[Electrification reference list] Grid connections/traction power networks on DC railways

[GraphitProjekt]

I've been looking into how the railway's 33kV AC feeders and how they are supplied by the 'Grid' power network(s) and have noticed two general formats that I'll explain in a couple diagrams.
a)b)
The arrangement in A (left) is by far the most common: here the railway gets one or more 33kV circuits off a switchboard that is shared with the local primary distribution network in that area.
The arrangement in B (right) is different because the railway has (normally 2) 132/33kV transformers dedicated to its load, and so you only see them in the most high demand grid connections.

My question is: which grid connections have transformers dedicated to railway use?

Here I'll show a list of all the grid connections I'm aware of and whether or not I've seen that they have dedicated transformers. Although most Network Rail HVAC feeders are 33kV, a few are at lower voltages.
GSPs (that I know of!) with transformers dedicated to railway supply:

• Southern
  • New Cross
    • actually from the 275kV transmission substation with 2x 275/33kV transformers
    • prior to ~2015, New Cross was actually 3x 66kV cables from the switchboard of UKPN's New Cross 275/66 substation. The cables went to Lewisham, Nunhead and South Bermondsey. Was this the only time 66kV was used by the railway?
  • Wimbledon
    • 2x 132/33kV transformers onto a dedicated switchboard ("Wimbledon D") of 5x 33kV feeds. Fed from Wimbledon 275/132.
  • Hastings
    • 1x 132/33kV transformer off Hastings Grid, which itself is supplied by Ninfield 400/132
  • Bournemouth-Weymouth 11kV electrification
    • Wareham
      • 1x 33/11kV transformer from 33kV switchboard at Wareham 132/33kV substation, 11kV transformer seems to be owned by NwR
    • Redlands
      • 1x 33/11kV transformer from 33kV switchboard at Redlands Primary substation, 11kV transformer seems to be owned by NwR
• East London Line
  • Canal Junction
    • 2x 132/33kV transformers off of New Cross 275/132
  • Hoxton
    • 1x 132/33kV transformer off of City Road [Main] 400/132
    • I think this one is backup only
• Isle of Wight
  • The three DC traction substations each have their own 33kV connection to the local grid with no railway HV cables on the island (Ryde, Rowborough, Sandown)
• North London
  • Willesden (for Watford DC)
    • 2x 132/11kV transformers from NG "Willesden Grid" 275/132. The 2x 132kV lines to Willesden 11kV are tee'd off the 2 lines going to Acton Lane 25kV
• Merseyrail
  • Instead of 132kV and 33kV, Merseyrail is all at 11kV connecting the local power grid's 33kV network
  • I think all the Merseyside GSPs have dedicated railway transformers though I could be wrong on this.
  • Bank Hall (x2)
    • direct connections from the 33kV switchboard at Lister Drive (275/132/33)
  • Shore Road (x2)
    • off 2x 33kV powerlines directly from Woodside Grid B, and 1 more powerline from Wallesey via other 33/11 substations
  • Bromborough (x2)
    • from the dual circuit 33kV powerline between Bromborough Grid and Rock Ferry Grid
  • Hillside (x2)
    • one 33kV powerline from Formby Grid, and another powerline from Southport Grid via other substations
  • Birkenhead (x?)
• LUL
  • Lots Road
    • 2x 132/22kV transformers connected to Wimbledon 275/132
  • Neasden
    • 2x 132/22kV transformers connected to Hendon 132
  • Mansell Street
    • 2x 132/22kV transformers connected to City Road [main] 400/132
  • Stephenson Street
    • 2x 132/22kV transformers connected to West Ham 400/132
  • Griffith House aka Chapel Street
    • 2x 132/22kV transformers connected to St Johns Wood "B" 132kV
  • Manor House
    • 2x 132/11kV transformers connected to Tottenham
  • (East) Finchley
    • 2x 33/11kV transformers connected to Finchley Grid 132/33
    • The source for LUL mentions Finchley as one of the "low" power connections along with Acton Lane, but it still has dedicated transformers

And for the sake of completeness, all the other GSPs I know of (2x 33kV connections unless otherwise stated)

• South East
  • Bromley
  • Northfleet
  • Maidstone
  • Sittingbourne
  • Queenborough (x1, backup connection for Sheerness branch)
  • Thanet
  • Canterbury
  • Folkstone
  • Ashford
  • Tunbridge Wells
  • (the line between Hastings and Tunbridge Wells is at 11kV, the railway internally steps down the 33kV supplies from Tunbridge Wells and Hastings GSPs)
• South Central
  • Croydon "B"
  • Ashburton
  • Three Bridges (x3)
  • Eastbourne
  • Dormansland
    • This one is absolutely weird.
    • 1x 33kV line which Network Rail immediately steps down to 11kV (for the East Grinstead line), and also to 22kV for the Redhill-Tonbridge line. And then another separate 11kV connection only for the East Grinstead line.
  • Fishergate
  • Hunston (x1)
• Wessex
  • Leatherhead
  • Byfleet (x3)
  • Reading (x1)
  • Camberley
  • Aldershot
  • Alton (x1)
  • Wymering
    • 2x 33kV lines and 1x 11kV for the lines between Cosham and St Denys/Eastleigh
  • Basingstoke
  • St Cross (x1)
  • Southampton
  • Bournemouth
• North London
  • Acton Lane (1x 22kV for West London Line)
  • Poole Street (2x 11kV for Northern City Line)
  • Maiden Lane (1x 11kV for the last remnants of NLL 3rd rail)
  • Stratford International (1x 11kV backup for Maiden Lane)
• LUL
  • Acton Lane
    • 3x powerlines from the 22kV Switchboard at Acton Lane 66/22. This is the same substation that supplied the West London Line connection
    • The powerlines seem to go to 3 different LUL 22kV switching stations named: Brentham New, Greenford New, and Park Royal.
    • Considered a "low power" grid connection like LUL Finchley.

