Olin Lathrop wrote:

>>Now, is it recommended to just shoot 6J in every shot...?
>>
>>
>
>I don't know anything about electric fences or sheep, but this doesn't make
>sense to me.  I thought the point was to make touching the fence
>uncomfortable enough so that the sheep will eventually learn not to do it,
>without creating well done lamb chops on the spot (Baah, Bzzzzz, Pfft,
>sheep--).
>
That is exactly the point.  But there's a gotcha - weeds.  Most zappers
now are 'weed cutters', and will zap plants that get close enough.
 Obviously a lower power fence won't damage the weeds faster than they
can grow, and will quickly be dampened by them necessitating a manual
weed whacking job around the fence line - not fun for even small pastures.

Sheep, IIRC, need rather large pastures since a lot more of their food
comes from the grass rather than normal feeding.

Therefore a good fencer will have to remove several /miles/ of actively
growing weeds in order to stay in good shape.  Each zap is going to not
only zap any sheep that is close, but 300-3000 or more weed leaves that
are also in contact with the fence.  The sheep will get only a very
small current, and during the active growing season will get much less
unless the fencer can tell how much of its previous zap was actually
consumed.

I'm curious what the speed of adaptation is though - I hope it on the
order of minutes or hours.  A small child who grabs on to the fence may
not have the reflexes or ability to unlatch their hand in he 1-2 seconds
between zaps.  If the current gets stronger each zap it would be a Bad
Thing (TM).

As an aside, horses like to touch things they plan on jumping with their
noses before they do so.  The nose is one of the most sensitive parts of
a horse...  Cows, on the other hand, won't jump a fence so much as run
it over (or get tangled in it).  They are affected very little by
fencers and thus barb wire is still preferred to a fencer.  I don't know
about sheep, though.  I suspect that they are more like cows, but you
don't want to damage the skin/fur with barb wire (if it reaches all the
way through the fur - curious thought).

-Adam

>
>I would think the two relevant parameters are the spike voltage and
>duration.  The fence leakage resistance and capacitance to ground can vary
>due to environmental conditions and from installation to installation, so
>the manufacturer may have added a circuit to adjust the strength of the
>pulse automatically.  So far OK, but why doesn't the circuit try to hold the
>spike amplitude (or some measure of "feelability") constant instead of its
>power into the fence?  Why isn't the power per pulse only whatever is
>required to overcome the leakage?  For the same effect per pulse, wouldn't a
>long fence on a damp day require more power than a short one on a dry day?
>What am I missing here?
>
>
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