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Mark,<br>
<br>
Separately derived is defined in article 100. Basically, a separately
derived system has no common conductors other than possibly equipment
ground.<br>
<br>
By the definition in article 100 the feeder from the house may be a
separately derived system at the shop. It may not be if the house and
shop are feed off of the same transformer because the two systems would
both have a neutral connection at the transformer. <br>
<br>
The ac output of a grid interactive inverter with no batteries cannot
be a separately derived system because it connects to conductors on the
premises.<br>
<br>
There must be an equipment ground with the inverter output wires
(feeder between house and shop). And the equipment ground needs to
connect to the grounding system at both buildings. That does make a
connection between the two grounding systems - just as happens whenever
a feeder is run from a house to an outbuilding.<br>
<br>
Kent Osterberg<br>
Blue Mountain Solar<br>
<br>
<br>
<br>
<br>
<br>
Mark Frye wrote:
<blockquote cite="mid:CAE62A588D9C4DCA906B59AE38D96FC0@marksdell"
type="cite">
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<div dir="ltr" align="left"><span class="000565816-18042011"><font
color="#0000ff" face="Arial" size="2">Thanks Ken,</font></span></div>
<div dir="ltr" align="left"><span class="000565816-18042011"></span> </div>
<div dir="ltr" align="left"><span class="000565816-18042011"><font
color="#0000ff" face="Arial" size="2">I still don't see any
configuration of equipment that would not involve making an electrical
connection between the two grounding systems of the two seperate
dwellings</font></span></div>
<div dir="ltr" align="left"><span class="000565816-18042011"></span> </div>
<div dir="ltr" align="left"><span class="000565816-18042011"><font
color="#0000ff" face="Arial" size="2">In order to provide the required
GFP for the PV modules, it seems both inverters would have to mounted
on the shop.</font></span></div>
<div dir="ltr" align="left"><span class="000565816-18042011"></span> </div>
<div dir="ltr" align="left"><span class="000565816-18042011"><font
color="#0000ff" face="Arial" size="2">If I put all modules, and both
inverters on the shop and run a feeder (?) from one of the inverters
back to the house, could I get away with not running a equipment ground
conductor along with the inverter output circuit conductors? If I do
run an EGC then it will connect the two grounding systems.</font></span></div>
<div dir="ltr" align="left"><span class="000565816-18042011"></span> </div>
<div dir="ltr" align="left"><span class="000565816-18042011"><font
color="#0000ff" face="Arial" size="2">I guess 230 does allow multiple
service on a single dwelling where justified by the size of the
building. Perhaps one could, by bonding the grounding systems of house
and the shop, argue that they basically constitute one large dwelling.</font></span></div>
<div dir="ltr" align="left"><span class="000565816-18042011"></span> </div>
<div dir="ltr" align="left"><span class="000565816-18042011"><font
color="#0000ff" face="Arial" size="2">The questions keep mounting up.
250 allows bonding the groundingstem of multiple seperately derived
systems, but could we construe a utility service to one dwelling as a
seperately derived system relative to another dwelling with it's own
service? Where can one find the definition of a "seperately derived
system" in the Code?</font></span></div>
<div dir="ltr" align="left"><span class="000565816-18042011"></span> </div>
<div dir="ltr" align="left"><span lang="en-us"><font face="Arial"
size="2">Mark Frye</font></span> <br>
<span lang="en-us"><font face="Arial" size="2">Berkeley Solar
Electric Systems</font></span> <br>
<span lang="en-us"><font face="Arial" size="2">303 Redbud Way</font></span>
<br>
<span lang="en-us"><font face="Arial" size="2">Nevada City, CA 95959</font></span>
<br>
<span lang="en-us"><font face="Arial" size="2">(530) 401-8024</font></span>
<br>
<span lang="en-us"></span><a moz-do-not-send="true"
href="http://www.berkeleysolar.com/"><span lang="en-us"><u><font
color="#0000ff" face="Arial" size="2">www.berkeleysolar.com</font></u></span></a><span
lang="en-us"><font face="Arial" size="2"> </font></span> </div>
<div> </div>
<br>
<div dir="ltr" class="OutlookMessageHeader" align="left" lang="en-us">
<hr tabindex="-1"><font face="Tahoma" size="2"><b>From:</b>
<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>Kent
Osterberg<br>
<b>Sent:</b> Monday, April 18, 2011 7:58 AM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] Two Buildings, Two Services, One
Roof<br>
</font><br>
</div>
Mark,<br>
<br>
NEC 230.2(A) specifically allows two services for parallel power
production sources. While a feeder from the house is technically not
the same as a service, it should be allowed provided that there is a
disconnect grouped with the main service disconnect. A discussion with
the inspector ahead of time should make this work smoothly.<br>
<br>
Kent Osterberg<br>
Blue Mountain Solar<br>
<br>
<br>
Mark Frye wrote:
<blockquote cite="mid:F7255AA45F2041AE8395271F61F86886@marksdell"
type="cite">
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<div dir="ltr" align="left"><span class="171071013-18042011"><font
color="#0000ff" face="Arial" size="2">Thanks Nick,</font></span></div>
<div dir="ltr" align="left"><span class="171071013-18042011"></span> </div>
<div dir="ltr" align="left"><span class="171071013-18042011"><font
color="#0000ff" face="Arial" size="2">250 talks about two seperate
buildings with one service, and 230 talks about one building with two
services.</font></span></div>
<div> </div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="171071013-18042011">I don't think this particular situation has
been contempated by the Code.</span></font></div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="171071013-18042011"></span></font> </div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="171071013-18042011">How big a deal would it be to just bond the
two ground electrode systems together and go along my merry way?</span></font></div>
<div><br>
<span lang="en-us"><font face="Arial" size="2">Mark Frye</font></span>
<br>
<span lang="en-us"><font face="Arial" size="2">Berkeley Solar
Electric Systems</font></span> <br>
<span lang="en-us"><font face="Arial" size="2">303 Redbud Way</font></span>
<br>
<span lang="en-us"><font face="Arial" size="2">Nevada City, CA
95959</font></span> <br>
<span lang="en-us"><font face="Arial" size="2">(530) 401-8024</font></span>
<br>
<span lang="en-us"></span><a href="http://www.berkeleysolar.com/"
moz-do-not-send="true"><span lang="en-us"><u><font color="#0000ff"
face="Arial" size="2">www.berkeleysolar.com</font></u></span></a><span
lang="en-us"><font face="Arial" size="2"> </font></span> </div>
</blockquote>
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