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<DIV dir=ltr align=left><SPAN class=218162420-30032011><FONT color=#0000ff
size=2 face=Arial>Right, so going totally on the fly at the white board, let's
say we have an inverter with a 45A AC output, it see's the short and pours it's
little heart out at 45A for 0.1 sec before shutting out, delivering 4.5 A-sec of
energy into the fault. Meanwhile we take out a clearing time curve
for the generic 60A breaker that the inverter would be backfeed at the
other end of the feeder. It will deliver 10 times it's rating or 600A for 0.5
secs before clearing. That's 300 A-sec of energy, 66 times more than the
inverter.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=218162420-30032011><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=218162420-30032011><FONT color=#0000ff
size=2 face=Arial>So can we say that when looking at sizing the AC side of these
inverters we need more to concern ourselves with continuous overload
conditions and not so much with short-circuit/ground fault
conditions?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=218162420-30032011></SPAN> <BR><SPAN
lang=en-us><FONT size=2 face=Arial>Mark Frye</FONT></SPAN> <BR><SPAN
lang=en-us><FONT size=2 face=Arial>Berkeley Solar Electric Systems</FONT></SPAN>
<BR><SPAN lang=en-us><FONT size=2 face=Arial>303 Redbud Way</FONT></SPAN>
<BR><SPAN lang=en-us><FONT size=2 face=Arial>Nevada City, CA
95959</FONT></SPAN> <BR><SPAN lang=en-us><FONT size=2 face=Arial>(530)
401-8024</FONT></SPAN> <BR><SPAN lang=en-us></SPAN><A
href="http://www.berkeleysolar.com/"><SPAN lang=en-us><U><FONT color=#0000ff
size=2 face=Arial>www.berkeleysolar.com</FONT></U></SPAN></A><SPAN
lang=en-us><FONT size=2 face=Arial> </FONT></SPAN> </DIV>
<DIV> </DIV><BR>
<DIV dir=ltr lang=en-us class=OutlookMessageHeader align=left>
<HR tabIndex=-1>
<FONT size=2 face=Tahoma><B>From:</B> re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <B>On Behalf Of
</B>Exeltech<BR><B>Sent:</B> Wednesday, March 30, 2011 12:04 PM<BR><B>To:</B>
RE-wrenches<BR><B>Subject:</B> Re: [RE-wrenches] sizing a sub-panel used
tocombinemultipleinverter outputs<BR></FONT><BR></DIV>
<DIV></DIV>
<TABLE border=0 cellSpacing=0 cellPadding=0>
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<TR>
<TD vAlign=top>Per your question:<BR><BR><SPAN
class=yiv1283215088828221817-30032011><FONT color=#0000ff size=2
face=Arial>> 1 - What does a UL1741 inverter do when it is
connected<BR>> to a line that is experiencing a short-circuit or ground
fault?<BR></FONT></SPAN><BR>Presuming a hard short, the voltage in that
circuit would be essentially zero, and a UL1741 compliant inverter would
cease producing power in less than 0.1 second.<BR><BR><BR>Dan<BR>Sr.
Engineer<BR>Exeltech<BR><BR><BR><BR><BR><BR><BR><BR><BR>--- On <B>Wed,
3/30/11, Mark Frye <I><markf@berkeleysolar.com></I></B> wrote:<BR>
<BLOCKQUOTE
style="BORDER-LEFT: rgb(16,16,255) 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px"><BR>From:
Mark Frye <markf@berkeleysolar.com><BR>Subject: Re: [RE-wrenches]
sizing a sub-panel used tocombine multipleinverter outputs<BR>To:
"'RE-wrenches'" <re-wrenches@lists.re-wrenches.org><BR>Date:
Wednesday, March 30, 2011, 12:37 PM<BR><BR>
<DIV id=yiv1283215088>
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<DIV dir=ltr align=left><SPAN
class=yiv1283215088828221817-30032011><FONT color=#0000ff size=2
face=Arial>That is a really good question Brian.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN
class=yiv1283215088828221817-30032011><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN
class=yiv1283215088828221817-30032011><FONT color=#0000ff size=2
face=Arial>Mostly when thinking about these sizing issues I think about
overload conditions and not so much about short-circuit and ground fault
conditions.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN
class=yiv1283215088828221817-30032011><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN
class=yiv1283215088828221817-30032011><FONT color=#0000ff size=2
face=Arial>So two questions come up:</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN
class=yiv1283215088828221817-30032011><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN
class=yiv1283215088828221817-30032011><FONT color=#0000ff size=2
face=Arial>1 - What does a UL1741 inverter do when it is connected to a
line that is experiencing a short-circuit or ground
fault?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN
class=yiv1283215088828221817-30032011><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN
