Consider a very basic, ONE service from ONE transformer installation where the underground metal water pipe is in close proximity to the utility ground on the transformer (this is not uncommon). Consider the resistance through earth as relatively low across the gap between the transformer ground and the pipe. The neutral is bonded to the grounding electrode at the transformer AND at the service. Therefore the electrical circuit through neutral conductor and the electrical circuit through the grounding electrode conductors, the pipe and earth (together) are in PARALLEL. The neutral current WILL divide between the two. The amount on each depends on the impedance of each. BASIC ELECTRICITY. In the case I describe above, with a reasonable neutral current, 4 amps could easily be expected!! Add in multiple currents from different services and utility connections (maybe a miswire too)and the picture become more complicated....but still obeys the same rule!
