On Monday, November 25, 2013 3:18:49 AM UTC-5, Danny D'Amico wrote:
On Sat, 23 Nov 2013 10:17:08 +1100, John G wrote:



No current flows in around or thru the ground if all the conductors are

installed to code. :-Z



That's not how I understand it.



Even though the ground is so big that even all the nuclear power plants

in the world pumping electrons into the ground couldn't change its

potential, that doesn't mean that the ground doesn't complete the

circuit.



If the power company chose any other conductor other than "the" ground,

then they would have to have a wire for each phase distributed.



Since the power company chose to use "the" ground as "their" ground,

the way I understand it, "my" ground is connected to "their" ground,

so, the electron that flows into the primary of my transformer came

from the ground at the power plant, and it goes back into the ground

at my house, to (theoretically) make it back to the power plant.



Of course, the ground is so big that it's like pouring a glass of

water into the ocean, where that molecule eventually will make it

around the earth - but the immensity of the ground should not be

construed as implying there isn't a loop from the earth at the

power company to the wires to my transformer primary to the earth

at my transformer.



At least that's how *I* understand the typical mains power in the US.

Most of the current doesn't have to flow back via the earth. You
have a transformer that is connected on one phase of the primary.
It serves several houses. Further down the street, there is another
transformer, it is on a different phase. Even further down, there
is another transformer on the third phase. The other sides of all
those transformers are all tied together on the primary neutral.
If those loads are equal, then the sum of the currents in the
neutral is zero, you have a balanced wye configuration and the only
net current flow is in the 3 primary phase wires.