supply side PV connection

pv_n00b

Senior Member
Location
CA, USA
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.
The question posed was specifically about the conductors between the PV disconnect and the POCC. The person at NFPA was quite aware of this the his answer related just to those conductors. The conductors on the PV system side of the disconnect are not part of the question or answer.
 

pv_n00b

Senior Member
Location
CA, USA
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.
The fact that the NEC would allow conductors connected between the PV disconnect and a supply side POCC to be unprotected is not particularly shocking to me. We do similar things all the time with the tap rules, and service entrance conductors are unprotected by default. Whether the connection is made as a feeder or as a service entrance those conductors are going to be unprotected. No way around that.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
If your AHJ's want you to make installations more dangerous than they have to be, that's on them.
I have yet to see how keeping G and N separate back to the service is more dangerous than bonding them in the disco.
 

Smart $

Esteemed Member
Location
Ohio
...
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.
...
The question posed was specifically about the conductors between the PV disconnect and the POCC. The person at NFPA was quite aware of this the his answer related just to those conductors. The conductors on the PV system side of the disconnect are not part of the question or answer.
You took the focus off the set of service-entrance conductors permitted under 230.40 Exception No. 5 when you brought 230.2(5) into the question. 230.2 is about the number of services and PV systems are not a service. The answer you got focused on 230.2(5) and consumer-owned parallel power production systems not being a qualified service.

Direct link to your entire Q&A post: http://forums.mikeholt.com/showthread.php?t=177368&p=1748833#post1748833

You would be better served to ask the question again and leave any reference to 230.2 out of it.
 

jaggedben

Senior Member
I have yet to see how keeping G and N separate back to the service is more dangerous than bonding them in the disco.
Dude, for like the fifth time, it's not just about an N-G bond. It's all the other rules, too: number of disconnects, grouping, types of raceway required, etc. etc. etc... Would you run NM-B for these conductors because they are a 'feeder'?
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Dude, for like the fifth time, it's not just about an N-G bond. It's all the other rules, too: number of disconnects, grouping, types of raceway required, etc. etc. etc... Would you run NM-B for these conductors because they are a 'feeder'?
And for the fifth (at least) time I still do not see where the San Antonio method for connecting supply side PV is any safer than the way that the entire rest of Texas wants it done. Those rules are for service disconnects and Austin Energy (for one) engineers unequivocally state that the fused disconnect for supply side connected PV is NOT a service disconnect, the connection is NOT a tap, and the disco does NOT contribute to the six handle rule. Incidentally, there is video on Mike Holt's site that says the same thing.

I recently designed and sealed a commercial PV system supply side connected to the bus of a MLO MDP with six existing breakers through a fused disconnect right next to the MDP. It was green tagged by Austin Energy and it is up and running. I sleep just fine. :D
 
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mpd

Senior Member
Dude, for like the fifth time, it's not just about an N-G bond. It's all the other rules, too: number of disconnects, grouping, types of raceway required, etc. etc. etc... Would you run NM-B for these conductors because they are a 'feeder'?

article 230 would not apply for that supply side PV disconnect or wiring method and yes NM-B would be acceptable acceptable as a supply side PV feeder unless it was in a location that NM-B was not permitted per art. 334, I think some of the confusion with this supply side connection is if you want to install as service conductors,service disconnect & service grounding requirements NEC permits it but does not require it, if it is not a shall or shall not then other methods are permitted. I don't think either method is 3 wire PV supply side or 4 PV wire supply side is unsafe.
 

Smart $

Esteemed Member
Location
Ohio
article 230 would not apply for that supply side PV disconnect or wiring method and yes NM-B would be acceptable acceptable as a supply side PV feeder unless it was in a location that NM-B was not permitted per art. 334, I think some of the confusion with this supply side connection is if you want to install as service conductors,service disconnect & service grounding requirements NEC permits it but does not require it, if it is not a shall or shall not then other methods are permitted. I don't think either method is 3 wire PV supply side or 4 PV wire supply side is unsafe.
230.82(6) is the section that permits the supply side connection. Says so right in 705.12(A). As such, you cannot say Article 230 does not apply.

