<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div><span>Separately-derived means that there is physical isolation between two circuits in the same electrical system – usually this involves two circuits connected by a transformer</span></div><div><span><br></span></div><div><span>The DC side is separately derived in a transformer-based PV inverter. Most grid-tie inverters have a DC main bonding jumper internally. Other inverters (esp. small stand-alone inverters) may not, and so a main bonding jumper will need to be installed.</span></div><div><span><br></span></div><div><span>Jeffrey Quackenbush</span></div><div>NABCEP-certified PV Installer</div><div><br></div> <div style="font-size: 12pt; font-family: 'times new roman', 'new york', times, serif; "> <div style="font-size: 12pt; font-family: 'times new roman', 'new york', times, serif; "> <div dir="ltr"> <font size="2"
face="Arial"> <hr size="1"> <b><span style="font-weight:bold;">From:</span></b> Dave Palumbo <dave@independentpowerllc.com><br> <b><span style="font-weight: bold;">To:</span></b> 'RE-wrenches' <re-wrenches@lists.re-wrenches.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Tuesday, January 24, 2012 6:43 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [RE-wrenches] Grounding Separately Derived AC System<br> </font> </div> <br>
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--></style><div><div class="yiv784653244WordSection1"><div class="yiv784653244MsoNormal">Regarding NEC Article 250.30 does Informational Note #1 mean that a standard (no battery) grid-tied PV system is not a Separately Derived System?</div><div class="yiv784653244MsoNormal"> </div><div class="yiv784653244MsoNormal">I’m primarily interested on the consensus view of Bonding the Neutral (grounded conductor) to Equipment Ground in a 60 Amp Fused Disconnect located between the 240VAC inverter output and AC point of connection on the load side of the meter in the service disconnect enclosure in a <u>supply side connected PV system</u>. </div><div class="yiv784653244MsoNormal"> </div><div class="yiv784653244MsoNormal">250.30 Informational Note 1 reads: “<i>An alternate ac power source, such as an on-site generator, is <u>not</u> a separately derived system if the grounded conductor is solidly interconnected to a service-supplied system grounded
conductor…” </i> I believe a PV system meets that description as the Neutral stays connected at all times. <i></i></div><div class="yiv784653244MsoNormal"><i> </i></div><div class="yiv784653244MsoNormal">My interpretation is that a standard net-metered PV system is therefore not a separately derived system and the Neutral should not have a bonding jumper to equipment ground in the Fused Disconnect.</div><div class="yiv784653244MsoNormal"> </div><div class="yiv784653244MsoNormal">Is this the correct interpretation?</div><div class="yiv784653244MsoNormal"> </div><div class="yiv784653244MsoNormal">David Palumbo</div><div class="yiv784653244MsoNormal">Independent Power LLC </div><div class="yiv784653244MsoNormal">462 Solar Way Drive</div><div class="yiv784653244MsoNormal">Hyde Park, VT 05655<b></b></div><div class="yiv784653244MsoNormal"><b><i><a target="_blank"
href="http://www.independentpowerllc.com">www.independentpowerllc.com</a> </i></b></div><div class="yiv784653244MsoNormal">NABCEP Certified PV Installer</div><div class="yiv784653244MsoNormal">Vermont Solar Partner</div><div class="yiv784653244MsoNormal">24 Years Experience, (802) 888-7194 </div><div class="yiv784653244MsoNormal"> </div></div></div></div><br>_______________________________________________<br>List sponsored by Home Power magazine<br><br>List Address: <a ymailto="mailto:RE-wrenches@lists.re-wrenches.org" href="mailto:RE-wrenches@lists.re-wrenches.org">RE-wrenches@lists.re-wrenches.org</a><br><br>Options & settings:<br><a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org" target="_blank">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a><br><br>List-Archive: <a href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org"
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