<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
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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'>Hi Don,<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 your reply. Good idea on the single 480V inverter, but multiple subarrays at different tilts/orientations and strings lengths make that impractical unfortunately. <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 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?<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><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"'> don@energysolarnow.com [mailto:don@energysolarnow.com] <br><b>Sent:</b> Thursday, April 03, 2014 1:55 PM<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'>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.<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:black'>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. <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:black'>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.<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:black'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:black'>Don Barch<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:black'>Energy Solar<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:black'><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><br>Message: 1<br>Date: Wed, 2 Apr 2014 17:20:36 -0500<br>From: "Garrison Riegel" <<a href="mailto:garrison@solarserviceinc.com">garrison@solarserviceinc.com</a>><br>To: "'RE-wrenches'" <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>><br>Subject: [RE-wrenches] Three Inverters, One Disconnect?<br>Message-ID: <817a01cf4ec1$c5d8ad00$518a0700$@<a href="http://solarserviceinc.com">solarserviceinc.com</a>><br>Content-Type: text/plain; charset="us-ascii"<br><br>Hello Wrenches,<br><br><br><br>On an upcoming project we are interconnecting (3) Power-One, ahem, ABB PVI<br>3.6 inverters to a 3Ph 277/480V service. Each inverter output is 16A at<br>277V, 1Ph. Is it code compliant to run the single phase output of each<br>inverter to a single pole of a 3-pole [utility required] AC disconnect<br>before landing at each 1-pole 20A breaker in the main panel? It would be<br>great to avoid an inverter subpanel and 3-pole breaker in the MDP if<br>possible.<br><br><br><br>Thanks for your thoughts.<br><br><br><br>Garrison<br><br><br><br>Garrison Riegel<br><br>Project Manager | <http://www.<a href="http://solarserviceinc.com">solarserviceinc.com</a>/> Solar Service Inc<br><br>[p] 847-677-0950 | <<a href="mailto:garrison@solarserviceinc.com">mailto:garrison@solarserviceinc.com</a>><br><a href="mailto:garrison@solarserviceinc.com">garrison@solarserviceinc.com</a><br><br><br><br>NABCEP Certified PV Installation ProfessionalT<br><br><br><o:p></o:p></span></p></div></blockquote></div></body></html>