My apologies in advance for a very long post. I have a number of questions
and your help would be much appreciated.
My flat has a small plastic cupboard just inside the from door containing
the elecric meter. This also contains the original pressed steel fuse box
from the 60's with 3 fuses, one for the cooker, one for the ring and one for
lights. The flat is wired in micc. There is a chunky plastic junction device
after the main fuse that goes to the original fuse box and to a newer single
fusebox that has been added for an electric shower.
I have removed various other later additions to the circuits as they were
very badly done. I'd now like to do the following:
Add an addional double socket in each bedroom as a spur from a socket on the
ring that has no other spur on it. I would use standard 2.5 T&E. The earth
arrives at the original socket via the MICC casing, and is conducted to the
socket via the backbox and socket screws. As suggested on this group I have
added an earth cable from the backbox to the socket's earth. As the
backboxes had no earth terminal I have bolted the cable to the box or used
one of the extra tags on the box for socket screws with a 3.5mm bolt and
small washer (each double back box has 6 tags for socket screws in total). I
would have replaced the backboxes but I didn't want to disturb the micc. I
would now expect to take my earth for the new sockets from the earth
connector on the original socket. Does this sound OK in principal? Anything
to watch out for?
I'd also like to remove the extra fusebox for the shower and replace it with
a RCD 'shower' unit that accommodates 2 MCBs. One MCB will be for the
shower, the second would be to add a ring for the kitchen. The kitchen now
has only 2 sockets since I removed some that had been added and wired in
flex from the cooker switch. I want to add more sockets and sockets spurred
from switched fcu's for washing machine etc. This shower consumer unit will
just fit in the gap left by the shower fuse. I'd like to replace the
original fuse box as well but that would mean disturbing all the micc
cabling fixed to it via brass glands; I also doubt whether the wires from
the micc would reach the terminals in a larger consumer unit. If I do this
much work then am I liable to rewire the whole flat? I really don't want to
do a complete rewire because routing the cables in this flat would be a
nightmare.
The cooker will also be moved and I need to move the cooker switch/socket.
This could be an opportunity to lose the existing massive switch/socket unit
and replace with a small 45a isolator. However, is there any reason why I
should not rip out the existing micc for the cooker and replace with 6mm
T&E? This would be a very short run of about 3m from the fuse box to the new
isolator. This would mean that I have a mix of MICC and T&E at the original
fuse box. Is that a problem?

TIA for any help.
KW