OT ...one for the sparkies

[Matt]

Nothing new there. The UK has been doing something similar for many years. A proof of concept exercise was done by the CEGB in the 1970's and was eventually revived and became normal practice in the early

1990's. They do it from a wheeled trolley though rather than crawling along the line. The discharge you see in the video is completely normal and it's just a case of equalising the charge. The line is fully in service - which is precisely why it is done live, to save the costs of constraining generation, and in the case of operations in the UK could be carrying around 2000A per phase - or 500-1000A per individual conductor

Spacer replacement (the H or X shaped bars between individual conductors) on 2 and 4 conductor overhead 400 and 275kV lines is routinely done live in the UK. Last time I saw them in person was two or three years ago on the 400kV line that passes over the A55 near Bangor in North Wales.

[Matt]

>

If you visited in the 60's then you visited the old now defunct 160MW link. The new one, rated at 2000MW only entered service in 1986.

There is also a link to the Isle of Man built about 6 years ago, one under construction to the Netherlands for completion in 2010, and two others planned to link to Ireland and Norway.

[Matt]

Oh yes they are.

For a start there is no such thing as half AC and more to the point if the lines were out of service then they would always be earthed at the remote ends, with earths placed at the adjacent towers from the conductors to the pylon structure / earthwire and the overhead line worker would approach the conductor by climbing across the insulator strings. In such circumstances you shouldn't ever see discharge and you'd only wear normal clothing rather than a mesh suit.

So what you are seeing is not just pickup from an adjacent in service line and in essence that is *exactly* how live line working on HV is performed.

[The Natural Philosopher]

>>>>>>> Yes. I visited it in the 60's and it was as far as I know the ONLY

Yup. That was it!

2GW? I suppose solid state switches make it feasible.

Found that one.

and two

Norway sounds unlikely..why there?

[Matt]

Cheap hydro

[The Natural Philosopher]

Fairy Nuff.

That probably stands on its own two feet then.

And the Finns are next door with their reactors...

[tony sayer]

In article , Matt scribeth thus

When they were rewiring the line for Wisbech to Stocking Pelham it seemed they had earths on every pylon!...

This is quite a good site on the subject...

[Andy Hall]

Next door but one unless you go a tortuous way round,

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Matt saying something like:

Earlier than that. I was told about this in 1970 by a physics lecturer who was ex-industry. Subsequent to that, anytime I saw blokes crawling or trollying around EHV cables I assumed they were doing it live in their mesh suits.