In article , G&M writes
Well its very debatable. It can show up faults in leakage between the wires in cooker and immersion elements before they finally break down which can be a good thing. I've never had a problem with it causing a cold supper or bath tho. Course there might be a time when you inadvertently connect yourself to the cooker or immersion circuits then perhaps you'll wish you had;!..
The possible best bet is to use combined overcurrent and leakage units to protect each circuit at the CU board.....