Hi, I was changing a bathroom 'light' 'switch ,which was actually a 45 amp pull cord shower switch controlling 4 downlights and the fan.( A separate switch beside the light switch has been installed at some point to feed an electric shower, but only has the supply cable connected). I connected the new switch, powered up and the socket mcb tripped and this has fried the consumer unit main isolator switch. On Investigation there is a loose , and split 1mm cable lying in the ceiling space which I am assuming is the cause of the short. The wiring to the downlighters is really poor quality work and certainly.ly needs to be done properly. No earth wires visible!. I will not have the chance to investigate further until tomorrow but would welcome any suggestions/ ideas. Why would a cable in a ceiling space cause this situation.
Thanks
Thanks