 

[GRALISTAIR]

Wow - looks like you are undertaking another major electrification project. Thanks for posting, I will follow with interest and post in the pinned Electrification Resources thread this weekend.

 

[youngpete]

Update re Hastngs.

I've been looking into how the railway's 33kV AC feeders and how they are supplied by the 'Grid' power network(s) and have noticed two general formats that I'll explain in a couple diagrams.
a)View attachment 185274b)View attachment 185275
The arrangement in A (left) is by far the most common: here the railway gets one or more 33kV circuits off a switchboard that is shared with the local primary distribution network in that area.
The arrangement in B (right) is different because the railway has (normally 2) 132/33kV transformers dedicated to its load, and so you only see them in the most high demand grid connections.

My question is: which grid connections have transformers dedicated to railway use?

Here I'll show a list of all the grid connections I'm aware of and whether or not I've seen that they have dedicated transformers. Although most Network Rail HVAC feeders are 33kV, a few are at lower voltages.
GSPs (that I know of!) with transformers dedicated to railway supply:

• Southern
  • New Cross
    • actually from the 275kV transmission substation with 2x 275/33kV transformers
    • prior to ~2015, New Cross was actually 3x 66kV cables from the switchboard of UKPN's New Cross 275/66 substation. The cables went to Lewisham, Nunhead and South Bermondsey. Was this the only time 66kV was used by the railway?
  • Wimbledon
    • 2x 132/33kV transformers onto a dedicated switchboard ("Wimbledon D") of 5x 33kV feeds. Fed from Wimbledon 275/132 which also feeds LUL's Lots Road.
• East London Line
  • Canal Junction
    • 2x 132/33kV transformers off of New Cross 275/132
  • Hoxton
    • 1x 132/33kV transformer off of City Road (Main) 400/132
    • I think this one is backup only
• Isle of Wight
  • The three DC traction substations each have their own 33kV connection to the local grid with no railway HV cables on the island (Ryde, Rowborough, Sandown)
• North London
  • Willesden (for Watford DC)
    • 2x 132/11kV transformers from NG "Willesden Grid" 275/132. The 2x 132kV lines to Willesden 11kV are tee'd off the 2 lines going to Acton Lane 25kV
• Merseyrail
  • Instead of 132kV and 33kV, Merseyrail is all at 11kV connecting the local power grid's 33kV network
  • I think all the Merseyside GSPs have dedicated railway transformers though I could be wrong on this.
  • Bank Hall (x2)
    • direct connections from the 33kV switchboard at Lister Drive (275/132/33)
  • Shore Road (x2)
    • off 2x 33kV powerlines directly from Woodside Grid B, and 1 more powerline from Wallesey via other 33/11 substations
  • Bromborough (x2)
    • from the dual circuit 33kV powerline between Bromborough Grid and Rock Ferry Grid
  • Hillside (x2)
    • one 33kV powerline from Formby Grid, and another powerline from Southport Grid via other substations
  • Birkenhead (x?)

And for the sake of completeness, all the other GSPs I know of (2x 33kV connections unless otherwise stated)

• South East
  • Bromley
  • Northfleet
  • Maidstone
  • Sittingbourne
  • Queensborough
  • Thanet
  • Canterbury
  • Folkstone
  • Ashford
  • Tunbridge Wells
  • Hastings
  • (the line between Hastings and Tunbridge Wells is at 11kV, the railway internally steps down the 33kV supplies from the last two GSPs)
• South Central
  • Croydon "B"
  • Ashburton
  • Three Bridges (x3)
  • Eastbourne
  • Dormansland
    • This one is absolutely weird. 1x 33kV line which Network Rail immediately steps down to 11kV (for the East Grinstead line), and to 22kV for the Redhill-Tonbridge line. And then another separate 11kV connection only for the East Grinstead line.
  • Fishergate
  • Hunston (x1)
• Wessex
  • Leatherhead
  • Byfleet (x3)
  • Reading (x1)
  • Camberley
  • Aldershot
  • Alton (x1)
  • Wymering
    • 2x 33kV lines and 1x 11kV for the lines between Cosham and St Denys/Eastleigh
  • Basingstoke
  • St Cross (x1)
  • Southampton
  • Bournemouth
  • Wareham (1x 11kV)
  • Redlands (1x 11kV)
• North London
  • Acton Lane (1x 22kV for West London Line)
  • Poole Street (2x 11kV for Northern City Line)
  • Maiden Lane (1x 11kV for the last remnants of NLL 3rd rail)
  • Stratford International (1x 11kV backup for Maiden Lane)

A 132/33kV feed was provided at Hastings at the time of the East Coastway Electrification from Brighton to Ore (1930?). When the Tonbridge Hastings Line was electrified a 33kv connection was made from this circuit to a 33/11kV Transformer in the St Leonards area and then an 11kV cable was laid up the track as usual to meet the 11kV cable coming from Tunbridge Wells Grid. About midway along the circuit (Etchingham I believe) an 11kV/11kV transformer was installed capable of boosting voltage either way in the event of the whole circuit needing to be fed from one end or the other. Normal feeding was with a split at halfway.

== Doublepost prevention - post automatically merged: 1 Aug 2025 ==

I've been looking into how the railway's 33kV AC feeders and how they are supplied by the 'Grid' power network(s) and have noticed two general formats that I'll explain in a couple diagrams.
a)View attachment 185274b)View attachment 185275
The arrangement in A (left) is by far the most common: here the railway gets one or more 33kV circuits off a switchboard that is shared with the local primary distribution network in that area.
The arrangement in B (right) is different because the railway has (normally 2) 132/33kV transformers dedicated to its load, and so you only see them in the most high demand grid connections.

My question is: which grid connections have transformers dedicated to railway use?

