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--></style></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 Mac,</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I think the answer to your "separately derived system" question is in the code snippet you pasted in below. Clearly, your Enphase grid tied system has a direct electrical connection to the utility. A generator system that runs while the grid is down would be an example of a separately derived system since it will always have a transfer switch to separate the electrical connections. In other words, the grid tied solar system is designed to work in unison with the grid while a separately must only operate independently. At least that is how I try to explain it to inspectors around here.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I believe Brian Mehalic's email clearly speaks to why you still need a GEC for the Enphase based system. Incidentally, we're starting to work with listed ACPV modules and transformerless (non-isolated) inverters which don't have a DC GEC requirement. This is a major benefit to help reduce installed costs.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Best,</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">August</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">August Goers</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Luminalt Energy Corporation</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">1320 Potrero Avenue</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">San Francisco, CA 94110</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">m: 415.559.1525</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">o: 415.641.4000</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><a href="mailto:august@luminalt.com">august@luminalt.com</a></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p><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""> <a href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a> [mailto:<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On Behalf Of </b>mac Lewis<br>
<b>Sent:</b> Wednesday, November 28, 2012 7:56 PM<br><b>To:</b> RE-wrenches<br><b>Subject:</b> [RE-wrenches] EGC vs GEC, separately derived system</span></p><p class="MsoNormal"> </p><p class="MsoNormal">Hello wrenches,</p>
<div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">What constitutes a separately derived system? Would you consider a breaker tied enphase system a separately-derived system? Suddenly, inspectors in our AHJ are considering all PV systems separately derived systems and thus requiring applying GEC sizing (as opposed to EGC sizing) from the inverter(s) to the tie in point. This does not jive with my understanding. Would like to hear other thoughts about this.</p>
</div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">Here is the definition of a separately derived system as per 2008 NEC Article 100 Definitions:</p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">
<u>Separately Derived System</u>: <i>A premises wiring system whose power is derived from a source of electric energy or equipment other than a service. Such systems have no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system.</i></p>
</div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">For your enphase systems do you size your ground from roof to the breaker panel as an EGC or a GEC?</p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">
</p></div><div><p class="MsoNormal">Thanks in advance for your thoughts.<br clear="all"></p><div><p class="MsoNormal"> </p></div><p class="MsoNormal">-- </p><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">
</p></div><div><p class="MsoNormal"> </p></div><p class="MsoNormal" style="margin-bottom:12.0pt">Mac Lewis<b><span style="font-family:"Arial","sans-serif";color:#ff9900"></span></b></p><p><span style="color:#305a78">"Yo solo sé que no sé nada." </span><b><span style="color:#686868">-Sócrates</span></b><b><span style="font-family:"Arial","sans-serif";color:#ff9900"></span></b></p>
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