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<DIV dir=ltr align=left><SPAN class=578563916-19082010><FONT color=#0000ff
size=2 face=Arial>Good questions, Jason. </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=578563916-19082010><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=578563916-19082010><FONT color=#0000ff
size=2 face=Arial>No. Yes (2008 NEC 690.47(C) & (D)).</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=578563916-19082010><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN><SPAN class=578563916-19082010><FONT
color=#0000ff size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN
class=578563916-19082010>Alternative considerations that might result in a
"maybe": Does the system in question have storage (i.e. batteries)? Is your POCC
on a Delta system? (your hi-rise example says Wye... But if it is directly tied
to a Delta system, you might gotta run back to
basement.)</SPAN></FONT></FONT></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN
class=578563916-19082010></SPAN></FONT></FONT></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN
class=578563916-19082010></SPAN></FONT></FONT></FONT><FONT face=Arial><FONT
size=2><FONT color=#0000ff><SPAN class=578563916-19082010>If you are talking
about a standard, grid-tied, non-backup system, and the AC distribution between
your tie-in and the utility is suitably sized for the PV,
you should hit the GE system where your AC system is getting
it's neutral bond. (Closest steel OK for PV grounding electrode.)
</SPAN></FONT></FONT></FONT><FONT face=Arial><FONT size=2><FONT
color=#0000ff><SPAN class=578563916-19082010>Equipment ground, same thing. Be
sure to run an equipment grounding conductor from the inverter to the array
(i.e. don't just bond the rack to building steel).
</SPAN></FONT></FONT></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN
class=578563916-19082010></SPAN></FONT></FONT></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN
class=578563916-19082010>Regarding your Additional Info
items:</SPAN></FONT></FONT></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN
class=578563916-19082010>1. Yep.</SPAN></FONT></FONT></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN
class=578563916-19082010>2. </SPAN></FONT></FONT></FONT><FONT face=Arial><FONT
size=2><FONT color=#0000ff><SPAN class=578563916-19082010>Some people
on this list and in the AHJ community would argue that the AC side of
the inverter in this case IS a separately derived system in all cases (I'm
not among that bunch). Either way, the output of your entire system is going
thru the building's AC distribution system. ESPECIALLY if you are on the
secondary of a WYE xfrmer, you can and SHOULD source your PV GEC where the
xfrmer neutral is bonded. </SPAN></FONT></FONT></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN
class=578563916-19082010></SPAN></FONT></FONT></FONT><FONT face=Arial><FONT
size=2><FONT color=#0000ff><SPAN class=578563916-19082010>3. You are right. The
various provisions of 690.47(C) allow/require this. In particular,
(C)5 & 6.</SPAN></FONT></FONT></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN
class=578563916-19082010></SPAN></FONT></FONT></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN
class=578563916-19082010>The underlying principle that counts here is, "Get your
GEC where your AC source gets its system ground."
</SPAN></FONT></FONT></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT size=2><FONT color=#0000ff><SPAN
class=578563916-19082010></SPAN></FONT></FONT></FONT><FONT face=Arial><FONT
size=2><FONT color=#0000ff><SPAN
class=578563916-19082010></SPAN></FONT></FONT></FONT><FONT face=Arial><FONT
size=2><FONT color=#0000ff><SPAN
class=578563916-19082010></SPAN></FONT></FONT></FONT> </DIV>
<DIV dir=ltr align=left><STRONG><I><SPAN
style="FONT-FAMILY: 'Monotype Corsiva'; mso-bidi-font-family: Tahoma">Matt <SPAN
class=578563916-19082010>"I'm no building inspector"
</SPAN>Lafferty</SPAN></I></STRONG></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>Jason
Szrom<BR><B>Sent:</B> Thursday, August 19, 2010 7:38 AM<BR><B>To:</B>
re-wrenches@lists.re-wrenches.org<BR><B>Subject:</B> [RE-wrenches] PV GEC to the
same point as the utility service GEC?<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=WordSection1>
<P class=MsoNormal>Wrenches,<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>Questions: Does the PV GEC have to be bonded to the
ground electrode system at the same point as the utility service equipment GEC?
Is there a code section to back this up?<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>Additional info:<o:p></o:p></P>
<P style="TEXT-INDENT: -0.25in; mso-list: l0 level1 lfo1"
class=MsoListParagraph><![if !supportLists]><SPAN
style="mso-list: Ignore">1.<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN><![endif]>The DC side of the inverter is a separately derived
system and therefore needs a GEC to a ground electrode.<o:p></o:p></P>
<P style="TEXT-INDENT: -0.25in; mso-list: l0 level1 lfo1"
class=MsoListParagraph><![if !supportLists]><SPAN
style="mso-list: Ignore">2.<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN><![endif]>The AC side of the inverter is not a separately derived
system therefore 250.30(A)(7) does not apply. This section states that AC
separately derived systems should be grounded to the nearest ground electrode
(building steel in many cases) and therefore does not need to be bonded to the
same point as the utility service GEC.<o:p></o:p></P>
<P style="TEXT-INDENT: -0.25in; mso-list: l0 level1 lfo1"
class=MsoListParagraph><![if !supportLists]><SPAN
style="mso-list: Ignore">3.<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN><![endif]>My thought process is this: The PV GEC can be
bonded to the nearest ground electrode as long as this electrode is tied to the
same ground electrode as the utility service electrode, forming one complete
‘ground electrode system’. My opinion is that this setup is analogous to this
example which is regularly seen in the field. High rise building with
structural steel bonded to water main with utility service GEC bonded as well.
Delta-wye step-down transformer on an upper level with the derived neutral on
the secondary bonded to closest building steel. Yet there is still an equipment
grounding connection to both the primary and secondary sides of the transformer.
This implies that it is OK and even preferable to tie the PV GEC to the nearest
ground electrode, but I can’t find any evidence or section in the code
that confirms or denies this.<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>Thanks for any input,<o:p></o:p></P>
<P class=MsoNormal>Jason<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal><B><SPAN style="COLOR: #244061; FONT-SIZE: 12pt">Jason M.
Szrom, PE<o:p></o:p></SPAN></B></P>
<P class=MsoNormal><SPAN
style="COLOR: #244061; FONT-SIZE: 12pt">Engineer<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="COLOR: #244061; FONT-SIZE: 12pt"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: #244061">Solar Energy Systems,
LLC<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: #244061">1205 Manhattan
Ave<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: #244061">Suite 1210<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: #244061">Brooklyn, NY
11222<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: #244061"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: #244061">718-389-1545
x13<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Verdana','sans-serif'; COLOR: #244061; FONT-SIZE: 10pt"><A
href="http://www.solaresystems.com/"><SPAN
style="COLOR: #244061">www.solarEsystems.com</SPAN></A></SPAN><SPAN
style="COLOR: #244061; FONT-SIZE: 10pt"><o:p></o:p></SPAN></P>
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