Here I'll show a list of all the grid connections I'm aware of and whether or not I've seen that they have dedicated transformers. Although most Network Rail HVAC feeders are 33kV, a few are at lower voltages.
GSPs (that I know of!) with transformers dedicated to railway supply:

• Southern
  • New Cross
    • actually from the 275kV transmission substation with 2x 275/33kV transformers
    • prior to ~2015, New Cross was actually 3x 66kV cables from the switchboard of UKPN's New Cross 275/66 substation. The cables went to Lewisham, Nunhead and South Bermondsey. Was this the only time 66kV was used by the railway?
  • Wimbledon
    • 2x 132/33kV transformers onto a dedicated switchboard ("Wimbledon D") of 5x 33kV feeds. Fed from Wimbledon 275/132 which also feeds LUL's Lots Road.
• East London Line
  • Canal Junction
    • 2x 132/33kV transformers off of New Cross 275/132
  • Hoxton
    • 1x 132/33kV transformer off of City Road (Main) 400/132
    • I think this one is backup only
• Isle of Wight
  • The three DC traction substations each have their own 33kV connection to the local grid with no railway HV cables on the island (Ryde, Rowborough, Sandown)
• North London
  • Willesden (for Watford DC)
    • 2x 132/11kV transformers from NG "Willesden Grid" 275/132. The 2x 132kV lines to Willesden 11kV are tee'd off the 2 lines going to Acton Lane 25kV
• Merseyrail
  • Instead of 132kV and 33kV, Merseyrail is all at 11kV connecting the local power grid's 33kV network
  • I think all the Merseyside GSPs have dedicated railway transformers though I could be wrong on this.
  • Bank Hall (x2)
    • direct connections from the 33kV switchboard at Lister Drive (275/132/33)
  • Shore Road (x2)
    • off 2x 33kV powerlines directly from Woodside Grid B, and 1 more powerline from Wallesey via other 33/11 substations
  • Bromborough (x2)
    • from the dual circuit 33kV powerline between Bromborough Grid and Rock Ferry Grid
  • Hillside (x2)
    • one 33kV powerline from Formby Grid, and another powerline from Southport Grid via other substations
  • Birkenhead (x?)

And for the sake of completeness, all the other GSPs I know of (2x 33kV connections unless otherwise stated)

• South East
  • Bromley
  • Northfleet
  • Maidstone
  • Sittingbourne
  • Queensborough
  • Thanet
  • Canterbury
  • Folkstone
  • Ashford
  • Tunbridge Wells
  • Hastings
  • (the line between Hastings and Tunbridge Wells is at 11kV, the railway internally steps down the 33kV supplies from the last two GSPs)
• South Central
  • Croydon "B"
  • Ashburton
  • Three Bridges (x3)
  • Eastbourne
  • Dormansland
    • This one is absolutely weird. 1x 33kV line which Network Rail immediately steps down to 11kV (for the East Grinstead line), and to 22kV for the Redhill-Tonbridge line. And then another separate 11kV connection only for the East Grinstead line.
  • Fishergate
  • Hunston (x1)
• Wessex
  • Leatherhead
  • Byfleet (x3)
  • Reading (x1)
  • Camberley
  • Aldershot
  • Alton (x1)
  • Wymering
    • 2x 33kV lines and 1x 11kV for the lines between Cosham and St Denys/Eastleigh
  • Basingstoke
  • St Cross (x1)
  • Southampton
  • Bournemouth
  • Wareham (1x 11kV)
  • Redlands (1x 11kV)
• North London
  • Acton Lane (1x 22kV for West London Line)
  • Poole Street (2x 11kV for Northern City Line)
  • Maiden Lane (1x 11kV for the last remnants of NLL 3rd rail)
  • Stratford International (1x 11kV backup for Maiden Lane)

More information about the South East.

Queensborough is Queenborough and is a single 33kV feed from the UKPN Network and acts as a standby supply only for the Sheerness Branch.

Tunbridge Wells is two 33kV feeds and one is taken to a 33/11kV Transformer for feeding the Hastings Line at 11kV. The second is the initial 33kV feed installed for the 1930s electrification to Sevenoaks, Medway Towns and Maidstone.

Hastings is a single 132/33kV feed and as stated earlier was installed for the Coastway East Electrification in the 1930s and is dedicated to railway use. All other loads in the Hastings area were and are still generally fed from 132/11kV Transformers.

Maidstone and Ashford supplies were installed rather later than the other ones and were initially for Eurostar on the 3rd Rail and also the added load of the newer trains.

Northfleet was initially 4 feeders,, 2 to the Dartford line and 2 to the Victoria Chatham line. One of these 4 has been decommssioned but I dont know which one.

 

[GraphitProjekt]

Wow - looks like you are undertaking another major electrification project. Thanks for posting, I will follow with interest and post in the pinned Electrification Resources thread this weekend.

yes thank you! I've actually recently finished the big project this was a part of - which is a map showing the extents of railway grid connections in the London area, but going quite far south. You should be able to download it here from my Flickr. But i'll put a couple screenshots here for preview. But this whole thing about dedicated railway transformers was an interesting loose end that I just couldn't find anything about online.

I think my next trick will be adding some traces of powerlines from openinframap to show how the grid infrastructure relates to railway GSPs.
Regarding other DC railways:
- For LUL i know where the grid connections are (in fact i'll add them now to my original message) but no idea where the DC substations are.
- For DLR I think i have enough to find where the DC substations are but no idea how the power is supplied/whether they have HV AC
- For Tyne & Wear, I've found nothing at all! I could probably sit down and watch a few hours of cabview footage looking out for DC substations cross-referencing with Google Earth to locate transformers (to tell if it's a TPH or a TSS) but that could be quite inaccurate and maybe too dull even for me. Still, no idea of the supply side. So if anyone has some insights for T&W specifically I'd be interested!
- For the tram systems, ditto everything I've said about T&W. Although there is some good info on Croydon i found.

== Doublepost prevention - post automatically merged: 1 Aug 2025 ==

Update re Hastngs.

