I would think you would disconnect both cables from the CU
and then insulation test, (or resistance test if you havn't got one) between the L / N / E connections to see if there is a short. (unplug everything first and switch off FCU's).
Is it an RCD or MCB that's tripping ?
You may struggle with test equipment you have, but you could disconnect one half of the ring safetly and try it like that for a few days and see if the tripping stops
and then insulation test, (or resistance test if you havn't got one) between the L / N / E connections to see if there is a short. (unplug everything first and switch off FCU's).
Is it an RCD or MCB that's tripping ?
You may struggle with test equipment you have, but you could disconnect one half of the ring safetly and try it like that for a few days and see if the tripping stops