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<div class="moz-cite-prefix">HI Chris;<br>
<br>
Just to be clear, the cables are not going to fail just because
they aren't code compliant; unless you meant they would fail an
inspection. I've included a picture of my own service rated at
150 amps. Using table 310.15(B)7 (which I believe is the correct
table for sizing the service conductors, not 310.B16 or 17), My
side is 2/0 aluminum, but the utility side is #4 aluminum. The
utility is not held to NEC requirements, but a fire isn't starting
just because they're grossly undersized by NEC standards. NEC has
huge safety factors, which are appropriate for wires hidden in
walls that are expected to last the life of the house.<br>
Finally, to be code compliant with a supply side 60 A connection,
I believe the service conductors would need to be 3/0 Cu or 250
MCM Aluminum. That would correspond to a 225 A service (x 120%)
or 270 amps, leaving 5 amps to spare. As Dave mentioned,
replacing the service conductors would probably not be a
reasonable option. Downsizing the main breaker to 175 A, would
also work (175 + 60 < 200 x 120%) and since some of the loads
are being transferred to the 60A breaker, downsizing the main
should be compliant.<br>
<br>
<br>
<pre class="moz-signature" cols="72">R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified, Licensed Contractor
808 269-7491</pre>
On 3/9/2013 8:17 AM, Christopher Warfel wrote:<br>
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<font size="-1">Had a couple of minutes here, so with the load
side connection, the 200 amp breaker would operate to protect
all conductors. With a supply side connection, the battery
charger could be pulling 60 amps, the main panel 200, and the
service conductors sized for 240 amps would fail. 2/0 in f</font><small>ree
air is rated for 265A T310.15(B)(17), but would you say that
T310.(B)(16)</small> <small>applies for service conductors and
then 2/0 is 175?</small><br>
<br>
<small>I am really starting to hate solar. </small><br>
<div class="moz-cite-prefix">On 2/28/2013 10:21 AM, Dave Click
wrote:<br>
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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 moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>
[<a moz-do-not-send="true"
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>
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<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 </span><o:p></o:p> </p>
<blockquote
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<pre> <o:p></o:p></pre>
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