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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 Bill and Wrenches -</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">For ungrounded arrays what specific fusing and or DC disconnect requirements are needed compared to grounded arrays? </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'm trying to sort through the code but nothing is popping out at me besides what was already mentioned about needing to disconnect both the positive and negative lines on the DC side. In SMA's case I'm guessing that their new transformerless inverters with integrated DC disconnects and fuses may already take of all the requirements?</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"><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><div><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in"><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>Bill Brooks<br>
<b>Sent:</b> Friday, October 01, 2010 8:29 AM<br><b>To:</b> 'RE-wrenches'<br><b>Subject:</b> Re: [RE-wrenches] Tranformless inverter</span></p></div></div><p class="MsoNormal"> </p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">All,</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">Transformerless inverters are simply a subset of ungrounded or resistively grounded PV systems covered by the NEC in 690.35 since the 2005 code cycle. Power-One has been marketing their ungrounded inverter in the U.S. for several years now. It was listed by CSA. The requirements for ungrounded systems in 690.35 are as follows:</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span></p><p class="MsoNormal" style="margin-left:.5in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<span style="font-size:11.0pt;color:#1F497D"><span style="mso-list:Ignore">•<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">“Photovoltaic power systems shall be permitted to operate with ungrounded photovoltaic source and output circuits where the system complies with 690.35(A) through 690.35(G).</span></p>
<p class="MsoNormal" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo2"><span style="font-size:11.0pt;font-family:"Trebuchet MS","sans-serif";color:#1F497D"><span style="mso-list:Ignore">−<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(A) Disconnects. </span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">All photovoltaic source and output circuit conductors shall have disconnects complying with 690, Part III.</span></p>
<p class="MsoNormal" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo2"><span style="font-size:11.0pt;font-family:"Trebuchet MS","sans-serif";color:#1F497D"><span style="mso-list:Ignore">−<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(B) Overcurrent Protection. </span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">All photovoltaic source and output circuit conductors shall have overcurrent protection complying with 690.9.</span></p>
<p class="MsoNormal" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level2 lfo2"><span style="font-size:11.0pt;font-family:"Trebuchet MS","sans-serif";color:#1F497D"><span style="mso-list:Ignore">−<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(C) Ground-Fault Protection. </span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">All photovoltaic source and output circuits shall be provided with a ground-fault protection device or system that complies with (1) through (3):</span></p>
<p class="MsoNormal" style="margin-left:1.5in;text-indent:-.25in;mso-list:l0 level3 lfo2"><span style="font-size:11.0pt;color:#1F497D"><span style="mso-list:Ignore">•<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(1) Detects a ground fault.</span></p>
<p class="MsoNormal" style="margin-left:1.5in;text-indent:-.25in;mso-list:l0 level3 lfo2"><span style="font-size:11.0pt;color:#1F497D"><span style="mso-list:Ignore">•<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(2) Indicates that a ground fault has occurred</span></p>
<p class="MsoNormal" style="margin-left:1.5in;text-indent:-.25in;mso-list:l0 level3 lfo2"><span style="font-size:11.0pt;color:#1F497D"><span style="mso-list:Ignore">•<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(3) Automatically disconnects all conductors or causes the inverter or charge controller connected to the faulted circuit to automatically cease supplying power to output circuits.</span></p>
<p class="MsoNormal" style="margin-left:1.0in;text-indent:-.25in;mso-list:l2 level2 lfo4"><span style="font-size:11.0pt;font-family:"Trebuchet MS","sans-serif";color:#1F497D"><span style="mso-list:Ignore">−<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(D) </span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The photovoltaic source and output conductors shall consist of the following:</span></p>
<p class="MsoNormal" style="margin-left:1.0in;text-indent:-.25in;mso-list:l2 level2 lfo4"><span style="font-size:11.0pt;font-family:"Trebuchet MS","sans-serif";color:#1F497D"><span style="mso-list:Ignore">−<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(1) Nonmetallic jacketed multiconductor cables</span></p>
<p class="MsoNormal" style="margin-left:1.0in;text-indent:-.25in;mso-list:l2 level2 lfo4"><span style="font-size:11.0pt;font-family:"Trebuchet MS","sans-serif";color:#1F497D"><span style="mso-list:Ignore">−<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(2) Conductors installed in raceways, or</span></p>
<p class="MsoNormal" style="margin-left:1.0in;text-indent:-.25in;mso-list:l2 level2 lfo4"><span style="font-size:11.0pt;font-family:"Trebuchet MS","sans-serif";color:#1F497D"><span style="mso-list:Ignore">−<span style="font:7.0pt "Times New Roman""> </span></span></span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(3) Conductors listed and identified as Photovoltaic (PV) Wire installed as exposed, single conductors.</span></p>
