I recently cut through the live 240V power cable of a plane the tool is double insulated, the blade exposed and combined both conductors. The supply is protected by a 30ma RCD and 30Amp MCB (10 yera old installation), the RCD didn't trip, it does trip when the test button is pressed. Could it be the case that in this situation the RCB won't trip or is it likely there is some sort of fault in the system? Thanks