And what if it trips because of the UPS ? I haven't measured the leakage current for the present one, but after stripping down the old one for scrap, given the amount of filtering (extra for the Euro market I guess as the filter boards had the only metric threads I found) I suspect the earth leakage is not insignificant.... fit a RCD even if it will never work because of the UPS.
Hmm, now I'm wondering whether my clamp meter is sensitive enough to measure it ...