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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Bill,<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'>Thank you for clarifying the intent of 705.12(D)(1). <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'>It’s good to hear the 2014 NEC has improved language regarding single phase interconnections on 3-phase services, although I’m not sure my utility will care, and we in Chicago are working with the 1999 NEC…which is fun. That said, they do often listen to logic and reason if you can get through to the right people. <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'>Do you have an opinion on using a single 3-pole unfused switch as an AC disconnect for 3 single phase inverters? Good, bad, or ugly?<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><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Garrison<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><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> Bill Brooks [mailto:billbrooks7@yahoo.com] <br><b>Sent:</b> Friday, April 04, 2014 2:09 PM<br><b>To:</b> 'RE-wrenches'; 'Garrison Riegel'<br><b>Subject:</b> RE: [RE-wrenches] Three Inverters, One Disconnect?<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Don and Garrison,<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 word “dedicated” means “no loads”. That is why, the way the code is written today, you cannot plug a microinverter into a wall outlet. There is no limit to the number of inverters that can be placed on a single breaker. The limitation for inverters, is the maximum overcurrent device specification for the inverter and the ampacity of the conductors being protected by the inverter output circuit breaker in the ac panel.<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'>There are emphatically single pole breakers for 277Vac single phase circuits and it is completely valid to place 277Vac single phase inverters on these breakers. There is no need to place them on 3-pole breakers, nor does it provide any significant benefit to turn off inverters on other phases when one phase faults or goes down. Sometimes utilities get crazy on this point and require single phase inverters to have this capability. There are several single phase inverters on the market today with RJ45 jacks in order to trip the other two inverters on different phases when one inverter trips. This comes from utility requirements and is absolutely ridiculous. This all proceeds from 705.100 in the 2011 NEC and prior that was very poorly worded. The wording was updated and improved in the 2014 NEC to make it clear that single phase inverters on 3-phase services is just fine and that imbalances are handled the exact same way imbalances are handled with single phase loads on 3-phase services.<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'>Until utility commission ban single phase loads on 3-phase services (that’s a joke—it will never happen), we should always be allowed to put single phase inverters on 3-phase services. As we do this smartly and correctly, we reduce site voltage imbalance rather than increasing imbalance.<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'>Bill.<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'><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'><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><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'> re-wrenches-bounces@lists.re-wrenches.org [mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>don@energysolarnow.com<br><b>Sent:</b> Friday, April 04, 2014 11:36 AM<br><b>To:</b> re-wrenches@lists.re-wrenches.org; Garrison Riegel<br><b>Subject:</b> Re: [RE-wrenches] Three Inverters, One Disconnect?<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:black'>Hi Garrison- The dedicated breaker referred to in 705.12(D)(1) means they do not want the inverters plugged into branch breakers. One (and only one) inverter into each pole of a 3-pole breaker seems safer and better than 3 individual breakers, and seems to fit the definition of "dedicated" breaker.<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:black'>I don't know that you can even find single-pole 277 Vac breakers....<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:black'>DonB<o:p></o:p></span></p></div><blockquote style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 6.0pt;margin-left:6.0pt;margin-top:5.0pt;margin-bottom:5.0pt' id=replyBlockquote><div id=wmQuoteWrapper><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:black'>-------- Original Message --------<br><br>Message: 6<br>Date: Fri, 4 Apr 2014 08:01:00 -0500<br>From: "Garrison Riegel" <<a href="mailto:garrison@solarserviceinc.com">garrison@solarserviceinc.com</a>><br>To: <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>><br>Subject: Re: [RE-wrenches] Three Inverters, One Disconnect?<br>Message-ID: <828201cf5005$edd065b0$c9713110$@<a href="http://solarserviceinc.com">solarserviceinc.com</a>><br>Content-Type: text/plain; charset="utf-8"<br><br>Hi Don,<br><br>Thank you for your reply. Good idea on the single 480V inverter, but multiple subarrays at different tilts/orientations and strings lengths make that impractical unfortunately. <br><br>It also seems like a good idea to use a single 3-pole breaker to prevent phase imbalance, but I thought each inverter required a dedicated breaker as per 705.12(D)(1). Thoughts?<br><br>Thanks,<br><br>Garrison<br><br>From: <a href="mailto:don@energysolarnow.com">don@energysolarnow.com</a> [<a href="mailto:don@energysolarnow.com">mailto:don@energysolarnow.com</a>] <br>Sent: Thursday, April 03, 2014 1:55 PM<br>To: <a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>; Garrison Riegel<br>Subject: RE: [RE-wrenches] Three Inverters, One Disconnect?<br><br>With single phase 240 each inverter output is two poles; but since you are using 277 each inverter output is between one pole and neutral, so you could indeed use a 3-pole disconnect since the neutrals are not switched.<br><br>A 3-pole breaker is usually used with 3-phase systems, but since there are 3 separate inverters it is legal to use 3 single pole breakers provided you get them into separate phase poles. However, there would be a phase imbalance if one breaker tripped and the others were still sourcing current, so it's better to use a 3-pole breaker here. <br><br>But rather than go to all the work of wiring 3 separate 3.6 kW inverters, why not just use the PowerOne 10.0 or 12.0 kW 3-phase inverters? This would be less expensive and would need just one conduit run for input and output.<br><br>Don Barch<br><br>Energy Solar<o:p></o:p></span></p></div></blockquote><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><div class=MsoNormal align=center style='text-align:center'><hr size=1 width="99%" noshade style='color:#909090' align=center></div><table class=MsoNormalTable border=0 cellspacing=0 cellpadding=0 style='border-collapse:collapse'><tr><td style='padding:0in 11.25pt 0in 6.0pt'><p class=MsoNormal><a href="http://www.avast.com/"><span style='border:solid windowtext 1.0pt;padding:0in;text-decoration:none'><img border=0 width=100 height=100 id="_x0000_i1026" src="cid:~WRD000.jpg" alt="Image removed by sender."></span></a><o:p></o:p></p></td><td style='padding:.75pt .75pt .75pt .75pt'><p><span style='font-family:"Calibri","sans-serif";color:#3D4D5A'>This email is free from viruses and malware because <a href="http://www.avast.com/">avast! 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