltham Cross | Hertfordshire | Warley | ||
| Brimsdown | ||||
| Elstree | ||||
| Warley | Essex | Tilbury | Code Z3B | 132kV |
| Waltham Cross | ||||
| Washway Farm | Lancashire | Penwortham | 132kV | |
| Kirkby | ||||
| Watford | Hertfordshire | Elstree | 132kV | |
| Iver | ||||
| West Boldon | Tyne and Wear | Offerton | 66kV | |
| Tynemouth | ||||
| West Melton | South Yorkshire | Thorpe Marsh | ||
| Thurcroft | ||||
| West Weybridge | Surrey | Laleham | 132kV | |
| Chessington | Code ZM | |||
| Whitegate | Greater Manchester | Kearsley | 132kV | |
| Rochdale | ||||
| Whitson | Newport | Iron Acton | ||
| Uskmouth | ||||
| Cardiff East | ||||
| Tremorfa | ||||
| Wincobank | South Yorkshire | Pitsmoor | ||
| Templeborough | ||||
| Willenhall | West Midlands | Bushbury | ||
| Ocker Hill | ||||
| Willesden | Greater London | Ealing | 132kV, 66kV | |
| Willington | Derbyshire | 400kV feed | ||
| Wilton | Redcar and Cleveland | Feed from Wilton power stations | ||
| Wimbledon | Greater London | Beddington | 132kV | |
| New Cross |
The 400kV substations in Scotland and their interconnections are given in the following table. The identification codes for the interconnecting lines and the lower voltage transmission, if any, from the substation are also given.
There are two interconnections between England and Scotland. On the west coast the 400kV overland line between Harker substation in Cumbria and Gretna substation, Dumfries and Galloway. On the east coast the 400kV line between Stella West substation, Tyne and Wear and Eccles substation, Borders.
In addition the Western HVDC underground and sub-marine link connects Flintshire Bridge Converter station, in Flintshire Wales, to the Western HVDC Converter station near Hunterston.
| Beauly | Highland | Fort Augustus | 275kV, 132kV | |
| Branxton | East Lothian | Torness | ||
| Coalburn | South Lanarkshire | Strathaven | ||
| Elvanfoot | ||||
| Cockenzie | East Lothian | Eccles | 275kV | |
| Crystal Rig wind farm | East Lothian | On Torness–Smeaton circuits | ||
| Denny North | Falkirk | Fort Augustus | 275kV, 132kV | |
| Devol Moor | Inverclyde | Inverkip | 132kV, 33kV | |
| Eccles | Borders | Stella West (England) | 132kV, 33kV | |
| Torness | ||||
| Cockenzie | ||||
| Elvanfoot | South Lanarkshire | Moffat | 275kV | |
| Coalburn | ||||
| Elvanfoot North | South Lanarkshire | |||
| Fallago Rig wind farm | East Lothian | On Torness–Smeaton circuits | ||
| Fort Augustus | Highland | Beauly | 275kV, 132kV | |
| Denny | ||||
| Gretna | Dumfries and Galloway | Harker (England) | 132kV | |
| Moffat | ||||
| Hunterston Power station | North Ayrshire | Hunterston North & East | 400kV | |
| Hunterston Western HVDC Converter (600 kV DC) | Flintshire Bridge Converter (Wales) | |||
| Hunterston North | Neilston/Windyhill | |||
| Hunterston East | Neilston | |||
| Inverkip | Inverclyde | Devol Moor | ||
| Link on Neilston–Windy Hill circuit | ||||
| Neilston | ||||
| Kilmarnock South | East Ayrshire | Neilston | 275kV | |
| Strathven | ||||
| Melgarve | Highland | Link on Fort Augustus–Denny circuit | 275kV | |
| Moffat | Dumfries | Gretna | ||
| Elvanfoot | ||||
| Neilston | Renfrewshire | Kilmarnock South | 275kV,132kV | |
| Hunterston | ||||
| Inverkip | ||||
| Windyhill | ||||
| Smeaton | East Lothian | Torness | 275kV | |
| Wishaw | ||||
| Strathaven | South Lanarkshire | Kilmarnock South | 275kV | |
| Wishaw | ||||
| Coalburn | ||||
| Torness | East Lothian | Smeaton | ||
| Eccles | ||||
| Windyhill | West Dunbarton | Neilston | 275kV,132kV | |
| Wishaw | North Lanarkshire | Strathaven | 275kV | |
| Smeaton |
The 275kV substations in Scotland and their interconnections are given in the following table. The identification codes for the interconnecting lines and the lower voltage transmission, if any, from the substation are also given.
