Ray and August:
Thanks for the speedy reply. I did confuse M250s with the M215s. The actual inverters to be used are the M215s. I swear I had a spec sheet for the M190 that showed 0.75 A but I can't find it anymore. So using 0.8A: 9 * 0.8A = 7.2A 10 * .9A = 9.0A Total = 16.2 De-rate: 16.2*1.25 = 20.25. Maybe that will fly. The other question is: I don't have to use the value of the three breakers in the Solar load center to calculate my POC in the M/M/C? The code says: The sum of the ampere ratings of overcurrent devices feeding a busbar or conductor shall not exceed 120% of the rating of the busbar or conductor. I am assuming I don't have to add the two 15s and the 20 and use that in figuring the back feed to the M/M/C since the M/MC is fed by a 20. Thanks so much for your help. I am going to send this on to the lead inspector for the County. I am fortunate that he has always been willing to review these problems and flexible where appropriate, at least in my view. Sincerely, William Miller PS: I update the drawing. Wm From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of August Goers Sent: Wednesday, October 09, 2013 3:40 PM To: RE-wrenches Subject: Re: [RE-wrenches] Point of connection question William, You have 9 M190s each running at 800 mA according to spec sheet. That equals 7.2 A nominal output current. Plus you have 10 M250s (if you look at your drawing) each running at 1 A = 10 A. 7.2 A + 10 A = 17.2 A * 1.25 = 21.5 A min breaker size. So, you'll need to round your breaker to a 25 A or 30 A breaker in the sub. You don't have any problem in the sub panel but the meter main is going to be a problem if it is a 100 A meter/main. Your drawing and case study notes don't seem to correspond - you mention M215s in the case study and show M250s on the drawing. If you indeed have 10 M215s then you're at 10 * 0.9 A = 9 A. 7.2 A + 9 A = 16.2 A * 1.25 = 20.25 A min breaker size. This is where it gets tricky. My fellow engineer just pointed out NEC 220.5(B) which allows you to drop fractions of amperes less than 0.5. So, I think you'd be okay with a 20 A solar breaker in this case. Best, August From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of William Miller Sent: Wednesday, October 09, 2013 3:07 PM To: RE-wrenches Subject: [RE-wrenches] Point of connection question Friends: At the risk of asking a question that may have been asked and answered here in the past, I wish to pose a question about Point of Connection. Rather than outline the situation here I put it all on a web page. If any of you have a moment to review this, I would be most appreciative. http://www.millersolar.com/MillerSolar/case_studies/POC/_POC_Question.html Thanks in advance, William Miller _____ No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4142 / Virus Database: 3604/6722 - Release Date: 10/04/13
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