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Anyone have any idea why the cables are arranged like this? https://8400e186.delivery.rocketcdn.me/articles/wp-content/uploads/sites/2/2025/12/National-Grid-Lon

by luma 10mo ago

Anyone have any idea why the cables are arranged like this? https://8400e186.delivery.rocketcdn.me/articles/wp-content/uploads/sites/2/2025/12/National-Grid-London-Power-Tunnels-2_cropped.jpg https://8400e186.delivery.rocketcdn.me/articles/wp-content/u... What's the zig-zag pattern for, seems like a fair bit of extra conductor.

probablypower 10mo ago
First guess (may be wrong) is to manage thermal expansion/contraction constantly on a micro-scale.
- nraynaud 10mo ago
  I would also add that there some slack for repairs.
jo909 10mo ago
This view is just very extreme, it is much less zig zag. It is just mounted to the wall at the high points and slack in between. Certainly there is also a reason for the exact amount of slack like thermal expansion. https://cdn.ca.emap.com/wp-content/uploads/sites/9/2018/04/londonpowertunnelsphase13to2.jpg https://cdn.ca.emap.com/wp-content/uploads/sites/9/2018/04/l...
- deleted 10mo ago
  [deleted]
- markdown 10mo ago
  A thousand words but 200 of them are bullshit, and they didn't even have to use Photoshop.
defrost 10mo ago
There are three reasons: * Cable thermal expansion under current load: https://www.ahelek.com/news/cable-thermal-expansion-and-its-solutions/ https://www.ahelek.com/news/cable-thermal-expansion-and-its-... * The amount pictured is in excess of that required for thermal expansion. The excess is to have some spare length in case of modifications. For example if you have to replace the transformer and the terminals are not in the same location. You cannot extend a massive cable like that easily or without degrading its specs. * The sine wave pattern makes it into AC of course (/s)
locknitpicker 10mo ago
> Anyone have any idea why the cables are arranged like this? I think that's just cables sagging, which is a requirement to accommodate thermal and seismic displacements.
Reason077 10mo ago
Is that a tandem bicycle? Cute.
- _trampeltier 10mo ago
  Yes. First time I see a tandem in such tunnel. Until know I just saw and used normal bicycles in such kind of tunnels.
- zeristor 10mo ago
  Tandem bike or a new SCP variant.
bregma 10mo ago
Do you mean the catenary [0]? [0] https://en.wikipedia.org/wiki/Catenary https://en.wikipedia.org/wiki/Catenary
chadcmulligan 10mo ago
Maybe to reduce electromagnetic coupling? Seems they're offset a bit.
BrtByte 10mo ago
My understanding is that it's mostly mechanical and thermal, not electrical cleverness
nkrisc 10mo ago
That’s just slack. You’re seeing a very long distance with extreme foreshortening in this image.
deleted 10mo ago
[deleted]
1-6 10mo ago
It looks like AI slop to be honest. My second best guess is that it could be arrayed transformers. I don't think a utility company in their right mind would allow workers to bicycle inside a tunnel powering the grid.
- Gud 10mo ago
  Question. Have you worked for a utility company?
ryanjshaw 10mo ago
Great photo from an artistic POV, completely useless to get a sense of the main subject of the tunnel: the cables carrying electricity.
W3zzy 10mo ago
It's the lens distorting the view.

by luma 10mo ago

probablypower 10mo ago

First guess (may be wrong) is to manage thermal expansion/contraction constantly on a micro-scale.

nraynaud 10mo ago
I would also add that there some slack for repairs.

jo909 10mo ago

This view is just very extreme, it is much less zig zag. It is just mounted to the wall at the high points and slack in between. Certainly there is also a reason for the exact amount of slack like thermal expansion. https://cdn.ca.emap.com/wp-content/uploads/sites/9/2018/04/londonpowertunnelsphase13to2.jpg https://cdn.ca.emap.com/wp-content/uploads/sites/9/2018/04/l...

deleted 10mo ago
[deleted]
markdown 10mo ago
A thousand words but 200 of them are bullshit, and they didn't even have to use Photoshop.

defrost 10mo ago

There are three reasons: * Cable thermal expansion under current load: https://www.ahelek.com/news/cable-thermal-expansion-and-its-solutions/ https://www.ahelek.com/news/cable-thermal-expansion-and-its-... * The amount pictured is in excess of that required for thermal expansion. The excess is to have some spare length in case of modifications. For example if you have to replace the transformer and the terminals are not in the same location. You cannot extend a massive cable like that easily or without degrading its specs. * The sine wave pattern makes it into AC of course (/s)

locknitpicker 10mo ago

> Anyone have any idea why the cables are arranged like this? I think that's just cables sagging, which is a requirement to accommodate thermal and seismic displacements.

Reason077 10mo ago

Is that a tandem bicycle? Cute.

_trampeltier 10mo ago
Yes. First time I see a tandem in such tunnel. Until know I just saw and used normal bicycles in such kind of tunnels.
zeristor 10mo ago
Tandem bike or a new SCP variant.

bregma 10mo ago

Do you mean the catenary [0]? [0] https://en.wikipedia.org/wiki/Catenary https://en.wikipedia.org/wiki/Catenary

chadcmulligan 10mo ago

Maybe to reduce electromagnetic coupling? Seems they're offset a bit.

BrtByte 10mo ago

My understanding is that it's mostly mechanical and thermal, not electrical cleverness

nkrisc 10mo ago

That’s just slack. You’re seeing a very long distance with extreme foreshortening in this image.

deleted 10mo ago

[deleted]

1-6 10mo ago

It looks like AI slop to be honest. My second best guess is that it could be arrayed transformers. I don't think a utility company in their right mind would allow workers to bicycle inside a tunnel powering the grid.

Gud 10mo ago
Question. Have you worked for a utility company?

ryanjshaw 10mo ago

Great photo from an artistic POV, completely useless to get a sense of the main subject of the tunnel: the cables carrying electricity.

W3zzy 10mo ago

It's the lens distorting the view.