<div dir="ltr"><div><div><div><div>Hello wrenches,<br><br></div>705.12(D)(1) does require a single dedicated OCPD and single disconnect for a load side interconnection. 705.12 is only applying to the point of connection and 705.12(D) only applies to load side connected systems less than 100kW, otherwise 705.12(A), (B), <b>or </b>(C) applies. <br>
<br></div>The requirements of 705.12 only apply to the point of connection though. 705.21 does not seem to indicate that the disconnecting means must be "dedicated." In fact, 690.15 specifically states that "A single disconnecting means in accordance with 690.17 shall be permitted for the combined ac output of multiple inverters or ac modules.<br>
<br></div>690.15(A) in the 2014 code and 690.14(D) in the 2011 code applies to utility-interactive inverters installed in not readily accessible locations. This states that a disconnecting means must be installed within site of or in each inverter. This disconnecting means does not need to be suitable as service equipment [690.14(A) in 2011 and 690.13(C) in 2014.] <br>
<br>The disconnecting means must meet 690.17. Article 690.17 <i>exception</i> allows that, "<i>a connector shall be allowed to be used for an ac or dc disconnecting means, provided that it complies with 690.33..."<br>
<br></i></div><div>In and Enphase microinverter system, the AC breaker provides for the interruption and the ac and dc connectors provide the service disconnecting means. Enphase connectors meet the ac and dc connector requirements as called out in 690.33 and are rated for the application. 690.33 calls out that the connectors must be polarized, guarded, and of the locking type. 690.33 also allows for the disconnect to be either rated to interrupt the current or require a tool to open the connector.<br>
<br></div><div>Enphase has published a couple of documents on this topic, based upon the 2011 NEC. See attached.<br>
</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Jun 30, 2014 at 1:02 PM, Glenn Burt <span dir="ltr"><<a href="mailto:glenn.burt@glbcc.com" target="_blank">glenn.burt@glbcc.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div link="blue" vlink="purple" lang="EN-US"><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">What am I missing here?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">In the 2014 NEC, 705.21 seems to indicate that every inverter needs to have its own AC disconnect. Most inverters only have integrated DC disconnects (SMA, Power One, Fronius) as I recall. Or has this been interpreted to only apply to the DC side of the system?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Since NYS is still on the 2008 NEC, and the handbook has a note in 690.64B)1:<u></u><u></u></span></p>
<p class="MsoNormal"><i><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">The outputs of utility-interactive inverters may not be connected directly in parallel without first being connected to the required dedicated circuit breaker or fusible disconnecting means.<u></u><u></u></span></i></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Further, I believe it can be interpreted that each inverter source circuit connection “shall be made at a dedicated circuit breaker or fusible disconnecting means” as directly quoted from 690.64(B)1.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I see a dedicated OCPD being required for each inverter output, unless the manufacturer has installation instructions which have been approved by UL indicating that more than one can be paralleled and retain its listing (ala microinverters).<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">-Glenn<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p><div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0in 0in 0in">
<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""> RE-wrenches [mailto:<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On Behalf Of </b>Corey Shalanski<br>
<b>Sent:</b> Monday, June 30, 2014 2:38 PM</span></p><div><div class="h5"><br><b>To:</b> <a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a><br><b>Subject:</b> Re: [RE-wrenches] Combining Multiple Inverters<u></u><u></u></div>
</div><p></p></div><div><div class="h5"><p class="MsoNormal"><u></u> <u></u></p><div><p class="MsoNormal">Thank you to all who responded to this thread - particularly Jason/Dave/Jay for pointing out the maximum OCPD requirements.<u></u><u></u></p>
