I really hated that rule when I first encountered it back in 2005. Hey, we gots a spec, the rod's gotta be under 25 ohms...if it's over, like 1000 ohms, just put a second rod in, don't bother measuring anymore..
In "most locations"..do you have a link to data supporting that, I'd be interested. In my neck of the woods, that doesn't happen. In fact, my water table is about 2 inches below the basement floor during dry spells, and I'm on a steep hill. I have a sump on a battery backup in the event a storm takes out the power.
I mentioned 25 ohms to point out the fact that measurement of the ground loop resistance using a fluke 1630 would clearly indicate the neutral is fully connected if the resistance shows as not infinite. 100 ohms would still show neutral is good, which is the point of this discussion.
John
I like the new forum software because I can click on that little bell icon thingy and it reports responses to a previous post. I can never remember what forum I posted in, it helps me.
John
Yes.
Altho I have read that they like to run two conductors for redundancy.
Altho I have read that whenever possible, or optimum, they run both wires as a metallic pair rather than fight the problems of ground currents.
Under-sea mono-cables work too.
That "can" be "normal". It is here, because 500 feet of #2 Al neutral. Washing machine not so much, but the well-pump is a 115V 1/2HP job and throws a several-Volt jog in the neutral when its 44A start-surge happens. Yes, half the house gets darker and half gets a little brighter. OTOH the 240V water heater and dryer hardly affect the lights.
But as said before, when I discovered a bad neutral, it was 170V one side and 60V on the other. You don't have to watch any light, just listen for the smoke.