<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:arial,helvetica,sans-serif;font-size:12pt">Hi Mark, Ray, and wrenches:<br> I agree that the grounding requirements can be onerous, but I have to interject that most generator manufacturers do specify a dedicated grounding electrode conductor. Also, I do not feel that a #8 ground is too big. Probably unnecessary 99% of the time, but with all the shorts and arced connections that I have found in j-boxes, I feel good about running a larger grounding conductor.<br> With regard to the Enphase grounded with WEEB; which I have done many times, I would recommend spelling out the exact grounding method for the micro-inverters on the permit package. We should have this issue resolved before installation begins.<br><div> </div>Nick Soleil<br>Project Manager<br>Advanced Alternative Energy Solutions,
LLC<br>PO Box 657<br>Petaluma, CA 94953<br>Cell: 707-321-2937<br>Office: 707-789-9537<br>Fax: 707-769-9037<div><br></div><div style="font-family: arial,helvetica,sans-serif; font-size: 12pt;"><br><div style="font-family: arial,helvetica,sans-serif; font-size: 10pt;"><font face="Tahoma" size="2"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> Mark Frye <markf@berkeleysolar.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> Fri, March 4, 2011 10:53:46 AM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [RE-wrenches] grounding the Enphase inverter<br></font><br>
Yes, but that comes from the assumption that the inverter constitutes a<br>seperately derived "system".<br><br>But if the only purpose or use of the DC power derived from the DC system is<br>to drive the AC side of the inverter, how closely does it realy resemble a<br>classic seperately derived system. As opposed to having the DC power source<br>actually run DC utilization equipment such as motors and appliances.<br><br>It is interesting that the very language in the code descibes the inverter<br>as "utility interactive". Is it really correct to describe a UL174 inverter<br>operating only in parrallel with the utility as a seperately derived system?<br><br>To what degree has the Code failed to reflect the evolution of technology?<br>Yes, battery-based inverter systems capable of powering a facility in the<br>absense of a utility power souce do in fact become a seperately derived<br>system which need to have a GEC. But to impose the same requirement on
an<br>inverter which cannot possibly deliver power to anything other than a system<br>that already has a GEC seems to me to be a crude cookie cutter response to a<br>far more complex situation.<br><br>We have put the complexity into the inverters. Recogonizing this we see that<br>we don't need the complexity in wiring?<br> <br>Mark Frye<br>Berkeley Solar Electric Systems<br>303 Redbud Way<br>Nevada City, CA 95959<br>(530) 401-8024<br><a target="_blank" href="http://www.berkeleysolar.com">www.berkeleysolar.com</a> <br><br>-----Original Message-----<br>From: <a ymailto="mailto:re-wrenches-bounces@lists.re-wrenches.org" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a><br>[mailto:<a ymailto="mailto:re-wrenches-bounces@lists.re-wrenches.org" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>] On Behalf Of Bill Brooks<br>Sent: Friday, March 04, 2011
9:51 AM<br>To: 'RE-wrenches'<br>Subject: Re: [RE-wrenches] grounding the Enphase inverter<br><br>System grounding requirements.<br><br>-----Original Message-----<br>From: <a ymailto="mailto:re-wrenches-bounces@lists.re-wrenches.org" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a><br>[mailto:<a ymailto="mailto:re-wrenches-bounces@lists.re-wrenches.org" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>] On Behalf Of Mark Frye<br>Sent: Friday, March 04, 2011 7:51 AM<br>To: 'RE-wrenches'<br>Subject: Re: [RE-wrenches] grounding the Enphase inverter<br><br>The interesting thing to me is the underlying assumption in the Code that a<br>GEC is requried for grid-tied inverters at all. Why isn't EG sufficient for<br>function and safety. <br><br>Which of the following common electrical equipment has the same requirement:<br><br>UPS<br>Motors with regenerative
