Thoughts on fitting RCBOs

In message , ARW writes

I'm not sure that I am brave enough to do that, but here goes.

Taken with a rather washed out phone. The spaghetti to the right is alarm and door bell wiring. The 3 terminal combination on the right hand side of the DIN rail is for the smoke detectors and their interconnecting line.

Yes there is still an MCB in there, not too sure what to do about that, it is the feed to the garage, about 3m of internal cable to a 2 way "garage" CU with RCD and 2 MCBs for lights and power. Ideas please?

There is about a 2" gap behind the CU Don't look too closely at the 2 copper pipes to the right, they are central heating, when it was put to bed the cabling was cable tied together and away from the pipes.

All thoughts, comments etc. most welcomed, what ever they maybe.

No requirement (in fact it would actually be a disadvantage) to have RCD protection at the head (assuming its not a TT install) of a submain to another CU. Its better discrimination of a leakage situation on a garage circuit causes a tip there rather than at the house CU.

All in all very neat and tidy[1]. It can be very difficult with so little working room using tall RCBOs in many CUs. Assuming the boxing in will cover the wire entrance to the tops of the tops of the CU/Din rail box there is no need for additional packing to fill the gaps. Else you would need something to close off the gaps.