Re: [RE-wrenches] grounding the Enphase inverter
I agree that it just ain't worth it to do work twice. The bottom line is that if you insist on using the Enphase WEEB solution, ask your inspector it if it will pass before you do it. Once you develop a rapport, most are willing to discuss these issues in advance of the inspection. It doesn't hurt to clearly indicate your intentions on your plans. I also agree that a bare #6 to each microinverter is not that difficult to accomplish, and not much more expensive if at all. It's a little more painful when using a microinverter mounted to a Zep Solar rail-less system, but there is no approved WEEB for that anyway. I wonder what Enphase has to say about industry experts disagreeing with their assessment of the WEEB. Hopefully they understand that I as an installer am not trying to just make things a) cheap and b) easy. I am trying to make things a) right, and b) clear. Jason Szumlanski Fafco Solar -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Bill Brooks Sent: Friday, March 04, 2011 1:48 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter All, While there is ambiguity in the 2008 NEC in 690.47(C) on the requirements for system grounding of PV systems, the 2011 NEC in 690.47(C) clarifies the intent. While an application note from Enphase may state that WEEBs can be used as part of the grounding electrode system, I disagree with this concept and do not believe it meets the requirements or intent of the NEC as clarified in the 2011 NEC. The problem with a grounded PV inverter is that it requires a grounding electrode conductor (GEC) from the grounding point (on the inverter) to the grounding electrode. The 2008 and 2011 NEC allows for that connection to be terminated at the grounding bar in the service panel supplying the micro-inverters. There is no problem with using the WEEB to bond the rails to the modules and then to the Enphase Micro-inverter. From the micro-inverter, a bare 6AWG could be run to pick up each micro-inveter in each row of micro-inverters with splices made to a single bare 6AWG made with irreversible splices. At the rooftop junction box, the GEC could be irreversibly spliced to an 8AWG green insulated conductor to run unbroken to the grounding busbar in the service equipment. While this may not be in agreement with the Enphase application note, I believe it meets the intent and letter of the NEC as clarified in the 2011 NEC 690.47(C). While using the WEEBs in the GEC circuit may not cause a life or death issue, it is absolutely open to being questioned by the electrical inspector. If the electrical inspector decides it is wrong--it is wrong. If you or the field inspector appeals to me or an expert like John Wiles, we will state what I have stated above. Then you would have to remove all the modules, throw away the WEEBs, put in new WEEBs with the new bare copper 6AWG and reinstall the modules--it just ain't worth it. 690.47(D) was removed from the 2011 NEC because it was primarily for lightning protection (not a safety issue according to the NEC) and was ambiguously worded with respect to residential rooftop PV systems. If the local jurisdiction requires the additional electrode, install a j-box at the point near ground-level where the conduit transitions from vertical to horizontal and install an irreversibly spliced bare 6AWG to run from the j-box to a ground rod below the j-box--mildly painful, but very doable. Bill. Bill Brooks, PE Principal Brooks Engineering 873 Kells Circle Vacaville, CA 95688 707-332-0761 (office and mobile) 707-451-7739 (fax) b...@brooksolar.com (email) www.brooksolar.com (web) -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Jason Szumlanski Sent: Thursday, March 03, 2011 12:55 PM To: RE-wrenches Subject: Re: [RE-wrenches] grounding the Enphase inverter I don't see it in your comments. At least that wasn't clear. Anyway, in that case there is absolutely no reason to use the inverter ground clip. The whole purpose of the inverter- rail WEEB is to eliminate the ground wire. Take a look at the Enphase App Note here: http://www.enphaseenergy.com/downloads/EnphaseAppNote_WEEB_Installation. pdf It starts out, As an alternative to installing a continuous grounding electrode conductor connected to each microinverter chassis, a grounding washer may be used to ground the microinverter to grounded racking. It couldn't be more clear for an inspector, but I understand that sometimes it's hard to convince them. Hope this helps! Jason Szumlanski Fafco Solar -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Kirk Herander, VSE Sent: Thursday, March 03, 2011 8:46 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter As an aside, why didn't you
Re: [RE-wrenches] York furnace
