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<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2>Ray and Matt,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2>Thanks for sharing your perspective on the EGC and GEC
requirements. I share Ray's distaste for creating ground loops with redundant
GECs, and I'm thankful for 690.47(C)(3), particularly the last
sentence:</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2>"A single conductor shall be permitted to be used to
perform the multiple functions of dc grounding, ac grounding, and bonding
between ac and dc systems."</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2>In the draft of the 2011 NEC, there is completely new
wording for 690.47(C). I find it to be more understandable than the 2008 code,
and I recommend checking it out:</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2><A
href="http://www.solarabcs.com/index.php?option=com_docman&task=doc_download&gid=248&&Itemid=72">http://www.solarabcs.com/index.php?option=com_docman&task=doc_download&gid=248&&Itemid=72</A></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2>As for 690.47(D)... I just can't stop hating this one. I
was dismayed to find that it made it into the 2011 NEC without
changes. Is there any purpose for 690.47(D) other than enhanced protection
from direct lightning strikes? If so, and you're installing in an area where
direct lightning strikes are a problem, shouldn't you be installing a proper
lightning protection system per NFPA 780? As far as I can tell, the main
practical consequence from implementation of 690.47(D) is that you're almost
guaranteed to set up a big ground loop that will suffer induced currents from
nearby lightning strikes. Please, somebody justify the existence of 690.47(D),
particularly for those of us that live in areas where lightning is rare, so I
can stop hating it.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2>Regards,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2>-Hans</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=616290121-24082010><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV><FONT face=Arial color=#0000ff
size=2></FONT><FONT face=Arial color=#0000ff size=2></FONT><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <B>On Behalf Of </B>R Ray
Walters<BR><B>Sent:</B> Monday, August 23, 2010 1:55 PM<BR><B>To:</B>
RE-wrenches<BR><B>Subject:</B> Re: [RE-wrenches] PV GEC to the same point as
theutilityservice GEC?<BR></FONT><BR></DIV>
<DIV></DIV>I think the issue is that some installers are wanting the
supplementary electrode for the array tied to the building grounding system in
two places. I saw this in BIll Brooks seminar too, but then he said it wasn't
necessary. Basically the EGC system already ties both electrodes together as
required, and a 2nd conductor directly between the two electrodes can create a
lightning loop.
<DIV>If the electrodes would be close together, you can actually drop the array
electrode, and tie straight to the building electrode. But if it is on the other
side of the building for instance, some have run 2 conductors, 1) the already
required EGC through the AC conduit, and then 2) a separate GEC on the outside
of the building that connects the electrodes a 2nd time. </DIV>
<DIV><BR></DIV>
<DIV>This would be the same logic as bonding your electrode of your house to
your neighbor's house: it's not necessary ( they're already bonded through the
services) and it can cause trouble, especially with lightning.</DIV>
<DIV>Even my new ground impedance tester only works, if each grounding electrode
is bonded once (and only once) to the rest of the grounding system. </DIV>
<DIV>It's a key point of lighting protection in multiple electrode grounding
systems too: never create loops in your grounding system. </DIV>
<DIV><BR>
<DIV><SPAN class=Apple-style-span
style="WORD-SPACING: 0px; FONT: 12px Helvetica; TEXT-TRANSFORM: none; COLOR: rgb(0,0,0); TEXT-INDENT: 0px; WHITE-SPACE: normal; LETTER-SPACING: normal; BORDER-COLLAPSE: separate; border-spacing: 0px 0px; -khtml-text-decorations-in-effect: none; -apple-text-size-adjust: auto; orphans: 2; widows: 2">
<DIV>R. Walters</DIV>
<DIV><A href="mailto:ray@solarray.com">ray@solarray.com</A></DIV>
<DIV>Solar Engineer</DIV>
<DIV><BR class=khtml-block-placeholder></DIV>
<DIV><BR class=khtml-block-placeholder></DIV><BR
class=Apple-interchange-newline></SPAN></DIV><BR>
<DIV>
<DIV>On Aug 23, 2010, at 9:27 AM, Matt Lafferty wrote:</DIV><BR
class=Apple-interchange-newline>
<BLOCKQUOTE type="cite"><SPAN class=Apple-style-span
style="WORD-SPACING: 0px; FONT: medium Helvetica; TEXT-TRANSFORM: none; TEXT-INDENT: 0px; WHITE-SPACE: normal; LETTER-SPACING: normal; BORDER-COLLAPSE: separate; orphans: 2; widows: 2; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px">
