How about off grid arc fault ??
It seems that I don't see much talk or interest in that.
Thanks !
boB
On 10/14/2012 9:44 AM, Bill Brooks wrote:
August,
Who at SMA said that they won't be shipping AFCI inverters? I know
they have been manufacturing. I have two of the AFCI inverters in
operation at my office and they are very impressive. Three months of
operation since startup without a single nuisance trip and it trips
every time I simulate a fault. I would press SMA on delivery since I
believe they are available. It may be either an internal hold on the
product or bad information.
Eaton has released their AFCI component but it is not a listed
component so it has to be incorporated into a listed product like a
combiner box or inverter.
Although the AFCI technology will have some issues in implementation,
I believe that it is going to solve a lot of safety issues,
particularly with residential systems. We have been seeing more and
more series arc fault failures in the field, so the timing could not
be better. Even if you are in a region that does not enforce the 2011
NEC yet, I would recommend seriously looking at products in this area.
One word of caution. I believe AFCI products incorporated into
inverters will be more successful in the short term than products that
are independent of the inverter. The reason for this is simple. When
the product developer has the defined noise signature of the inverter,
they can build a product that accounts for the that noise signature
(transistor switching). Without that key piece of data, there will be
stand-alone AFCI products that have problems with particular inverters
and other components (dc-dc converters). These interactions are
difficult to predict without product by product testing.
Over the next few years, products like the one from Eaton will create
lists of inverters that they know work well with their products. Until
you get some good data on that issue, be careful.
Lastly, it is way cool to be able to walk up to a combiner box or plug
connector and open it under load and see the inverter trip on the
detected arc-fault. These products will become common retrofit items
as modules, connectors, combiner boxes, and inverters have connection
defects that start fires. Often, the only cost-effective way to fix
these connection problems is with detection since replacing PV arrays
and other products may be far more costly than installing an AFCI
detector.
Bill.
*From:*re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*August Goers
*Sent:* Sunday, October 14, 2012 9:11 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Two NEC questions
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-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>
[mailto:re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@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 ^(TM)
david.brear...@solarprofessional.com
<mailto:david.brear...@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.lundb...@powerfullygreen.com
<mailto:rebecca.lundb...@powerfullygreen.com>
763-438-1976
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