Ragnar,
I thought I'd bring this oldie up again, since I had a similar thing happen to me last week.
And also, because of the fact that I've since learned that it doesn't pay to have a refrigeration unit on an RCD.
This is because of the leakage currents caused by the Compressor in the fridge.
Fridges and the like are always excluded from RCD protection here. [Linked Image]