Why is voltage detected in my ceramic tile floor?
Check the voltage with an analog voltmeter. Digital voltmeters will register a voltage from almost anything as they have a very high impedance and draw very little power. You could also use a regular incandescent bulb and see if it glows a little.This will let you know if there is any power behind the voltage. If by phase line, you mean the neutral incoming wire, it's possible it's not groundedat the panel and/or the pole transformer. Measure from the neutral to ground to see if you have a potential difference. It's possible the shock you received was static electricity and nothing to do with voltage difference between the tiles and the neutral..