A 132/33kV feed was provided at Hastings at the time of the East Coastway Electrification from Brighton to Ore (1930?). When the Tonbridge Hastings Line was electrified a 33kv connection was made from this circuit to a 33/11kV Transformer in the St Leonards area and then an 11kV cable was laid up the track as usual to meet the 11kV cable coming from Tunbridge Wells Grid. About midway along the circuit (Etchingham I believe) an 11kV/11kV transformer was installed capable of boosting voltage either way in the event of the whole circuit needing to be fed from one end or the other. Normal feeding was with a split at halfway.

A one-to-one transformer that is mean to "boost" voltage, how intriguing! Everytime I think I understand what a transformer can be used for, there's always something more. That piece of equipment sounds eerily familiar to the so-called "booster transformers" used on 25kV lines although for a completely different purpose.

== Doublepost prevention - post automatically merged: 1 Aug 2025 ==


More information about the South East.

thank you, edits made

Northfleet was initially 4 feeders,, 2 to the Dartford line and 2 to the Victoria Chatham line. One of these 4 has been decommssioned but I dont know which one.

Interesting you say that! In a 2014ish UKPN document I found online they give this blurry schematic.

Northfleet East (the main 400/132 substation in the area) has a 33kV local switchboard shown on the left with 3x 132/33kV transformers. I take it the diagram there is incomplete because elsewhere it shows Northfleet East 132/33 supplying a range of local primary substations. But in this diagram it does seem to be discussing BR feeds - perhaps shown here due to their priority? It seems to be saying BR1112, BR1126, BR1637 and BR 1639 although it's too blurry to tell some of those digits definitively.
My main source for all of this is a network rail document briefly shown in a PWI lecture on youtube that seems to be more up to date but even more blurry.


But I can make out feeder 1112 going down towards the Chatham mainline so these schematics must be talking about the same thing.

 

[swt_passenger]

I think there were a couple of RAIB reports that included a bit about TW Metro power supplies after incidents that led to fires. I think the protection couldn’t detect a partial short on a unit. The reports give a bit of a steer on how the power is set up, but neither of them list every location.

South Gosforth 2013:

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/410719/130925_R182013_South_Gosforth.pdf

Walkergate 2014:

https://assets.publishing.service.gov.uk/media/55b8b9bbe5274a151e000011/R092015_150730_Walkergate.pdf

But there may be more reports I didn’t search for long…

 

[GraphitProjekt]

thanks for those! I'll have a look later

 

[Elecman]

I've been looking into how the railway's 33kV AC feeders and how they are supplied by the 'Grid' power network(s) and have noticed two general formats that I'll explain in a couple diagrams.
a)View attachment 185274b)View attachment 185275
The arrangement in A (left) is by far the most common: here the railway gets one or more 33kV circuits off a switchboard that is shared with the local primary distribution network in that area.
The arrangement in B (right) is different because the railway has (normally 2) 132/33kV transformers dedicated to its load, and so you only see them in the most high demand grid connections.

My question is: which grid connections have transformers dedicated to railway use?

Here I'll show a list of all the grid connections I'm aware of and whether or not I've seen that they have dedicated transformers. Although most Network Rail HVAC feeders are 33kV, a few are at lower voltages.
GSPs (that I know of!) with transformers dedicated to railway supply:

• Southern
  • New Cross
    • actually from the 275kV transmission substation with 2x 275/33kV transformers
    • prior to ~2015, New Cross was actually 3x 66kV cables from the switchboard of UKPN's New Cross 275/66 substation. The cables went to Lewisham, Nunhead and South Bermondsey. Was this the only time 66kV was used by the railway?
  • Wimbledon
    • 2x 132/33kV transformers onto a dedicated switchboard ("Wimbledon D") of 5x 33kV feeds. Fed from Wimbledon 275/132.
  • Hastings
    • 1x 132/33kV transformer off Hastings Grid, which itself is supplied by Ninfield 400/132
• East London Line
  • Canal Junction
    • 2x 132/33kV transformers off of New Cross 275/132
  • Hoxton
    • 1x 132/33kV transformer off of City Road [Main] 400/132
    • I think this one is backup only
• Isle of Wight
  • The three DC traction substations each have their own 33kV connection to the local grid with no railway HV cables on the island (Ryde, Rowborough, Sandown)
• North London
  • Willesden (for Watford DC)
    • 2x 132/11kV transformers from NG "Willesden Grid" 275/132. The 2x 132kV lines to Willesden 11kV are tee'd off the 2 lines going to Acton Lane 25kV
• Merseyrail
  • Instead of 132kV and 33kV, Merseyrail is all at 11kV connecting the local power grid's 33kV network
  • I think all the Merseyside GSPs have dedicated railway transformers though I could be wrong on this.
  • Bank Hall (x2)
    • direct connections from the 33kV switchboard at Lister Drive (275/132/33)
  • Shore Road (x2)
    • off 2x 33kV powerlines directly from Woodside Grid B, and 1 more powerline from Wallesey via other 33/11 substations
  • Bromborough (x2)
    • from the dual circuit 33kV powerline between Bromborough Grid and Rock Ferry Grid
  • Hillside (x2)
    • one 33kV powerline from Formby Grid, and another powerline from Southport Grid via other substations
  • Birkenhead (x?)

Birkenhead is a single 33/11kV feed and is actually the new feeder at West Float near Birkenhead Depot

 

[GraphitProjekt]

This thing looks suspiciously DNO like and was constructed since 2020. I know that Birkenhead is one of the new GSPs done for the PSU.

 

[Nicholas Lewis]

• Dormansland
  • This one is absolutely weird.
  • 1x 33kV line which Network Rail immediately steps down to 11kV (for the East Grinstead line), and also to 22kV for the Redhill-Tonbridge line. And then another separate 11kV connection only for the East Grinstead line.

There was originally a single 33kV feeder to Dormansland s/stn installed as part of the East Grinstead Line electrification in 1987. A 2nd 33kV feeder was then installed in 1992/3 to power the Redhill to Tonbridge line electrification. It was stepped down to 22kV at Crowhurst Jcn. This line was intended as the prime freight route from the Channel Tunnel using the class 92's so was not suitable for 11kV. Subsequently to allow 12 car Electrostar working on the East Grinstead line a feed was taken from the Crowhurst 33kV feeder to reinforce the original 11kV system at Eden via a step down transformer.

