Things would be a bit more reasonable if it were time-daelayed.May be the main switch has a time delay will let you have all the details tomorrow not sure how to include a picture.
That's all as expected. However, I thought your explanation for the lack of RCD protection of the lighting circuit was that when halogens die, they would trip it - which, as I said, is very unlikely.The main switch has never tripped. Halogeng bulbs have tripped the lighting circuit mcb's . A faulty toaster and a kettle both tripped the RCCB on the power CU . It also tripped when I stripped. Wall and got a socket wet. The pond RCBO trips every time you cough but that is when the rain got into the external boxes when I left them open and a pump that had a fault on it. But as I say never the main switch.
As I think BAS suggested, the simplest 'quick fix' (albeit not the ideal) would be to get rid of the up-front single RCD and have it replaced just by a 'junction box' (probably 'Henley blocks') which directly fed the three CUs in the house - and have all circuits protected by a RCD in each of those three CUs (i.e. I think that would mean just putting one into the lighting CU - the other two already have, or will have, RCDs). That still wouldn't represent the ideal split of circuits between RCDs (e.g. the entire house's lighting would be on the same RCD), but it would certainly be better than having everything on one RCD.If as at seems 1 main switch is bad practice can I ask why and what it should be like.
Kind Regards, John