I changed some old tired 13a sockets for new ones in a kitchen the board is a starbreaker type, I will have to replace the CB with a RCBO,I've checked the main earth and bonding this is undersized I'll replace the undersized earth and bonding cables, is this the extent of my work or does it go further ie replace all the CB's with RCBO's I know this would be good practice but the financial side for the client will be quite considereable as the RCBO's for these babies are about £40 each.