<DIV lang=EN-US vlink="purple" link="blue">
<DIV dir=ltr align=left><SPAN class=328123715-23082010><FONT face=Arial
color=#0000ff size=2>Hi Jason,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=328123715-23082010><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=328123715-23082010>I'm
a little confused about your intention.<SPAN
class=Apple-converted-space> </SPAN></SPAN></FONT><FONT face=Arial
color=#0000ff size=2><SPAN class=328123715-23082010>I think you might be
making this harder than it needs to be. Everything you need is right
there in 2008 NEC 690.47(C).</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=328123715-23082010></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=328123715-23082010>Where are you tying into the building AC distribution
system? Get your GEC the same place the existing AC distribution system
at your point of interconnection is bonded.<SPAN
class=Apple-converted-space> </SPAN></SPAN></FONT><FONT face=Arial
color=#0000ff size=2><SPAN class=328123715-23082010>If the grounding electrode
conductor for the point of interconnection is building steel (like the
delta-wye transformer scenario described in your original
post), source your GEC there.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=328123715-23082010></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=328123715-23082010>Your
AC & DC grounding system(s) must be bonded together per<FONT face=Arial
color=#0000ff size=2><SPAN class=328123715-23082010> 690.47(C)(1).<SPAN
class=Apple-converted-space> </SPAN></SPAN></FONT>For "normal"
interactive, non-backup systems, I use a common ground bus for both
AC & DC (690.47(C)(5). I size it and any bonding
jumpers as the smaller of #8 CU or whatever 690.47(C)(2) &
690.47(C)(7) comes out to.<SPAN
class=Apple-converted-space> </SPAN></SPAN></FONT><FONT face=Arial
color=#0000ff size=2><SPAN class=328123715-23082010>My common GEC
originates at the AC interconnection per 690.47(C)(6) &
690.47(C)(8). I run the common GEC to and thru the inverter(s) and out to the
array thru the raceway system.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=328123715-23082010></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=328123715-23082010></SPAN></FONT><SPAN class=328123715-23082010>
<DIV><FONT face=Arial><FONT color=#0000ff><FONT size=2>NOTE: Once you are on
the <SPAN class=328123715-23082010>array</SPAN><SPAN
class=Apple-converted-space> </SPAN>side of the inverter(s), the GEC is
a<SPAN class=328123715-23082010><SPAN
class=Apple-converted-space> </SPAN>DC</SPAN> equipment
ground. <SPAN class=328123715-23082010>I size it not smaller than #8 and
large enough to carry any unintentional system currents safely to ground based
on the DC configuration. This may result in multiple ground conductors running
thru different conduits. Every pipe (AC & DC) gets a ground wire in
my systems. DC raceways should also be bonded to the GEC (meyers-hub,
ground-bushing, etc.). AC raceways on the load side of an OCP do not require
this provision by code, but it doesn't hurt to go ahead and do it
anyway.</SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV></SPAN></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=328123715-23082010>690.47(D) is for equipment grounding.<SPAN
class=Apple-converted-space> </SPAN><SPAN class=328123715-23082010>This
is a separate issue from the system GECs described in 690.47(C). I consider it
to be "enhanced" or "bonus" equipment
grounding. </SPAN></SPAN></FONT><FONT face=Arial color=#0000ff
size=2><SPAN class=328123715-23082010><U><STRONG>In addition</STRONG></U><SPAN
class=Apple-converted-space> </SPAN>to the requirements of 690.47(C), you
must<SPAN
class=Apple-converted-space> </SPAN><STRONG><U>ALSO</U></STRONG><SPAN
class=Apple-converted-space> </SPAN>bond your rack to the building steel
and make sure the steel is properly bonded to earth,<SPAN
class=Apple-converted-space> </SPAN><EM>OR</EM> run a
separate ground conductor from the rack to a grounding
electrode. Either way, this becomes another grounding electrode system
that you need to bond to your 690.47(C) GEC system. If you are bonding all
your equipment correctly, this<SPAN
class=Apple-converted-space> </SPAN><EM>should</EM><SPAN
class=Apple-converted-space> </SPAN>happen via the equipment grounding
conductor(s) mentioned in the NOTE above.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=328123715-23082010></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=328123715-23082010>I
hope this helps clarify it for you.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=328123715-23082010></SPAN></FONT> </DIV>
<DIV><STRONG><I><SPAN style="FONT-FAMILY: 'Monotype Corsiva'">Matt
Lafferty</SPAN></I></STRONG></DIV>
