Friday, 16 September 2011

Sitting on a high voltage line without getting electrocuted

Warning: this post contains explicit photographs of pylons and transmission lines. This might not be to everyone's taste.

Now, there are many places to see pylons from, and I can think of one famous canal-straddling pylon on the Huddersfield Narrow Canal. Are there others? Most of the time we see them and ignore them. Some might rather they didn't march across the countryside, but we live in an electrical age, and we have to get the power somehow.

pylons crossing the Fens, as seen from the Cambridge to Norwich train

Over the last three months National Grid has been upgrading their transmission lines in Norfolk, the "Norwich Main to Walpole 400kV Overhead Line Refurbishment". My route to work passes under these lines, and I've been watching with interest what's been going on.

The first noticeable event was pulley wheels appearing under new insulators on one side of the pylons.

I was pleased with this next photo. The pylon has a dramatic cloud backdrop which gives the sense of plasma radiating from it.

Then, where there were two lines for each insulator, suddenly there were three.

A bit of conductor pulling had happened.

Or "conducter pulling" as National Grid has it.

Then the lines acquired cylinders pointing to each other either side of the insulators, and jumbles of metalwork dangling nearby.

I don't know what the cylinders are (anyone?), but the tangles I think are the triangular spacers which were fitted to the lines on their run between pylons, four per run.

On another cycle to work I could hardly believe what I was seeing above me. Using the cables as an extreme aerial runway (or "zipwire" as I believe Americans say), National Grid workers were travelling along in trolleys suspended from the lines.

It was the most amazing sight. I assume they were removing the spacers from the old two-wire runs ready for pulling through the new cables.

Lowering a pulley set from the restrung pylon. Both sides have now been done.

Presumably the first requirement for these workers is a head for heights.

Taking a breather straddling the 400kV lines. It doesn't look the most comfortable seat! But do you see how thick the cables are? I hadn't really thought about it before, other than knowing that the higher the voltage the thinner the cable can be for a given power transfer. These look to be about three inches in diameter. That will take a considerable quantity of amps, and at 400kV, that's lots of megawatts!

Finally (phew!), what a difference the sun makes.


Vallypee said...

I rather like pylons, but then I love cranes, and even wind turbines...anything that stands tall and striking against the sky.

Vallypee said...

Your photos of the men at work are very good too. Brave souls they are!

Sarah said...

When we visited Norwich (well, the general area) last week, we remarked that we'd never seen so many line crossings at once before (Jim looks at these things from a scaffolder's point of view). Sounds like this might explain it. A line crossong is where they sling a big net across the road under the wires, to stop them landing on the road if they should come down, I guess.

Halfie said...

The line crossing is about the only thing I didn't take a photo of.