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As a note, supply side connections have an extra complication with
battery backup systems. With a regular GT inverter you're just
pushing current into that interconnection point and you can work out
easily that you won't have any overcurrent issues unless you made a
big mistake and your inverter output exceeds the rating of your
service conductors. However, with a battery system you're also
potentially pulling current from that point. Before the battery
inverter is installed your main breaker protects your service
conductors, but if the inverter is pulling in 60A and the main
breaker is also operating near its capacity, you could have >240A
running over 200A service conductors with no breakers tripping. You
would overwhelm the capacity of the service [230.23(A)] and no
breakers would trip. You could fix this by replacing your service
conductors back to the transformer (I'm just saying that it's an
option) or downsizing the main breaker, and at that point you're
probably better off just making it a load side connection. I'd go
load side and argue with the AHJ to use the 2011 update mentioned
earlier.<br>
<br>
Dave<br>
<br>
<div class="moz-cite-prefix">On 2013/2/28 9:55, Garrison Riegel
wrote:<br>
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<p class="MsoNormal"><span style="color:#1F497D">Allen,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">The benefit I
see would be to allow for a code compliant load side
connection on a 200A panel with a 200A MB, where the AHJ is
on the 2008 NEC or older and will not listen to your good
logic. I don’t think this would always be the best option,
but if backup loads and inverter output were less than 32A
then a 40A OCPD in the main panel should be fine? Since it
sounds like the 60A breaker in the main panel is not a
safety issue, but a design consideration, I suppose I would
just prefer flexibility when possible.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">That said, this
AHJ is on the 2008, and the loads will be less than 30A, but
based on this conversation I plan to go with a 60A and try
to convince the AHJ that it will be code compliant in their
future!<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Garrison<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></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 class="moz-txt-link-abbreviated" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>
[<a class="moz-txt-link-freetext" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">mailto:re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On
Behalf Of </b>Allan Sindelar<br>
<b>Sent:</b> Thursday, February 28, 2013 8:14 AM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] Conductor Sizing for
Supply Side Connection<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal" style="margin-bottom:12.0pt">Garrison,<br>
I don't know why it's not listed as 60A max, but my own
internal logic would ask why it should be. The only benefit
I could see for using smaller than a 60A breaker would be to
allow use of #8 conductors (allowed with a 40A or 50A
breaker) instead of the #6 necessary with a 60A breaker. And
of course, you could use a 40A breaker with #6 conductors,
so theoretically it would be fine. I just fail to see any
benefit to doing so.<br>
Allan<o:p></o:p></p>
<div>
<p class="MsoNormal"><b>Allan Sindelar</b><br>
<span style="font-size:10.0pt"><a moz-do-not-send="true"
href="mailto:Allan@positiveenergysolar.com"><span
style="color:#000099">Allan@positiveenergysolar.com</span></a></span><br>
<span style="font-size:10.0pt">NABCEP Certified
Photovoltaic Installer<br>
NABCEP Certified Technical Sales Professional<br>
New Mexico EE98J Journeyman Electrician<br>
Founder and Chief Technology Officer<br>
<b>Positive Energy, Inc.</b><br>
3209 Richards Lane (note new address)<br>
Santa Fe, New Mexico 87507<br>
<b>505 424-1112</b><br>
<a moz-do-not-send="true"
href="http://www.positiveenergysolar.com/"
target="_blank">www.positiveenergysolar.com</a></span>
<o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;margin-right:722.25pt;mso-margin-bottom-alt:auto"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<p class="MsoNormal">On 2/28/2013 6:27 AM, Garrison Riegel
wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span style="color:#1F497D">Thanks Allen
for clarifying why a 60A is required. I was wondering.
The spec does list a surge current of 9000W so I thought
that may be the rationale, but even that would only
require a 50A, and since this surge occurs during
‘stand-alone mode’ it didn’t seem to apply to the OCPD at
the main panel. Your explanation makes more sense, but I
wonder why then they don’t list the AC input breaker size
as 60A <i>max</i>. If you have few backup loads, and are
not on the 2011 NEC, a 40A could theoretically be fine?</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Thanks all
for your thoughts, much appreciated.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Garrison</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></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 moz-do-not-send="true"
href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>
[<a moz-do-not-send="true"
href="mailto:re-wrenches-bounces@lists.re-wrenches.org">mailto:re-wrenches-bounces@lists.re-wrenches.org</a>]
<b>On Behalf Of </b>Allan Sindelar<br>
<b>Sent:</b> Wednesday, February 27, 2013 6:08 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] Conductor Sizing for
Supply Side Connection</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<div>
<p class="MsoNormal" style="margin-bottom:12.0pt">August,<br>
The 60A breaker is intended to allow grid power to pass
through to the loads in excess of the inverter's
stand-alone output. The point of 705.12 (moved in the 2011
NEC from 690.64 (B)(2)) is to differentiate between load
pass-through current and sell current. The amount of
current fed into the grid is (4500/230 =) 19.56A, while
the amount that can be taken from the grid and passed
through to the load is much greater. If you were limited
to a 40A breaker in order to maintain 120% of a 200A main
bus, you'd be prone to nuisance trips under large
cumulative loads.<br>
<br>
Allan<o:p></o:p></p>
<div>
<p class="MsoNormal"><b>Allan Sindelar</b><br>
<span style="font-size:10.0pt"><a moz-do-not-send="true"
href="mailto:Allan@positiveenergysolar.com"><span
style="color:#000099">Allan@positiveenergysolar.com</span></a></span><br>
<span style="font-size:10.0pt">NABCEP Certified
Photovoltaic Installer<br>
NABCEP Certified Technical Sales Professional<br>
New Mexico EE98J Journeyman Electrician<br>
Founder and Chief Technology Officer<br>
<b>Positive Energy, Inc.</b><br>
3209 Richards Lane (note new address)<br>
Santa Fe, New Mexico 87507<br>
<b>505 424-1112</b><br>
<a moz-do-not-send="true"
href="http://www.positiveenergysolar.com/"
target="_blank">www.positiveenergysolar.com</a></span>
<o:p></o:p></p>
<p class="MsoNormal"
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