I wonder if the afci disturbances are caused (in part) at all from the wire size used on the AC side in the inverter? I just noticed the Sunny Tripower, which has a max AC output current of 14.5A, states in the manual that it requires #8 or #6. ? That is pretty big wire for 14A, don't ya think? What is the reasoning behind requiring such a large wire size? With our 4 inverters being within 15' of the AC panelboard, voltage drop is not an issue and first thought is to go with #12. I suspect it has to do with the terminal block in the inverter. I checked and the #12 holds pretty tight, but that doesn't mean it was approved for #12. benn
> On Jun 25, 2014, at 10:46 AM, Steve Jefferson > <steve.jeffer...@sma-america.com> wrote: > > Bill, > > For the 6 years I have been with SMA, I (and Service as a whole) will always > advise against using wire nuts. > > For the 13 years I have been in the solar industry, there are only a handful > of systems that I have installed that I used wire nuts. > > There is no cover up. This has been in our manuals since the beginning of SMA. > > The AFCI circuit is really sensitive to noise, therefore eliminating most > possibilities of issues that installers may come across is our goal. > Wire nuts is a simple thing to not use, and there are many alternatives. > > SMA America, LLC > Steve Jefferson > Service Line Supervisor > 3925 Atherton Ave > Rocklin, CA 95765 - 3714 > U.S.A. > Tel: +1 916 625 3185 (direct) > Fax: +1 916 625 0871 > Mobile: +1 916 622 4253 > Email: steve.jeffer...@sma-america.com > www.SMA-America.com > > <image001.png> > > This email and any attachments thereto may contain SMA America, LLC > confidential, privileged and private material for the sole use of the > intended recipient. Any review, copying, or distribution of this email (or > any attachments thereto) by others is strictly prohibited. If you are not the > intended recipient, please contact the sender immediately and permanently > delete the original and any copies of this email and any attachments thereto. > Thank you. > > > > From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On > Behalf Of Bill Hoffer > Sent: Wednesday, June 25, 2014 9:13 AM > To: RE-wrenches > Subject: Re: [RE-wrenches] AFCI disturbances. > > William > > I agree with Bob-O, wire nuts are not the best choice for DC connections, for > all the reasons he mentioned, but SMA claiming that wire nuts are causing > arc faults seems like a long shot at covering up an arc fault detection > nuisance tripping problem. IMHO AFCI protection circuits are far from > perfected at this time and Inverters and optimizers have enough inherent > switching noise to cause nuisance tripping ( and there is ample evidence > supporting numerous inverter manufacturers having issues). I believe we are > going to have similar growing pains as we did in the beginning of requiring > ARC Fault panel mounted breakers for bedrooms. I have since replaced all my > Square D Arc Fault breakers due to failure, ie nuisance tripping. I > understand the intent of adding arc fault to the 2014 code, but I am > concerned that as installers we will again become the guinea pigs in this > crazy experiment! Don't gt me started on the fact that they are required to > only detect series faults and that opening the circuit on a parallel fault > will likely make the arc increase rather than extinguish! > > Bill > > > On Wed, Jun 25, 2014 at 8:40 AM, William Miller <will...@millersolar.com> > wrote: > Richard: > > Possibly. I think I prefer din mount connector blocks. However, if a wire nut > can arc internally a connector block might also. I am still wondering about > this concept. > > William > > Miller Solar > > > On Jun 25, 2014, at 6:09 AM, richard.l.rat...@valley.net (Richard L Ratico) > > wrote: > > > > William, > > Would UL listed crimp sleeves be an acceptable substitute where you would > > otherwise use wirenuts? > > > > Dick Ratico > > Solarwind Electric > > > > > > --- You wrote: > > Bob-O: > > > > > > > > When you say verboten, what does that mean? Not kosher? Frowned upon? > > Disallowed by law??? > > > > > > > > I am quite curious about this subject. Here is what I have learned so far: > > > > > > > > This is a unique case where we are replacing 3 dead SMA U series inverters > > with 2 US series inverters. The U series seem to all be dying at about 12 > > to 14 years of age. We have about a dozen of these to swap on our calendar > > and expect more. It may be that to do this right requires that we pull new > > wire from the arrays. This makes the job a lot more expensive. > > > > > > > > We have never used a wire nut on a PV lead until this project. It's not > > that we disapprove of wire nuts in general, it is because we know that if we > > were to use them regularly we would eventually have failures and call backs. > > We allow only one splice in a PV lead: between the cable provided by the > > manufacturer of the module and a bulkhead mounted MC4 connector direct to > > THWN in conduit > > (http://millersolar.com/MillerSolar/practices/PV_wiring/PV_Cable_wiring/_PV_ > > Cable_Wiring.html). > > > > > > > > We checked the manufacturer's listing and the wire nuts are rated for 600 > > volts. We do use wire nuts on AC circuits, such as switch and receptacle > > circuits in a power room. > > > > > > > > A tech at SMA told me that wire nuts "arc internally to the spring" causing > > the AFCI faults. I am not aware of any process of "internal arcing." To > > me, arcing means, as per the dictionary definition: "a luminous bridge > > formed in a gap between two electrodes." The same tech told me to solder > > the leads and apply shrink tubing. I don't believe this is an approved > > method. By the way, we have spliced leads on both US series inverters and > > only one is exhibiting AFCI disturbances. > > > > > > > > I do favor mounted terminal blocks, either screw or tubular type. I need to > > check if the Amp model we stock are 600 volt rated. > > > > > > > > I was told by another representative from SMA that on a ground-mount system > > it is legal to disable the AFCI protection. > > > > > > > > I will be troubleshooting this job tomorrow and I will let you all know what > > I learn. > > > > > > > > William Miller > > --- end of quote --- > > _______________________________________________ > > 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 > > > > > -- > William Hoffer > 161 SE Fourth Ave > P.O. Box 1823 > White Salmon, WA 98672-1823 > suneng...@gmail.com > > _______________________________________________ > 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 >
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