<div dir="ltr">Hey Jason, <div>Here's the 2020 text:</div><div><br></div><div>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;font-family:"Helvetica Neue Light";color:rgb(0,0,0)">6)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span> Connections shall be permitted on busbars of panelboards that supply lugs connected to feed-through conductors. The feed-through conductors shall be sized in accordance with 705.12(B)(1). Where an overcurrent device is installed at the supply end of the feed-through conductors, the busbar in the supplying panelboard shall be permitted to be sized in accordance with 705.12(B)\u2060(3)\u2060(1) through 705.12(B)(3)(3).</p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;line-height:normal;font-family:"Helvetica Neue Light";color:rgb(0,0,0)"><br></p><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>The OCPD on the supply end of the feed-through conductors would be in the form of a sub-feed breaker at the point of supply to those conductors, re-establishing overcurrent protection of the conductors (likely at the same ampacity as the main breaker in the supplying panel. The feed-through conductors are basically an extension of the busbar in the supplying panel; they can either be protected by the main, or in the presence of multiple sources of power in the supplying panel (such as a backfed PV system breaker) they can be protected based on (B)(3)(1) - "the 125% rule" - or they can be protected by a new overcurrent device at their point of supply, in which case current on them is limited based on that OCPD size; in this latter scenario the busbar in the supplying panel is allowed to be sized based on one of (B)(3)(1) - (3) because it is protected downstream at its end.</div><div><br></div><div>The theory is pretty much the same as 705.12(B)(1) for feeders - when not connecting at the end of the feeder, use the "125% rule" or re-establish overcurrent protection for that portion of the feeder subject to multiple power sources.</div><div><br></div><div>In your drawing the 200 A feeder conductors, as well as the busbar below the PV system breaker, could be subject to > 200 A in the event of a fault somewhere along those conductors. </div><div><br></div><div>Brian Mehalic <br>NABCEP Certified Solar PV Installation Professional\u2122 R031508-59</div><div>National Electrical Code® CMP-4 Member</div><div>(520) 204-6639<br><div><br></div><div><div><div>Solar Energy International<br><a href="http://www.solarenergy.org" target="_blank">http://www.solarenergy.org</a></div></div></div></div><div><br></div><div>SEI Professional Services</div><div><a href="http://www.seisolarpros.com" target="_blank"><span style="font-size:12.8px">http://www.s</span>eisolarpros.com</a><br></div><div><br></div></div></div></div></div></div></div></div></div></div></div></div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Oct 28, 2020 at 10:18 AM Jason Szumlanski <<a href="mailto:jason@floridasolardesigngroup.com">jason@floridasolardesigngroup.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Does anyone else think they botched the wording in this section? It's still not clear, and we have a ton of meter/main combos with feed-through lugs around here.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Where is it written, "where an overcurrent device is installed at the <b><i>supply end</i></b> of the feed-through conductors," (emphasis added) are they referring to the solar backfed breaker on the busbar or another breaker somewhere along the feeder circuit? It goes on to state that the loads on the supplying busbar can comply with any method in 705.12(B)(3), which prescribes an OCPD at the load end of the feeder in 705.12(B)(3)(3), so they can't be talking about that. I have to assume it is the solar backfed breaker they are referencing.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">See my interpretation of one scenario in the attached image. </div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">We're a long way off from the 2020 code implementation here, but it can help sway plans examiners looking to clarify the intent of the 2014/2017 code cycles.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Jason Szumlanski</div><img width="0" height="0" alt="" style="display: flex;" src="https://mailtrack.io/trace/mail/8a28728bf2d2ddf6a89dd048964246ff451afde2.png?u=1613865"></div>
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