[RE-wrenches] Two NEC questions

Sun Oct 14 09:11:19 PDT 2012

Hi David and Rebecca -

We're still in the 2008 code cycle here in California so AFCI hasn't become
an issue yet. I just listened to a webinar by SMA last week and I believe
that their AFCI Sunny Boys wont' be shipping for at least a couple of
months.

Rebecca, have you already installed this system? What type of inverter do
you want to use? NEC 90.4 (Enforcement) states this:

"This *Code* may require new products, constructions, or materials that may
not yet be available at the time the *Code* is adopted. In such event, the
authority having jurisdiction may permit the use of the products,
constructions, or materials that comply with the most recent previous
edition of this *Code* adopted by the jurisdiction."

So, you might be able to convince the AHJ to enforce the 2008 NEC which
doesn't require AFCI. Or, use microinverters or ACPV as David mentioned
below.

Good luck out there!

-August

*From:* re-wrenches-bounces at lists.re-wrenches.org [mailto:
re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of *David Brearley
*Sent:* Saturday, October 13, 2012 9:02 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Two NEC questions

RE Question #2:

Article 100 defines a service as:

*Service.* The conductors and equipment for delivering electric energy *from
* the serving utility to the wiring system of the premises served. (*emphasis
added*)

PV system wiring simply does not fit that definition. The PV system is not
part of the serving utility. And inverters are not service equipment.

You need to refers them to this definition in Article 705.2 (added in NEC
2011):

*Power Production Equipment.* The generating source, and *all* distribution
equipment associated with it, that generates electricity from a source *other
than* a utility supplied service. (*emphasis added*)

FWIW: Mike Holt has written for SP about the Code requirements for
interconnecting PV systems, as well as some additional recommendations for
making supply side connections:

http://solarprofessional.com/article/?file=SP5_1_pg14_QA&search=

RE Question #1: I had a local inspector ask me about this in late-August &
there were relatively few listed products at that time:

   - SMA America has dc AFCI in their standard SunnyBoy US-series inverters
   (SB 3000-US, SB 3800-US, SB 4000-US, SB 5000-US, SB 6000-US, SB7000-US, SB
   8000-US):
   http://www.sma-america.com/en_US/news-information/current-news/news/news/1487.html
   - Microinverter systems (Enphase, Enecsys, etc.) typically do not
   operate above 80 Vdc and are therefore exempt from 690.11
   - AC module systems (powered by SolarBridge, Exeltech, etc.)
   typically do not operate above 80 Vdc and are therefore exempt from 690.11
   - SolarBOS reportedly has a dc AFDI and GFI combiner box:
   http://www.solarbos.com/news/solarbos-puts-out-the-fire-in-pv-systems
(However,
   I don't see this product on their website under their regular lists of
   products.)
   - While module-level dc-to-dc converters—like those from SolarEdge and
   Tigo Energy—presumably have the ability to provide dc AFCI capabilities,
   last I checked it didn't look like any of them were formally listed to do
   so.

I suspect that most manufacturers are trying to avoid spending additional
money on testing until the market requires this.

Have any wrenches here actually had an inspector required dc AFCI? Also, is
the dc AFCI test standard actually finalized and adopted at this point or
are companies testing to a draft standard?

David Brearley, Senior Technical Editor

SolarPro magazine
NABCEP Certified PV Installer ™
david.brearley at solarprofessional.com
Direct: 541.261.6545

On Oct 13, 2012, at 10:12 AM, Rebecca Lundberg wrote:

Dear fellow wrenches,

Does anyone have suggestions for the 'best' way to keep up with product
availability for meeting 690.11 on DC AFCI? I understand that when this
code section was written there was no available device, and know that at
least several companies are working on devices. How will I know (before the
AHJ knows :-) that residential-scale products are available for purchase,
and at what point would you say now should be required over every other
option?

Second question: I have an inspector insisting that the solar PV system is
the same as a utility service, and is requiring all of the required service
code references to apply. Anybody have a concise reference that might
convince him otherwise? This same inspector has decided that the electrical
permit will have adders for each inverter as service equipment, and each
module as an electrical device. It would sure be nice if there was more
consistency...we're still in the early adopter phase here in Minnesota.

Thanks in advance for your input.

Keep Shining!
Rebecca Lundberg
NABCEP Certified Solar PV Installer ®
Owner/CEO, Powerfully Green
Rebecca.Lundberg at PowerfullyGreen.com
763-438-1976

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