please bear in mind i'm only a humble brickie and my following question(s) might seem daft to a qualified sparkie! 1)what is the difference between an rcd and mcb? 2)is one safer than the other? 3)could i,in theory,change (not by me i might add!)whatever i have in my cu for the "safer" option? 4)would it be worthwhile? 5)how can i tell what i have in my cu at present? my(wylex) cu consists of a 100 amp "main" switch on the right and 7 mcb/rcd? to the left,made up of nsb06(lights) and nsb32(power).the above might sound stupid to you but after reading about other posts regarding rcd's these do seem to be the way "you lot" prefer to go.last point what is,and what is the purpose of a split load cu? i hope you understand this is only really for my personal knowledge and not to start rewiring my house!!!! thanx chaps.