PV Disconnect N/G bonded

[Fred B]

Question,
I've attached a drawing (I'm not an artist) of an installation of a solar system that doesn't seem right. It has N/G bonded in 2 spots, at the PV disconnect and the main house panel. Plus grounding and grounded conductors running between both panels, plus the EMT bonded. It has a supply side Polaris connection for the pv feeders and the disconnect is fused.
Is this code compliant? What code section allows the bonding of N/G in 2 locations?
NYSERTA claims this is how they want it done but unable to substantiate it with a code reference? What am I missing in the code? (2017)

 

[don_resqcapt19]

For all practical purposes, a disconnect for a line side solar tap is a service disconnect and you bond in all service disconnects.
The 2023 code will take a big step in clearing this up as the Correlating Committee has directed such disconnects will be called service disconnects in the 2023 code. They are connected to the utility supply as have all of the hazards as any other disconnect connected to the utility supply.

I am not sure that the 2017 and earlier codes directly addressed this issue, but the 2020 code does in 250.25.

 

[Fred B]

For all practical purposes, a disconnect for a line side solar tap is a service disconnect and you bond in all service disconnects.
The 2023 code will take a big step in clearing this up as the Correlating Committee has directed such disconnects will be called service disconnects in the 2023 code. They are connected to the utility supply as have all of the hazards as any other disconnect connected to the utility supply.

I am not sure that the 2017 and earlier codes directly addressed this issue, but the 2020 code does in 250.25.

What about the parallel N/G between the 2 disconnects

 

[don_resqcapt19]

What about the parallel N/G between the 2 disconnects

I missed the grounding conductor...that does not get installed to the solar disconnect. It is wired just like any other service disconnect under the 2020 code.

 

[ggunn]

For all practical purposes, a disconnect for a line side solar tap is a service disconnect and you bond in all service disconnects.
The 2023 code will take a big step in clearing this up as the Correlating Committee has directed such disconnects will be called service disconnects in the 2023 code. They are connected to the utility supply as have all of the hazards as any other disconnect connected to the utility supply.

I am not sure that the 2017 and earlier codes directly addressed this issue, but the 2020 code does in 250.25.

Even under the 2020 NEC, in Texas the only AHJ that considers the disco of a supply side connected PV system to be a service disco with a N-G bond is CPS in San Antonio.

 

[Fred B]

Thanks Don for your reply with how the newer codes are viewing it.
Did some digging with that in mind while waiting, found this.
Tell me if I'm seeing this correctly as allowing all this mess.
690.59 references 705. Interconnected Electric Power Production Sources
705.50 shall be grounded according to Article 250.
250.30 is Grounding Separately Derived Alternating-Current Systems, and states for separately derived systems connected in parallel shall be installed in accordance with 250.30
250.30(A)(6) Grounding Electrode Conductor, Multiple Separately Derived Systems. Says that the common Grounding Electrode per 250.30(A)(4) shall be used if both SDS are in same building. And a shared conductor can be used. Exception 1 allows for the connection to take place on a bus bar. So I guess as much as it doesn't seem right, it's allowed.
NYSERDA finally replied with reference to 250.24(C). I don't see that, without all the others I found above, as being the reasoning.

 

[don_resqcapt19]

Even under the 2020 NEC, in Texas the only AHJ that considers the disco of a supply side connected PV system to be a service disco with a N-G bond is CPS in San Antonio.

There is a lot of confusion on this issue, but any line side connection to the service conductors needs to follow the same rules as service disconnects as the hazard is the same. That is why the Correlating Committee said that for the 2023 code, not only will the line side disconnects be treated like service disconnects, they will be called service disconnects.
It appears for the purpose of line side disconnects, the scope of 705 will start at the "load" side of the disconnect.
Line and load gets all messed up for these installations as the supply is not really the "line" side of the disconnect, so by load, I mean the side of the disconnect that is not connected to the utility.

Thanks Don for your reply with how the newer codes are viewing it.
Did some digging with that in mind while waiting, found this.
Tell me if I'm seeing this correctly as allowing all this mess.
690.59 references 705. Interconnected Electric Power Production Sources
705.50 shall be grounded according to Article 250.
250.30 is Grounding Separately Derived Alternating-Current Systems, and states for separately derived systems connected in parallel shall be installed in accordance with 250.30
250.30(A)(6) Grounding Electrode Conductor, Multiple Separately Derived Systems. Says that the common Grounding Electrode per 250.30(A)(4) shall be used if both SDS are in same building. And a shared conductor can be used. Exception 1 allows for the connection to take place on a bus bar. So I guess as much as it doesn't seem right, it's allowed.
NYSERDA finally replied with reference to 250.24(C). I don't see that, without all the others I found above, as being the reasoning.

I don't think that prior to the 2020 code there is really anything that requires the solar disconnect to be treated like a service disconnect.

 

[Fred B]

There is a lot of confusion on this issue, but any line side connection to the service conductors needs to follow the same rules as service disconnects as the hazard is the same. That is why the Correlating Committee said that for the 2023 code, not only will the line side disconnects be treated like service disconnects, they will be called service disconnects.
It appears for the purpose of line side disconnects, the scope of 705 will start at the "load" side of the disconnect.

