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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>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.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>They work off of the combined circuit to offer the AFCI
protection.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>The units are listed but, won’t be available for another couple
of months. We are in the field testing stage now.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Thanks <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>SMA America, LLC<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>Steve Jefferson<o:p></o:p></span></p>
<p class=MsoNormal><i><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>Sr. Technical Service Specialist, Sunny Family</span></i><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>6020 West Oaks Blvd, Suite 300<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>Rocklin, CA 95765 - 3714<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>U.S.A.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>Tel: +1 916 625 0870<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>Fax: +1 916 624-2445<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>Service Line +1 877 697 6283 (Toll Free)<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>Email: steve.jefferson@sma-america.com<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'><a href="http://www.sma-america.com/">www.SMA-America.com</a><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'> <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:#1F497D'>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.<o:p></o:p></span></p>
</div>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>JRQ<br>
<b>Sent:</b> Monday, March 12, 2012 9:09 AM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] Starting fires for fun with string wiring<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<div>
<div>
<p class=MsoNormal style='background:white'><span style='color:black'>I've been
wondering about this since I read over the 2011 code:<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='background:white'><span style='color:black'><o:p> </o:p></span></p>
</div>
<div>
<p class=MsoNormal style='background:white'><span style='color:black'>Are there
any listed DC arc-flash products on the market yet, or scheduled to come to
market within the next year?<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='background:white'><span style='color:black'><o:p> </o:p></span></p>
</div>
<div>
<p class=MsoNormal style='background:white'><span style='color:black'>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?<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='background:white'><span style='color:black'><o:p> </o:p></span></p>
</div>
<div>
<p class=MsoNormal style='background:white'><span style='color:black'>Do
systems with DC optimizers or with micro-inverters have arc-fault protection at
the module level?<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='background:white'><span style='color:black'><o:p> </o:p></span></p>
</div>
<div>
<p class=MsoNormal style='background:white'><span style='color:black'>Jeffrey
Quackenbush<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='background:white'><span style='color:black'>NABCEP
Certified PV Installer<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='background:white'><span style='color:black'>Peripatetic
Solar Technician<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='background:white'><span style='color:black'><o:p> </o:p></span></p>
</div>
<div>
<div>
<div>
<div class=MsoNormal align=center style='text-align:center;background:white'><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>
<hr size=1 width="100%" align=center>
</span></div>
<p class=MsoNormal style='background:white'><b><span style='font-size:10.0pt;
font-family:"Arial","sans-serif";color:black'>From:</span></b><span
style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>
"boB@midnitesolar.com" <boB@midnitesolar.com><br>
<b>To:</b> RE-wrenches <re-wrenches@lists.re-wrenches.org> <br>
<b>Sent:</b> Monday, March 12, 2012 12:37 AM<br>
<b>Subject:</b> Re: [RE-wrenches] Starting fires for fun with string wiring</span><span
style='color:black'><o:p></o:p></span></p>
</div>
<p class=MsoNormal style='background:white'><span style='color:black'><o:p> </o:p></span></p>
<div id=yiv1744623988>
<div>
<p class=MsoNormal style='background:white'><span style='color:black'>On
3/11/2012 9:26 PM, Kent Osterberg wrote: <o:p></o:p></span></p>
<p class=MsoNormal style='background:white'><span style='color:black'>boB,<br>
<br>
Most local codes, have granted a delay on implementing arc fault protection.
Also, the code only requires series faults to be cleared.<o:p></o:p></span></p>
<p class=MsoNormal style='background:white'><span style='color:black'><br>
<br>
I mentioned this because arc fault is already in the 2011 NEC whether it is
adopted or not.<br>
<br>
I have a feeling that Jeff was referring to some of the changes that are in the
works for 2014.<br>
<br>
As far as I understand, the code cannot be required unless there are products
that fill the requirement.<br>
<br>
Also, the UL spec was not quite complete, but that didn't stop many of us
from starting to work on it<br>
before even 2011 code was out, even releasing "something", even if it
did not have a spec<br>
to test to yet.<br>
<br>
This code is going to get interesting for sure. It's also going to
make installations more expensive so<br>
it's good that PV prices are falling some to help make up for it !<br>
<br>
boB<br>
<br>
<br>
<br>
<br>
<br>
<br>
<o:p></o:p></span></p>
<pre style='background:white'><span style='color:black'>Kent Osterberg<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>Blue Mountain Solar, Inc.<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'><a
href="http://www.bluemountainsolar.com" target="_blank">www.bluemountainsolar.com</a><o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>t: 541-568-4882<o:p></o:p></span></pre>
<p class=MsoNormal style='background:white'><span style='color:black'><br>
On 3/11/2012 8:28 PM, <a href="mailto:boB@midnitesolar.com" target="_blank">boB@midnitesolar.com</a>
wrote: <o:p></o:p></span></p>
<p class=MsoNormal style='background:white'><span style='color:black'>On
3/11/2012 7:35 PM, Jeff Yago wrote: <o:p></o:p></span></p>
<pre style='background:white'><span style='color:black'>I just sent a post about people not understanding the dangers of fire in the<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>array strings between the modules and before the combiner because its high<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>voltage DC and there are no fuses or circuit breakers to shut down the power<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>source (at least not until the next code requires arc-fault sensing!).<o:p></o:p></span></pre>
<p class=MsoNormal style='background:white'><span style='color:black'><br>
<br>
</span><span style='font-size:11.0pt;color:#1F497D'>Jeff,<br>
<br>
Arc fault was required as of NEC2011.</span><span style='color:black'><br>
<br>
boB<br>
<br>
<br>
<br>
<br>
<o:p></o:p></span></p>
