It don't take much voltage with wet skin to bloody hurt! Possibly only 50V or so, not exactly dangerous, but wet skin, wet concrete floor, possibly some soap.... Yea, that will tickle.
My betting is that the suppliers earth moved, and your concrete floor didn't.
Incidentally, given your user name, you might wish to pay attention to the earthing on any aerial structures outside the equipotential zone (Can of worms), but IIRC the suppliers recommendation for the earthing of radio stations is to go TT with an RCD instead of TN-C-S.