<div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">Getting back to my original question.. I would like to use Dave's "extremely small subset" example of two SB5s operating at 277V. In this case, if we were to parallel the output of each inverter onto a 50A OCPD (#6 wire), could we downsize the wire to #10 from the split going back to each individual inverter? or would we be better served (required?) to run #6 all the way back to each unit? Since we are dealing with current-limited devices I would tend to think we can downsize but wanted to get Wrenches' feedback on this.<u></u><u></u></p>
</div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">--<u></u><u></u></p></div><div><p class="MsoNormal">Corey Shalanski<u></u><u></u></p></div><div><p class="MsoNormal">Joule Energy<u></u><u></u></p>
</div><div><p class="MsoNormal">New Orleans, LA<u></u><u></u></p><div><p class="MsoNormal"><img src="https://mailfoogae.appspot.com/t?sender=aY3NoYWxhbnNraUBqb3VsZS1lbmVyZ3kuY29t&type=zerocontent&guid=4bec5788-9903-4ff4-8f92-031ee1997a9c"><span style="font-size:7.5pt;font-family:"Euphemia","sans-serif";color:white">ᐧ</span><u></u><u></u></p>
</div><div><p class="MsoNormal" style="margin-bottom:12.0pt"><u></u> <u></u></p><div><p class="MsoNormal">On Fri, Jun 27, 2014 at 12:41 PM, <<a href="mailto:re-wrenches-request@lists.re-wrenches.org" target="_blank">re-wrenches-request@lists.re-wrenches.org</a>> wrote:<u></u><u></u></p>
<p class="MsoNormal"><br>Message: 5<br>Date: Fri, 27 Jun 2014 11:32:02 -0400<br>From: Dave Click <<a href="mailto:daveclick@fsec.ucf.edu" target="_blank">daveclick@fsec.ucf.edu</a>><br>To: <a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a><br>
Subject: Re: [RE-wrenches] Combining Multiple Inverters<br>Message-ID: <<a href="mailto:53AD8E72.4080009@fsec.ucf.edu" target="_blank">53AD8E72.4080009@fsec.ucf.edu</a>><br>Content-Type: text/plain; format=flowed; charset=ISO-8859-1<br>
<br>This is an interesting conversation, but I'm not sure it's going to<br>really impact anything.<br><br>When an inverter is listed, it is tested with some "maximum output<br>overcurrent protection" as part of its rating per UL 1741. Typically<br>
inverter manufacturers set this to be just above the inverter's max<br>current + 25%. As you know, many inverters can work at more than one<br>voltage, so for the SB5s their max current ratings at 277/240/208V are<br>
18/20.8/24A, respectively. The max overcurrent protection is 50A. This<br>figure often appears in the manual but not in the data sheet. For SMA,<br>it's in the manuals. For some manufacturers, it's only available from<br>
tech support.<br><br>For the Sunny Boy line, the only way you could have more than one<br>inverter on a shared OCPD is if you have two SB5s operating at 277V<br>(18.1A rated current each, so 2x18.1x1.25 < 50A). The SB6, SB7, and SB8<br>
all have currents too high to make this work, as they share the 50A max<br>OCPD. The SB3/3.8/4 have a max OCPD of 30A, which is too low to<br>double-up since each SB3 requires an OCPD of at least 20A. The TLs don't<br>
work either, as the max for any unit is too low. I don't see it in the<br>SMA manual, but I know that in other manuals I've seen a manufacturer<br>requirement for a dedicated OCPD. The only inverters I know of that have<br>
a max OCPD rating far beyond their rated current are micro-inverters.<br><br>As for the shared disconnect, since at least the 2005, 690.15 has noted,<br>"A single disconnecting means in accordance with 690.17 shall be<br>
permitted for the combined ac output of one or more inverters or ac<br>modules in an interactive system." That being said, the NEC requires ac<br>modules and micro-inverters to have ac disconnects (connectors,<br>typically) per 690.6 and 690.15(A). 690.15 notes that an inverter be<br>
able to be disconnected from all sources, but if doubling up these SB5s<br>you could argue that this shared disconnect accomplishes that via the<br>anti-islanding protection... so I agree now that this is a grey area.<br>
<br>Anyway, it comes down to whether it's worth worrying about this for what<br>is an extremely small subset of compatible inverter configurations, when<br>you can just do something like install a $50 Eaton BR24L70RP (70A bus,<br>
240V, 4 spaces) with two 30A breakers and be on your way.<br><br>DKC<u></u><u></u></p></div></div></div></div></div></div></div></div><br>_______________________________________________<br>
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<br></blockquote></div><br><br clear="all"><br>-- <br><div dir="ltr"><p style="margin:0in 0in 0.0001pt"><span style="font-size:14pt">Cordially,</span></p><p style="margin:0in 0in 0.0001pt"><b><span style="font-size:14pt">Nick Soleil</span></b><span style="font-size:14pt"></span></p>
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