I have used one before and I will say that it must have been ok because cold showers are right up there with getting my eyes gouged out. I don't know what the differential is for GFI at voltage above 110vac but I am not fuzzy wondering what happens when and if the thing shorts out..the idea of running electricity into the shower in the first world scares me..third world..electric run into the shower..? Gotta a reason not to many countries do this..?