supply side PV connection

mpd

Senior Member
I got a response back from NFPA, either way is code compliant, 3 wire supply side connection with the bond screw installed at the supply side PV disconnect or 4 wire supply side connection with the bond screw not installed at the PV supply side disconnect and the EGC used for grounding, but NFPA is very clear that these supply side conductors are not service conductors and are not required to be treated as service conductors and the supply side PV disconnect is not a service disconnect
 

Smart $

Esteemed Member
Location
Ohio
I got a response back from NFPA, either way is code compliant, 3 wire supply side connection with the bond screw installed at the supply side PV disconnect or 4 wire supply side connection with the bond screw not installed at the PV supply side disconnect and the EGC used for grounding, but NFPA is very clear that these supply side conductors are not service conductors and are not required to be treated as service conductors and the supply side PV disconnect is not a service disconnect
Then that should be the NFPA is NOT very clear...

Clipped from 230.40...
Exception No. 5: One set of service-entrance conductors
connected to the supply side of the normal service disconnecting
means shall be permitted to supply each or several
systems covered by 230.82(5) or 230.82(6).
And 230.82...
(6) Solar photovoltaic systems, fuel cell systems, or interconnected
electric power production sources.
 

mpd

Senior Member
Then that should be the NFPA is NOT very clear...

Clipped from 230.40...


And 230.82...

I agree they have made it more confusing, I asked the same question and NFPA's response was that the conductors permitted per 230.40 exception (5) and 230.82 (6) act as supply conductors for the PV system to detect loss of utility power for utility interactive inverters, but they are not service conductors they are power production source conductors per 705.31 and are considered feeders, still does not make sense to me, the supply side connection needs some work in the NEC to make it clear to everybody
 

jaggedben

Senior Member
I agree they have made it more confusing, I asked the same question and NFPA's response was that the conductors permitted per 230.40 exception (5) and 230.82 (6) act as supply conductors for the PV system to detect loss of utility power for utility interactive inverters, but they are not service conductors they are power production source conductors per 705.31 and are considered feeders, still does not make sense to me, the supply side connection needs some work in the NEC to make it clear to everybody
Another online forum I used to visit had a GIF of a smiley bashing it's head against a brick wall. I could really use that now.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Another online forum I used to visit had a GIF of a smiley bashing it's head against a brick wall. I could really use that now.
Really, it's not that hard. Ask the AHJ how they want it done and do it that way.
 

jaggedben

Senior Member
Really, it's not that hard. Ask the AHJ how they want it done and do it that way.
Lest my last post seemed exaggerated, it was not about how it affects me or my projects personally or professionally. It just offends my sensibilities that NFPA is twisting things around so much to the point where safety is now being compromised, in my opinion. The conductors are *@#%ing service conductors, in every sense except officially in the code.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Lest my last post seemed exaggerated, it was not about how it affects me or my projects personally or professionally. It just offends my sensibilities that NFPA is twisting things around so much to the point where safety is now being compromised, in my opinion. The conductors are *@#%ing service conductors, in every sense except officially in the code.
Frankly, I don't see that it makes all that much difference if the neutral to ground connection is in the disco or in the service less than 10 feet away. The only AHJ that I know of in Texas who wants it in the disco is San Antonio, and I don't know of a single case where a fire or an injury resulted from running the ground all the way back to the service. I don't see how safety is compromised.

Maybe the 2017 NEC will clearly and unambiguously declare itself on the issue one way or the other. Hope springs eternal. :D
 

jaggedben

Senior Member
Frankly, I don't see that it makes all that much difference if the neutral to ground connection is in the disco or in the service less than 10 feet away. The only AHJ that I know of in Texas who wants it in the disco is San Antonio, and I don't know of a single case where a fire or an injury resulted from running the ground all the way back to the service. I don't see how safety is compromised.

Maybe the 2017 NEC will clearly and unambiguously declare itself on the issue one way or the other. Hope springs eternal. :D
I just think if safety is not being compromised, then all these rules in 230 and 250 are questionable. Granted, I don't claim to be knowledgeable about the original justification for all those rules. But if seven handles is too many for a service without PV, there's no logical reason it should be acceptable on a service with PV. If a 10ft EGC is acceptable for a PV disconnect, it should be acceptable for any other service enclosure and 250.24.(C) is not necessary. Etc. Etc. The bottom line is, they're conductors connected directly to the utility, they should be treated as such.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I just think if safety is not being compromised, then all these rules in 230 and 250 are questionable. Granted, I don't claim to be knowledgeable about the original justification for all those rules. But if seven handles is too many for a service without PV, there's no logical reason it should be acceptable on a service with PV. If a 10ft EGC is acceptable for a PV disconnect, it should be acceptable for any other service enclosure and 250.24.(C) is not necessary. Etc. Etc. The bottom line is, they're conductors connected directly to the utility, they should be treated as such.
How, exactly, do you see safety being compromised if we leave N and G separate at the disco and carry the EGC all the way back to the service vs. bonding N and G in the disco, breaking the EGC, and driving an electrode at the disco which is bonded to building ground? Designing safe systems is by far my primary concern and a case for code compliance can be made for either method. As long as it is safe either way (and I think it is) I really don't care how the AHJ interprets the code. I'll build it to pass inspection.
 

jaggedben

Senior Member
My first response is that we are not merely talking about the location of an N-G bond. We are talking about whether whole articles of the code apply or don't apply. We are talking about how things should be labeled for first responders and service technicians. I'm not going to sum that up as 'no safety implications'. I think there are arguably a few.

