thanks jj. so lets say on a lighting circuit, all lamps/tubes must be removed,any electronics ie dimmers disconnnected,(what if something in the loft or hidden elsewhere is still connected) or something has been taken off the lighting circuit by a previous owner that new owner knows nothing about,which i assume would mean reading a fault,this then has to be tracked down,taking hours maybe? so a job that should be an hour could end up costing a fortune, or does this not happen