 

[Elecman]

This thing looks suspiciously DNO like and was constructed since 2020. I know that Birkenhead is one of the new GSPs done for the PSU.

That link doesn’t work for me

== Doublepost prevention - post automatically merged: 2 Aug 2025 ==

This is the Birkenhead Feeder

 

[etr221]

yes thank you! I've actually recently finished the big project this was a part of - which is a map showing the extents of railway grid connections in the London area, but going quite far south. You should be able to download it here from my Flickr.

Unfortunately only in low resolution (1024 × 481) format

 

[GraphitProjekt]

Unfortunately only in low resolution (1024 × 481) format

damm! Today I learned you have to have a paying subscription to flikr to download above 1024x481, even though the original image i put up there is way bigger. Hosting images online is such a palaver! I can just send it hear as a vector though, let me know the if the fonts are messed up.

 

[etr221]

Thanks. Downloaded it ok, and it looks ok generally in my PDF viewer, except that the AT Feeder Station symbol is a bit corrupt in places. The text appears ok on looking at it, but doing a copy and paste (to, e.g., put link into my browser) doesn't work - some sort of coding error, methinks.
One question - am I right in thinking that Note B should read Queens Road (not Park)?. Also I've spotted a couple of typos (Wallington, Addlestone)

Now I have to try and make and make sense of it all!

 

[GraphitProjekt]

Your eye is much keener than mine, thanks for that - you're right on all counts.
Thanks for pointing that out about the fonts. I was initially wondering if they'd show up at all. I did some reading and text pasting wrongly seems to be an issue with those particular typefaces I used (Acumin variable concept, Myriad variable concept) or more likely whatever kind of outdated strange version of them came built in with my old copy of illustrator. In particular, those typefaces' Encoding system (whatever that exactly is) is of an unrecognised/non-standard variant. If you went to copy the text "romford rail operating centre", that typeface (Bahnschrift) does paste correctly. Something I had no idea about which I'll have to keep in mind going forwards.

I'll have to just put the links here: PWI 2024, romford ecr 2010, UKPN 2014

 

[Trainguy34]

Does the Canterbury one serve both the Dover Branch of the Chatham Main Line and Ashford - Ramsgate or just one?

 

[GraphitProjekt]

It does both lines. In fact, even the individual DC substation at Canterbury serves both lines as they cross each other. This is pretty much the case whenever two lines cross each other but are not connected by any rail line.

 

[Nicholas Lewis]

It does both lines. In fact, even the individual DC substation at Canterbury serves both lines as they cross each other. This is pretty much the case whenever two lines cross each other but are not connected by any rail line.

Indeed happens at Maidstone and Chislehurst substations. Then you have Penge s/stn on the South Central lines feeding the South Eastern lines below. There were also a few track paralleling huts where it happened as well (Chiswick & New Beckenham) although both subsequently upgraded to substations.

 

[GraphitProjekt]

There was originally a single 33kV feeder to Dormansland s/stn installed as part of the East Grinstead Line electrification in 1987. A 2nd 33kV feeder was then installed in 1992/3 to power the Redhill to Tonbridge line electrification. It was stepped down to 22kV at Crowhurst Jcn. This line was intended as the prime freight route from the Channel Tunnel using the class 92's so was not suitable for 11kV. Subsequently to allow 12 car Electrostar working on the East Grinstead line a feed was taken from the Crowhurst 33kV feeder to reinforce the original 11kV system at Eden via a step down transformer.

Sorry it's taken me so long to get back to this but: two questions.
Is the 33kV feed from Dormansland Grid to Crowhurst Jnc switching station any relation to UKPNs 33kV powerline also from Dormansland Grid to their Crowhurst Primary? Because in the UKPN docs I'm working off I did find this curious extra circuit breaker hanging off the end at Crowhurst primary.



Secondly, why did they choose 22kV and not just 33kV for Redhill-Tonbridge?

 

[Nicholas Lewis]

Sorry it's taken me so long to get back to this but: two questions.
Is the 33kV feed from Dormansland Grid to Crowhurst Jnc switching station any relation to UKPNs 33kV powerline also from Dormansland Grid to their Crowhurst Primary? Because in the UKPN docs I'm working off I did find this curious extra circuit breaker hanging off the end at Crowhurst primary.

View attachment 186848

Secondly, why did they choose 22kV and not just 33kV for Redhill-Tonbridge?

No they are separate supplies both 33kV circuits run in the road from Dormansland Grid to Dormans station.

The reason 22kV was selected is the power demand of the class 92's was nominally 3.4MW which would have translated to voltage regulation on a 11kV system beyond 10%. The same voltage was used for the HV distribution system for the West London Line electification upto North Pole. At that end we were able to connect at 22kV into Acton substation as that is standard voltage in the London area.

 

[Bodiam]

...

More information about the South East.

Queensborough is Queenborough and is a single 33kV feed from the UKPN Network and acts as a standby supply only for the Sheerness Branch.

...

Northfleet was initially 4 feeders,, 2 to the Dartford line and 2 to the Victoria Chatham line. One of these 4 has been decommssioned but I dont know which one.

As I understand it, under the old regime Queenborough was fed from a SE Electricity Board supply rather than the CEGB and was unusual (if not unique) on the Southern Region in that respect. Presumably it's all UKPN nowadays?

The feeder from Northfleet to the Swanley-Rochester line ran along the side of the Gravesend West branch, so the right of way was maintained even after coal traffic to Southfleet stopped.

 

[GraphitProjekt]

No they are separate supplies both 33kV circuits run in the road from Dormansland Grid to Dormans station.

The reason 22kV was selected is the power demand of the class 92's was nominally 3.4MW which would have translated to voltage regulation on a 11kV system beyond 10%. The same voltage was used for the HV distribution system for the West London Line electification upto North Pole. At that end we were able to connect at 22kV into Acton substation as that is standard voltage in the London area.

