In message , at 00:17:42 on Fri, 29 May
2009, David A Stocks remarked:

"Roland Perry" wrote in message
news

This is a classic example of market failure. Why should I run around
putting all those things on timers, with all the inconvenience of
taking 2 days to wash clothes [wash at 2am one day, dry at 2am the
next day], just to return my bill to the level it used to be before!!

I don't! You completely missed the point of my post and assumed I was
talking about Economy7 tariffs.

In my case I have a separate supply which is connected to the heating
system *only*, and it's switched via the electricity suppliers switch.
My main supply is charged at the standard rate - I effectively get two
bills. The switched supply has a simple mechanical time switch which
gives me 7 hours overnight and a 3.5 hours during the afternoon.

I've never come across such a supply, hence the confusion.

HOWEVER, my parents have the radio controlled switch that I described
in my original post and (like me) it controls the heating circuits and
(like me) it gives them 7 hours overnight and 3.5 hours in the
afternoon. However, they don't know for certain when the supply is
active,

And presumably (unlike Economy7) they can't do a "Boost" during the day
(albeit at a higher price).

because their supplier can remotely switch the supply at their
convenience in order to get the best prices from the National Grid - in
effect the local supplier will selectively shed load when the grid
'market' price rises, whilst ensuring that everyone gets their quota of
cheap rate hours fed to their heating systems.

With the heating system requiring separate wiring, I suppose.

For obvious reasons consumers aren't allowed to connect appliances like
dishwashers and washing machines to a supply that is controlled in this
manner, but my parents get cheap rate overnight electricity on their
main supply (per Economy7) as well.

But if their heating is on this separate "7 hour only" scheme, it's
virtually impossible that Economy7 would be value for money, because
with so little off-peak use of Economy7, and the hike in daytime rates
for E7 customers, the sums just don't work out.

Just to get us back to the original thread, I was suggesting that a
similar mechanism could be used to control car charging points in order
to avoid overloading local and national electricity distribution
networks during peaks in demand, thus delaying (or possibly avoiding
altogether) the requirement for the major upgrades that you had
suggested would be necessary.

But if the chargers are on separate circuits that only work at dead of
night, it's another case of "no Boost available", and you are in effect
rationing people to one-charge-per-day.
--
Roland Perry