<DIV class=Section1>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><A
style="COLOR: blue; TEXT-DECORATION: underline"
href="mailto:gilligan06@gmail.com">gilligan06@gmail.com</A></SPAN></DIV></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B><SPAN
class=Apple-converted-space> </SPAN><A
style="COLOR: blue; TEXT-DECORATION: underline"
href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</A><SPAN
class=Apple-converted-space> </SPAN>[mailto:re-wrenches-bounces@lists.re-wrenches.org]<SPAN
class=Apple-converted-space> </SPAN><B>On Behalf Of<SPAN
class=Apple-converted-space> </SPAN></B>Jason Szrom<BR><B>Sent:</B><SPAN
class=Apple-converted-space> </SPAN>Monday, August 23, 2010 6:41
AM<BR><B>To:</B><SPAN
class=Apple-converted-space> </SPAN>RE-wrenches<BR><B>Subject:</B><SPAN
class=Apple-converted-space> </SPAN>Re: [RE-wrenches] PV GEC to the same
point as the utilityservice GEC?<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=WordSection1 style="page: WordSection1">
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="COLOR: rgb(31,73,125)">Matt,<O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="COLOR: rgb(31,73,125)"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="COLOR: rgb(31,73,125)">Thanks for the reply. I should have clarified,
but I am talking about a standard grid-tied, non-backup
system.<O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="COLOR: rgb(31,73,125)"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="COLOR: rgb(31,73,125)">I’m still not quite sure I have any solid code
sections to back up my assumption that it is OK to tie the inverter GEC to the
nearest steel, rather than running all the way back to the water main (where
the utility service entrance GEC is tied).<O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="COLOR: rgb(31,73,125)"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="COLOR: rgb(31,73,125)">If we have an inverter mounted on a roof, are
you saying we can or cannot go to the closest building steel with the GEC?
690.47(C)(6) sounds like we have to go back to the water main. While 690.47(D)
sounds like we are supposed to tie to the nearest building steel (“Grounding
electrodes shall be installed… as close as practicable to the location of
roof-mounted photovoltaic arrays”).<O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="COLOR: rgb(31,73,125)"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="COLOR: rgb(31,73,125)">Thanks for any
clarifications,<O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="COLOR: rgb(31,73,125)"><O:P></O:P></SPAN></DIV>
<DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><B><SPAN
style="FONT-SIZE: 12pt; COLOR: rgb(36,64,97)">Jason M. Szrom,
PE<O:P></O:P></SPAN></B></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 12pt; COLOR: rgb(36,64,97)">Engineer<O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="COLOR: rgb(36,64,97)">Solar Energy Systems, LLC<O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="COLOR: rgb(36,64,97)">718-389-1545 x13<O:P></O:P></SPAN></DIV></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="COLOR: rgb(31,73,125)"><O:P></O:P></SPAN></DIV>
<DIV>
<DIV
style="BORDER-RIGHT: medium none; PADDING-RIGHT: 0in; BORDER-TOP: rgb(181,196,223) 1pt solid; PADDING-LEFT: 0in; PADDING-BOTTOM: 0in; BORDER-LEFT: medium none; PADDING-TOP: 3pt; BORDER-BOTTOM: medium none">
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><B><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma, sans-serif">From:</SPAN></B><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma, sans-serif"><SPAN
class=Apple-converted-space> </SPAN><A
style="COLOR: blue; TEXT-DECORATION: underline"
href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</A><SPAN
class=Apple-converted-space> </SPAN>[mailto:re-wrenches-bounces@lists.re-wrenches.org]<SPAN
class=Apple-converted-space> </SPAN><B>On Behalf Of<SPAN
class=Apple-converted-space> </SPAN></B>Matt
Lafferty<BR><B>Sent:</B><SPAN
class=Apple-converted-space> </SPAN>Thursday, August 19, 2010 2:01
PM<BR><B>To:</B><SPAN
class=Apple-converted-space> </SPAN>'RE-wrenches'<BR><B>Subject:</B><SPAN
class=Apple-converted-space> </SPAN>Re: [RE-wrenches] PV GEC to the same
point as the utility service GEC?<O:P></O:P></SPAN></DIV></DIV></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><O:P></O:P></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial, sans-serif">Good
questions, Jason.</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial, sans-serif">No. Yes
(2008 NEC 690.47(C) & (D)).</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial, sans-serif">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><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial, sans-serif">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.)