class=yiv1283215088828221817-30032011><FONT color=#0000ff size=2
face=Arial>2 - What does the feeder breaker do when it is connected to a
line that is experiencing a short-circuit or ground
fault?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN
class=yiv1283215088828221817-30032011><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN
class=yiv1283215088828221817-30032011><FONT color=#0000ff size=2
face=Arial>As far as number two, thanks to all the great work we do
establishing low impedence fault paths back to circuirt protectors, the
breaker is going to trip at it's rating and protect the wire at the same
rating. But that doesn't mean that the conductor won't see more
than rated amps during the fault. It will see alot more than
for a very short time. During this very short time frame, the actual
currents flowing into the fault from the utility side of the equation
far far exceed the currents contributed by the power limited inverter
side.</FONT></SPAN></DIV>
<DIV><BR><SPAN lang=en-us><FONT size=2 face=Arial>Mark
Frye</FONT></SPAN> <BR><SPAN lang=en-us><FONT size=2 face=Arial>Berkeley
Solar Electric Systems</FONT></SPAN> <BR><SPAN lang=en-us><FONT size=2
face=Arial>303 Redbud Way</FONT></SPAN> <BR><SPAN lang=en-us><FONT
size=2 face=Arial>Nevada City, CA 95959</FONT></SPAN> <BR><SPAN
lang=en-us><FONT size=2 face=Arial>(530) 401-8024</FONT></SPAN>
<BR><SPAN lang=en-us></SPAN><A href="http://www.berkeleysolar.com/"
rel=nofollow target=_blank><SPAN lang=en-us><U><FONT color=#0000ff
size=2 face=Arial>www.berkeleysolar.com</FONT></U></SPAN></A><SPAN
lang=en-us><FONT size=2 face=Arial> </FONT></SPAN> </DIV>
<DIV> </DIV><BR>
<DIV dir=ltr lang=en-us class=yiv1283215088OutlookMessageHeader
align=left>
<HR tabIndex=-1>
<FONT size=2 face=Tahoma><B>From:</B>
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <B>On Behalf Of
</B>Brian Teitelbaum<BR><B>Sent:</B> Wednesday, March 30, 2011 10:02
AM<BR><B>To:</B> RE-wrenches<BR><B>Subject:</B> Re: [RE-wrenches] sizing
a sub-panel used tocombine multipleinverter outputs<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=yiv1283215088WordSection1>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">Wouldn’t
a fault in that conductor between the main and the sub have a potential
for up to 160A of current? I would think that at noon on a sunny day,
the inverter system could produce 80A from one direction (albeit really
only the max amperage outputs of the inverters) and 80A of grid current
from the main into a partial fault.</SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt"></SPAN> </P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">Brian
Teitelbaum</SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">AEE
Solar </SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt"></SPAN> </P>
<DIV>
<DIV
style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; PADDING-BOTTOM: 0in; PADDING-LEFT: 0in; PADDING-RIGHT: 0in; BORDER-TOP: rgb(181,196,223) 1pt solid; BORDER-RIGHT: medium none; PADDING-TOP: 3pt">
<P class=yiv1283215088MsoNormal><B><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">From:</SPAN></B><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <B>On Behalf Of
</B>Mark Frye<BR><B>Sent:</B> Wednesday, March 30, 2011 9:49
AM<BR><B>To:</B> 'RE-wrenches'<BR><B>Subject:</B> Re: [RE-wrenches]
sizing a sub-panel used to combine multipleinverter
outputs</SPAN></P></DIV></DIV>
<P class=yiv1283215088MsoNormal> </P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: blue; FONT-SIZE: 10pt">Al,</SPAN><SPAN
style="COLOR: windowtext"></SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="COLOR: windowtext"></SPAN> </P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: blue; FONT-SIZE: 10pt">I would
say that yes the meter is a load and this goes to show the relative
inadequacy of the vocabulary we are using in the discussion. In the
example we have been using with the 80A breaker, wire and sub panel, you
could have up to 80A of loads installed in the sub and still not create
an over current condition in any of that equipment.</SPAN><SPAN
style="COLOR: windowtext"></SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="COLOR: windowtext"><BR></SPAN><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">Mark
Frye</SPAN><SPAN style="COLOR: windowtext"> <BR></SPAN><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">Berkeley
Solar Electric Systems</SPAN><SPAN style="COLOR: windowtext">
<BR></SPAN><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">303
