Thanks ericmark for your detailed advice. To cover the issues you highlighted:-
I am moving a kitchen tower with integrated cooker 12" sideways. The tower will then hide the existing cooker switch. The only way to access the existing swiitch would then be via withdrawal of the cooker. This is unacceptable. hence the need to have a new switch fitted 12" to the right of existing location.
The house / wiring was built in 1987 and I wish to leave the existing cooker circuit un modified to avoid a complete new installation.
It seems better to remove the switch from the existing MK fitting and to replace internals with a connection terminal block, rather than leave the switch as is. I was planning to fabricate a full face cover for the exisiting MK so as to block it off completely, with appropriate external warning label.
I did not intend to have 2 switches in series, but I presume another option could be to leave the exisitng switch un touched and to fit a second (new) switch in series downstream in an accessible location, connected on the existing cooker cable end. This option does appear to fall clearly under Approved Document P table 1 non-notifiable works however,
As owner occupier, I was looking for a DIY solution in accordance with Building Control section P and for which notification was not necessary.
I get your point re RCD's, cable specification and deadline. The work will be completed before 1st July.
Access to the existing MK patress would still be possible for maintenance via withdrawal of the cooker - suitable for inspection and maintenance, but not convenient enough for isolation purposes. Does this avoid crimping/potting?
The existing terminals are integrated with the user switch, protruding through the MK cover plate. Reusing these terminals, even of the switch is stuffed inside the patresse, seems to be a bodge, and the aging switch contacts an unneccessary component. Hence the question about terminal block features.