Will James Wrote:
Thanks for everyones replies. I am in the UK, if I understood Sean
correctly
I think you are saying if I cannot get hold of a 5mA RCD, it would be
better
to have an RCD with an earth as near as possible in cable length terms
to
the pond as well as an RCD inside which would trip the circuit if a
spade
went through the outdoor cable?

Thanks,

Will

[/i][/color]
Sorry but no, what I am saying is that in my opinion a 30mA RCD cant be
relied upon to make a pond safe. The problem is that the water is
resistive and as such as the distance between the source of the leakage
and whatever provides the electrical earth in the pond increases the
leakage current quickly drops below the trip value for a 30mA RCD,
salted water is probably more conductive than unsalted water so this
may not be a concern in a salted pond but I dont salt my pond.
In practical terms I assume that most UK pond devices, pumps, lights
etc, are earthed, I have yet to see an unearhed UK device, and that the
earth point is very close to any likely source of leakage, UNLESS a
cable gets nicked, so a 30mA RCD would most likely trip. However should
the fault be a cable nick etc the RCD may not trip. IMO the length of
the earth wire is irrelevant providing all connections are good.


--
sean mckinney