<p class="MsoNormal" style="margin-left:1.0in;text-indent:-.25in;mso-list:l2 level2 lfo4"><span style="font-size:11.0pt;font-family:"Trebuchet MS","sans-serif";color:#1F497D"><span style="mso-list:Ignore">−<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(E) </span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The photovoltaic power system direct-current circuits shall be permitted to be used with ungrounded battery systems complying with 690.71(G).</span></p>
<p class="MsoNormal" style="margin-left:1.0in;text-indent:-.25in;mso-list:l2 level2 lfo4"><span style="font-size:11.0pt;font-family:"Trebuchet MS","sans-serif";color:#1F497D"><span style="mso-list:Ignore">−<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(F) </span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The photovoltaic power source shall be labeled with the following warning at each junction box, combiner box, disconnect, and device where the ungrounded circuits may be exposed during service:</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">WARNING</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">ELECTRIC SHOCK HAZARD</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">THE DC CIRCUIT CONDUCTORS OF THIS</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">PHOTOVOLTAIC POWER SYSTEM ARE</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">UNGROUNDED AND MAY BE ENERGIZED</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">WITH RESPECT TO GROUND DUE TO</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">LEAKAGE PATHS AND/OR GROUND FAULTS.</span></p><p class="MsoNormal" style="margin-left:1.0in;text-indent:-.25in;mso-list:l1 level2 lfo6">
<span style="font-size:11.0pt;font-family:"Trebuchet MS","sans-serif";color:#1F497D"><span style="mso-list:Ignore">−<span style="font:7.0pt "Times New Roman""> </span></span></span><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(G) </span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The inverters or charge controllers used in systems with ungrounded photovoltaic source and output circuits shall be listed for the purpose.</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">We now have several products newly on the market to include on the list such as the SMA and Exeltech products. Ungrounding the array requires additional fusing and disconnects, but the most significant difference is that the module wiring and all external cable must be PV Wire/Cable. Therefore only modules with PV Wire/Cable can be used in these systems. You must confirm from the manufacturer that they have made the switch. Hopefully all manufacturers will be installing PV Wire/Cable soon so that this will not be a problem anymore.</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">It is a good call to use up your USE-2 and order PV Wire/Cable from now on.</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">Bill.</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span></p><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in"><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>Exeltech<br>
<b>Sent:</b> Friday, October 01, 2010 6:39 AM<br><b>To:</b> RE-wrenches<br><b>Subject:</b> Re: [RE-wrenches] Tranformless inverter</span></p></div><p class="MsoNormal"> </p><table class="MsoNormalTable" border="0" cellspacing="0" cellpadding="0">
<tr><td valign="top" style="padding:0in 0in 0in 0in"><p class="MsoNormal">Transformerless grid-tie inverters are permitted under the National Electric Code as of 2008. The Nationally Recognized Testing Laboratories (UL, ETL/Intertek, CSA, etc.) took a while to develop the testing procedures for testing to UL1741, which was the basis for most of the delay.<br>
<br>SMA isn't the only company with transformerless grid-tie inverters. I know of one American manufacturer with transformerless models on the market as well.<br><br>Transformerless inverters are smaller, much lighter, and tend to be more efficient than transformer-based units. No transformer also means lower product cost, and less shipping expense. Win-win-win.<br>
<br><br>Dan<br><br><br>--- On <b>Fri, 10/1/10, Drake <i><<a href="mailto:drake.chamberlin@redwoodalliance.org">drake.chamberlin@redwoodalliance.org</a>></i></b> wrote:</p><p class="MsoNormal" style="margin-bottom:12.0pt">
<br>From: Drake <<a href="mailto:drake.chamberlin@redwoodalliance.org">drake.chamberlin@redwoodalliance.org</a>><br>Subject: Re: [RE-wrenches] Tranformless inverter<br>To: "RE-wrenches" <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>><br>
Date: Friday, October 1, 2010, 6:58 AM</p><div id="yiv831815003"><p class="MsoNormal" style="margin-bottom:12.0pt">I also received this advertisement. Previously I had investigated the smaller SMA transformerless inverters, and was told that this type would not be allowed in the US until the 2011 code. Has the ban been lifted?<br>
<br><br><br>At 12:52 AM 9/29/2010, you wrote:</p><p class="MsoNormal">Wrenches:<br><br>I received an advertisement from a distributor that SMA is now shipping 8, 9 and 10 KW transformerless inverters. Don't these require double insulated PV wiring and no connection to ground on the AC side? It's been too long since this subject last crossed my desk and I want to refresh my memory on the specifics.<br>
<br>William Miller<br><br><br><u>Please note new e-mail address and domain:<br><br></u>William Miller <br>Miller Solar<br>Voice :805-438-5600<br>email: <a href="mailto:william@millersolar.com">william@millersolar.com</a><br>
<a href="http://millersolar.com/" target="_blank">http://millersolar.com</a><br>License No. C-10-773985</p></div></td></tr></table><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Calibri","sans-serif""> </span></p>
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