I have been out on a few tripping problems in the past few months and have found that the RCD has had some nuisance tripping, Im finding that the electrical circuits are all ok with a good reading's on the insulation test.
Im now going looking for earth leakage problems on the circuits which will cause nuisance tripping, looking at any thing with a electronic circuit ie LED downlights, fridges, freezers ect ect.
Im looking for readings around the 15ma range as i know this is enough to trip out a RCD.
Today I also found out that a DC current can keep a RCD in a non tripping state, this is rather worrying as your RCD will not trip as long as it had a DC voltage across the RCD.
I am now going to fit RCBO's as this will alleviate a lot of the above problems with the RCD.