Since Amd 3 and much arguing, the industry and IET seem to have become more settled about use of no up-front RCD on all TT when using all-RCBO installation in metal boards. (GN3 takes a slightly more dim view of doing this on split load boards due to the unprotected feeds to the RCCB’s).
Since we are now duly fitting SPD device directly after the main switch, even on an all RCBO set-up, we have now added additional non-RCD'ed vulnerable wiring - The cable loop from MCB to SPD, or depending if MCB is not necessary for the SPD, maybe from main switch direct to SPD. Since few manufacturers yet seem to offer factory made cables or a specified methodology to do this, (Some do- Hager being one, most don't), connectivity is likely as not to get made up on-site, maybe not as reliable as they could otherwise be, and certainly outside the control of the board manufacturer.
So does this raise the bar WRT the practice on TT of neglecting to fit up-front S type on all RCBO board? There are certainly now more flappy bits to fall out than there were. - Do we still rely on our good workmanship and tight connections or does it suggest up-front 100mA S type in place of main switch needs to be a recommendation again?
