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--></style></head><body bgcolor="white" 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">Kent, Brian,</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 still seems like a grey area to me. I think that from a conservative point of view that we cannot apply the 120% rule to a center fed panel. In my experience, AHJs around the Bay Area know a little about the 120% rule but haven't thought about it to this level of detail. In other words, they're probably fine with it in part perhaps due to ignorance. If we point out the issue to them then we might very well have a problem.</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 the vast majority of our projects we can find a solution but for a small portion of projects we cannot downsize the main breaker and we're really stuck. In the example photo that I sent the only option might be switching out the main service panel. </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><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";color:windowtext">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"> <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>Kent Osterberg<br>
<b>Sent:</b> Monday, October 15, 2012 12:07 PM<br><b>To:</b> RE-wrenches<br><b>Subject:</b> Re: [RE-wrenches] center fed main panel and 120% rule</span></p></div></div><p class="MsoNormal"> </p><div><p class="MsoNormal">If you back feed at the end of the bus bar where the main is connected to the middle of the bus bar, the back fed breaker cannot overload the bus bar between the main and the back fed breaker, but it would be possible to overload the other side of the bus bar - it's being fed by both the main and the back fed breaker. Seems like you shouldn't apply the 120% rule to these panels. But realistically, the panel isn't likely to be overloaded because most 200-amp panels are fed by services that can't really deliver 200 amps, at least not for more than a very brief time.<br>
<br>And what about the SQ D QO or HOM 6-12L100 or 8-16L100 panels that can be fed with main lugs that are on opposite ends (left for L1 and right for L2)? Seems like you shouldn't apply the 120% rule to these either. <br>
<br><br></p><pre>Kent Osterberg</pre><pre>Blue Mountain Solar, Inc.</pre><pre><a href="http://www.bluemountainsolar.com">www.bluemountainsolar.com</a></pre><p class="MsoNormal">On 10/15/2012 9:32 AM, August Goers wrote:</p>
</div><blockquote style="margin-top:5.0pt;margin-bottom:5.0pt"><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Hi 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">Here is yet another 120% rule question as it relates to center fed main panels. 2011 NEC 705.12 deals with inverter point of connection and 705.12(D)(7) reads:</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><b>Inverter Output Connection.</b><span class="apple-converted-space"> </span>Unless the panelboard is rated not less than the sum of the ampere ratings of all overcurrent devices supplying it, a connection in a panelboard shall be positioned at the opposite (load) end from the input feeder location or main circuit location."</p>
<p class="MsoNormal"> </p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">We are seeing more and more center fed main panels where the main breaker is in the middle of the busbars and there are branch circuit breakers located both above and below the main breaker. The question is whether it is possible to meet the intent of the code if the main breaker is rated the same as the panel. Here is a picture to illustrate:</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"><a href="https://docs.google.com/open?id=0BxRKBvO2EOGudU5KSUJnYnFRYnc">https://docs.google.com/open?id=0BxRKBvO2EOGudU5KSUJnYnFRYnc</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">In this example, is it okay to install our inverter breaker on either the bottom or the top? If not, then our only resort is to either upgrade the service or downsize the main breaker which isn't always possible to do.</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">Thanks for your thoughts in advance.</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">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"> </p></blockquote><p class="MsoNormal"> </p></div></body></html>