the twirling fish.....

On Mon, 21 Feb 2005 11:46:00 -0800, ~ jan JJsPond.us wrote:

On Mon, 21 Feb 2005 09:33:03 -0500, Hal wrote:

That's interesting. Why not just use a GFI? That stops the circuit
from operating if it loses more than 400milliamps. I've never tried
it, but understand you don't even feel it when that amount of voltage
is contacted.

They should switch at a lot less than that. Looking at some UK products
http://www.toolstation.com/shop/Elec...es/d190/sd2659
(about halfway down) they switch at either 30ua or 30ma and in something
like 40ms.

When I was first shown this device I felt "snake oil" but I don't know, I'm
not an electrician. I don't use one on my ponds, but the OP had a problem
where the fish got better out of the pond, yet still in the same water, so
the water quality wasn't an issue. Why I suggested it. ~ jan

It's not the voltage at the fish that harms it but the voltage gradient
across it. In a pond with no earth the voltage would go to whatever your
mains is but it would be the same all over so there wouldn't be a current
passing through the fish. With an earth spike the voltage would drop from
mains to 0 between the pump (or whatever was leaking voltage) to the earth
spike. If you have a trip the spike would probably cause the trip to fire
sooner but if you don't have a trip I would expect the spike to cause more
harm to the fish. There is a 33,000volt power line going across the field
next to me and the birds happily sit on it without getting fried even
though they are at 33,000 volts but there isn't any current flow.

I think the spike is just 'marketing hype' but one might just help a trip
to work if there is no other path to ground. Usually there is either, via
an earth wire in the pump or even through a plant leaf that goes between
the pond and the outside.

Going slightly off topic the BS kitemark is misused quite a lot in this
context. BS1363 (I think it's that one but it's a while since I dealt
with them) used to be used by the marketing people to say how good their
computer spike suppressor was but all it means is that the insulation will
withstand 2,000 volts before electrocuting you :-)

--
Regards - Rodney Pont
The from address exists but is mostly dumped,
please send any emails to the address below
e-mail ngpsm4 (at) infohitsystems (dot) ltd (dot) uk