On Tue, 6 May 2014 18:14:02 +0200, Mervington wrote:

The nearest part of our bottom garden will be 60 metres from an
electricity point. The furthest will be almost double that. I
certainly cannot run a supply for an electric power mower or to charge
batteries on one.

60 m isn't very far. In my day job I regulary use main kit on the end
of 200 m of cable, admitedly not a great load maybe 250 W but there
is no hint of problematic volt drop. When I was pressure washing the
outside of the house prioer to repainting I used two 50 m extension
cables in series again no problems.

Not sure of the power of a lawn mower but to run of a single 13 A
socket it's not likely to be above 2 kW or about 9A. 2.5 mm^2 has a
volt drop of about 0.02 mV/A/m. 9 A over 60 M is 10 V for a simple
motor not worth bothering about and within the 230 V +10/-6% (253 -
216 V) tolerance on the supply voltage anyway.

If you used 4 mm^2 flex instead of 2.5 mm^2 the volt drop would
halve. 4 mm^2 flex at that length would start being rather heavy to
hand coil, 2.5 mm^2 is OK with large loops.

--
Cheers
Dave.