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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'>Andy,<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'>How are you testing the ground impedance of the EGC?<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><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>Andrew Truitt<br><b>Sent:</b> Tuesday, January 14, 2014 7:25 AM<br><b>To:</b> RE-wrenches<br><b>Subject:</b> [RE-wrenches] EGC ground impedance<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Wrenches - What do you consider to be a safe ground impedance for a PV array equipment grounding conductor? NEC2011 250.53(A) says that if the impedance between the grounding <i>electrode</i> and earth is less than 25 ohms then no supplementary grounding electrode is needed, but I'm not clear on what that means for the ground impedance measurement within the array. For example, I am inspecting a ballasted landfill system (i.e. no penetrating the earth allowed - just a UFER at the equipment pad) where the ground impedance at the GEC is very low (<1 Ohm), but the array EGCs are showing ground impedances of between 500 and 1000 Ohms. The EGCs (#4) are connected to Cope cable trays, which are in turn connected to the inverter grounding bar via #4 bonding jumpers. The cable tray is grounded per manufacturer specs (large bonding jumpers at each joint), but the runs can be quite long (300'+) with many connections, though nothing appears to be loose. I intend to recommend that continuous conductors be installed to reduce array ground impedance, but any input on the issue would be very much appreciated.<o:p></o:p></p><div><div><div><div><div><p class=MsoNormal><o:p> </o:p></p><div><div><div><div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#38761D'>For a brighter energy future,<br><br><br>Andrew Truitt </span><o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#38761D'>Principal<br>Truitt Renewable Energy Consulting, LLC</span><o:p></o:p></p></div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#38761D'><a href="tel:%28202%29%20486-7507" target="_blank">(202) 486-7507</a></span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><a href="http://www.linkedin.com/pub/andrew-truitt/8/622/713" target="_blank">LinkedIn Profile</a><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><a href="http://truittreconsulting.weebly.com/" target="_blank">Company Website</a><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#38761D'>NABCEP Certified PV Installation Professional ID: 032407-66</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='color:#38761D'>Colorado Journeyman Electrician License No.: 600132</span><o:p></o:p></p></div></div></div></div></div></div></div></div><div><div><div><div><div><p><span style='color:#147DBA'><img border=0 width=200 height=133 id="_x0000_i1025" src="cid:image002.jpg@01CF1137.83995010" alt="24 copy.jpg"></span><br><span style='color:#147DBA'><br></span>"Don't get me wrong: I love nuclear energy! It's just that I prefer fusion to fission. And it just so happens that there's an enormous fusion reactor safely banked a few million miles from us. It delivers more than we could ever use in just about 8 minutes. And it's wireless!"<br><br>~William McDonough<o:p></o:p></p><div><div><p class=MsoNormal><o:p> </o:p></p></div></div></div><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p></div></div></div></div></div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div></div></div>
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