Re: [RE-wrenches] conductors and the 120% rule
Changes to <http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact =8&ved=0CEoQFjAC&url=http%3A%2F%2Fwww.slideshare.net%2Fsolpowerpeople%2Finte rconnection-rule&ei=FZcYU5e_LsSi0QH5yICQCQ&usg=AFQjCNGypW0SbS6-POHt4d82Sxc-- kZ0ig&sig2=Kz2661LzDghXtx9GwuhOfw&bvm=bv.62577051,d.dmQ> 2014 NEC Interconnection Rule 705.12 Here's a link to a powerpoint (slideshare.net) by Richard Stovall which clarifies 705.12 using some excellent illustrations. Maybe some have seen it already. Works for me. Contact me off-list if you'd like a pdf version. 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 Brian Mehalic Sent: Wednesday, March 05, 2014 10:02 AM To: RE-wrenches Subject: Re: [RE-wrenches] conductors and the 120% rule A very clarifying change is what I'd call it! First off, rather than being based on the actual breaker size on the inverter output circuit, calcs are instead based on 125% of the inverter rated output current. 705.12(D)(2)(1) addresses "Feeders" - but only applies when the inverter output circuit connection is made somewhere other than the opposite end of the feeder from the utility supply. This addresses concerns about whether the feeder conductor needs to be larger due to the presence of the additional source of supply, and so long as the inverter isn't connected to the feeder in the middle of it then the existing conductor size should be okay (because if it is at the opposite end of the feeder than there is nowhere where the utility and inverter current will be additive). 705.12(D)(2)(3) addresses "Busbars" and allows several options, including the familiar "120% rule" as you stated in your original post. Also check out 705.12(D)(2)(3)(c) - depending on the load breakers in the subpanel, the 120% rule may not even need to be used (if the sum of the inverter and load breakers is less than or equal to the busbar rating). And remember, even if your AHJ hasn't adopted 2014 yet it is worth having a conversation with them to see if they'll allow you to design the system based on the new Code - after all, in a certain sense, the 2014 NEC is what "they" meant the 2011 NEC to say! Cheers, Brian Mehalic NABCEP Certified Solar PV Installation ProfessionalT R031508-59 IREC ISPQ Certified Affiliated Instructor/PV US-0132 PV Curriculum Developer and Instructor Solar Energy International http://www.solarenergy.org On Tue, Mar 4, 2014 at 5:21 PM, Kirk wrote: 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 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" 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 <http://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
Re: [RE-wrenches] conductors and the 120% rule
Even in a feeder with line-neutral loads, the neutral still only carries the imbalance between the phase loads: the case of maximum possible neutral current is the hypothetical situation of the phase with largest line-neutral load current, with all those loads on, and both other phases having all line-neutral loads off---in order to get neutral current, you have to reduce the phase current in two legs--- So normally in 4-wire star feeders, you only need to rate for 3 current carrying conductors. If the neutral conductor connects to a solar inverter, the neutral load is either zero (3 phase inverter) or non-additive if you have a bank of 1 phase line/neutral (120 or 277 volt) inverters /wk William Korthof 714.875.3576 Sustainable Solutions #956904 On Mar 4, 2014, at 1:31 PM, Allen Frishman wrote: 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. > ___ 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
Re: [RE-wrenches] conductors and the 120% rule
00 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" 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 <%28917%29%20699-6641> - cell* >> *(888) 460-2867 <%2%29%20460-2867>* >> *www.aeonsolar.com <http://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 >> >> >> >> >> >> >> On Tue, Mar 4, 2014 at 12:05 PM, Kirk Herander 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
Re: [RE-wrenches] conductors and the 120% rule
A very clarifying change is what I'd call it! First off, rather than being based on the actual breaker size on the inverter output circuit, calcs are instead based on 125% of the inverter rated output current. 705.12(D)(2)(1) addresses "Feeders" - but only applies when the inverter output circuit connection is made somewhere other than the opposite end of the feeder from the utility supply. This addresses concerns about whether the feeder conductor needs to be larger due to the presence of the additional source of supply, and so long as the inverter isn't connected to the feeder in the middle of it then the existing conductor size should be okay (because if it is at the opposite end of the feeder than there is nowhere where the utility and inverter current will be additive). 705.12(D)(2)(3) addresses "Busbars" and allows several options, including the familiar "120% rule" as you stated in your original post. Also check out 705.12(D)(2)(3)(c) - depending on the load breakers in the subpanel, the 120% rule may not even need to be used (if the sum of the inverter and load breakers is less than or equal to the busbar rating). And remember, even if your AHJ hasn't adopted 2014 yet it is worth having a conversation with them to see if they'll allow you to design the system based on the new Code - after all, in a certain sense, the 2014 NEC is what "they" meant the 2011 NEC to say! Cheers, Brian Mehalic NABCEP Certified Solar PV Installation Professional(tm) R031508-59 IREC ISPQ Certified Affiliated Instructor/PV US-0132 PV Curriculum Developer and Instructor Solar Energy International http://www.solarenergy.org On Tue, Mar 4, 2014 at 5:21 PM, Kirk wrote: > 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 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" 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 <%28917%29%20699-6641> - cell* > *(888) 460-2867 <%2%29%20460-2867>* > *www.aeonsolar.com <http://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.