William, Reportedly this is the same issue that Staber (the top loading, horizontal axis clothes washer manufacturer) has made their quest to solve. Reportedly configuring their washer with different caps. for different inverter models. You might want to touch base with them for suggestions. Good luck, Bill - Original Message - From: William Miller To: RE-wrenches Sent: Friday, March 04, 2011 12:25 AM Subject: Re: [RE-wrenches] York furnace Dave: What value was the capacitor? Wm At 06:58 PM 3/3/2011, you wrote: Content-Type: multipart/alternative; boundary==_NextPart_000_0028_01CBD9EE.292D4E70 Content-Language: en-us William, It's been yrs since I dealt with this issue, and it wasn't a York specifically.. But I had an issue with a furnace and an old black Trace mod sine. A capacitor in the feed to the furnace did the trick. Dave From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of William Miller Sent: Thursday, March 03, 2011 7:42 PM To: RE-wrenches Subject: [RE-wrenches] York furnace Friends: Have any of you ever had problems with a York furnace on a modified sine wave inverter? What steps did you take to resolve the issues? Thanks in advance, William Miller Please note new e-mail address and domain: William Miller Miller Solar Voice :805-438-5600 email: will...@millersolar.com http://millersolar.com License No. C-10-773985 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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 No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1204 / Virus Database: 1435/3480 - Release Date: 03/03/11 Please note new e-mail address and domain: William Miller Miller Solar Voice :805-438-5600 email: will...@millersolar.com http://millersolar.com License No. C-10-773985 -- ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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 Options 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] York furnace
William, I do not recall. Presently I'm away from my office. I could check tomorrow on that. Dave Sent via BlackBerry by ATT -Original Message- From: William Miller will...@millersolar.com Sender: re-wrenches-boun...@lists.re-wrenches.orgDate: Thu, 03 Mar 2011 22:25:29 To: RE-wrenchesre-wrenches@lists.re-wrenches.org Reply-To: RE-wrenches re-wrenches@lists.re-wrenches.org Subject: Re: [RE-wrenches] York furnace ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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 Options 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] grounding the Enphase inverter
Hi Bill - I see that you recommend that the GEC between the micro inverters be run in 6AWG before it enters the conduit and transitions to 8AWG. I assume this is to meet the intent of 250.64(B) - Securing and Protection Against Physical Damage? Switching over to equipment grounding, it is very common in the industry to run bare 10AWG between the modules and racks. Does this still seem acceptable to you? Best, August August Goers Luminalt Energy Corporation 1320 Potrero Avenue San Francisco, CA 94110 m: 415.559.1525 o: 415.641.4000 aug...@luminalt.com -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Bill Brooks Sent: Thursday, March 03, 2011 10:48 PM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter All, While there is ambiguity in the 2008 NEC in 690.47(C) on the requirements for system grounding of PV systems, the 2011 NEC in 690.47(C) clarifies the intent. While an application note from Enphase may state that WEEBs can be used as part of the grounding electrode system, I disagree with this concept and do not believe it meets the requirements or intent of the NEC as clarified in the 2011 NEC. The problem with a grounded PV inverter is that it requires a grounding electrode conductor (GEC) from the grounding point (on the inverter) to the grounding electrode. The 2008 and 2011 NEC allows for that connection to be terminated at the grounding bar in the service panel supplying the micro-inverters. There is no problem with using the WEEB to bond the rails to the modules and then to the Enphase Micro-inverter. From the micro-inverter, a bare 6AWG could be run to pick up each micro-inveter in each row of micro-inverters with splices made to a single bare 6AWG made with irreversible splices. At the rooftop junction box, the GEC could be irreversibly spliced to an 8AWG green insulated conductor to run unbroken to the grounding busbar in the service equipment. While this may not be in agreement with the Enphase application note, I believe it meets the intent and letter of the NEC as clarified in the 2011 NEC 690.47(C). While using the WEEBs in the GEC circuit may not cause a life or death issue, it is absolutely open to being questioned by the electrical inspector. If the electrical inspector decides it is wrong--it is wrong. If you or the field inspector appeals to me or an expert like John Wiles, we will