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Grounding - Bonding - GEC


Erby
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So help me I'll never fully understand Grounding and Bonding.

There's a meter box at the exterior right back of the house. A Grounding Conductor runs from the meter into the ground, presumably to the ground rod. The service is underground.

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200921118222_1Panel%20Ext%20Distant.jpg

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Three wires run from the meter to the exterior Service Disconnect (located a foot or so to the right of the meter box) thru plastic conduit.

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200921118325_2Panel%20Ext%20ServDisconnect.jpg

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Four wires run to the distribution panel on the back wall of the garage.

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200921118421_3Panel%20Top.jpg

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Copper wire runs from the Service Disconnect Equipment Ground to the copper pipes above the water heater.

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200921118456_4Panel%20Equip%20Ground.jpg

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The Service Disconnect Panel Diagram.

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200921118738_5ServDiscInst.jpg

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Why is there no need to connect the ground rod to the Service Disconnect Equipment Ground?

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Erby, I'm a little confused here. I see the SE-Cable exiting the service panel along with a separate copper grounding conductor into PVC conduit (pics 2 & 4). At the distribution panel (pic 3) I see only the SE-Cable entering (and it looks like a metal bushing there). Where does the copper GEC, the one connected to the pipes, split off? You say there is a GEC from the meter to, presumably, ground rods and another to the copper pipes. Are you sure the first is actually coming from the meter base and not from another "box" where the two GECs might be connected? Could it actually be a UFER ground and the connection made behind a wall plate in the garage?

That make any sense?

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Ah, just the person I'd hoped for.

So, you're saying they ARE already connected because the neutral carries the ground between the meter base and the service disconnect?

Yes.

The grounding electrode conductor can connect to the neutral at the service disconnect or before it. (250.24(A)(1))

If I understand your situation correctly, you've got a grounding electrode conductor going from a ground rod to the meter can. Then you have another grounding electrode conductor from the metal water piping (and possibly to a Ufer as well) to the service disconnect panel. They're both connected to the neutral at the service disconnect or before it, so I don't see a problem. As far as I can tell, there's no rule that says multiple grounding electrode conductors have to terminate at the same spot.

The equipment grounding conductor has to be bonded to the neutral and to the grounding electrode conductor. (250.130(A)) Your equipment grounding conductor is bonded to the water-pipe grounding electrode conductor by sharing a lug with it and it's connected to the ground-rod grounding electrode conductor via the green screw and the service neutral.

Is that more confusing, or less?

I think that the contents of Article 250 would be a whole lot easier to understand if they stopped using the term "ground" to mean so many different things. They need to overhaul their terminology.

- Jim Katen, Oregon

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