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Comment by luma | Hacker News Reader

Anyone have any idea why the cables are arranged like this? https://8400e186.delivery.rocketcdn.me/articles/wp-content/u...

What's the zig-zag pattern for, seems like a fair bit of extra conductor.

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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/l...

A thousand words but 200 of them are bullshit, and they didn't even have to use Photoshop.

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

Do you mean the catenary [0]?

[0] https://en.wikipedia.org/wiki/Catenary

> 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.

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

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

I would also add that there some slack for repairs.

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

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

It's the lens distorting the view.

Is that a tandem bicycle? Cute.

Tandem bike or a new SCP variant.

Yes. First time I see a tandem in such tunnel. Until know I just saw and used normal bicycles in such kind of tunnels.

There are three reasons:

* Cable thermal expansion under current load: 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)

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.

Question. Have you worked for a utility company?

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