Is this a code change in 2014 vs 2011 or merely a clarification? Vt has not adopted 2014 yet. What was the original rationale for the 120% rule to apply to conductors in addition to a panel bus?
Kirk Herander VSE > On Mar 4, 2014, at 6:20 PM, Brian Mehalic <br...@solarenergy.org> wrote: > > If the subpanel is at the end if the feeder, and there are no taps in between > the main and the sub then I don't see any reason that the conductors need to > be any larger than 200 A as there is no where on the feeder conductors where > grid and PV current will be additive. > > The changes in 705.12 in 2014 address this in large part. > > Brian > >> On Mar 4, 2014, at 2:41 PM, "Kirk Herander" <k...@vtsolar.com> wrote: >> >> Solaredge 20 kw, 480 3-phase. Good point, but that may be irrelevant. The >> feed-in subpanel is also powering unrelated loads, which use the neutral as >> a conductor from the main panel. So 4 conductors from the main. >> >> Kirk Herander >> VT Solar, LLC >> dba Vermont Solar Engineering >> NABCEPTM Certified Inaugural Certificant >> NYSERDA-eligible Installer >> VT RE Incentive Program Partner >> 802.863.1202 >> >> From: re-wrenches-boun...@lists.re-wrenches.org >> [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Allen >> Frishman >> Sent: Tuesday, March 04, 2014 4:32 PM >> To: RE-wrenches >> Subject: Re: [RE-wrenches] conductors and the 120% rule >> >> what inverter(s) are you using? In many cases the Neutral is not >> considered a Current Carying Conductor by the Manufacturer and therefore you >> only have 3 CCC. >> Al Frishman >> AeonSolar >> (917) 699-6641 - cell >> (888) 460-2867 >> www.aeonsolar.com >> >> On Mar 4, 2014, at 4:20 PM, Kirk Herander wrote: >> >> >> Approx.. 50 – 60ft. >> >> Kirk Herander >> VT Solar, LLC >> dba Vermont Solar Engineering >> NABCEPTM Certified Inaugural Certificant >> NYSERDA-eligible Installer >> VT RE Incentive Program Partner >> 802.863.1202 >> >> From: re-wrenches-boun...@lists.re-wrenches.org >> [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Ray Walters >> Sent: Tuesday, March 04, 2014 4:05 PM >> To: RE-wrenches >> Subject: Re: [RE-wrenches] conductors and the 120% rule >> >> What is the length of the conduit to the subpanel? That will determine >> whether to apply the derates. >> >> >> R.Ray Walters >> CTO, Solarray, Inc >> Nabcep Certified PV Installer, >> Licensed Master Electrician >> Solar Design Engineer >> 303 505-8760 >> On 3/4/2014 1:34 PM, Kirk Herander wrote: >> 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. >> >> Kirk Herander >> VT Solar, LLC >> dba Vermont Solar Engineering >> NABCEPTM Certified Inaugural Certificant >> NYSERDA-eligible Installer >> VT RE Incentive Program Partner >> 802.863.1202 >> >> From: re-wrenches-boun...@lists.re-wrenches.org >> [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Jason >> Szumlanski >> Sent: Tuesday, March 04, 2014 2:57 PM >> To: RE-wrenches >> Subject: Re: [RE-wrenches] conductors and the 120% rule >> >> 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. >> >> 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. >> >> Jason Szumlanski >> Fafco Solar >> >> >> <image001.jpg> >> >> >> On Tue, Mar 4, 2014 at 12:05 PM, Kirk Herander <k...@vtsolar.com> wrote: >> Hello, >> 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? >> >> >> Kirk Herander >> VT Solar, LLC >> dba Vermont Solar Engineering >> NABCEPTM Certified Inaugural Certificant >> NYSERDA-eligible Installer >> VT RE Incentive Program Partner >> 802.863.1202 >> >> >> >> >> >> >> _______________________________________________ >> List sponsored by Home Power magazine >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out participant bios: >> www.members.re-wrenches.org >> >> >> _______________________________________________ >> List sponsored by Home Power magazine >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out participant bios: >> www.members.re-wrenches.org >> >> >> _______________________________________________ >> List sponsored by Home Power magazine >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out participant bios: >> www.members.re-wrenches.org > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Change email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org >
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