It makes sense for WLL, they could connect straight to Acton Lane 66/22kV (as does LUL at that location).

But surely it would have been easier to use 33kV on Redhill-Tonbridge since it's the same voltage as the lines either side of it? Or is it the case that those lines weren't all 33kV back then?

 

[Nicholas Lewis]

It makes sense for WLL, they could connect straight to Acton Lane 66/22kV (as does LUL at that location).

But surely it would have been easier to use 33kV on Redhill-Tonbridge since it's the same voltage as the lines either side of it? Or is it the case that those lines weren't all 33kV back then?

22kV was a lot cheaper than 33kV at the time as XLPE cables at that voltage were well established with multiple manufactures across Europe. CEGB and area boards were very anti XLPE through the 80's so UK manufacturing was slow to convert give they were the primary customers not BR.

 

[hwl]

It makes sense for WLL, they could connect straight to Acton Lane 66/22kV (as does LUL at that location).

But surely it would have been easier to use 33kV on Redhill-Tonbridge since it's the same voltage as the lines either side of it? Or is it the case that those lines weren't all 33kV back then?

22kV was a lot cheaper than 33kV at the time as XLPE cables at that voltage were well established with multiple manufactures across Europe. CEGB and area boards were very anti XLPE through the 80's so UK manufacturing was slow to convert give they were the primary customers not BR.

Agree with Nicholas - the situation has changed substantially since Redhill - Tonbridge and WLL and UKPN (all 3 DNOs) defaulting to 132/33 for big upgrades now.

One interesting conundrum:
Wimbledon and New Cross were traditionally 275kV fed but are now getting 400kV but the existing rail power comes from 275kV fed transformers so what might happen? How long will the dual 400/275 set up at the sites last? The Wimbledon rail transformer is very old but New Cross is ~10 years old.
Wimbledon got the first 400kV ~5 years ago, New Cross is going live shortly and there is the new 400kV link between the two via Bengeworth Road (out the back of Kings College Hospital at Denmark Hill) which will enable UKPN to remove lots of really old oil filled cabling south of the Thames in Z1-3 (including some running along side the SLL on NR turf - thankfully the digger operator excavating the lift shaft for Denmark Hill station was very observant, the TfL station upgrade contractor hadn't bother checking for DNO assets, net result an 8 month project delay).
Getting the reconfigured Bengeworth Road substation up and fully running may be the key point when demand on Wimbledon and New Cross Transformers then drops allowing more head room for changes.

 

[GraphitProjekt]

22kV was a lot cheaper than 33kV at the time as XLPE cables at that voltage were well established with multiple manufactures across Europe. CEGB and area boards were very anti XLPE through the 80's so UK manufacturing was slow to convert give they were the primary customers not BR.

Fascinating! I've heard 20kV is an international standard as well, although 22kV is well used by LUL. I've heard the original 1930s electrification of the brighton mainline used i think 66kV oil-filled cables in south london.

Agree with Nicholas - the situation has changed substantially since Redhill - Tonbridge and WLL and UKPN (all 3 DNOs) defaulting to 132/33 for big upgrades now.

It seems Hastings was one of these?

One interesting conundrum:
Wimbledon and New Cross were traditionally 275kV fed but are now getting 400kV but the existing rail power comes from 275kV fed transformers so what might happen? How long will the dual 400/275 set up at the sites last? The Wimbledon rail transformer is very old

isn't the Wimbledon rail feed off of the 132kV side. I assume the Wimbledon 132kV will continue to operate after the 400kV comes in? Is there an intention to replace the railway supply with one from the 400kV site in the future? I've heard Wimbledon's supply is quite constrained - no new services can run on hounslow loop due to this which is affecting LO's plan for their new line

but New Cross is ~10 years old.

yeah i found a load of articles about it's recent upgrade. Beforehand it was 3x 66kV circuits i believe to south bermondsey, nunhead and lewisham - with at least some of the NwR sides being originally 11kV?

 

[hwl]

Fascinating! I've heard 20kV is an international standard as well, although 22kV is well used by LUL. I've heard the original 1930s electrification of the brighton mainline used i think 66kV oil-filled cables in south london.

It did indeed.

It seems Hastings was one of these?

And Uckfield in progress at the moment too...

isn't the Wimbledon rail feed off of the 132kV side. I assume the Wimbledon 132kV will continue to operate after the 400kV comes in? Is there an intention to replace the railway supply with one from the 400kV site in the future? I've heard Wimbledon's supply is quite constrained - no new services can run on hounslow loop due to this which is affecting LO's plan for their new line

but the existing 275-132kV transformer would need replacing hence it looks like Wimbledon may stay a both 275 and 400kV site for while or would they go for multiple 400- 33kV to replace it and other equipment at the same time. At New Cross the young age of the 275- 33kV transformers suggest they may be hanging around for a while.
Nationally there might be quite a lot of 275kV stranded assets given the requirements of grid upgrades.

yeah i found a load of articles about it's recent upgrade. Beforehand it was 3x 66kV circuits i believe to south bermondsey, nunhead and lewisham - with at least some of the NwR sides being originally 11kV?

Yep with oil top up and pressurising points visible along side the track.

Two quick questions
1. There is a massive substation at Wandsworth Common which is fed from Wimbledon but what is the cable routing? The existing UKPN and new NG tunnels (Wimbledon - Bengeworth) both pass very close by...
2. Is grey on you 3rd rail map unknown feeding?

 

[GraphitProjekt]

It did indeed.

And Uckfield in progress at the moment too...

That line is actually getting electrified! News in and of itself to me!

but the existing 275-132kV transformer would need replacing hence it looks like Wimbledon may stay a both 275 and 400kV site for while or would they go for multiple 400- 33kV to replace it and other equipment at the same time. At New Cross the young age of the 275- 33kV transformers suggest they may be hanging around for a while.
Nationally there might be quite a lot of 275kV stranded assets given the requirements of grid upgrades.

