On Thu, 15 Mar 2012 13:42:47 +0000, Fred wrote:

Then I came and read here and I learnt that long leads had
disadvantages. I can't remember now whether this was because of
voltage drop or fault currents, or may be both. Can someone remind me?

Both but as others have said volt drop won't upset many things a
great deal. Fault currents could be an issue but as you will always
be running the extension via an RCD (won't you...) that isn't such a
problem either.

So it is time to buy a new lead or leads.

If the cable is in otherwise good condition just replace the socket
and if the plug isn't an RCD one replace that as well. You may say
that all your 13A sockets are RCD protected but what if you use it
elsewhere?

I seem to remember reading that 1.5mm^2 cores could only be used safely
up to 15m and 2.5mm^2 cores (in a caravan power lead) could be used up
to 25m.

A little bell jingles that the length limits are something like that
so as not to have too much (FSVO "too much") volt drop at full load.

Is there any advantage to buying a short "caravan hook-up" cable to use
for lengths under 25m?

I have a couple of 25m "caravan hook up" cables, for several reasons:

The cable is bright orange.
The cable is nice and flexible and coils nicely.
They are 2.5mm^2 cross section.

It is quite chunky stuff to have a 13A plug attached, so I have 16A
IEE connectors and adapters to 13A, primary use is from the generator
but as the IEE's are bit more water resistant than a 13A the pressure
washer has an IEE plug on it.

Unless you are working outside in winter I wouldn't bother with
arctic flex, the caravan hook stuff handles well and doesn't fight
back a great deal even when near freezing.

--
Cheers
Dave.