energy disipators DC power supplies Standby<br>generators<br><br>??<br> <br>Mark Frye<br>Berkeley Solar Electric Systems<br>303 Redbud Way<br>Nevada City, CA 95959<br>(530) 401-8024<br><span><a target="_blank" href="http://www.berkeleysolar.com">www.berkeleysolar.com</a> </span><br><br>-----Original Message-----<br>From: <a ymailto="mailto:re-wrenches-bounces@lists.re-wrenches.org" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a><br>[mailto:<a ymailto="mailto:re-wrenches-bounces@lists.re-wrenches.org" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>] On Behalf Of Bill Brooks<br>Sent: Thursday, March 03, 2011 10:48 PM<br>To: 'RE-wrenches'<br>Subject: Re: [RE-wrenches] grounding the Enphase inverter<br><br>All,<br><br>While there is ambiguity in the 2008 NEC in 690.47(C) on the requirements<br>for system grounding of PV systems, the 2011 NEC in
690.47(C) clarifies the<br>intent. <br><br>While an application note from Enphase may state that WEEBs can be used as<br>part of the grounding electrode system, I disagree with this concept and do<br>not believe it meets the requirements or intent of the NEC as clarified in<br>the 2011 NEC. The problem with a grounded PV inverter is that it requires a<br>grounding electrode conductor (GEC) from the grounding point (on the<br>inverter) to the grounding electrode. The 2008 and 2011 NEC allows for that<br>connection to be terminated at the grounding bar in the service panel<br>supplying the micro-inverters.<br><br>There is no problem with using the WEEB to bond the rails to the modules and<br>then to the Enphase Micro-inverter. From the micro-inverter, a bare 6AWG<br>could be run to pick up each micro-inveter in each row of micro-inverters<br>with splices made to a single bare 6AWG made with irreversible splices. At<br>the rooftop junction box, the GEC
could be irreversibly spliced to an 8AWG<br>green insulated conductor to run unbroken to the grounding busbar in the<br>service equipment.<br><br>While this may not be in agreement with the Enphase application note, I<br>believe it meets the intent and letter of the NEC as clarified in the 2011<br>NEC 690.47(C). While using the WEEBs in the GEC circuit may not cause a life<br>or death issue, it is absolutely open to being questioned by the electrical<br>inspector. If the electrical inspector decides it is wrong--it is wrong. If<br>you or the field inspector appeals to me or an expert like John Wiles, we<br>will state what I have stated above. Then you would have to remove all the<br>modules, throw away the WEEBs, put in new WEEBs with the new bare copper<br>6AWG and reinstall the modules--it just ain't worth it.<br><br>690.47(D) was removed from the 2011 NEC because it was primarily for<br>lightning protection (not a safety issue according to the NEC)
and was<br>ambiguously worded with respect to residential rooftop PV systems. If the<br>local jurisdiction requires the additional electrode, install a j-box at the<br>point near ground-level where the conduit transitions from vertical to<br>horizontal and install an irreversibly spliced bare 6AWG to run from the<br>j-box to a ground rod below the j-box--mildly painful, but very doable.<br><br>Bill.<br><br>Bill Brooks, PE<br>Principal<br>Brooks Engineering<br>873 Kells Circle<br>Vacaville, CA 95688<br>707-332-0761 (office and mobile)<br>707-451-7739 (fax)<br><a ymailto="mailto:bill@brooksolar.com" href="mailto:bill@brooksolar.com">bill@brooksolar.com</a> (email)<br><a target="_blank" href="http://www.brooksolar.com">www.brooksolar.com</a> (web)<br><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><span><a target="_blank" href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a></span><br><br>List-Archive:<br><span><a target="_blank" href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org">http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a></span><br><br>List rules & etiquette:<br><a target="_blank" href="http://www.re-wrenches.org/etiquette.htm">www.re-wrenches.org/etiquette.htm</a><br><br>Check out participant bios:<br><a target="_blank" href="http://www.members.re-wrenches.org">www.members.re-wrenches.org</a><br><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:<br><a href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org" target="_blank">http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a><br><br>List rules & etiquette:<br>www.re-wrenches.org/etiquette.htm<br><br>Check out participant bios:<br><span><a target="_blank" href="http://www.members.re-wrenches.org">www.members.re-wrenches.org</a></span><br><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" target="_blank">http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a><br><br>List rules & etiquette:<br>www.re-wrenches.org/etiquette.htm<br><br>Check out participant bios:<br><span><a target="_blank" href="http://www.members.re-wrenches.org">www.members.re-wrenches.org</a></span><br><br></div></div>
</div><br>
</body></html>