state what I have stated above. Then you would have to remove all the modules, throw away the WEEBs, put in new WEEBs with the new bare copper 6AWG and reinstall the modules--it just ain't worth it. 690.47(D) was removed from the 2011 NEC because it was primarily for lightning protection (not a safety issue according to the NEC) and was ambiguously worded with respect to residential rooftop PV systems. If the local jurisdiction requires the additional electrode, install a j-box at the point near ground-level where the conduit transitions from vertical to horizontal and install an irreversibly spliced bare 6AWG to run from the j-box to a ground rod below the j-box--mildly painful, but very doable. Bill. Bill Brooks, PE Principal Brooks Engineering 873 Kells Circle Vacaville, CA 95688 707-332-0761 (office and mobile) 707-451-7739 (fax) b...@brooksolar.com (email) www.brooksolar.com (web) -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Jason Szumlanski Sent: Thursday, March 03, 2011 12:55 PM To: RE-wrenches Subject: Re: [RE-wrenches] grounding the Enphase inverter I don't see it in your comments. At least that wasn't clear. Anyway, in that case there is absolutely no reason to use the inverter ground clip. The whole purpose of the inverter- rail WEEB is to eliminate the ground wire. Take a look at the Enphase App Note here: http://www.enphaseenergy.com/downloads/EnphaseAppNote_WEEB_Installation. pdf It starts out, As an alternative to installing a continuous grounding electrode conductor connected to each microinverter chassis, a grounding washer may be used to ground the microinverter to grounded racking. It couldn't be more clear for an inspector, but I understand that sometimes it's hard to convince them. Hope this helps! Jason Szumlanski Fafco Solar -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Kirk Herander, VSE Sent: Thursday, March 03, 2011 8:46 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter As an aside, why didn't you use approved WEEB's to bond the inverters to the rails? This eliminates the ground wire to each inverter. Simpler IMHO. I did. It is in my comments. Kirk Herander Vermont Solar Engineering 802.863.1202 NABCEP(tm) Certified Solar Installer NYSERDA-eligible Installer VT Solar Incentive Program Partner
Re: [RE-wrenches] grounding the Enphase inverter
The interesting thing to me is the underlying assumption in the Code that a GEC is requried for grid-tied inverters at all. Why isn't EG sufficient for function and safety. Which of the following common electrical equipment has the same requirement: UPS Motors with regenerative energy disipators DC power supplies Standby generators ?? Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 www.berkeleysolar.com -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Bill Brooks Sent: Thursday, March 03, 2011 10:48 PM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter All, While there is ambiguity in the 2008 NEC in 690.47(C) on the requirements for system grounding of PV systems, the 2011 NEC in 690.47(C) clarifies the intent. While an application note from Enphase may state that WEEBs can be used as part of the grounding electrode system, I disagree with this concept and do not believe it meets the requirements or intent of the NEC as clarified in the 2011 NEC. The problem with a grounded PV inverter is that it requires a grounding electrode conductor (GEC) from the grounding point (on the inverter) to the grounding electrode. The 2008 and 2011 NEC allows for that connection to be terminated at the grounding bar in the service panel supplying the micro-inverters. There is no problem with using the WEEB to bond the rails to the modules and then to the Enphase Micro-inverter. From the micro-inverter, a bare 6AWG could be run to pick up each micro-inveter in each row of micro-inverters with splices made to a single bare 6AWG made with irreversible splices. At the rooftop junction box, the GEC could be irreversibly spliced to an 8AWG green insulated conductor to run unbroken to the grounding busbar in the service equipment. While this may not be in agreement with the Enphase application note, I believe it meets the intent and letter of the NEC as clarified in the 2011 NEC 690.47(C). While using the WEEBs in the GEC circuit may not cause a life or death issue, it is absolutely open to being questioned by the electrical inspector. If the electrical inspector decides it is wrong--it is wrong. If you or the field inspector appeals to me or an expert like John Wiles, we will state what I have stated above. Then you would have to remove all the modules, throw away the WEEBs, put in new WEEBs with the new bare copper 6AWG and reinstall the modules--it just ain't worth it. 690.47(D) was removed from the 2011 NEC because it was primarily for lightning protection (not a safety issue according to the NEC) and was ambiguously worded with respect to residential rooftop PV systems. If the local jurisdiction requires the additional electrode, install a j-box at the point near ground-level where the conduit transitions from vertical to horizontal and install an irreversibly spliced bare 6AWG to run from the j-box to a ground rod below the j-box--mildly painful, but very doable. Bill. Bill Brooks, PE Principal Brooks Engineering 873 Kells Circle Vacaville, CA 95688 707-332-0761 (office and mobile) 707-451-7739 (fax) b...