PV switchgear Main bonding jumper?

[AmpsOverVolts]

I have a set of canopy pv arrays and rooftop pv arrays that all feed to inverters that then feed to PV switch gear which is separate from the buildings main switchgear (30'.) the PV switchgear is protected by a 2000A switch/Fuse and is sized with 6 parallel runs of (3) 400s, (1) 250N, and (1) 250G. (sized according to NEC 2017.)

The AHJ is asking for a GEC(3/0 according to 250.122) to tie the PV switch gear to the MSB (run separately) as well as a main bonding jumper in the PV switch gear(sized to 250.102.)

My question is where is the MBJ and GEC required by code? Wouldn't this end up with parallel grounds back to the service? The neutral in this PV arrangement is just for reference. The EGC is going to be able to handle any ground fault better than the GEC? Also the gear has built in GFCI if that makes any difference.

photo for reference

https://imgur.com/erMm87k

 

[wwhitney]

Since you show the PV interconnection upstream of the existing Switchboard service disconnect, you are in effect adding a second service and should treat it as such. Thus the conductor set attached to the "CL Fuses" will be service conductors and should not have an EGC.

This will result in the blue GEC shown being a path for neutral current to be shared between the two services, but that always happens when you have two services.

Cheers, Wayne

 

[jaggedben]

..., you are in effect adding a second service and should treat it as such. ...

New service entrance, not new service. But that's a minor point.

@AmpsOverVolts
If you happen to be on the 2023 NEC then what Wayne said is definitely correct. If you are on earlier cycles then it's not clear, and you could argue the point. But why? Treating it like a additional service disconnect makes sense. See 250.24.(C) and 250.64(D) for guidance. If that's how an AHJ sees it I wouldn't argue because there's probabably little to be gained.

(BTW, the 2023 NEC no longer allows for current limiting fuses to extend the length of conductors.)

Your new GEC should really go directly to the electrode or be tapped to the existing GEC. Also it's sized to 250.66.

... The neutral in this PV arrangement is just for reference.

It's also an effective ground fault current path, which is not a trifling thing to be overlooked.

The EGC is going to be able to handle any ground fault better than the GEC?

Is there an EGC run with the circuit conductors? You cut off that part of the picture.

When treated as a service entrance, you don't need an EGC. You do need a neutral, MBJ, and GEC.

 

[wwhitney]

New service entrance, not new service. But that's a minor point.

Thanks, I should have said "service disconnects" rather than services.

(BTW, the 2023 NEC no longer allows for current limiting fuses to extend the length of conductors.)

Ah, so I should have inferred from the presence of the CL fuses that all the switchgear (existing and new) are indoors, as are the new 30' of conductors, and so the allowances of 2020 NEC 705.11(C)(2) are required. Even though that deviates from the "new conductors are just service entrance conductors" paradigm (which under the 2023 NEC no longer allows that 30' indoor run), (2020) 250.25 still requires that paradigm for bonding and grounding, i.e. a second MBJ, no EGC or SSBJ and a new GEC.

But the OP mentions the 2017 NEC. If the project is in California and was permitted prior to January 1, 2023, then the 2017 NEC would apply, and then other bonding/grounding options are available? Likewise if it is in a jurisdiction still using the 2017 NEC?

Cheers, Wayne

 

[jaggedben]

...

But the OP mentions the 2017 NEC. If the project is in California and was permitted prior to January 1, 2023, then the 2017 NEC would apply, and then other bonding/grounding options are available? Likewise if it is in a jurisdiction still using the 2017 NEC?...

More or less, yes. But I wouldn't make assumptions about what an AHJ will accept under earlier cycles.

 

[shortcircuit2]

Now that 10', 16.5', and 71' allowances of 2020 705.11(C)(2) are gone in the 2023 NEC...what direction are we all going with line side connections? I guess it will be up to the AHJ's on the permissible distance of the service entrance conductors inside the building. But will 1-and 2-family dwellings need to comply with 230.85...

 

[pv_n00b]

Under the 2017 NEC the main bond could be in the PV SWBD or it could rely on the main bond in the existing SWBD for supply-side interconnections. It was kind of dealer's choice, with the AHJ being the dealer. Some AHJs want it one place, some the other, some don't care about the location.
This was changed in the 2020 NEC with the addition of 250.25(A) which requires the main bond in the PV disconnect. Significant changes in the 2023 NEC pretty much make a supply-side interconnection an additional service and it has to comply with 230.

 

[pv_n00b]

But will 1-and 2-family dwellings need to comply with 230.85...

As far as I can tell there will need to be readily accessible PV disconnect on supply side interconnections. Just as there will need to be a readily accessible service disconnect. No more putting the main service disconnect in the basement of the home.

 

[ggunn]

(BTW, the 2023 NEC no longer allows for current limiting fuses to extend the length of conductors.)

That's cable limiters you are thinking of. Current limiting fuses are different gear.