My particular response is that you may or may not be right, but if you are right then I think 250.24(C) should not be necessary for service disconnects. Whoever thought 250.24(C) needed to be part of the code, I suspect their justification for it applies logically to a PV disconnect as well. Again, this is just one example...
 

pv_n00b

Senior Member
Location
CA, USA
I posted this in another thread but it seems to be applicable here too.

When the question about supply side interconnections was submitted to the NFPA in 2013 for guidance here was the response:


Q:

I and the PV industry need some further guidance on how we should be handling the "feeder" circuit for the Supply Side (of the service disconnect) Connection of a Photovoltaic Power system as allowed by 705.12(A), and 230.82(6). It is not clear also why 230.2(5) mentions additional "services" for parallel power production systems, which seems to indicate that a utility interactive PV system could be considered being connected by a service.

A:

Section 230.2(A)(5) retained the “parallel power production systems” as a special condition for an additional service from the 1984 NEC 230-2 exception No. 2. Based on the definition of a service at that time being an “electric supply system” the substantiation which stated “The addition to Exception No. 2 is necessary to permit a solar photovoltaic, wind or other electric power production source to be installed in addition to a (utility) service in a building or other structure” made sense as an additional “electric supply system.” However, once the service was redefined and specified as only being supplied by a utility other solar photovoltaic, wind or other electric power production sources no longer fit the description and more specifically the service cannot “supply” them as 230.2(A) permits.

A service can only be supplied by the serving utility. If electric energy is supplied by other than the serving utility, the supplied conductors and equipment are considered feeders, not a service. See the definition of service in Article 100. The understanding of other electric supply systems being considered a service changed when the definition of service changed during the A98 code cycle. ROC A98 Comment 1-199 Log # 2472 on Proposal 1-132 was accepted and specified that the term “serving utility” not an “electric supply system” be the language used to define a service.



This indicates to me that in 2013 the NFPA considered supply side interconnections of PV systems to be feeders and not services. The addition of 705.31 in 2014 strengthens this determination. It still looks like a service entrance to me so that's how I design them and the NEC does not say I can't do it that way.
 

Smart $

Esteemed Member
Location
Ohio
...This indicates to me that in 2013 the NFPA considered supply side interconnections of PV systems to be feeders and not services. The addition of 705.31 in 2014 strengthens this determination. It still looks like a service entrance to me so that's how I design them and the NEC does not say I can't do it that way.
I think the point you are missing is that nobody is challenging that the conductors on the PV side of the disconnecting means are in fact feeder conductors... or better yet, non-service supply conductors. The question you asked of the NFPA did not distinguish concern solely for the conductors on the service side of the disconnecting means. Maybe to you it did, but I don't read it that way, and I don't believe the NFPA representative did either. The reply you received only addressed your query from the standpoint of "supply" conductors. Conductors on both sides of the disconnecting means are "supply" conductors... and the response addressed the PV supply conductors but did not offer a precise point of demarcation.. which is what we want. You assume the reply says the tap point rather than at the disconnecting means... but I don't see it that way.

705.31 doesn't factor into this debacle other than it requiring the OCPD to be within 10 ft of the service connection point. Well if the conductors on the service side of the disconnecting means (with OCPD, such as a fused disconnect or MCCB) are service-entrance conductors, then the OCPD will always be within 10'. Here you have to remember that (though debatable to some) the disconnecting means is not a service disconnecting means, so OCPD is not required to be integral or immediately adjacent thereto the disconnecting means... so that is the reason I see for 705.31 being put in the 2014 edition of the NEC.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
My first response is that we are not merely talking about the location of an N-G bond. We are talking about whether whole articles of the code apply or don't apply. We are talking about how things should be labeled for first responders and service technicians. I'm not going to sum that up as 'no safety implications'. I think there are arguably a few.

My particular response is that you may or may not be right, but if you are right then I think 250.24(C) should not be necessary for service disconnects. Whoever thought 250.24(C) needed to be part of the code, I suspect their justification for it applies logically to a PV disconnect as well. Again, this is just one example...
In my discussion with the engineering staff at Austin Energy, the lead engineer in charge of solar interconnections said to me flatly, "A supply side PV connection is not a service." The head of the AE metering department agreed. That pretty much ended the discussion. The engineers at CPS (San Antonio) do not agree; the same discussion with them would go very differently.

