Hi Chris, For string inverters, the OCPD is sized per 705.60(B) which will specify the minimum breaker rating you need. Then, you can't go above the maximum OCPD specified by the manufacturer. For most string inverters that I can think of, this limits us to one breaker (OCPD) per inverter. I recall bumping into a string inverter without a maximum specificed OCPD rating, but I don't recall which one at the moment.
However, for microinverter based systems it is standard to install multiple inverters on one branch circuit with one OCPD. August On Wed, Feb 27, 2019 at 10:43 AM Christopher Warfel < cwar...@entech-engineering.com> wrote: > I know I keep popping up on this, but 2014 makes no sense if it is saying > to connect multiple inverters to one disconnect. It would be difficult and > dangerous to take one out of service for any reason including replacement. > I would that that you'd have to shut down all the inverters just to replace > one. Some of the large commercial/industrial/utility systems have hundreds > of inverters and there is no way they would install a system to this > interpretation of the NEC. > On 2/27/2019 12:22 PM, Starlight Solar Power Systems wrote: > > William, > > It seems this question needs to be addressed: What is the intended meaning > of “installed in one system” in 2014? If you have separate “systems”, they > should not be governed by 705.12. So, at what point does a “system” begin > and end? PV modules to the disconnect? ...to the load panel? ...to the > service entrance? > > Larry > > > On Feb 25, 2019, at 10:42 PM, William Miller <will...@millersolar.com> > wrote: > > August: > > > The 2014 code, which the AHJ for this project is using, states the > following: > > > (*1) Dedicated Overcurrent and Disconnect. The source* > *interconnection of one or more inverters installed in one* > *system shall be made at a dedicated circuit breaker or fusible* > *disconnecting means.* > > > Note that the language says, “The source interconnection…” (singular), and > “at a dedicated circuit breaker…”(again singular). This makes it obvious > to me that the language says that the outputs of multiple inverters need to > be aggregated and connected via *one* OCPD. I think the other wrenches > missed this point. > > > Your input is valuable by contrasting the language of the 2014 code with > that of the 2017 version. The inclusion of the phrase “Each source…” in > the 2017 code completely changes the meaning. Some AHJs will look to > future code versions for clarity even if they are not yet adopted. I think > this is a good thing, and I really appreciate you bringing up the new > language. > > > The article from AEIA magazine ratifies the conclusion I drew from the > 2014 code. Fortunately the AHJ is misinterpreting the section to allow the > more liberal interpretation, the one that the 2017 code reflects. I find > it best to contact the plan checker directly, which I did, and we are > approved for multiple OCPDs. By the way, I think that article is well > written and I have book marked it. > > > I don’t know if the 2014 language was a mistake corrected in 2107, or what > the thinking was of the authors. Regardless, we live by the language, not > the intent. > > > Thank you as well to all who responded. > > > William Miller > > > > > > > > > *From:* August Goers [mailto:aug...@luminalt.com] > *Sent:* Monday, February 25, 2019 9:07 AM > *To:* William Miller; RE-wrenches > *Subject:* Re: [RE-wrenches] Multiple inverters > > > Hi William - > > > In this case, it is helpful to look forward to the 2017 NEC for guidance: > > > <image001.png> > > > I believe it's perfectly fine to have multiple inverter breakers in your > main. > > > August > Luminalt > > > > > On Mon, Feb 25, 2019 at 8:42 AM William Miller <will...@millersolar.com> > wrote: > > Friends: > > > I have an NEC code question on an upcoming project. It is a home that has > an existing 8 kW ground-mounted grid-tied system. The owner wants to add > another 10 kW of grid-tied PV. My question is about 705.12, point of > connection. Specifically section (D)(1). That section states: > > > *The source interconnection of one or more inverters installed in one > system shall be made at a dedicated circuit breaker or fusible > disconnecting means.* > > > So if there are going to be two inverters on premise, do the outputs have > to be aggregated to connect via one circuit breaker? This might be > difficult to do as the exiting inverter is connected via a different > sub-panel than the one that is planned to receive the new inverter output. > > > This article > <https://iaeimagazine.org/magazine/2014/01/16/load-side-pv-connections/> > addresses > the question. > > > I would be very grateful if any of you can share any experience you might > have in interpreting this section of the code. > > > Thanks in advance. > > > William > > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & > settings:http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette:www.re-wrenches.org/etiquette.htm > > Check out or update participant bios:www.members.re-wrenches.org > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > >
_______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
