Ground Interconnections 1

[electrix]

Should the ground rod of the utility transformer be connected/bonded to the service entrance ground rod. Is there a minimum separation between the two system rods.

 

[dpc]

In the US, they need to be bonded together.

 

[waross]

Hi dcp;
When the original poster says the ground rod of the distribution transformer, I visualize a pole mounted transformer with a ground rod at the base of the pole.
respectfully

 

[jghrist]

Normally, in the US, the connection between the utility ground at the transformer and the service entrance ground is through the service drop neutral. Both ground rods are connected to the neutral.

 

[dpc]

waross - that's what I visualize too.

 

[waross]

Hi fellows;
I think we are basically in agreement with the connections.
We may have a disagreement on terminology.
In the building the neutral system will be connected to the ground grid in one place only.
At the pole, the utility neutral, which often serves as both primary and secondary neutral, will be connected to ground rods at regular intervals. One point of connection to ground is always at a transformer. This is the utility's ground system.
If the neutral is supplied to the building it will be grounded at one point to the building ground grid.
The neutral will also be connected to the utility's ground system at the pole.
The point of confusion seems to be the word "Bonding".
To me, bonding the ground rods together implies that another cable is run directly from one ground rod to the other. This may have been the intent of the OP's question.
I do not think that this is required or allowed.
I am not sure about the spacing issue. Is anyone familiar with the applicable NEC rules?

 

[dpc]

waross,

I think we're all saying the same thing. NEC defines bonding as a "permanent joining of metallic parts to form a path that ensures electrical continuity". But I'm OK with saying that that ground rods are "connected" together, if that sits better with you.

I think spacing between the two ground rods is not relevant, at least in the US, since they are electrically connected.