@brooksolar.com (email) www.brooksolar.com (web) ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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] Mage NABCEP Training
Hello Wrenches, Does anyone have experience with Mage NABCEP course prep? Thanks in advance, Dean -- Dean T. Newberry Talbott Solar Radiant Homes Inc. 397 B Street Davis, CA 95616 T: 530 753-1900 F: 530 758-2050 E: de...@talbottsolar.com W: http://www.TalbottSolar.com/ ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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] Mage NABCEP Training
Dean, No experience with Mage but the two prep courses I took were a waist of time and money (IMHO). Find yourself a one day John Wiles seminar for $100, that is well worth it. Study, study, study. I would set aside 3-4 hours a day until test time. Become quick and sure at referencing the NEC, they supply you with one at the test. Buy the Casio FX260 calculator, again supplied at the test, and become familiar with it. Use the NABCEP study guide. Get your PV math down pat. Read Dunlop's book. I failed it because I did not study hard enough. It's really not that difficult a test to pass (70 grade) if you know the material. I will send you my prep material if you want to use it as a guideline. Good luck. I'm the guy who whined about the NABCEP ad and kind of regret doing so. My apologies to all who studied hard and passed the test. Larry Liesner System Design Elektron Solar, LLC 16 Ketchum St. Westport, CT 06880 203-557-3127 (office) 203-644-2404 (cell) 203-549-0977 (fax) wire...@gmail.com On Fri, Mar 4, 2011 at 11:27 AM, Dean T. Newberry de...@dcn.org wrote: Hello Wrenches, Does anyone have experience with Mage NABCEP course prep? Thanks in advance, Dean -- Dean T. Newberry Talbott Solar Radiant Homes Inc. 397 B Street Davis, CA 95616 T: 530 753-1900 F: 530 758-2050 E: de...@talbottsolar.com W: http://www.TalbottSolar.com/ ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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 Options 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] grounding the Enphase inverter
System grounding requirements. -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Frye Sent: Friday, March 04, 2011 7:51 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter The interesting thing to me is the underlying assumption in the Code that a GEC is requried for grid-tied inverters at all. Why isn't EG sufficient for function and safety. Which of the following common electrical equipment has the same requirement: UPS Motors with regenerative energy disipators DC power supplies Standby generators ?? Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 www.berkeleysolar.com -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Bill Brooks Sent: Thursday, March 03, 2011 10:48 PM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter All, While there is ambiguity in the 2008 NEC in 690.47(C) on the requirements for system grounding of PV systems, the 2011 NEC in 690.47(C) clarifies the intent. While an application note from Enphase may state that WEEBs can be used as part of the grounding electrode system, I disagree with this concept and do not believe it meets the requirements or intent of the NEC as clarified in the 2011 NEC. The problem with a grounded PV inverter is that it requires a grounding electrode conductor (GEC) from the grounding point (on the inverter) to the grounding electrode. The 2008 and 2011 NEC allows for that connection to be terminated at the grounding bar in the service panel supplying the micro-inverters. There is no problem with using the WEEB to bond the rails to the modules and then to the Enphase Micro-inverter. From the micro-inverter, a bare 6AWG could be run to pick up each micro-inveter in each row of micro-inverters with splices made to a single bare 6AWG made with irreversible splices. At the rooftop junction box, the GEC could be irreversibly spliced to an 8AWG green insulated conductor to run unbroken to the grounding busbar in the service equipment. While this may not be in agreement with the Enphase application note, I believe it meets the intent and letter of the NEC as clarified in the 2011 NEC 690.47(C). While using the WEEBs in the GEC circuit may not