Yeah i see how this could be the case at New Cross for quite a while. That site also must still have a lot of 66kV presence, multiple generations of orphaned voltages.

Two quick questions
1. There is a massive substation at Wandsworth Common which is fed from Wimbledon but what is the cable routing? The existing UKPN and new NG tunnels (Wimbledon - Bengeworth) both pass very close by...

Do you mean the 132/66kV Wandsworth Grid (basically on Wandsworth Town station, couldn't find anything significant around Wandsworth Common specifically). Openinframap.org says this:


I don't know where they got the route from but it looks fairly deliberate (as opposed to that straight up one that goes to Lots Road LUL). Skimming through UKPN's 2014 plans for the Wimbledon fed area (read them all here they're often insightful), they talk a lot about a pre-existing Wimbledon-Pimlico tunnel that I think must go via Wandsworth Grid On its way to Moreton Street (just over Vauxhall bridge). Further they said they were planning to put a new 132/11kV substation on that line for the Battersea Park area ahead of its significant redevelopment. This must be Stewarts Lane 132 which you can see on openinfra. They also say:

Wandsworth Grid 66kV is supplied from Wimbledon Grid 132kV via four 132kV circuits. Due to the increasing demand at the primary sites fed from Wandsworth and the commissioning of the new Moreton Street C and Kingsgate House substations, the load on the four circuits is expected to reach 300MW by winter 2014/15...It is proposed to install 3 new 132kV circuits from Wimbledon in the Wimbledon-Wandsworth tunnel, supplying a new 132kV gas insulated switchboard, on the Wandsworth site, which will feed Moreton Street, Kingsgate House and the future substation at Battersea. This will split the network and keep the load on the four initial circuits below 300MW. Completion of the scheme will see a new 9 panel gas insulated switchboard and 3x132kV circuits from Wimbledon. The 132kV circuit breakers at Wimbledon are to be installed as part of the replacement of the air insulated switchgear by a new 31-panel switchboard (project 3730).

So I suppose the answer is, a bit of both.
Also in this document in reference to 275kV connections:

National Grid are upgrading their 275kV Wimbledon substation to 400kV... All 275/132kV SGTs on site will be replaced by 400/132kV units. As part of this work it is necessary to divert a number of UK Power Networks 132kV and 33kV cables all within the site boundary of Wimbledon North 132kV substation.

It's possible this didn't materialise in the end. I had a brief look in the document on New Cross which didn't have a lot to say on the matter, other than that delivery of the new NG Bengeworth Road and New Cross-Wimbledon 400kV wouldn't be finished until the mid 2020s so was too far in the future for that report.

2. Is grey on you 3rd rail map unknown feeding?

No it means more so that I don't believe there are any HVAC feeders along that line. Ergo, there will only by TPHs on grey routes. East Putney is perhaps the exception to this as once it goes into LUL controlled territory I have no idea what's going on.

 

[bramling]

yes thank you! I've actually recently finished the big project this was a part of - which is a map showing the extents of railway grid connections in the London area, but going quite far south. You should be able to download it here from my Flickr. But i'll put a couple screenshots here for preview. But this whole thing about dedicated railway transformers was an interesting loose end that I just couldn't find anything about online.
View attachment 185302View attachment 185303
I think my next trick will be adding some traces of powerlines from openinframap to show how the grid infrastructure relates to railway GSPs.
Regarding other DC railways:
- For LUL i know where the grid connections are (in fact i'll add them now to my original message) but no idea where the DC substations are.
- For DLR I think i have enough to find where the DC substations are but no idea how the power is supplied/whether they have HV AC
- For Tyne & Wear, I've found nothing at all! I could probably sit down and watch a few hours of cabview footage looking out for DC substations cross-referencing with Google Earth to locate transformers (to tell if it's a TPH or a TSS) but that could be quite inaccurate and maybe too dull even for me. Still, no idea of the supply side. So if anyone has some insights for T&W specifically I'd be interested!
- For the tram systems, ditto everything I've said about T&W. Although there is some good info on Croydon i found.

== Doublepost prevention - post automatically merged: 1 Aug 2025 ==


A one-to-one transformer that is mean to "boost" voltage, how intriguing! Everytime I think I understand what a transformer can be used for, there's always something more. That piece of equipment sounds eerily familiar to the so-called "booster transformers" used on 25kV lines although for a completely different purpose.

thank you, edits made

Interesting you say that! In a 2014ish UKPN document I found online they give this blurry schematic.
View attachment 185304
Northfleet East (the main 400/132 substation in the area) has a 33kV local switchboard shown on the left with 3x 132/33kV transformers. I take it the diagram there is incomplete because elsewhere it shows Northfleet East 132/33 supplying a range of local primary substations. But in this diagram it does seem to be discussing BR feeds - perhaps shown here due to their priority? It seems to be saying BR1112, BR1126, BR1637 and BR 1639 although it's too blurry to tell some of those digits definitively.
My main source for all of this is a network rail document briefly shown in a PWI lecture on youtube that seems to be more up to date but even more blurry.

View attachment 185305
But I can make out feeder 1112 going down towards the Chatham mainline so these schematics must be talking about the same thing.

Tyne & Wear Metro substations:

Airport TPR
Kenton Bank Metro Substation
Gosforth Metro Substation
Monument TPR
Old Fold Substation
Pelaw TPH
Fellgate Substation
Seaburn Substation
Pallion Substation
South Hylton TPH

Monument TPR
Byker Substation
Percy Main Metro Substation
Whitley Bay Metro Substation
Benton Square Metro Substation
Gosforth Metro Substation
Monument TPR
Old Fold Substation
Pelaw TPH
Hebburn Metro Substation
Chichester Metro Substation

There are also station supplies substations at Regent Centre, Control Centre, Jesmond Metro, Haymarket, Monument, Central, Gateshead, St James and Manors. And depot substations at Howdon and Nexus Learning Centre (not sure the official names of these two).

