This isn't a question of bonding vs. grounding, I understand the concept of equipotential bonding is distinct from grounding. I just want to confirm my understanding that the pump's casing is connected to the electrical system earth via the ground wire on the plug, and therefore the bond wire is connected to the electrical earth by that connection too.
On an AGP the bond wire is buried a significant length. Doesn't this create the potential for a ground loop if there is a difference in potential between that ground contact and the house ground, or the utility ground for that matter?
There are usually several pieces of equipment that are both bonded and grounded where the bond and ground both connect to the same metal frame.
So, yes, they are connected, but it's not done intentionally.
The bonding system does effectively constitute a grounding electrode.
For subpanels in a detached building, a separate grounding electrode is sometimes used.
Both grounding electrodes should be bonded together by the equipment grounding conductor.
So, there should not be much difference in potential.
Also, the neutral at the pool equipment is not grounded. So, any current going through the bonding grid would have to go from the main panel neutral to the main panel ground and back to the pool equipment ground and then to the bonding grid and then through the earth to the transformer neutral.
The neutral in the main panel is grounded and the neutral at the transformer is also grounded.
Since both neutrals are grounded, there will be some current that travels through the ground from the house grounding electrode the the transformer grounding electrode.
The amount of current going through the ground depends on the impedance of the ground, the impedance of the neutral wire between the house and the transformer and the amount of current that the neutral needs to carry.
