<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=us-ascii"><meta name=Generator content="Microsoft Word 14 (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:14.0pt'>Hello transformer gurus,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>I am in the middle of a good sized PV job and we need to use a 75 kva 480/208 3 phase transformer (standard delta to wye) to connect the 208 3 phase output to the building service 480. So the transformer/PV constitutes a separately derived system. The OEM’s transformer wiring diagram is vague but is prewired for H1,2,3 inputs and X0 – x4 outputs at 208. I think I got this right: the 480 primary feeder neutral is not used, primary gnd goes to xformer equipment gnd, secondary 208 neutral is created on secondary X0, secondary X0 is bonded to equipment gnd, and the 208 gnd originates at the equipment gnd terminal. And a GEC must travel from xformer gnd terminal to a code-approved grounding electrode (rod, building steel, etc).<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>I am gleaning some of this from a Mike Holt article, just want to make sure I’m not missing anything obvious. Thanks.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>Kirk Herander<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>VT Solar, LLC<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>dba Vermont Solar Engineering<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>NABCEP<sup>TM </sup>Certified installer Charter Member<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>NYSERDA-eligible Installer<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>VT RE Incentive Program Partner<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:14.0pt'>802.863.1202<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>