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Per 705.12(D) the sub-panel could be any distribution equipment on the
premises. So the question becomes: is the sub-panel capable of
supplying branch circuits or feeder loads? If yes, then the sum of the
breakers (potentially) feeding the bus is 180 amps so a 150-amp rating
is required and the inverters would have to feed the opposite end of
the bus bars. If no, the code is not clear on the requirement, but
obviously the 80-amp breaker in the main panel limits the maximum
current flowing through the sub-panel. <br>
<br>
Kent Osterberg<br>
Blue Mountain Solar<br>
<br>
<br>
<br>
Al Frishman wrote:
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<p class="MsoNormal">Hi Wrenchers,<o:p></o:p></p>
<p class="MsoNormal">When using a sub-panel for the sole purpose of
combining the output of multiple single phase inverters does NEC 690.64
(B) (2) apply? I know that this topic has been discussed but I am
still not clear.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The “Can we Land” Article pg 11 Diagram 2b shows
that using a Subpanel eliminates the problem of exceeding the 120% rule
illustrated in diagram 2a but it does not show the rating of the
sub-panel. In the example it shows 3 Fronius 7500W single phase
inverters landing in a sub-panel and then the 3-phase sub-panel grid
connected to a 80A 3-phase breaker in a 400A main panel. What is the
minimum Amp rating required for the 3-phase Sub-panel in diagram 2b?
Do we only need to size it for the OCP for the combined outputs of the
3 inverters (80A) or do the three 50A two-pole breakers need to be
considered? <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">For easy reference here is a link to the
article: <a moz-do-not-send="true"
href="http://www.spgsolar.com/wp-content/uploads/2010/05/SPGLeBlancYates.pdf">http://www.spgsolar.com/wp-content/uploads/2010/05/SPGLeBlancYates.pdf</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">All feedback is appreciated.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><i><span
style="font-size: 10.5pt; font-family: "Helvetica","sans-serif"; color: black;">Al
Frishman</span></i><span
style="font-size: 13.5pt; font-family: "Helvetica","sans-serif"; color: black;"><br>
</span><span
style="font-size: 13.5pt; font-family: "'Microsoft Sans Serif'"; color: rgb(3, 1, 0);">Aeon</span><span
style="font-size: 13.5pt; font-family: "'Microsoft Sans Serif'"; color: rgb(255, 151, 0);">Solar</span><span
style="font-size: 13.5pt; font-family: "Helvetica","sans-serif"; color: black;"><o:p></o:p></span></p>
<p class="MsoNormal"><i><span
style="font-size: 10.5pt; font-family: "Helvetica","sans-serif"; color: black;">(917)
699-6641 - cell</span></i><span
style="font-size: 10.5pt; font-family: "Helvetica","sans-serif"; color: black;"><br>
</span><i><span
style="font-size: 10.5pt; font-family: "Helvetica","sans-serif"; color: black;">(888)
460-2867</span></i><span
style="font-size: 10.5pt; font-family: "Helvetica","sans-serif"; color: black;"><br>
</span><i><span
style="font-size: 10.5pt; font-family: "Helvetica","sans-serif"; color: black;"><a
moz-do-not-send="true" href="http://www.aeonsolar.com/"><span
style="color: blue;">www.aeonsolar.com</span></a></span></i><span
style="font-size: 13.5pt; font-family: "Helvetica","sans-serif"; color: black;"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-align: center;" align="center"><i><span
style="font-size: 14pt;"><o:p> </o:p></span></i></p>
<p class="MsoNormal"><o:p> </o:p></p>
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