Well if you know the route it takes one could start at the furthest one and
disconnect, then reconnect if it still trips and move closer etc. the snag
occurs if its branched ie several circuits or you do not know what goes
where first!

Brian

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From the Sofa of Brian Gaff Reply address is active
"Richard Russell" wrote in message
...
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/