My electrical system uses the armored cable sheathing as a ground path. I was placing some lines of AC in my walls, and I uncovered a drain pipe in the way. At first, I covered the AC with electrical tape, then I decided to wedge a piece of plywood between the AC and the pipe. At this point, I'm not concerned of any problems with contact between the two metal objects, but my question is: If I allowed the bare AC to cross the drain pipe, would that be hazardous? I'm thinking that if there was a ground fault, and the AC sheathing was used to carry a current, the drain pipe would become energized and could shock someone taking a shower. Am I right?