My drain lines at home are all metallic. I've got brass tailpieces and traps, and cast iron (with old oakum & lead joints) waste piping. These are connected to a vitreous clay (read ungrounded) sewer lateral.
Contact on the system anywhere to an energized conductor would cause the drain system to become energized. The only saving grace that I've got is that the kitchen sink is made of cast iron, and might (or might not) have continuity to ground, either through contact with the garbage disposal, or contact with the water supply.
I think "electrical dummy" has a point...S
