Electrical question

It carries the power back to the source on a two or three wire system. It is NOT a ground

In your typical center tapped 120/240v system it carries the unbalanced current back to the transformer. In the 120v circuits that is equal to the ungrounded (hot) conductor current. In a 120/240 circuit (AKA multiwire or Edison) it truly does carry the unbalanced current. The fact that it is grounded is just for safety, to stabilize the voltage of the service to ground but the ground should not enter into the current equation. This is what your typical service looks like

In reality the grounding system will still carry a little current because of the voltage drop in the service drop and MV distribution. At my house the ground is carrying a couple amps most of the time and every ground on every utility pole is carrying some current.

Main MV distribution pole with all 3 phases present

First pole on a single phase MV (13.5 kv) distribution string with a transformer.

Although it USUALLY is at ground potential.

Earl Grey posted for all of us...

DAGS - but I see Greg Fretwell did all your work for you.