cause a life or death issue, it is absolutely open to being questioned by the electrical inspector. If the electrical inspector decides it is wrong--it is wrong. If you or the field inspector appeals to me or an expert like John Wiles, we will state what I have stated above. Then you would have to remove all the modules, throw away the WEEBs, put in new WEEBs with the new bare copper 6AWG and reinstall the modules--it just ain't worth it. 690.47(D) was removed from the 2011 NEC because it was primarily for lightning protection (not a safety issue according to the NEC) and was ambiguously worded with respect to residential rooftop PV systems. If the local jurisdiction requires the additional electrode, install a j-box at the point near ground-level where the conduit transitions from vertical to horizontal and install an irreversibly spliced bare 6AWG to run from the j-box to a ground rod below the j-box--mildly painful, but very doable. Bill. Bill Brooks, PE Principal Brooks Engineering 873 Kells Circle Vacaville, CA 95688 707-332-0761 (office and mobile) 707-451-7739 (fax) b...@brooksolar.com (email) www.brooksolar.com (web) ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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 Options 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] grounding the Enphase inverter
Bill: Other than complying just because this is a rule that has to be followed, is there any logical foundation to the requirement to provide a #8 ground to a circuit with OC protection at 20 amps? If there is a valid safety reason, then let's all get behind it and become adept at providing this GEC. If the rule makes no sense, let's advocate that it be changed. What is the reason for providing this GEC to an inverter? Thanks in advance. William Miller At 09:51 AM 3/4/2011, you wrote: System grounding requirements. -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Frye Sent: Friday, March 04, 2011 7:51 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter The interesting thing to me is the underlying assumption in the Code that a GEC is requried for grid-tied inverters at all. Why isn't EG sufficient for function and safety. Which of the following common electrical equipment has the same requirement: UPS Motors with regenerative energy disipators DC power supplies Standby generators ?? Mark Frye ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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] grounding the Enphase inverter
To bring the discussion back around to Enphase, at least in the case of the D380, there is a green wire in the AC Interconnect. This is irreversibly crimped to a GEC in the rooftop J-Box. The same question applies: why a GEC to each microinverter case, and/or why require an inverter-rail WEEB at all? Jason Szumlanski Fafco Solar From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of William Miller Sent: Friday, March 04, 2011 12:58 PM To: RE-wrenches Subject: Re: [RE-wrenches] grounding the Enphase inverter Bill: Other than complying just because this is a rule that has to be followed, is there any logical foundation to the requirement to provide a #8 ground to a circuit with OC protection at 20 amps? If there is a valid safety reason, then let's all get behind it and become adept at providing this GEC. If the rule makes no sense, let's advocate that it be changed. What is the reason for providing this GEC to an inverter? Thanks in advance. William Miller At 09:51 AM 3/4/2011, you wrote: System grounding requirements. -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Frye Sent: Friday, March 04, 2011 7:51 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter The interesting thing to me is the underlying assumption in the Code that a GEC is requried for grid-tied inverters at all. Why isn't EG sufficient for function and safety. Which of the following common electrical equipment has the same requirement: UPS Motors with regenerative energy disipators DC power supplies Standby generators ?? Mark Frye ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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] grounding the Enphase inverter
