So yesterday I've noticed something funny with one of my wall sockets. I've checked it out and bingo, the PEN (the most epic invention ever - PE and N wire together) was loose under the screw. Thus everything connected to sockets in next room was basically floating at live potential...
I live with 4 other people in a rented old slab block flat. And they really made the power net shitty back in the day (communistic regime pressed on building huge amount of cheap flats). So it's all in aluminum TN-C config, that stuff is just crazy.
Today i decided to check every socked and found this (image below). I don't know how, but i managed to run my PC from this socket whole year. Live wire connected on the wrong side (should be left) and I really don't know how, but it had connection to PEN from a wire that was coming from the earthing screw...
Best part is, that the remains were nowhere in the socket box, so someone really "clever" left it like this on purpose...
Damn I'm gonna check everything as soon as I move to the new flat next time...