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><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial, sans-serif">Regarding
your Additional Info items:</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial, sans-serif">1.
Yep.</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial, sans-serif">2. 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><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial, sans-serif">3. You
are right. The various provisions of 690.47(C)
allow/require this. In particular, (C)5 & 6.</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial, sans-serif">The
underlying principle that counts here is, "Get your GEC where your AC source
gets its system ground."</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><STRONG><I><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Monotype Corsiva'">Matt "I'm no
building inspector" Lafferty</SPAN></I></STRONG><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></DIV>
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align=center><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif">
<HR align=center width="100%" SIZE=2>
</SPAN></DIV>
<P class=MsoNormal
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 12pt; FONT-FAMILY: Calibri, sans-serif"><B><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma, sans-serif">From:</SPAN></B><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma, sans-serif"><SPAN
class=Apple-converted-space> </SPAN><A
style="COLOR: blue; TEXT-DECORATION: underline"
href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</A><SPAN
class=Apple-converted-space> </SPAN>[mailto:re-wrenches-bounces@lists.re-wrenches.org]<SPAN
class=Apple-converted-space> </SPAN><B>On Behalf Of<SPAN
class=Apple-converted-space> </SPAN></B>Jason Szrom<BR><B>Sent:</B><SPAN
class=Apple-converted-space> </SPAN>Thursday, August 19, 2010 7:38
AM<BR><B>To:</B><SPAN class=Apple-converted-space> </SPAN><A
style="COLOR: blue; TEXT-DECORATION: underline"
href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</A><BR><B>Subject:</B><SPAN
class=Apple-converted-space> </SPAN>[RE-wrenches] PV GEC to the same
point as the utility service GEC?</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Times New Roman', serif"><O:P></O:P></SPAN></P>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif">Wrenches,<O:P></O:P></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><O:P></O:P></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif">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></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><O:P></O:P></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif">Additional
info:<O:P></O:P></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt 0.5in; TEXT-INDENT: -0.25in; FONT-FAMILY: Calibri, sans-serif">1.<SPAN
style="FONT-SIZE: 7pt; FONT-FAMILY: 'Times New Roman', serif"> <SPAN
class=Apple-converted-space> </SPAN></SPAN>The DC side of the inverter is
a separately derived system and therefore needs a GEC to a ground
electrode.<O:P></O:P></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt 0.5in; TEXT-INDENT: -0.25in; FONT-FAMILY: Calibri, sans-serif">2.<SPAN
style="FONT-SIZE: 7pt; FONT-FAMILY: 'Times New Roman', serif"> <SPAN
class=Apple-converted-space> </SPAN></SPAN>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></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt 0.5in; TEXT-INDENT: -0.25in; FONT-FAMILY: Calibri, sans-serif">3.<SPAN
style="FONT-SIZE: 7pt; FONT-FAMILY: 'Times New Roman', serif"> <SPAN
class=Apple-converted-space> </SPAN></SPAN>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></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><O:P></O:P></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif">Thanks
for any input,<O:P></O:P></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif">Jason<O:P></O:P></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><O:P></O:P></DIV>
<DIV
style="FONT-SIZE: 11pt; MARGIN: 0in 0in 0pt; FONT-FAMILY: Calibri, sans-serif"><B><SPAN
style="FONT-SIZE: 12pt; COLOR: rgb(36,64,97)">Jason M. Szrom,
PE<O:P></O:P></SPAN></B></DIV>
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