Yes, but that comes from the assumption that the inverter constitutes a seperately derived system. But if the only purpose or use of the DC power derived from the DC system is to drive the AC side of the inverter, how closely does it realy resemble a classic seperately derived system. As opposed to having the DC power source actually run DC utilization equipment such as motors and appliances. It is interesting that the very language in the code descibes the inverter as utility interactive. Is it really correct to describe a UL174 inverter operating only in parrallel with the utility as a seperately derived system? To what degree has the Code failed to reflect the evolution of technology? Yes, battery-based inverter systems capable of powering a facility in the absense of a utility power souce do in fact become a seperately derived system which need to have a GEC. But to impose the same requirement on an inverter which cannot possibly deliver power to anything other than a system that already has a GEC seems to me to be a crude cookie cutter response to a far more complex situation. We have put the complexity into the inverters. Recogonizing this we see that we don't need the complexity in wiring? Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 www.berkeleysolar.com -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Bill Brooks Sent: Friday, March 04, 2011 9:51 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter System grounding requirements. -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Frye Sent: Friday, March 04, 2011 7:51 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter The interesting thing to me is the underlying assumption in the Code that a GEC is requried for grid-tied inverters at all. Why isn't EG sufficient for function and safety. Which of the following common electrical equipment has the same requirement: UPS Motors with regenerative energy disipators DC power supplies Standby generators ?? Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 www.berkeleysolar.com -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Bill Brooks Sent: Thursday, March 03, 2011 10:48 PM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter All, While there is ambiguity in the 2008 NEC in 690.47(C) on the requirements for system grounding of PV systems, the 2011 NEC in 690.47(C) clarifies the intent. While an application note from Enphase may state that WEEBs can be used as part of the grounding electrode system, I disagree with this concept and do not believe it meets the requirements or intent of the NEC as clarified in the 2011 NEC. The problem with a grounded PV inverter is that it requires a grounding electrode conductor (GEC) from the grounding point (on the inverter) to the grounding electrode. The 2008 and 2011 NEC allows for that connection to be terminated at the grounding bar in the service panel supplying the micro-inverters. There is no problem with using the WEEB to bond the rails to the modules and then to the Enphase Micro-inverter. From the micro-inverter, a bare 6AWG could be run to pick up each micro-inveter in each row of micro-inverters with splices made to a single bare 6AWG made with irreversible splices. At the rooftop junction box, the GEC could be irreversibly spliced to an 8AWG green insulated conductor to run unbroken to the grounding busbar in the service equipment. While this may not be in agreement with the Enphase application note, I believe it meets the intent and letter of the NEC as clarified in the 2011 NEC 690.47(C). While using the WEEBs in the GEC circuit may not cause a life or death issue, it is absolutely open to being questioned by the electrical inspector. If the electrical inspector decides it is wrong--it is wrong. If you or the field inspector appeals to me or an expert like John Wiles, we will state what I have stated above. Then you would have to remove all the modules, throw away the WEEBs, put in new WEEBs with the new bare copper 6AWG and reinstall the modules--it just ain't worth it. 690.47(D) was removed from the 2011 NEC because it was primarily for lightning protection (not a safety issue according to the NEC) and was ambiguously worded with respect to residential rooftop PV systems. If the local jurisdiction requires the additional electrode, install a j-box at the point near ground-level where the conduit transitions from vertical to horizontal and install an irreversibly spliced bare 6AWG to run from the j-box to a ground rod below the j-box--mildly painful, but very doable. Bill. Bill Brooks, PE
[RE-wrenches] Spot welding PV's to rails for theft prevention: bad idea?
Hello, we mounted some PV onesy modules as high as we could reach without a man-lift, but an enterprising thief could reach just as high. The side of pole mounts hold the bolt heads captive so I bought some aluminum breakaway nuts. However the nuts have a big diameter which would not fit inside the Kyocera PV frames. Has anyone tried spot welding the PV frames direct to the aluminum rails to which they are mounted? Would this over stress the glass laminate or cause other problems? I realize this would void the Kyo warranty but nothing voids system performance like a stolen PV module. Happy Friday, Mick Abraham, Proprietor www.abrahamsolar.com Voice: 970-731-4675 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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] Spot welding PV's to rails for theft prevention: bad idea?
