I don't care what they do, I just use fuses. And the equivalent to GFCI in the UK is just "earth leakage breaker" - we say ground for electronic circuits, and earth for mains We also don't call a wire hot when that's the last thing it should be. Anyway GFCI or whatever you call them are the pesky ones that trip for no reason. Usually something like operating a microwave oven (which have natural earth leakage), or I used an earth instead of a neutral because it happened to be there.