I have to upgrade the service I have for an exterior building.
The wiring follows the old code, and I'll need a permit to do it.
So I am going to have to update the service and everything to the newest code regulations, but have a little confusion on the bonding of the ground and neutrals.
Typically you bond the ground and neutral at the first cut off point after the meter, be that a panel or a disconnect.
But the meter and disconnect sit on one building, and the panel and grounding system sit at another building, with about 115feet of distance between them.
From what I understand, in theory, the area that you bond, should also be the entry point for the grounding. (I could be wrong about this though)
Aka my ground should initially enter my disconnect, then bond, then travel the 115 ft to my panel.
But since the grounding point is at the panel, I am not sure how to handle this.
I am not sure if I need to bring my ground wire, straight to the disconnect, then back to the panel.
Or Install a new ground bar at the disconnect, just to do the bonding and then tie the other ground system into it at the disconnect
Or do it as I have illustrated in the drawing attached
(which I believe might be the correct way of handling this)
which is:
bring the ground into the panel
tie it to the ground bar only
push it back through the conduit to the disconnect
and bond it with the neutral there.
Am I correct in this? or am I missing something?
Best Answer
You need a ground wire and ground rods at both structures
You are correct that you only bond neutral to ground at the service entrance. However, current Code not only calls for a grounding wire between the structures (which you have provided), but for a grounding electrode system at both buildings. This can be a concrete-encased electrode (if provided), or the old saw of two 8' ground rods driven 8' apart and connected with an appropriate-gauge wire if no better electrode (such as a concrete-encased electrode, foundation steel of some other sort, or a well casing) exists.
Each grounding electrode system gets a grounding electrode conductor back to the ground bar in the panel/disconnect for the associated structure, and the feeder equipment grounding conductor in the inter-building feeder connects the two together, from ground bar to ground bar.
You are also correct that the radio tower needs a ground rod, and that its ground needs to be bonded to the mains grounding system at the structure where the radio device (transmitter or receiver) is located. This ground wire goes to a tap on the structure's grounding electrode conductor, made using an intersystem bonding termination device or suitable tap connector.