Again for what it's worth, I've lived with my (several) dual-RCD CUs for very many years and have suffered virtually no 'nuisance' RCD trips during that period (i.e. virtually all trips have been 'for a good reason', usually water-related) ... so I really have no concerns about the level of 'baseline' residual earth leakage currents (and have no reason to expect that they are likely to increase in the foreseeable future.
You have said this before, and I have also said in my old house how I lost two freezers full of food when we had left the house for a few months to look after my mother, that old house had RCD's fitted in around 1992, and they would go for years without tripping, then trip many times in a couple of weeks then do another few years, never did find a fault using an insulation tester, but one when fitted RCBO's of single modular width were not readily available so no option but fit a RCD to each fuse box I had two, and this is true with many installations they had to fit what could be obtained in the local wholesale outlets. They could not have fitted RCBO's as simply not available.
Had a thought, an alternative could be to use a PoE video doorbell instead.
I'd have to read deeper to fully understand properly, but on the face of it I could get run some cat5 outside to the doorbell. So wouldn't have to touch the CU or house electrics.
I do wish now we had a video camera at the door, no point being in door bell the delivery people never press it, the take a photo and run, often opened to door to find soaking wet parcels, even a food parcel which said in large writing door bell must be rung. My door bell does log when used, so not a case of not hearing it ring.
I wonder if a simple PIR is the answer? And have that connected to a bell of some sort, however I don't really what it ringing when the milkman calls, as that is so early in the morning. My front door is at side of house now, but last house any PIR would have been set off by passing traffic, also no one can see parcels at door where I live now from the road, so theft is unlikely.
Covid has changed how parcels are delivered, I do wonder how many photos have been taken on my property without my permission? And of my security arrangements i.e. my front door? And I have seen on social media photos published of some random front door where a parcel has been left in error, with requests does anyone recognise this front door. But can't see how a video door bell helps? I used a pet cam to look after my mother before we had to move in to look after her, and it did work of sorts, but it would fail every so often as could not connect with internet, and I would need to drive down to check all OK. Internet is improving, but I am in the outback of Wales, so not really good enough to use phone for door bell answering if not at home, hard enough getting a mobile phone signal never mind video.