Re: [RE-wrenches] conductors and the 120% rule
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 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" 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 >> >> >> >> >> >> On Tue, Mar 4, 2014 at 12:05 PM, Kirk Herander wrote: >> Hello, >> I have a 225 amp 3-phase main lug sub-panel protected by a 200 amp breaker. >> My i
Re: [RE-wrenches] conductors and the 120% rule
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" 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 > > > > > > On Tue, Mar 4, 2014 at 12:05 PM, Kirk Herander 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 m
Re: [RE-wrenches] conductors and the 120% rule
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 <http://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 On Tue, Mar 4, 2014 at 12:05 PM, Kirk Herander 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:
Re: [RE-wrenches] conductors and the 120% rule
The other thing I could do is downsize the main to 190 amps or less. 190 + 60(pv) = 250 / 1.2 = 208 amps, exactly the 4/0 derate amperage. Unfortunately I can't get away with downsizing the 60 amp pv breaker, unless I could find a breaker rated to operate continuously at greater than 80% of its trip rating. I guess they do exist. Then you don't have to apply the 1.25 multiplier when sizing the breaker. This is a SQD industrial panel the inverter is feeding into. Any SQD gurus out there who know of these types of breakers? 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 4:06 PM To: RE-wrenches Subject: Re: [RE-wrenches] conductors and the 120% rule Yeah, I assumed you meant the four conductors. The exception would solve your problem if it's physically possible. How long of a run are we talking about? The cost difference shouldn't be bad for a short distance. Jason Szumlansk i Fafco Solar Description: Image removed by sender. On Tue, Mar 4, 2014 at 3:34 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 Description: Description: Image removed by sender. On Tue, Mar 4, 2014 at 12:05 PM, Kirk Herander 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
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 > > > > > > On Tue, Mar 4, 2014 at 12:05 PM, Kirk Herander 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
Re: [RE-wrenches] conductors and the 120% rule
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 Description: Image removed by sender. On Tue, Mar 4, 2014 at 12:05 PM, Kirk Herander 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
Re: [RE-wrenches] conductors and the 120% rule
Yeah, I assumed you meant the four conductors. The exception would solve your problem if it's physically possible. How long of a run are we talking about? The cost difference shouldn't be bad for a short distance. Jason Szumlansk i Fafco Solar On Tue, Mar 4, 2014 at 3:34 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 > > > > > [image: Description: Image removed by sender.] > > > > On Tue, Mar 4, 2014 at 12:05 PM, Kirk Herander 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
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 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
Re: [RE-wrenches] conductors and the 120% rule
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 Description: Image removed by sender. On Tue, Mar 4, 2014 at 12:05 PM, Kirk Herander 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
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 On Tue, Mar 4, 2014 at 12:05 PM, Kirk Herander 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
Re: [RE-wrenches] conductors and the 120% rule
The conductors have to be rated for 200A as normal. Fault current can only come from the grid. While the total available current on the bus of a panel is the total of the source breakers, in the conductors, grid and solar power cancel out and the total is not the sum of the two. On Tue, Mar 4, 2014 at 1:05 PM, Kirk Herander 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 > > > -- Chris Mason President, Comet Systems Ltd www.cometenergysystems.com Cell: 264.235.5670 Skype: netconcepts ___ 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
[RE-wrenches] conductors and the 120% rule
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
