On Wed, 30 Apr 2008 11:25:46 +1200, grumpyoldhori
wrote:
Don Foreman wrote:

37 ohms per km of 4 mm iron/steel wire strongly suggests *a splice
that may be mechanically strong but has poor conductivity due to
corrosion.

Yes, good point, I will put 4 mm copper wire jumpers
across all splices.
What figure should I be looking for on a km of 4 mm
steel wire in ohms ?

No, you should get a portable torch rig with some horsepower (Oxy-
Acetylene or Air-Acetylene or MAPP) and go silver-braze or silver
solder all the splice points - or even 60/40 lead/tin solder if you
don't worry about RoHS, but no acid flux unless you clean it up.

Get the resistance down enough, and 24V (AC or DC) at the bottom of
the hill will be enough to get 12VDC at the top (after regulating,
filtering and surge/lightning arresting).

I still say AC is better for longer distance work at low voltage,
but as always Your Mileage May Vary.

-- Bruce --