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
<mailto: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
<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 <mailto: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.
Thisarticle
<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
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