230.40 Exception No. 5 permits one set of service-entrance conductors for each or several systems covered by 230.82(5) or (6). Being a service-entrance conductor set, NM is not permitted to be used per 334.12(3).
 

mpd

Senior Member
230.82(6) is the section that permits the supply side connection. Says so right in 705.12(A). As such, you cannot say Article 230 does not apply.

230.40 Exception No. 5 permits one set of service-entrance conductors for each or several systems covered by 230.82(5) or (6). Being a service-entrance conductor set, NM is not permitted to be used per 334.12(3).

705.31 designates those supply side conductors as electric power production source conductors not service conductors, and I asked NFPA the same question in reference to 230.40 exception #5 and there response was those conductors act as supply conductors for the PV system to detect loss of utility power for interactive inverters, but like I said before NFPA was very clear in there response that those conductors are feeders not service conductors and none of article 230 or 250 applies in reference to service conductors, equipment or service grounding & bonding.
 
705.31 designates those supply side conductors as electric power production source conductors not service conductors, and I asked NFPA the same question in reference to 230.40 exception #5 and there response was those conductors act as supply conductors for the PV system to detect loss of utility power for interactive inverters, but like I said before NFPA was very clear in there response that those conductors are feeders not service conductors and none of article 230 or 250 applies in reference to service conductors, equipment or service grounding & bonding.
Funny, it says right in the NEC that they are service entrance conductors. I would ignore that opinion you got from someone at the NFPA who had no idea what they were talking about and should have kept their pie hole shut, and wait for a formal interpretation or clarification in a future edition :)
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Funny, it says right in the NEC that they are service entrance conductors.
Where, exactly, does it say that? 705.12(A) sends us to 230.82(6), and all it says is that PV systems may be connected to the supply side of the service disconnecting means.

If this were simple or staightforward we wouldn't be arguing about it constantly.
 

Smart $

Esteemed Member
Location
Ohio
Where, exactly, does it say that? 705.12(A) sends us to 230.82(6), and all it says is that PV systems may be connected to the supply side of the service disconnecting means.

If this were simple or staightforward we wouldn't be arguing about it constantly.
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).
 

mpd

Senior Member
Funny, it says right in the NEC that they are service entrance conductors. I would ignore that opinion you got from someone at the NFPA who had no idea what they were talking about and should have kept their pie hole shut, and wait for a formal interpretation or clarification in a future edition :)

the service entrance conductor response still has me confused, but I still respect there opinion, and like I said if you want to install them as service conductors and apply all the NEC requirements that is up to the installer but it is not a code requirement
 

Smart $

Esteemed Member
Location
Ohio
And apparently some of you need reminded...

90.3 Code Arrangement. This Code is divided into the introduction
and nine chapters, as shown in Figure 90.3. Chapters
1, 2, 3, and 4 apply generally; Chapters 5, 6, and 7 apply
to special occupancies, special equipment, or other special
conditions. These latter chapters supplement or modify the
general rules. Chapters 1 through 4 apply except as amended
by Chapters 5, 6, and 7 for the particular conditions.

Chapter 8 covers communications systems and is not
subject to the requirements of Chapters 1 through 7 except
where the requirements are specifically referenced in Chapter
8.

Chapter 9 consists of tables that are applicable as referenced.
What section in 690 or 705 specifically amends 230.40 Exception No. 5, such that these supply side conductors are not service entrance conductors?
 

Smart $

Esteemed Member
Location
Ohio
That is a long way from saying 'they are service entrance conductors'
Well it may be a long way, but given the general statement of 230.40 says "Each service drop, set of overhead service conductors, set of underground service conductors, or service lateral shall supply only one set of service-entrance conductors", what other type of conductor can you connect?
 
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