SMA will have AFCI protection built into the inverters. It is integrated into the inside of the inverter, so there are no extra components to install. They work off of the combined circuit to offer the AFCI protection.
The units are listed but, won't be available for another couple of months. We are in the field testing stage now. Thanks SMA America, LLC Steve Jefferson Sr. Technical Service Specialist, Sunny Family 6020 West Oaks Blvd, Suite 300 Rocklin, CA 95765 - 3714 U.S.A. Tel: +1 916 625 0870 Fax: +1 916 624-2445 Service Line +1 877 697 6283 (Toll Free) Email: steve.jeffer...@sma-america.com www.SMA-America.com<http://www.sma-america.com/> 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-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of JRQ Sent: Monday, March 12, 2012 9:09 AM To: RE-wrenches Subject: Re: [RE-wrenches] Starting fires for fun with string wiring I've been wondering about this since I read over the 2011 code: Are there any listed DC arc-flash products on the market yet, or scheduled to come to market within the next year? Also: will arc-flash protection come in the form of breakers that need to be installed externally, or will it be something internal to the inverters or charge controllers to which source circuits are wired? Will they need to be installed on each string, or can they function on a combined circuit? Do systems with DC optimizers or with micro-inverters have arc-fault protection at the module level? Jeffrey Quackenbush NABCEP Certified PV Installer Peripatetic Solar Technician ________________________________ From: "b...@midnitesolar.com" <b...@midnitesolar.com> To: RE-wrenches <re-wrenches@lists.re-wrenches.org> Sent: Monday, March 12, 2012 12:37 AM Subject: Re: [RE-wrenches] Starting fires for fun with string wiring On 3/11/2012 9:26 PM, Kent Osterberg wrote: boB, Most local codes, have granted a delay on implementing arc fault protection. Also, the code only requires series faults to be cleared. I mentioned this because arc fault is already in the 2011 NEC whether it is adopted or not. I have a feeling that Jeff was referring to some of the changes that are in the works for 2014. As far as I understand, the code cannot be required unless there are products that fill the requirement. Also, the UL spec was not quite complete, but that didn't stop many of us from starting to work on it before even 2011 code was out, even releasing "something", even if it did not have a spec to test to yet. This code is going to get interesting for sure. It's also going to make installations more expensive so it's good that PV prices are falling some to help make up for it ! boB Kent Osterberg Blue Mountain Solar, Inc. www.bluemountainsolar.com<http://www.bluemountainsolar.com> t: 541-568-4882 On 3/11/2012 8:28 PM, b...@midnitesolar.com<mailto:b...@midnitesolar.com> wrote: On 3/11/2012 7:35 PM, Jeff Yago wrote: I just sent a post about people not understanding the dangers of fire in the array strings between the modules and before the combiner because its high voltage DC and there are no fuses or circuit breakers to shut down the power source (at least not until the next code requires arc-fault sensing!). Jeff, Arc fault was required as of NEC2011. boB Anyway, we have a 3 string, 4-module per string off-grid test system behind the shop wired for 88 volts peak into a charge controller and 24 volt battery bank. Last week as a test I temporarily disconnected the charge controller and re-wired the 3 strings together into a single string of 12 modules with a 264 volt open circuit voltage DC output at about 7 amps at dead short. When compared with most grid-tie systems, this is not that high a voltage or current, so what happened next would be far worse for a larger voltage array. I took a 2 x 4 and attached USE-2 single conductor wires using "wire staples" with the (+) and (-) cables routed side by side and down the 2 x 4. At the lower wire staple, I deliberately nailed through the wire insulation which nicked the insulation but did not cut the wires. After routing the array power through these test wires nothing happened since the wire staple was not making a very good contact with the bare wire at the insulation nick. I then moved the wires slowly from side to side by hand, which could have been caused in a real installation from wind, temperature expansion/contraction, somebody pulling on them, or just the action of age on the nicked wire insulation. Anyway, after only a few seconds of slowly moving these wires, suddenly the wiring where it passed under the wire staple burst into flame and started to arc. In about 5 seconds the 2 x 4 was burning and the string wires were burning like a powder fuse running up the 2 x 4. As the wire insulation was burning, it exposed the energized wires and allowed the arcing to continue up the wood 2 x 4 which was now also in flames . At times, the arc would pass between wires that were over 1" apart once the arc had started. In other words, the arc would not normally jump 1" through the air, but once an arc started it would continue to arc even when the wires were far apart since the plasma formed from the vaporized copper wire was conducting the electricity across the gap. I know the code requires any string wires to be in metal conduit from the point it enters a building to the first disconnect, but I am not sure this is enough protection. DC voltage is a very strange animal and even trained electricians do not always realize the strange behavior it has if they have only worked with AC wiring. Arc faults in older AC electrical panels are becoming a real danger to service technicians since sometimes just opening the panel door can cause something loose to fall across the interior buss bars and start the arc. Arc faults are really dangerous because the plasma formed from vaporized copper can be thousands of degrees in temperature in under a second, and since it is not technically a "short", an arc-fault condition will not usually trip the circuit breaker since there is enough resistance in the higher voltage arc to limit the amp flow to below the rating of the circuit breaker, which makes it very hard to stop. I think the solar industry will start seeing more of this type hazard as these array voltages continue to increase. I strongly suggest everyone should wear arc fault rated face shield and hand protection when working around energized high-voltage DC string circuits, as electricians gloves alone are not enough. I will try and down-load this video from my camera and convert to a file I can send as an email attachment. If interested, send me your email address. Jeff Yago jry...@dtisolar.com<mailto:jry...@dtisolar.com> 804-457-9566 _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org<mailto:RE-wrenches@lists.re-wrenches.org> Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm<http://www.re-wrenches.org/etiquette.htm> Check out participant bios: www.members.re-wrenches.org<http://www.members.re-wrenches.org> _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org<mailto:RE-wrenches@lists.re-wrenches.org> Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
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