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<div class="moz-cite-prefix">What is the length of the conduit to
the subpanel? That will determine whether to apply the derates.<br>
<pre class="moz-signature" cols="72">R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760</pre>
On 3/4/2014 1:34 PM, Kirk Herander wrote:<br>
</div>
<blockquote cite="mid:002101cf37e9$272b4ad0$7581e070$@vtsolar.com"
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<div class="WordSection1">
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Whether
or not a further derate has to be applied is the killer
here, as I am working with existing panels and conductors.
In an old Code Corner(HP140) J. Wiles goes through a similar
scenario and calls out the allowable current rating and
conductor in 310.15, but makes no mention of applying
additional derate factors. The .8 derate for 4-6
conductors(l1,l2,l3, & n) will put the existing 4/0
cable between feed-in and main panel at 208 amps, less than
the allowable 217. I’d hate to need to upsize the wire to
250 mcm.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Kirk
Herander<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">VT
Solar, LLC<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">dba
Vermont Solar Engineering<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">NABCEP<sup>TM
</sup>Certified Inaugural Certificant<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">NYSERDA-eligible
Installer<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">VT
RE Incentive Program Partner<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">802.863.1202<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
<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>Jason Szumlanski<br>
<b>Sent:</b> Tuesday, March 04, 2014 2:57 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] conductors and the 120%
rule<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal"><span
style="font-family:"Verdana","sans-serif"">Both
the bus and conductors need to be rated for 217 amps
minimum. As you mentioned, the bus is not a problem. The
way I interpret it, the conductor size required would be
after derate factors are applied. The rating of the
conductor is ultimately dependent on the derate factors.<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Verdana","sans-serif""><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Verdana","sans-serif"">If
you can locate your subpanel adjacent to the main
distribution panel, you may be able to use Exception #3
to 310.15(B)(2) by connecting the panels with a short
nipple. I assume you are just looking at a number of
conductor derate and not an ambient temperature derate.<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div id="WISESTAMP_SIG_gmail_session">
<div>
<div style="margin-bottom:6.0pt">
<p style="margin:0in;margin-bottom:.0001pt"><span
style="font-size:10.0pt;font-family:"Verdana","sans-serif"">Jason
Szumlanski<o:p></o:p></span></p>
<div>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Verdana","sans-serif"">Fafco
Solar<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Verdana","sans-serif""><br>
<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Verdana","sans-serif";border:solid
windowtext 1.0pt;padding:0in"><img
id="Picture_x0020_1"
src="cid:part1.07000805.02010703@solarray.com"
alt="Description: Image removed by sender."
height="1" width="1"></span><span
style="font-size:10.0pt;font-family:"Verdana","sans-serif""><o:p></o:p></span></p>
</div>
</div>
<div>
<p class="MsoNormal" style="margin-bottom:12.0pt"><o:p> </o:p></p>
<div>
<p class="MsoNormal">On Tue, Mar 4, 2014 at 12:05 PM, Kirk
Herander <<a moz-do-not-send="true"
href="mailto:kirk@vtsolar.com" target="_blank">kirk@vtsolar.com</a>>
wrote:<o:p></o:p></p>
<div>
<div>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:14.0pt">Hello,</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:14.0pt">I have a 225 amp 3-phase
main lug sub-panel protected by a 200 amp breaker.
My inverter breaker feeding the sub panel is 60
amps. So 225 a bus x 1.2 = 270 amps. That’s less
than the sum of the two breakers of 260 amps, so
no issue there. The conductors between sub and
main panel have to be rated for at least 260/1.2 =
217 amps, correct? Is this 217 amps before or
after derating the conductor?</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:14.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:14.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:14.0pt">Kirk Herander</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:14.0pt">VT Solar, LLC</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:14.0pt">dba Vermont Solar
Engineering</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:14.0pt">NABCEP<sup>TM </sup>Certified
Inaugural Certificant</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:14.0pt">NYSERDA-eligible
Installer</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:14.0pt">VT RE Incentive Program
Partner</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:14.0pt"><a moz-do-not-send="true"
href="tel:802.863.1202" target="_blank">802.863.1202</a></span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
</div>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</div>
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