[RE-wrenches] Two NEC questions

Sun Oct 14 15:07:25 PDT 2012

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-bounces at lists.re-wrenches.org 
> [mailto:re-wrenches-bounces at 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-bounces at lists.re-wrenches.org 
> <mailto:re-wrenches-bounces at lists.re-wrenches.org> 
> [mailto: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 ^(TM)
> david.brearley at solarprofessional.com 
> <mailto: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 
> <mailto:Rebecca.Lundberg at PowerfullyGreen.com>
> 763-438-1976
>
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