Mick Solar World welds their frame corners, but use a laser with high precision and very low heat. I have seen racks in Haiti welded instead of bolted to keep people from walking off with the entire rack. I would not recommend welding a module frame, Too risky and would probably void warranty. Of course you can not warranty a stolen module either! However welding a cross bar to the racking that locks the module in place may be a reasonable alternative because you could weld away from the frame. Use asbestos protection to keep harmful heat away from the module. That just might work, would be harder to replace, but harder to steal also...although some thief would still find a way around it! Now all we need is a way to protect against drunk hunters shooting holes in the modules for target practice! Bill On Fri, Mar 4, 2011 at 11:22 AM, Mick Abraham m...@abrahamsolar.com wrote: Hello, we mounted some PV onesy modules as high as we could reach without a man-lift, but an enterprising thief could reach just as high. The side of pole mounts hold the bolt heads captive so I bought some aluminum breakaway nuts. However the nuts have a big diameter which would not fit inside the Kyocera PV frames. Has anyone tried spot welding the PV frames direct to the aluminum rails to which they are mounted? Would this over stress the glass laminate or cause other problems? I realize this would void the Kyo warranty but nothing voids system performance like a stolen PV module. Happy Friday, Mick Abraham, Proprietor www.abrahamsolar.com Voice: 970-731-4675 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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 -- Bill Hoffer PE NABCEP Certified Solar PV Installer™ Sunergy Engineering Services PLLC 2504 Columbia Ave NW East Wenatchee WA 98802-3941 suneng...@gmail.com (509)470-7762 Cell(509)679-6165 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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] grounding the Enphase inverter
Excellent post Mark. We spend way too much time as an industry worrying about these mundane grounding (and over grounding) issues, when there are very little actual safety issues involved. Meanwhile, we're missing the real safety problems. (recent commercial system fires??) I can't wait for our industry to mature to the point that we treat grounding as other industries do. I don't see any technical reason (besides onerous NEC language) that would prevent us from safely grounding the Enphase inverters like any other permanently mounted AC appliance (#12 EGC on a 20A circuit, run with the conductors, forget about all the irreversible splices, ad nauseum) I respect BIll's points, too, as he is laying down the actual law as currently written to keep us out of trouble with the AHJs. (Thanks BIll) But, as with numerous other code issues over the years, the code needs to change to catch up with technology and the actual safety issues. (remember when we had to ground battery based inverters with a 4/0 cable? ugh!) Let's all work together to make micro-inverter grounding more sensible too. R. Walters r...@solarray.com Solar Engineer On Mar 4, 2011, at 11:53 AM, Mark Frye wrote: Yes, but that comes from the assumption that the inverter constitutes a seperately derived system. But if the only purpose or use of the DC power derived from the DC system is to drive the AC side of the inverter, how closely does it realy resemble a classic seperately derived system. As opposed to having the DC power source actually run DC utilization equipment such as motors and appliances. It is interesting that the very language in the code descibes the inverter as utility interactive. Is it really correct to describe a UL174 inverter operating only in parrallel with the utility as a seperately derived system? To what degree has the Code failed to reflect the evolution of technology? Yes, battery-based inverter systems capable of powering a facility in the absense of a utility power souce do in fact become a seperately derived system which need to have a GEC. But to impose the same requirement on an inverter which cannot possibly deliver power to anything other than a system that already has a GEC seems to me to be a crude cookie cutter response to a far more complex situation. We have put the complexity into the inverters. Recogonizing this we see that we don't need the complexity in wiring? Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 www.berkeleysolar.com -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Bill Brooks Sent: Friday, March 04, 2011 9:51 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter System grounding requirements. -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Frye Sent: Friday, March 04, 2011 7:51 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter The interesting thing to me is the underlying assumption in the Code that a GEC is requried for grid-tied inverters at all. Why isn't EG sufficient for function and safety. Which of the following common electrical equipment has the same requirement: UPS Motors with regenerative energy disipators DC power supplies Standby generators ?? Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 www.berkeleysolar.com -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Bill Brooks Sent: Thursday, March 03, 2011 10:48 PM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter All, While there is ambiguity in the 2008 NEC in 690.47(C) on the requirements for system grounding of PV systems, the 2011 NEC in 690.47(C) clarifies the intent. While an application note from Enphase may state that WEEBs can be used as part of the grounding electrode system, I disagree with this concept and do not believe it meets the requirements or intent of the NEC as clarified in the 2011 NEC. The problem with a grounded PV inverter is that it requires a grounding electrode conductor (GEC) from the grounding point (on the inverter) to the grounding electrode. The 2008 and 2011 NEC allows for that connection to be terminated at the grounding bar in the service panel supplying the micro-inverters. There is no problem with using the WEEB to bond the rails to the modules and then to the Enphase Micro-inverter. From the micro-inverter, a bare 6AWG could be run to pick up each micro-inveter in each row of micro-inverters with splices made to a single bare 6AWG made with irreversible splices. At the rooftop junction box, the GEC could be irreversibly
Re: [RE-wrenches] Spot welding PV's to rails for theft prevention: bad idea?
