How to detect current leakage from buried wire

Hi,
Our residual current device (RCD) keeps getting triggered even with all electrical appliance have unplugged. I know there is some
current leakage to ground from the wires. But all the wires are buried in the walls and hard to find where the problem is. Any help is highly appreciated. Thanks!
Tom
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snipped-for-privacy@gmail.com wrote:

Are you sure everything is disconnected/off? What about the cooker/immersion heater/central heating/electric shower/etc?
Earth leakage from the wires themselves is, IMHO, very unlikely*. Far more likely is one of the items above, or something similar, that is still connected and switched on - or you have water ingress into a switch/outlet box.
You presumably have several fuses/MCBs. switch off/Remove them all (with the consumer unit off) and see if the trip still operates. If it doesn't, switch on/replace them one by one until it does - the odds are that the problem is with the first circuit when that happens...
*Unless you have a really big problem, furry, with teeth..
-- Sue
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On Fri, 20 Feb 2009 06:23:42 -0800 (PST), " snipped-for-privacy@gmail.com"

A common cause of this, when you aren't operating the over-current device, is a short from the neutral to earth. Disconnect at the feed end and check for that.
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** Details please.
How often, any precursors involved, times of day or the weather maybe?

** How exactly do you know that?
Alluding to mysterious, private knowledge like you have just done does NOT help anyone to help you.
...... Phil
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On Fri, 20 Feb 2009 06:23:42 -0800 (PST) snipped-for-privacy@gmail.com
| Our residual current device (RCD) keeps getting triggered even | with all electrical appliance have unplugged. I know there is some | current leakage to ground from the wires. But all the wires are buried | in the walls and hard to find where the problem is. Any help is highly | appreciated. Thanks!
What did you find out when you separated each branch circuit individually? Does this leakage happen with each branch circuit, or does it only happen on some of them? Or maybe just one of them?
One remote possibility is something I've found can not only false trigger an RCD, but in certain cases actually damage them with risk of fire and personal injury or death. That is a radio energy induced into the wiring around the RCD in common mode. An improperly wired RCD leaves its triggering solenoid energized even when it opens the circuit, and the external triggering cause keeps the solenoid activated until it burns up. But even if properly wired so the solenoid is de-energized once it opens the circuit, it is still possible to cause a false trigger this way.
If this is a main RCD, shut off all branch circuits that follow the RCD and see if you can isolate which branch is, or branches are, involved in the problem.
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