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<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011>Larry,</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011>There are alot of ways to skin that
cat.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011>Here is what I am doing on my job.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011>I have a 400A main disconnect with a feeder running
directly to a 400 ATS then to a 400A main lug dedicated load center under the
switch. All conductors are double - 250 mcm.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011>I am going to tap the feeder on the line side, inside
the ATS cabinet, using a ten foot feeder tap of #3 running to a new 100A breaker
enclosure with an 80A breaker. From there I will go to a new 150A main lug load
center with 95A worth of PV backfeed breakers.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011>I really am enjoying this one because it brings up so
many interesting Code quandaries.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011>In my mind I am extending the premise wiring and
interconnecting at the new load center which is on the line side of the ATS.
Some folks might take issue with this, arguing that the "PV" circuit begins at
the tap in the ATS and as such is not at a dedicated OCPD. Some folks have
argued that feeder tap rules themselve do not apply to PV circuits. In any case,
the new 150A load center is not dedicated solely to backfeeding the PV, there
are other loads connected there. This is why I see it as an extension of the
premise wiring and as the point of interconnect of the PV
circuit.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011>Interestingly enough, in order to follow NEC 2008, I
will have to place the PV backfeed breakers at the bottom of the new 150A load
center.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011>But here is where it gets interesting. Taking the ATS
out of the picture for a moment, the existing 400A main lug load center is now
feed with through the main lug with a total of 480A of supply breakers. This
complies with NEC 2008 vis-a-vis the 120% allowance for conductors and busbars.
In this case it does sort of make it seem silly to go through the trouble of
putting the backfeed breakers on the bottom of the 150A load center. Especially
when thinking back, the whole idea of putting the breaker at the bottom of the
load center was that you could then have PV backfeed equal to the full rating of
load center busbar. Funny how things work out.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2 face=Arial><SPAN
class=546440715-27032011>Anyway, the real question comes up when we bring the
ATS back into the picture. The 400A ATS will see the same 480A of supply
breakers as the conductors and busbar of the 400A load center. Here is where I
am taking leap of faith that the AHJ will agree with me that the same 120%
allowance given to the conductors and load center will be given to ATS
itself.</SPAN></FONT></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/"><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>wirewiz@gmail.com<BR><B>Sent:</B> Sunday, March 27, 2011 7:11
AM<BR><B>To:</B> RE-wrenches<BR><B>Subject:</B> Re: [RE-wrenches] Generator and
Enphase<BR></FONT><BR></DIV>
<DIV></DIV>Kent, Jason, or anyone else
<DIV><BR></DIV>
<DIV>Would you a have a simple one-line you could share for wiring the inverter
on the utility side of the transfer switch? </DIV>
<DIV><BR></DIV>
<DIV>Thank you.</DIV>
<DIV><BR>
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<DIV
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<DIV>Larry Liesner</DIV>
<DIV>Wirewiz</DIV>
<DIV>Westport, CT</DIV>
<DIV>Phone: 203-644-2404</DIV>
<DIV>Fax: 203-557-0556</DIV>
<DIV><A href="mailto:wirewiz@gmail.com">wirewiz@gmail.com</A></DIV>
<DIV><A href="http://www.wire-wiz.com">www.wire-wiz.com</A></DIV>
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