On Tue, 20 Aug 2013 09:03:45 +0100, Tim Streater
wrote:

In article ,
Andy Burns wrote:

Tim Streater wrote:

And the cost, 10 times that of pylons. Anyone know the highest voltage
they put underground?

"Murphy is one of the UK’s leading tunnelling
contractors with a wealth of experience in the design,
construction and fitting out of cable tunnels. We have
successfully delivered a number of high-profile
infrastructure power projects, including the Olympic
Park (132/400kV Cable Tunnels)"

http://www.murphygroup.co.uk/uploads...er%20Brochure/
Power%20Brochure.html#/8/zoomed

So 400kV underground has to be in a tunnel rather than buried? Is that
AC? Not sure I'd like to be walking along next to it.

In rural areas they will almost all all be direct buried. In urban areas for
new installations it is more likely to be in a dedicated bored tunnel now. In
the past they just dug up the road, backfilled with sand and laid the cables.
Most of Sheffield is cabled this way at 275kV. A few cable routes have used
existing infrastructure such as old railway tunnels and canal towpaths.

There is no problem with being in physical contact with the sheath of 400kV
undercround cables either at AC or DC its just like large bore water pipe. Just
do it by hand rather than with a JCB.

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