Redbud Way</SPAN><SPAN style="COLOR: windowtext"> <BR></SPAN><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">Nevada
City, CA 95959</SPAN><SPAN style="COLOR: windowtext">
<BR></SPAN><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">(530)
401-8024</SPAN><SPAN style="COLOR: windowtext"> <BR><A
href="http://www.berkeleysolar.com/" rel=nofollow target=_blank><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">www.berkeleysolar.com</SPAN></A></SPAN><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt"> </SPAN><SPAN
style="COLOR: windowtext"> </SPAN></P>
<DIV>
<P class=yiv1283215088MsoNormal><SPAN
style="COLOR: windowtext"></SPAN> </P></DIV>
<P class=yiv1283215088MsoNormal><SPAN
style="COLOR: windowtext"></SPAN> </P>
<DIV style="TEXT-ALIGN: center" class=yiv1283215088MsoNormal
align=center><SPAN style="COLOR: windowtext">
<HR align=center SIZE=2 width="100%">
</SPAN></DIV>
<P style="MARGIN-BOTTOM: 12pt" class=yiv1283215088MsoNormal><B><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">From:</SPAN></B><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <B>On Behalf Of
</B>Al Frishman<BR><B>Sent:</B> Wednesday, March 30, 2011 9:00
AM<BR><B>To:</B> 'RE-wrenches'<BR><B>Subject:</B> Re: [RE-wrenches]
sizing a sub-panel used to combine multipleinverter outputs</SPAN><SPAN
style="COLOR: windowtext"></SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">Is
a monitoring system installed in the Load Center to measure the
cumulative kWh’s of the inverter’s considered a load? </SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">The
type of monitoring device I am talking about has CT’s that go around the
conductors and the Voltage ref is taken by attaching conductors to each
phase, the Neutral and the ground bar. The digital
Meter has a 3-pole 5A breaker in it so the conductors in the load center
can be connected to lugs on the bus bar directly.</SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt"></SPAN> </P>
<DIV>
<P class=yiv1283215088MsoNormal><I><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10.5pt">Al
Frishman</SPAN></I><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 13.5pt"><BR></SPAN><SPAN>Aeon</SPAN><SPAN>Solar</SPAN><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 13.5pt"></SPAN></P>
<P class=yiv1283215088MsoNormal><I><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10.5pt">(917) 699-6641 -
cell</SPAN></I><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10.5pt"><BR><I>(888)
460-2867</I><BR><I><A href="http://www.aeonsolar.com/" rel=nofollow
target=_blank>www.aeonsolar.com</A></I></SPAN><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 13.5pt"></SPAN></P>
<P style="TEXT-ALIGN: center" class=yiv1283215088MsoNormal
align=center><I><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 14pt"></SPAN></I> </P></DIV>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt"></SPAN> </P>
<DIV>
<DIV
style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; PADDING-BOTTOM: 0in; PADDING-LEFT: 0in; PADDING-RIGHT: 0in; BORDER-TOP: rgb(181,196,223) 1pt solid; BORDER-RIGHT: medium none; PADDING-TOP: 3pt">
<P class=yiv1283215088MsoNormal><B><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">From:</SPAN></B><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <B>On Behalf Of
</B>Jason Szumlanski<BR><B>Sent:</B> Wednesday, March 30, 2011 8:18
AM<BR><B>To:</B> RE-wrenches<BR><B>Subject:</B> Re: [RE-wrenches] sizing
a sub-panel used to combinemultipleinverter
outputs</SPAN></P></DIV></DIV>
<P class=yiv1283215088MsoNormal> </P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">Another
key is to remember that this discussion also applies to the conductor
between the main panel and subpanel. In a large PV system, this could
result in a pretty large wire between the two panels, and a significant
cost that is often overlooked. In some cases it makes sense to locate
the subpanel close to the main panel and run multiple sets of smaller
wires from the inverters to the subpanel.</SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt"></SPAN> </P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">And
because the calculation is based on the first OC protection connected to
the inverters, adding a main breaker (theoretically 80A in this example)
in the subpanel doesn’t change things. Even though this wire would be
theoretically protected by an 80A breaker at each end, you can’t size
the wire for 160A / 1.2 = 133.3A. You have to size for 180A/1.2 = 150A.
