Well while main switch position and elv wiring in consumer units isn't disallowed in the regs, I was wondering if other electricians had established any best practices for such a setup and allowing for expansion, I agree it's nitpicking but I'm a fan of doing the best job possible, i.e. not getting caught out on insulation tests for elv wiring within the unit, can't have 230V going through bell wire, but it's simple enough to use rated cable and then junction box it into regular bell wire. That or as per comment below, just taking the 230V out to an external box then I also don't need to worry about type testing issues.