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<div class="moz-cite-prefix">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>
<pre class="moz-signature" cols="72">Kent Osterberg
Blue Mountain Solar, Inc.
<a class="moz-txt-link-abbreviated" href="http://www.bluemountainsolar.com">www.bluemountainsolar.com</a>
</pre>
On 10/15/2012 9:32 AM, August Goers wrote:<br>
</div>
<blockquote
cite="mid:147c5bb8d949a8ed429698f7ecffce43@mail.gmail.com"
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<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><span
style="color:black">Inverter Output Connection.</span></b><span
class="apple-converted-space"><span style="color:black"> </span></span><span
style="color:black">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."</span></p>
<p class="MsoNormal"><span style="color:black"> </span></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
moz-do-not-send="true"
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
moz-do-not-send="true" 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>
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