The Moyle Interconnector provides a high-voltage link between the Scotland and Northern Ireland 275kV systems.
| Auchencrosh Static Inverter Plant | South Ayrshire | Mark Hill | ||
| Moyle Interconnector North and South | 250 kV DC to Northern Ireland | |||
| Ayr | South Ayrshiire | Link from Coylton-Kilmarnock Town circuits | ||
| Beauly | Highland | Feed from 400kV | 132kV | |
| Fasnakyle | ||||
| Fyrish | ||||
| Knocknagael | ||||
| Blackhillock | Moray | Knocknagael | ||
| Keith | ||||
| Kintore | ||||
| 400kV feed from Spittal | ||||
| Busby | East Renfewshire | Neilston | ||
| Giffnock | ||||
| Strathaven | ||||
| Clyde North | South Lanarkshire | Elvanfoot 400kV | ||
| Clyde South | South Lanarkshire | Elvanfoot 400kV | ||
| Clyde's Mill | Glasgow | 400kV feed from Strathaven | ||
| Easterhouse | ||||
| Longannet | ||||
| Dalmaarnock/Charlotte Street | ||||
| East Kilbride | ||||
| Coatbridge | North Lanarkshire | Newarthill | ||
| Cockenzie | East Lothian | 400kV feed from Eccles | ||
| Smeaton | ||||
| Kaimes | ||||
| Coylton | South Ayrshire | Kilmarnock Town | 132kV | |
| New Cumnock | ||||
| Cruachan | Argyll and Bute | Dalmally | ||
| Currie | Edinburgh | Grangemouth | 132kV (Sighthill) | |
| Kincardine | ||||
| Kaimes | ||||
| Sighthill | ||||
| Dalmally | Argyll and Bute | Windyhill | ||
| Inverarnan | ||||
| Cruachan | ||||
| Denny | Falkirk | 400kV feed from Melgrave | 132kV | |
| Longannet | ||||
| Bonnybridge | ||||
| Lambhill | ||||
| Tummel | ||||
| Dounreay | Highland | Thurso South | 132kV | |
| Loch Buidhe | ||||
| Easterhouse | Glasgow | Longannet | ||
| Clyde's Mill | ||||
| Newarthill | ||||
| East Kilbride South | South Lanarkshire | Strathaven | ||
| Neilston | ||||
| Whitelee | ||||
| Whitelee Extension | ||||
| Fasnakyle | Highland | Beauly | ||
| Fork Augustus | ||||
| Fetteresso | Aberdeenshire | Kintore | 132kV | |
| Tealing | ||||
| Kincardine | ||||
| Fort Augustus | Highland | Fasnakyle | 132kV | |
| Tummel | ||||
| Foyers | Highland | Knocknagael | ||
| Fyrish | Highland | Loch Buidhe | 132kV | |
| Beauly | ||||
| Glenrothes | Fife | Tealing | ||
| Westfield | ||||
| Grangemouth | Falkirk | Kincardine | 132kV | |
| Currie | ||||
| Inverarnan | Stirling | Windyhill | 132kV | |
| Dalmally | ||||
| Kaimes | Edinburgh | Currie | ||
| Dewar | ||||
| Cockenzie | ||||
| Smeaton | ||||
| Kilmarnock Town | East Ayrshire | Colyton | 132kV | |
| Feed from 400kV Kilmarnock South | ||||
| Kincardine | Fife | Fetteresso | ||
| Tealing | ||||
| Grangemouth | ||||
| Currie | ||||
| Longannet | ||||
| Kintore | Aberdeenshire | 400kV feed from Blackhillock | 132kV | |
| Blackhillock | ||||
| Fetteresso | ||||
| Tealing | ||||
| Peterhead | ||||
| Persley | ||||
| Knocknagael | Highland | Beauly | 132kV | |
| Foyers | ||||
| Tomatin | ||||
| Blackhillock | ||||
