Originally Posted by JoeD
Metal water lines will do the same thing by sending the neutral current out the water line to your neighbour's house.
This can be checked.
Turn off everything in the house except a 10A load like a hair dryer or room heater (to make an unbalanced load) and then use a clamp-on ammeter to check the water pipe.
It might be a close race between the pipe and the neutral line, depending on the relative resistance of each.
3/4" ID pipe is equal to about #1 or #2 AWG.