The current in the main neutral *should* be the difference in current between the main hot legs, right? However, it is usually off by between 1 and 1.5 amps, which seems to correspond to the current flow through/around the water meter. This would seem to be a *necessary* relationship, right?
My impression is that prior to the utility replacing the old wires along the poles and to my house, this current flow through/around the water meter was a lot higher -- 3-5 amps.
So the Q is: What is "acceptable" ito current flow through the water meter to the street?
My assumption is that if I took out the water meter, then all of the neutral current would necessarily flow through the main neutral, and it is just that apparently the water plumbing ground is "good enough" to share some of the return load -- which doesn't seem like such a terrible thing, esp. given the aluminum conductors used by the utility, vs. the copper plumbing to the street, and perhaps farther.
But again, what are acceptable limits ito of current flow through grounds? Is there an NEC ratio, a percentage? Mine seems to be pretty constant at this 1-1.5 A.