| 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.