<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">NEC 310.4 permits parallel conductors of 1/0 or larger. Conductors smaller than 1/0 are permitted, but with stipulations.<br><br>Nick's assertion "most if not all of the current will flow on the larger wires" is incorrect. The current will be shared proportionately between two paralleled conductors commensurate with their individual resistances.<br><br>The original query related to recreational vehicle PV DC-side installation, and referenced installation of a "second PV", implying only one existed initially. This would thus fall outside the bounds of the NEC, but shouldn't be interpreted to mean some of the common-sense aspects of the NEC aren't to be considered.<br><br>Dan<br><br><br><br>--- On <b>Wed, 2/2/11, Jason Szumlanski <i><Jason@fafcosolar.com></i></b> wrote:<br><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left:
5px; padding-left: 5px;"><br>From: Jason Szumlanski <Jason@fafcosolar.com><br>Subject: Re: [RE-wrenches] Parallel wire runs to increase size<br>To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org><br>Date: Wednesday, February 2, 2011, 11:15 AM<br><br><div id="yiv1123860912"><style><!--
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--></style><div class="yiv1123860912WordSection1"><p class="yiv1123860912MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">Nick,</span></p><p class="yiv1123860912MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="yiv1123860912MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">Can you cite a code section that supports this. (not challenging you – it makes sense and I agree)</span></p><p class="yiv1123860912MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="yiv1123860912MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);">I have been wondering about SMA’s recommendation to parallel two 1/0 cables for a Sunny Island. If the wire sizes and
lengths are identical, is this acceptable?</span></p><p class="yiv1123860912MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><div><p class="yiv1123860912MsoNormal"><span style="font-family: "serif"; color: rgb(31, 73, 125);">Jason Szumlanski</span></p><p class="yiv1123860912MsoNormal"><span style="font-family: "serif"; color: rgb(31, 73, 125);">Fafco Solar</span></p></div><p class="yiv1123860912MsoNormal"><span style="font-size: 11pt; font-family: "sans-serif"; color: rgb(31, 73, 125);"> </span></p><div><div style="border-right: medium none; border-width: 1pt medium medium; border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; padding: 3pt 0in 0in;"><p class="yiv1123860912MsoNormal"><b><span style="font-size: 10pt; font-family: "sans-serif";">From:</span></b><span style="font-size:
10pt; font-family: "sans-serif";"> re-wrenches-bounces@lists.re-wrenches.org [mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>Nick Soleil<br><b>Sent:</b> Wednesday, February 02, 2011 12:05 PM<br><b>To:</b> RE-wrenches<br><b>Subject:</b> Re: [RE-wrenches] Parallel wire runs to increase size</span></p></div></div><p class="yiv1123860912MsoNormal"> </p><div><p class="yiv1123860912MsoNormal"><span style="font-family: "sans-serif";">You shouldn't parallel wiring that way. That is not acceptable by code, and it is unnecessary. If the #10 is not sufficient just replace it. Due to the fact that the larger wiring has much less resistance, most if not all of the current will flow on the larger wires.</span></p><div><p class="yiv1123860912MsoNormal"><span style="font-family: "sans-serif";"> </span></p></div><p class="yiv1123860912MsoNormal"><span style="font-family:
"sans-serif";">Nick Soleil<br>Project Manager<br>Advanced Alternative Energy Solutions, LLC<br>PO Box 657<br>Petaluma, CA 94953<br>Cell: 707-321-2937<br>Office: 707-789-9537<br>Fax: 707-769-9037</span></p><div><p class="yiv1123860912MsoNormal"><span style="font-family: "sans-serif";"> </span></p></div><div><p class="yiv1123860912MsoNormal"><span style="font-family: "sans-serif";"> </span></p><div><div class="yiv1123860912MsoNormal" style="text-align: center;" align="center"><span style="font-size: 10pt; font-family: "sans-serif";"><hr align="center" size="1" width="100%"></span></div><p class="yiv1123860912MsoNormal" style="margin-bottom: 12pt;"><b><span style="font-size: 10pt; font-family: "sans-serif";">From:</span></b><span style="font-size: 10pt; font-family: "sans-serif";"> "Starlight Solar, Larry Crutcher" <larry@starlightsolar.com><br><b>To:</b> RE-wrenches
<re-wrenches@lists.re-wrenches.org><br><b>Sent:</b> Wed, February 2, 2011 8:00:07 AM<br><b>Subject:</b> [RE-wrenches] Parallel wire runs to increase size</span></p><div><p class="yiv1123860912MsoNormal"><span style="font-size: 10pt; font-family: "sans-serif";">Wrenches,</span></p></div><div><p class="yiv1123860912MsoNormal"> </p></div><div><p class="yiv1123860912MsoNormal"><span style="font-size: 10pt; font-family: "sans-serif";">Some of our business involves repairing poor PV solar installations on recreational vehicles. So often we wind up installing a roof junction box and running a second PV to controller wire and then replacing the controller to battery wire size. For instance, we may find a 10 gauge wire run to the controller. We then add #8, #6, #4 or even 2 gauge and parallel to the #10 depending on power and distance of the run. My question: Is there a calculator or chart that will tell me what the
combination of any two wire sizes equate to? example: #10 + #4 = X</span></p></div><div><p class="yiv1123860912MsoNormal"> </p></div><div><p class="yiv1123860912MsoNormal"><span style="font-size: 10pt; font-family: "sans-serif";">Thanks.</span></p></div><div><p><span style="font-size: 10pt; font-family: "sans-serif";">Larry Crutcher<br><a rel="nofollow" target="_blank" href="http://www.starlightsolar.com">Starlight Solar Power Systems</a><br></span><em><span style="font-size: 7.5pt; font-family: "serif"; color: red;">powered by </span></em><em><b><span style="font-size: 13.5pt; font-family: "serif"; color: red;">S</span></b></em><em><b><span style="font-size: 10pt; font-family: "serif"; color: red;">TARLIGHT</span></b></em><span style="font-size: 10pt; font-family: "serif"; color: red;">™</span></p></div></div></div></div><p class="yiv1123860912MsoNormal">
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