Here's an interesting question, that I'd be interested in getting an answer to. I'm subtly hinting that our Austrian friend Texas_Ranger might possibly know something about this one....
I've heard that the German wiring regulations specify that the only cables which can be routed in or through the walls surrounding a bathroom are cables going to fixtures in the bathroom itself.
Could this be true? If so, what is the reasoning behind it?
If it is true, does it apply only to a wooden stud partition wall? In other words, if the wall is solid brick or concrete (as is the case in many houses in Europe), is it still permissible to run wiring on the other side?
If not, or if the wall is timber frame, how would one get around the problem of wanting a receptacle or switch in a room adjoining the bathroom?