Snapey
The RCD covers you for leakage to earth I.E. it "measures" the current in the live wire and compares it with the current in the neutral and if theres a difference of more than the set limit it trips the circuit.
I think your wee visitors have been munching your cables and have left you with a live wire touching the "earth" or an earthed metal part. this is a risky situation and the system shuts down. the RCD can mess about but its really, really rare and I would not be inclined to believe thats the issue. check out the cavity for chewed cables, look for dead rats you may have got a little payback before the critter fused your cables.
It may be possible to check if there is an earth fault if you have a meter.
With the mains power off (and tested please) and all sockets cookers and shower switches off disconnect the live wire coming out of the RCD to the fuseboard also disconnect the main earth wire and check across these. there should be no circuit in the ohms scale. If there is try tripping fuses until the fault goes away, maybe this will reduce the search area. if you cant test for this or find the chewed cable you may need to ask a sparky to come in. make sure yoou make a good job of reconnecting the earth wire as its the important one.
Kenny F
December 2008