In article ,
MisterP writes:

This is a 50 year old installation with existing vertical steel oval
conduits to sockets plastered into the walls. The rubber(!) cable
enters from above and there is a grommet inserted into each of the
conduits to prevent damage to the cables.

Now if rewired with PVC sheathed cable, then
a) Can I re-use the steel conduit?
b) Where can I get suitable grommets? These are top hat shaped with
central hole for the cable.
c) The recessed steel boxes do not have an earth connection. Can one
be fitted or is it better to replace each box?

There's no requirement in the regs to earth back boxes unless
they are exposed. It's good practice of course, but I wouldn't
replace a back box just because it didn't have an earthing point.
It would be easier to drill a tiny hole for a self-tapping screw
if you really want to do this.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]