I bought a trivial low power 12V plug in from Maplins (RIP UK supplier of electronics kit) about a decade ago. I plugged it into my wall outlet and there was a big bang and the main 32A breaker tripped. I removed it and there was a notch missing from the copper so proving the well known truism that fuses blow after the damage has happened.
I took it back to Maplins for a replacement and insisted that they plug the new unit into the wall there before I accepted it. She did so with notable hesitation and a worried look but it was fine