In message , at 21:51:54 on Mon, 25 May
2009, David A Stocks remarked:

And in London the problem is distributing the electricity from the
grid to the end users. Even if there was a plentiful source of
electricity, you'd have to do quite a lot of work to get it where
it's needed.

Just dig up the relevant bit of road/pavement and tap into the
existing domestic supply cables that are under every street. This
must have been the approach for the existing charging points, and
it's hardly rocket science.

You'll soon overload it if it's more than a few charging points per
street.
A trickle-charge point is equivalent to a 13A socket inside a house.

You want a bit more than a trickle charge - we were talking earlier
about the use of three-phase and up to 100amps.

Typical cars I've seen take about 3 hours at 12kw (that's 48amps) to
charge up.

Nor does this approach solve getting the extra power from the outside
world to the substations.
We're talking about a gradual take-up over the next 20 years or so, and
it should all be very predictable. I suspect the major challenge is
generating the electricity, not the distribution.

More electricity requires more distribution. London is pretty much maxed
out at the moment.
--
Roland Perry