I decided to make something like the power switch tale with my relay and it worked fine at first then I plugged it into a surge protector and it killed the power to my hole house and tripped some fuses.
Did it trip your RCD? You probably have an earth leakage from live or even neutral. If it was a wired fuse, you probably have a live-neutral short! Maybe you need a battery powered project?
That fuse/RCD is there to protect you.... remember...
Remember, it's the volts that jolts and the millies that killies! smiley-wink
Take care friend