N-G bond at both panels and meters

[jaggedben]

I'm sure this has been discussed ad naseum already, but here goes. This has always confused me.

We installed a solar system on one meter of a building with three meters. The meters are in a single gutter with the panels right above them. The existing GEC was coming from the rod and water, passing through each panel, via nipples between them, and then going from the last panel into the meter enclosure. On the way it was put through bonding bushings on each offset nipple going to the meters.

We wanted to avoid opening the meters, so we crimped our solar to the GEC in the panel, and hoped it would fly, but it did not. The inspector says he can't pass if the system grounding is improper. No real argument with him there.

Here's the thing. He wants the GEC to go to the meters, and then he wants the N-G bonding jumper installed in each panel (the factory supplied jumpers had been left unconnected). So to my mind this creates an N-G bond in both the meters and the panels. Is this okay? Won't there be objectionable current on the bonding jumpers and offset nipples between each panel and the meters? How is this supposed to be done normally?

 

[don_resqcapt19]

...
Here's the thing. He wants the GEC to go to the meters, and then he wants the N-G bonding jumper installed in each panel (the factory supplied jumpers had been left unconnected). So to my mind this creates an N-G bond in both the meters and the panels. Is this okay? Won't there be objectionable current on the bonding jumpers and offset nipples between each panel and the meters? How is this supposed to be done normally?

The code permits the grounded conductor to be used for all bonding and grounding on the line side of the service disconnect and requires a main bonding jumper at each service disconnect.
This is a code required path for grounded conductor current, assuming that the service conductors between the meter and the service disconnect are in metallic conduit.

 

[jaggedben]

So if the GEC is coming into a panel first and then goes to the meter enclosure, it's supposed to be bonded to both ends of the raceway (in this case an offset nipple). But that creates a second path for grounded conductor current. So does that mean it's a code violation for the GEC to enter the panel on it's way to the meter?

Also a grounded conductor isn't supposed to be put throught bonding bushings, is it? I've never seen that done.

 

[don_resqcapt19]

So if the GEC is coming into a panel first and then goes to the meter enclosure, it's supposed to be bonded to both ends of the raceway (in this case an offset nipple). But that creates a second path for grounded conductor current. So does that mean it's a code violation for the GEC to enter the panel on it's way to the meter?

The GEC is not normally run from the panel to the meter. It is normally run to one or the other. The code only requires the metallic service raceway to be bonded at one end, but our local utility requires bonding at both ends. Yes there is a code permitted second path for the grounded conductor current.

Also a grounded conductor isn't supposed to be put throught bonding bushings, is it? I've never seen that done.

The grounded conducor is not normally connected to the bonding bushings, however the code would permit that.

 

[kwired]

I'm sure this has been discussed ad naseum already, but here goes. This has always confused me.

We installed a solar system on one meter of a building with three meters. The meters are in a single gutter with the panels right above them. The existing GEC was coming from the rod and water, passing through each panel, via nipples between them, and then going from the last panel into the meter enclosure. On the way it was put through bonding bushings on each offset nipple going to the meters.

We wanted to avoid opening the meters, so we crimped our solar to the GEC in the panel, and hoped it would fly, but it did not. The inspector says he can't pass if the system grounding is improper. No real argument with him there.

Here's the thing. He wants the GEC to go to the meters, and then he wants the N-G bonding jumper installed in each panel (the factory supplied jumpers had been left unconnected). So to my mind this creates an N-G bond in both the meters and the panels. Is this okay? Won't there be objectionable current on the bonding jumpers and offset nipples between each panel and the meters? How is this supposed to be done normally?

Just my suggestion but not the only way to do it - I would run GEC and make a tap from common GEC (which would be unbroken largest conductor required, in your case probably the one to the water line) to each service enclosure, as well as a tap to your solar system. I do this almost all the time when there is multiple service disconnects in multiple enclosures - seems to be the easiest way to handle it in most cases.

 

[jaggedben]

So just to clarify, it's okay for grounded conductor current to follow both the grounded conductor and the GEC between the disconnecting means and the meter?

 

[don_resqcapt19]

So just to clarify, it's okay for grounded conductor current to follow both the grounded conductor and the GEC between the disconnecting means and the meter?

I don't understand why there would be a GEC run between the meter and the service disconnects.

 

[augie47]

I don't understand why there would be a GEC run between the meter and the service disconnects.

Nor do I. If you have both the neutral and the GEC run between the meter and the service disconnects and connected at both, you are likely paralleling two different size conductors
Is there only (1) GEC from the water/rod ?
Are these (3) separate meters nippled to the wireway or a triple meter enclosure.
If it's three separate meters, locally the most common method would be to connect the GEC to the grounded conductor in the wireway whre the meters are tapped.

.

 

[don_resqcapt19]

Having the GEC connected to both points would very likely violate the parallel conductor rules. Having the metallic conduit in parallel with the grounded conductor between the meter and the service disconnect is not a violation.

 

[jaggedben]

I don't understand why there would be a GEC run between the meter and the service disconnects.

okay, good point. Answer: Because that's how it was done previously. Actually the original GEC goes from rod&water through each panel, then to the meters where presumably the only existing N-G bond is.

I'm getting now that the GECs should come straight into the meter enclosure without entering the panels.

Is there only (1) GEC from the water/rod ?

There was. We added a second one to a new rod, and crimped it to the first.

Are these (3) separate meters nippled to the wireway or a triple meter enclosure.

Triple meter enclosure. Panels are nippled to the meter enclosure.

If it's three separate meters, locally the most common method would be to connect the GEC to the grounded conductor in the wireway where the meters are tapped.

Okay, so that is not really different from connecting it to the grounded conductor bus in the three meter enclosure, right?

So... GEC(s) should come straight into meter enclosure and connect to the grounded conductor bus. Panel enclosures should be bonded to the neutral bar in each panel, and grounding bushings on nipples should be bonded to panel enclosure but no grounding conductor should go through the nipples. Would that be good?

 

[augie47]

I would suggest a change in "GEC(s) should come straight into meter enclosure and connect to the grounded conductor bus."
to "GEC(s) CAN"
It is often the easiest of connections, but some POCOs will not allow the connection in the meter socket.
NEC states "from the load end of the service drop or lateral to and including the service neutral bar" (paraphrased), so any of those points will suffice.

 

[jaggedben]

I would suggest a change in "GEC(s) should come straight into meter enclosure and connect to the grounded conductor bus."
to "GEC(s) CAN"
It is often the easiest of connections, but some POCOs will not allow the connection in the meter socket.
NEC states "from the load end of the service drop or lateral to and including the service neutral bar" (paraphrased), so any of those points will suffice.

Thanks. I don't think we'll have a problem with the POCO. Also the inspector specifically requested the GEC enter the meter enclosure. (It's almost the only thing he was really clear about.)

With that said, for the general case, I could bring a separate tap off the GEC to the ground bar in each panel, right? And not have anything enter the meter enclosure? (In this particular case it would be ugly, and there are the other considerations already mentioned, but generally that would be an okay way to do it, right?)