(not that it makes much of a difference in this example, but it still
must be considered)</SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt"></SPAN> </P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">At
least that’s how I understand it…</SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt"></SPAN> </P>
<DIV>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125)">Jason
Szumlanski</SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt">Fafco
Solar</SPAN><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 4pt">
</SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt"></SPAN> </P></DIV>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: rgb(31,73,125); FONT-SIZE: 11pt"></SPAN> </P>
<DIV>
<DIV
style="BORDER-BOTTOM: medium none; BORDER-LEFT: medium none; PADDING-BOTTOM: 0in; PADDING-LEFT: 0in; PADDING-RIGHT: 0in; BORDER-TOP: rgb(181,196,223) 1pt solid; BORDER-RIGHT: medium none; PADDING-TOP: 3pt">
<P class=yiv1283215088MsoNormal><B><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">From:</SPAN></B><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <B>On Behalf Of
</B>Mark Frye<BR><B>Sent:</B> Wednesday, March 30, 2011 1:33
AM<BR><B>To:</B> 'RE-wrenches'<BR><B>Subject:</B> Re: [RE-wrenches]
sizing a sub-panel used to combinemultipleinverter
outputs</SPAN></P></DIV></DIV>
<P class=yiv1283215088MsoNormal> </P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: blue; FONT-SIZE: 10pt">Opps!</SPAN></P>
<P class=yiv1283215088MsoNormal> </P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: blue; FONT-SIZE: 10pt">My bad,
I was thinking of a single phase system, not the three phase
system shown in the article.</SPAN></P>
<P class=yiv1283215088MsoNormal> </P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: blue; FONT-SIZE: 10pt">For the
three phase system Kent is correct in counting 180A of supply per
bar.</SPAN></P>
<P class=yiv1283215088MsoNormal> </P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">Mark Frye</SPAN>
<BR><SPAN style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">Berkeley
Solar Electric Systems</SPAN> <BR><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">303 Redbud Way</SPAN>
<BR><SPAN style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">Nevada
City, CA 95959</SPAN> <BR><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">(530) 401-8024</SPAN>
<BR><A href="http://www.berkeleysolar.com/" rel=nofollow
target=_blank><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">www.berkeleysolar.com</SPAN></A><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt"> </SPAN> </P>
<DIV>
<P class=yiv1283215088MsoNormal> </P></DIV>
<P class=yiv1283215088MsoNormal> </P>
<DIV style="TEXT-ALIGN: center" class=yiv1283215088MsoNormal
align=center>
<HR align=center SIZE=2 width="100%">
</DIV>
<P style="MARGIN-BOTTOM: 12pt" class=yiv1283215088MsoNormal><B><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">From:</SPAN></B><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <B>On Behalf Of
</B>Mark Frye<BR><B>Sent:</B> Tuesday, March 29, 2011 10:17
PM<BR><B>To:</B> 'RE-wrenches'<BR><B>Subject:</B> Re: [RE-wrenches]
sizing a sub-panel used to combine multipleinverter outputs</SPAN></P>
<P class=yiv1283215088MsoNormal><SPAN
style="FONT-FAMILY: 'sans-serif'; COLOR: blue; FONT-SIZE: 10pt">I think
Kent and I agree. For the case where the subpanel is not dedicated
a PV sub-panel he is calculating for 2 - 50A breakers and I calculated
for 3 - 50A breakers.</SPAN></P>
<P class=yiv1283215088MsoNormal><BR><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">Mark Frye</SPAN>
<BR><SPAN style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">Berkeley
Solar Electric Systems</SPAN> <BR><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">303 Redbud Way</SPAN>
<BR><SPAN style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">Nevada
City, CA 95959</SPAN> <BR><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">(530) 401-8024</SPAN>
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<P style="MARGIN-BOTTOM: 12pt" class=yiv1283215088MsoNormal><B><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">From:</SPAN></B><SPAN
style="FONT-FAMILY: 'sans-serif'; FONT-SIZE: 10pt">
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <B>On Behalf Of
</B>Kent Osterberg<BR><B>Sent:</B> Tuesday, March 29, 2011 9:26
PM<BR><B>To:</B> RE-wrenches<BR><B>Subject:</B> Re: [RE-wrenches] sizing
a sub-panel used to combine multiple inverter outputs</SPAN></P>
<P style="MARGIN-BOTTOM: 12pt" class=yiv1283215088MsoNormal>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</P></DIV></DIV><BR>-----Inline Attachment Follows-----<BR><BR>
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