<pre style='background:white'><span style='color:black'>Anyway, we have a 3 string, 4-module per string off-grid test system behind<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>the shop wired for 88 volts peak into a charge controller and 24 volt<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>battery bank. Last week as a test I temporarily disconnected the charge<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>controller and re-wired the 3 strings together into a single string of 12<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>modules with a 264 volt open circuit voltage DC output at about 7 amps at<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>dead short. When compared with most grid-tie systems, this is not that high<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>a voltage or current, so what happened next would be far worse for a larger<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>voltage array.<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'><o:p> </o:p></span></pre><pre
style='background:white'><span style='color:black'>I took a 2 x 4 and attached USE-2 single conductor wires using "wire<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>staples" with the (+) and (-) cables routed side by side and down the 2 x 4.<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>At the lower wire staple, I deliberately nailed through the wire insulation<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>which nicked the insulation but did not cut the wires. After routing the<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>array power through these test wires nothing happened since the wire staple<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>was not making a very good contact with the bare wire at the insulation<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>nick. I then moved the wires slowly from side to side by hand, which could<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>have been caused in a real installation from wind, temperature<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>expansion/contraction, somebody pulling on them, or just the action of age<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>on the nicked wire insulation. Anyway, after only a few seconds of slowly<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>moving these wires, suddenly the wiring where it passed under the wire<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>staple burst into flame and started to arc. In about 5 seconds the 2 x 4<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>was burning and the string wires were burning like a powder fuse running up<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>the 2 x 4. As the wire insulation was burning, it exposed the energized<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>wires and allowed the arcing to continue up the wood 2 x 4 which was now<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>also in flames . At times, the arc would pass between wires that were over<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>1" apart once the arc had started. In other words, the arc would not<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>normally jump 1" through the air, but once an arc started it would continue<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>to arc even when the wires were far apart since the plasma formed from the<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>vaporized copper wire was conducting the electricity across the gap.<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'><o:p> </o:p></span></pre><pre
style='background:white'><span style='color:black'>I know the code requires any string wires to be in metal conduit from the<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>point it enters a building to the first disconnect, but I am not sure this<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>is enough protection. DC voltage is a very strange animal and even trained<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>electricians do not always realize the strange behavior it has if they have<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>only worked with AC wiring. Arc faults in older AC electrical panels are<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>becoming a real danger to service technicians since sometimes just opening<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>the panel door can cause something loose to fall across the interior buss<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>bars and start the arc. <o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'><o:p> </o:p></span></pre><pre
style='background:white'><span style='color:black'>Arc faults are really dangerous because the plasma formed from vaporized<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>copper can be thousands of degrees in temperature in under a second, and<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>since it is not technically a "short", an arc-fault condition will not<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>usually trip the circuit breaker since there is enough resistance in the<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>higher voltage arc to limit the amp flow to below the rating of the circuit<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>breaker, which makes it very hard to stop. I think the solar industry will<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>start seeing more of this type hazard as these array voltages continue to<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>increase. I strongly suggest everyone should wear arc fault rated face<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>shield and hand protection when working around energized high-voltage DC<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>string circuits, as electricians gloves alone are not enough. <o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'><o:p> </o:p></span></pre><pre
style='background:white'><span style='color:black'>I will try and down-load this video from my camera and convert to a file I<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>can send as an email attachment. If interested, send me your email address.<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'><o:p> </o:p></span></pre><pre
style='background:white'><span style='color:black'>Jeff Yago<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'><a
href="mailto:jryago@dtisolar.com" target="_blank">jryago@dtisolar.com</a><o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'>804-457-9566<o:p></o:p></span></pre><pre
style='background:white'><span style='color:black'><o:p> </o:p></span></pre><pre
style='background:white'><span style='color:black'><o:p> </o:p></span></pre><pre
style='background:white'><span style='color:black'><o:p> </o:p></span></pre><pre
style='background:white'><span style='color:black'><o:p> </o:p></span></pre>
<p class=MsoNormal style='background:white'><span style='color:black'><br>
<br>
<o:p></o:p></span></p>
<pre style='background:white'><span style='color:black'>_______________________________________________<o:p></o:p></span></pre><pre
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