Uk sparky, just as a foot note. I am having a little difficulty thinking about removing the link from the met to the genny. This would require a new electrode at the installation met thereby converting system to TT. The system currently is TN-C-S on poco supply and TN-S on genny. The genny earth is to reference neutral with earth to stop the genny neutral floating. Fortuitous contact with earth via the met is certain as this is a steel frame building. The genny earth could really be described as superfluous in this case. However, I do recognise the point that when the gen-set is independently spiked there seems to be a cure to rcd tripping so obviously something is afoot! I have drawn the circuit arrangements out and I can see no advantage in separating the gen-set earth from the met.
The reason that I highlighted the fact that these rcds are electronic with loss of neutral protection is that it has been well reported that upstream faults can upset them.