| Lambhill | Glasgow | Denny | ||
| Windyhill | ||||
| Port Dundas | 132kV | |||
| West George Street | ||||
| Loch Buidhe | Highland | Dounreay | 132kV | |
| Fyrish | ||||
| Longannet | Fife | Westfield | ||
| Mossmorran | ||||
| Easterhouse | ||||
| Kincardine | ||||
| Bonnybridge | ||||
| Denny | ||||
| Clyde's Mill | ||||
| Mark Hill | South Ayrshire | Auchencrosh | 132kV | |
| Kilgallioch | ||||
| Coylton | ||||
| Neilston | East Renfewshire | 400kV feed from Hunterston East | 132kV | |
| East Kilbride South | ||||
| Busby | ||||
| Windyhill | ||||
| Newarthill | North Lanarkshire | 400kV feed from Wishaw | ||
| Easterhouse | ||||
| Coatbridge | ||||
| New Cumnock | East Ayrshire | Coylton | 132kV | |
| Persley | Aberdeen | Peterhead | 132kV | |
| Kintore | ||||
| Peterhead | Aberdeenshire | Blackhillock | 132kV | |
| Persley | ||||
| Kintore | ||||
| Smeaton | Fife | 400kV feed from Fallago | ||
| Cockenzie | ||||
| Kaimes | ||||
| Portobello | 132kV | |||
| Shrubhill | 132kV | |||
| Spittal | Highland | Thurso South | 132kV | |
| Tealing | Angus | Kintore | 132kV | |
| Kincardine | ||||
| Fetteresso | ||||
| Glenrothes | ||||
| Westfield | ||||
| Thurso South | Highland | Dounreay | 132kV | |
| Spittal | ||||
| Tomatin | Highland | Knocknagael | 132kV | |
| Tummel | Perthshire | Fort Augustus | 132kV | |
| Denny | ||||
| Westfield | Fife | Glenrothes | 132kV | |
| Mossmorran | ||||
| Tealing | ||||
| Longannet | ||||
| Whitelee | Borders | East Kilbride South | ||
| Whitelee Extension | Borders | East Kilbride South | ||
| Windyhill | West Dunbartonshire | Neilston | 132kV | |
| Lambhill | ||||
| Dalmally | ||||
| Inverarnan | ||||
| Drumchapel | 132kV |
There are no 400kV systems in Northern Ireland; the highest transmission voltage is 275kV. The substations and their interconnections are given in the table. The lower voltage (generally 110kV) transmission from the substation is also given.[15]
| Ballycronan More HVDC Inverter | Antrim | Moyle Interconnector North and South | 250 kV DC from Scotland | |
| Ballylumford | ||||
| Hannahstown | ||||
| Ballylumford power station | Antrim | Kells | 110kV | |
| Ballycronan More | ||||
| Castlereagh | Lisburn and Castlereagh City | Tandragee | 110kV | |
| Ballycronan More | ||||
| Hannahstown | Antrim | Castlereagh | ||
| Magherafelt | ||||
| Kells | Antrim | Ballylumford | 110kV | |
| Kilroot | ||||
| Kells | ||||
| Kilroot power station | Antrim | Tandragee–Castlereagh circuits | 110kV, 33kV | |
| Magherafelt | ||||
| Lisahally power station | Derry | Tamnamore | 110kV | |
| Magherafelt | Londonderry | Kells | ||
| Lisahally power station | ||||
| Tandragee | ||||
| Tamnamore | Tyrone | Magherafelt | 110kV | |
| Castlereagh | ||||
| Tandragee | Armagh | Louth (Republic of Ireland) | Interconnector | 110kV |
| Tamnamore | ||||
| Castlereagh |