On Wednesday, June 19, 2013 11:21:21 PM UTC+1, John Rumm wrote:
On 18/06/2013 20:38, wrote:
On Tuesday, June 18, 2013 3:19:47 PM UTC+1, Richard Russell wrote:

We have an extensive, professionally installed, garden lighting
system which has recently started tripping its dedicated RCD. I
have eliminated all the bulbs, luminaires and accessible cables
which, sadly, means the problem is almost certainly in one of the
many 'waterproof' underground connection boxes. How on earth does
one trace a fault like this? Dig up the entire garden? Richard.
http://www.rtrussell.co.uk/

Divide & conquer. Simple as that. Its going to mean undoing many
connections as you megger it all bit by bit.

If you go the binary chop route, you can eliminate 3/4s of the circuit
by digging up just two of the junctions...

Yup. You've got a fair chance of getting a lot of the circuit operational quite quickly. But it is also possible the OP has more than one leaky cable or jbox, or that the leak is in the one and only feed line for the lot.

There's really no other way to fix it than divide & conquer. The only other options are workarounds that keep going with wet cable or jboxes, which have a high risk of later total failure.

With luck you may be able to trace much of it with a basic metal detector.


NT