I really don't care. I am not going to get my panties in a wad over what folks think a wire should or should not be called. If this ambiguity in the Code affected safety in some significant way, I would be more concerned, but (IMO) it doesn't. PV is much newer than most of the rest of what the NEC addresses; as long as I have been in solar (7 years) I have always said that you have to sort of stand on your head when you apply the Code to solar. 690 and the attendant articles are some of the most (if not the most) rapidly evolving parts of the NEC. Ask me again after NEC2017 comes out and I may have a different answer. :D
 

SolarPro

Senior Member
Location
Austin, TX
Not only is 690 one of the most changeable Articles in the NEC, but the rewrite for 2017 introduces the most changes since its introduction in 1984. :jawdrop:
 

jaggedben

Senior Member
The bottom line for me is that the PV conductors tapped to the service conductors are physically the same as service conductors for all practical purposes. They have no overcurrent protection or disconecting means between them and the utility, and that is a fundamental saftey point. Now if someone wants to tell me that you can ignore all the rules specifically intended for conductors that are physically the same, my response is 'hold on, that's a lot of code that was presumably put in place to make those conductors safer.' Any one of those rules I can ask why it was put there in the first place and question whether it undermines saftey to not apply it.

What offends me is not what people choose to call the conductors. What offends me is they ignore the fundamental purpose of the code in the course of interpreting it. It seems like people have other motives besides saftey, whether it's just narrow legalism, not wanting to lose an argument, or not wanting to rethink the role of a utility in a changing world.
 

mpd

Senior Member
The bottom line for me is that the PV conductors tapped to the service conductors are physically the same as service conductors for all practical purposes. They have no overcurrent protection or disconecting means between them and the utility, and that is a fundamental saftey point. Now if someone wants to tell me that you can ignore all the rules specifically intended for conductors that are physically the same, my response is 'hold on, that's a lot of code that was presumably put in place to make those conductors safer.' Any one of those rules I can ask why it was put there in the first place and question whether it undermines saftey to not apply it.

What offends me is not what people choose to call the conductors. What offends me is they ignore the fundamental purpose of the code in the course of interpreting it. It seems like people have other motives besides saftey, whether it's just narrow legalism, not wanting to lose an argument, or not wanting to rethink the role of a utility in a changing world.

I agree with you completely, I don't know how the conductor definition changes at that connection point to service conductors, and my other question is when the PV system is not producing power on a typical interactive system what are those supply side conductors during those times, and what if the PV combiner panel supplies the receptacle for the PV monitor is that still considered part of the electric power production source conductors or is PV supply side conductors only for inverter output?
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
The bottom line for me is that the PV conductors tapped to the service conductors are physically the same as service conductors for all practical purposes. They have no overcurrent protection or disconecting means between them and the utility, and that is a fundamental saftey point. Now if someone wants to tell me that you can ignore all the rules specifically intended for conductors that are physically the same, my response is 'hold on, that's a lot of code that was presumably put in place to make those conductors safer.' Any one of those rules I can ask why it was put there in the first place and question whether it undermines saftey to not apply it.

What offends me is not what people choose to call the conductors. What offends me is they ignore the fundamental purpose of the code in the course of interpreting it. It seems like people have other motives besides saftey, whether it's just narrow legalism, not wanting to lose an argument, or not wanting to rethink the role of a utility in a changing world.
I hope you are not including me in that category. I take no position in the controversy apart from endeavoring to follow the AHJs' wishes in order not to fail inspections.
 

iwire

Moderator
Staff member
Location
Massachusetts
What offends me is not what people choose to call the conductors. What offends me is they ignore the fundamental purpose of the code in the course of interpreting it. It seems like people have other motives besides saftey, whether it's just narrow legalism, not wanting to lose an argument, or not wanting to rethink the role of a utility in a changing world.
No, lets be honest. What is offending you is many people do not have the same view as you do.

You can dress it up anyway you want to but the root issue is simply seeing things differently.

It is not like only one person, or one area, or even one inspection department sees it differently there many intelligent and safety minded folks that read this differently then either you or I.

That means to me that there is an issue with the NEC and not with the people trying to apply it.
 

jaggedben

Senior Member
I hope you are not including me in that category....
For the record I was not. If your AHJ's want you to make installations more dangerous than they have to be, that's on them.

No, lets be honest. What is offending you is many people do not have the same view as you do.
If by that you mean that others do not view safety as the paramount factor, then yes, you are right. :p

To be fair, I think that many just have not had enough time to follow all the way through what is a genuinely confused situation. But I also think there are some ulterior motives on the part of a few.

It is not like only one person, or one area, or even one inspection department sees it differently there many intelligent and safety minded folks that read this differently then either you or I.

That means to me that there is an issue with the NEC and not with the people trying to apply it.
We can agree on this part. Unfortunately, the NPFA, which you would think would be the ones to help clear up confusion, seem to be only be making it worse.
 
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