On 15/5/06 1:55 AM, "KV9U" <mrfarm@mwt.net> wrote:
> The size of most ground rods in the U.S. are based upon the efficient
> grounding of 60 Hz AC from the power company. Anything larger in
> diameter than around 5/8 of an inch does not increase the grounding
> effect, thus the selection of that size by the U.S. NEC (National
> Electric Code).
They are WRONG when it comes to fencing. Remember apples with apples.
60 Hz AC is a slow trickle of perhaps a millionth of the 5,000 volts and
five or more joules in 0.0003 of a second. An old electric motor could
increase the trickle when starting.
In Holland the law was (in 1980s and I hope they�ve changed it) that only
electricians could install the energizer and the earth peg which was 5/8
diameter and one metre long - and that is all they installed. As soon as the
electrician left most farmers would add to it. Working with electric fences
from 1955 to 1987 I got many shocks, but the worst was when in Holland in
1983 sorting out a problem for Gallagher. The farmer could not control his
animals. While leaning on the iron shed I touched the silly little 5/8 earth
peg a metre deep against a building so under the eve in dry soil. The
building was a better earth than the peg so the power went through me. There
was 3,500 volts on th earth peg. It should be zero or no more that 500 V.
On our drystock farm of 107 ha with 107 paddocks (264 acres with 107
paddocks 2.5 acres each) we erected 84 kilometres (52 miles) of two wire
fencing (168 km of wire) and we used a disused 30 metre deep 4 inch diameter
water pipe bore as the earth. It was perfect with no voltage on it at all
which is rare.
> The conductivity of copper is about 4 times that of zinc.
The problem with earthing is not conductivity to the energiser, it is
conductivity (contact or joining) from the soil to the earth stake.
> Rick Williams
> Misty Ridge Farm
> Viroqua, WI
Best wishes,
Vaughan Jones
Hamilton
New Zealand
