I found out (in a rather uncomfortable manner) that there is a potential difference between the phase line in my home and the ceramic tile floor. My Fluke multimeter reads 30V AC, I assume the reading is inaccurate because of the low conductivity of the tile surface. However, there was enough current to give me an unpleasant shock. I was dry, but my skin was in contact with the floor.
How is this possible? Are there tiles made of ceramic-like materials that are conductive? Are conductive ceramic tiles sometimes used in home construction?