705 in the 2017 makes reference to both supply side (705.12(A))and load side (705.12(B)).

Line and load gets all messed up for these installations as the supply is not really the "line" side of the disconnect, so by load, I mean the side of the disconnect that is not connected to the utility.

I agree, In solar it seems it references the supply side as the primary service supply side for a tap, but gets really confused for the solar side.

I don't think that prior to the 2020 code there is really anything that requires the solar disconnect to be treated like a service disconnect.

That is where NYSERDA reference particularly doesn't seem to fit, as NEC 2017 doesn't make the implicit link for solar to be a service. But the other references do seem to imply the connections provided in diagram.

 

[jaggedben]

Leave separately derived systems out of it. A solar inverter is not necessarily or usually these days a separately derived system.

I don't know about the 2023 NEC, but up to the 2020 NEC the CMP has steadfastly rejected all attempts to clarify grounding and bonding for supply side inverter output connections. I do agree that you shouldn't have both a green wire run to the disconnect and an N-G bond. It should be one or the other, i.e. treat it like a service disconnect or treat it like a feeder disconnect, but not both.

 

[BillK-AZ]

If the OP drawing of the disconnect switch is accurate, it is wired wrong. The utility connection must be made to the top terminals.

 

[Fred B]

If the OP drawing of the disconnect switch is accurate, it is wired wrong. The utility connection must be made to the top terminals.

The utility is on the top connection. Not an artist, and didn't have multiple colors to trying and get the zig zag of lines as really present if I did nobody would see anything. My concern trying to highlight was the N/G bonding. Didn't draw the fuses either but they're there.

 

[romex jockey]

NYSERTA claims this is how they want it done but unable to substantiate it with a code reference? What am I missing in the code? (2017)

690.47 & info note Fred>>>

functional grounded systems rather than
solidly grounded systems as defined in this Code.

some of the more patient EE's here tried to 'splain it .....

~RJ~

 

[Fred B]

690.47 & info note Fred>>>

functional grounded systems rather than
solidly grounded systems as defined in this Code.

some of the more patient EE's here tried to 'splain it .....

~RJ~

Thanks, I get bonding all the equipment back the GEC. But is the N/G bonding at the second location acceptable was my big concern with what I saw.

 

[don_resqcapt19]

Leave separately derived systems out of it. A solar inverter is not necessarily or usually these days a separately derived system.

I don't know about the 2023 NEC, but up to the 2020 NEC the CMP has steadfastly rejected all attempts to clarify grounding and bonding for supply side inverter output connections. I do agree that you shouldn't have both a green wire run to the disconnect and an N-G bond. It should be one or the other, i.e. treat it like a service disconnect or treat it like a feeder disconnect, but not both.

There has been a long standing fight between CMP 10 and CMP 4 over this issue. One of the purposes of the correlating committed is to resolve issues like this between code making panels. That have resolved it by saying it will be called a service disconnect and giving purview over the installation and line side connections of that disconnect to CMP 10.

 

[don_resqcapt19]

If the OP drawing of the disconnect switch is accurate, it is wired wrong. The utility connection must be made to the top terminals.

I am not aware of any code rule that requires the utility connections to be on the top. Can you cite the rule?

 

[jaggedben]

I am not aware of any code rule that requires the utility connections to be on the top. Can you cite the rule?

It's kind of implicit in the installation instructions. The 'line' side should be understood to be the side which remains energized when the disconnect is opened. Many people new to solar either don't understand that interactive inverters de-energize their outputs when disconnected, or they get confused by the typical direction of power flow, which they should ignore in this case.

 

[don_resqcapt19]

It's kind of implicit in the installation instructions. The 'line' side should be understood to be the side which remains energized when the disconnect is opened. Many people new to solar either don't understand that interactive inverters de-energize their outputs when disconnected, or they get confused by the typical direction of power flow, which they should ignore in this case.

Assuming a the disconnect is a breaker, there are very few marked line and load, and no breaker that is permitted to be used on a solar system could be marked line and load, as such markings mean that the breaker is not suitable for back-feeding.

If the disconnect, is a knife switch, then the top would be the line per code rules.

 

[electrofelon]

There has been a long standing fight between CMP 10 and CMP 4 over this issue. One of the purposes of the correlating committed is to resolve issues like this between code making panels. That have resolved it by saying it will be called a service disconnect and giving purview over the installation and line side connections of that disconnect to CMP 10.

Its too bad they cant figure out how to resolve these issues in a more timely fashion rather than draw it out and cause tons of confusion over more than 2 decades.

 

[romex jockey]

There has been a long standing fight between CMP 10 and CMP 4 over this issue. One of the purposes of the correlating committed is to resolve issues like this between code making panels. That have resolved it by saying it will be called a service disconnect and giving purview over the installation and line side connections of that disconnect to CMP 10.

so they consider it an SDS then?

~RJ~

 

[romex jockey]

Its too bad they cant figure out how to resolve these issues in a more timely fashion rather than draw it out and cause tons of confusion over more than 2 decades.

really ..... maybe the correlating committee could cater 3 martini luncheons ....? ~RJ~