Don’t ask why some have Metro in the name, there is a logic to it but I can’t remember the details. I think it’s something to do with the distribution network.

 

[GraphitProjekt]

wow! Thankyou so much for that - there are some partial and highly blurry pictures of the old T&W mimic panels so with these names I might be able to piece together the network now that I know what I'm trying to read (I wish these signalling photographers would take more than a token shot of these things!)

Don’t ask why some have Metro in the name, there is a logic to it but I can’t remember the details. I think it’s something to do with the distribution network.

I wonder if the "Metro" infix might be to do with locations with grid supplies? The other day I saw mention in a public facing northern power grid report of a dual circuit 132kV line from Tynemouth 275/132 to a "Gosforth Metro substation". Although that seems like way too many, unless it is that T&W operates their own HVAC network towards the inside of their area while the outer parts of the route have DC substations fed directly from the DNO network. I assume the internal HVAC network is 33kV?

Also why are some of the TPHs named TPRs? What does the R mean,

 

[hwl]

That line is actually getting electrified! News in and of itself to me!

Uckfield town is getting a decent 33kV supply amongst may local DNO upgrades which may open up possibilities.

Yeah i see how this could be the case at New Cross for quite a while. That site also must still have a lot of 66kV presence, multiple generations of orphaned voltages.

The retirement of the connections from New Cross to the former Deptford power station and then onwards will help get rid of lots of orphaned voltage in the area and some 100+ year old oil filled cables that are currently still in use. The question is how big the clear out is.
Deptford Power station (Ferranti "experiment") is the UK/global reason for 11kV* increments in power distribution - it needed to be 11kV at the power station to get 10kV at the substation in Zone1 due to losses. The Ferranti system at Deptford was 25Hz (tram and later LBSCR overhead) and 83.3Hz for domestic and light industry. (83.3Hz is 10/3rds of 25Hz if you want to understand the alternator poles and windings!)
* whole number multiples: 11/22/33/66/132 [x12] /275 [x25]. Fractional multiples: 6.6kV is 3/5ths of 11kV and 400kV is 36&1/3 x11kV (109/3rds) or 16/11ths of 275kV if thinking about winding ratios.

Do you mean the 132/66kV Wandsworth Grid (basically on Wandsworth Town station, couldn't find anything significant around Wandsworth Common specifically). Openinframap.org says this:

View attachment 187169

No Wandsworth Common NR substation on the opposite side of the B237 (Bellvue Road) from the station - you need to scroll right a tiny bit.
No cable routing marked going into it. (It is a very very big substation in 3rd rail terms)

I don't know where they got the route from but it looks fairly deliberate (as opposed to that straight up one that goes to Lots Road LUL).

The two straight line 132kV leaving Wimbledon were added by someone who doesn't have clue on actual routings - I'm fairly certain the east bound 132 to Bengeworth Road (bottom right of that image) is actually under Bellevue Road.

Skimming through UKPN's 2014 plans for the Wimbledon fed area (read them all here they're often insightful), they talk a lot about a pre-existing Wimbledon-Pimlico tunnel that I think must go via Wandsworth Grid On its way to Moreton Street (just over Vauxhall bridge).

Correct

Further they said they were planning to put a new 132/11kV substation on that line for the Battersea Park area ahead of its significant redevelopment. This must be Stewarts Lane 132 which you can see on openinfra.

Stewart Road - Stewart Lane Depot is named after Stewart Road... there is no street called Stewart lane even going back to pre railway times.

They also say:

So I suppose the answer is, a bit of both.
Also in this document in reference to 275kV connections:

It's possible this didn't materialise in the end. I had a brief look in the document on New Cross which didn't have a lot to say on the matter, other than that delivery of the new NG Bengeworth Road and New Cross-Wimbledon 400kV wouldn't be finished until the mid 2020s so was too far in the future for that report.

Going live in summer 2026

No it means more so that I don't believe there are any HVAC feeders along that line. Ergo, there will only by TPHs on grey routes.

East Putney is perhaps the exception to this as once it goes into LUL controlled territory I have no idea what's going on.

NR supply East Putney - Wimbledon

Two further thoughts/questions:
a) Chadwick Road (Peckham Rye) supply point. The original LBSCR 6.6kV 25Hz OHLE AC power generating station was here with links to Deptford Power station (for more power) was at located south of the track with the UKPN substation on part of the former site. Where is this currently fed from? The UKPN 33kV and 66kV cables follow the railway alignment here inside the fence (going to Bengeworth Road as the excavator operator digging the lift shaft at Denmark Hill discovered in 2011) not the straight lines on open infra map...
b) Loughborough Jn. supply point. Where is this fed from? it is just west of Bengeworth Road (UKPN and now NG too) substation, suspiciously close. Bengeworth Road was until recently just fed with 66kV & 33kV fed from the substation at the former Deptford Power Station (on the site of one of Henry VIIIs dry docks in the former naval yard) and Chadwick Road (and probably 11 and 22kV too at some point in the past too.)

 

[bramling]

wow! Thankyou so much for that - there are some partial and highly blurry pictures of the old T&W mimic panels so with these names I might be able to piece together the network now that I know what I'm trying to read (I wish these signalling photographers would take more than a token shot of these things!)

I wonder if the "Metro" infix might be to do with locations with grid supplies? The other day I saw mention in a public facing northern power grid report of a dual circuit 132kV line from Tynemouth 275/132 to a "Gosforth Metro substation". Although that seems like way too many, unless it is that T&W operates their own HVAC network towards the inside of their area while the outer parts of the route have DC substations fed directly from the DNO network. I assume the internal HVAC network is 33kV?

Also why are some of the TPHs named TPRs? What does the R mean,

Not sure on the former points, somewhere I have an article that explains it all.

TPR I believe is “track paralleling room”. In the case of Monument this is fair enough, however it’s a bit of a stretch to describe the Airport one as a room. It’s more of a cabinet.

Note that Pelaw to South Hylton is Network Rail, though there seems to be some integration between the two systems at Pelaw.