Has anybody been caught out with up and down lighting circuits split over 2 RCD's... .... as ya should by the book !!!!!! TURN ON LANDING LIGHT AND BAM!!!!! Both RCD's trip...... cause Landing light using upstairs N ,,, But switch wire coming via strappers from downstairs circuit....... shall we A: Tell customer the problem before we start....... and have to charge more !!!!!! or B Say nothing and connect to same mcb which solves the problem but not the thing to do if ya resd ya books...... Bet the smart a***s at the IEE / NIC/ ECA never thought of that one....... since most properties ( domestic ) would be wired this way!!!!!!!