From the bit of aluminum welding I've done (MIG not the preferred TIG) I'd say it would be pretty hard to do without damaging the laminate. I actually successfully welded attachments to salvage modules back in the 90s. Also the alloys are probably different between the module and rail, so even if you welded it without damage, the weld probably would just pop off when the industrious thief started twisting and pulling on it. I'd look at using a frame of angle iron over the module edges that captures the module. I've seen racks built this way, and then the 2 frames (upper and lower) can be welded together, or locked with a hasp and padlock) No warranty voided either. The breakaway nuts are a waste, we used them for a while, broke the special tool on a job where we needed to remove a module, and within seconds my very trusty old assistant Russ had the expensive security hardware off with a Leatherman, and a vice grips. R. Walters r...@solarray.com Solar Engineer On Mar 4, 2011, at 12:22 PM, Mick Abraham wrote: Hello, we mounted some PV onesy modules as high as we could reach without a man-lift, but an enterprising thief could reach just as high. The side of pole mounts hold the bolt heads captive so I bought some aluminum breakaway nuts. However the nuts have a big diameter which would not fit inside the Kyocera PV frames. Has anyone tried spot welding the PV frames direct to the aluminum rails to which they are mounted? Would this over stress the glass laminate or cause other problems? I realize this would void the Kyo warranty but nothing voids system performance like a stolen PV module. Happy Friday, Mick Abraham, Proprietor www.abrahamsolar.com Voice: 970-731-4675 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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 Options 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] grounding the Enphase inverter
I would like to remember us all back to 16-20 years ago when we were required to use a ground cable equal to the largest conductor in the system. This was typically sized by the inverter cable at 4/0 copper. I gotta say that was a really dumb rule. At that time we were to not create ground loops. One point of ground was the maximum for the DC circuit. Today's grounding requirements create ground loops [ in my opinion]. I wonder where this topic will ground out, 10 years from now. I am delighted to be done with 4/0 ground cable though. Dana Orzel Great Solar Works, Inc E - d...@solarwork.com V - 970.626.5253 F - 970.626.4140 C - 970.209.4076 web - www.solarwork.com Responsible Technologies for Responsible People since 1988 Do not ever believe anything, but seriously trust through action. ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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] Spot welding PV's to rails for theft prevention: bad idea?
Mick, I partially belt sanded off one side of the security nut flange on the cone part just enough to make it fit on one install. They are still there. Be sure to use gloves that belt sander is rough on the fingers. I resorted to holding with a Vice grip wrench. Even then they flew quite a distance if they came loose. Dana Orzel Great Solar Works, Inc E - d...@solarwork.com V - 970.626.5253 F - 970.626.4140 C - 970.209.4076 web - www.solarwork.com Responsible Technologies for Responsible People since 1988 Do not ever believe anything, but seriously trust through action. From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mick Abraham Sent: Friday, March 04, 2011 12:22 PM To: RE-wrenches Subject: [RE-wrenches] Spot welding PV's to rails for theft prevention: bad idea? Hello, we mounted some PV onesy modules as high as we could reach without a man-lift, but an enterprising thief could reach just as high. The side of pole mounts hold the bolt heads captive so I bought some aluminum breakaway nuts. However the nuts have a big diameter which would not fit inside the Kyocera PV frames. Has anyone tried spot welding the PV frames direct to the aluminum rails to which they are mounted? Would this over stress the glass laminate or cause other problems? I realize this would void the Kyo warranty but nothing voids system performance like a stolen PV module. Happy Friday, Mick Abraham, Proprietor www.abrahamsolar.com Voice: 970-731-4675 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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] Spot welding PV's to rails for theft prevention: bad idea?
Mick, Direct Power did this some years ago on a piece of Interstate roadside art. I think it worked quite well to discourage theft. You might want to call DPW for info; I'd talk with Jeff. Allan at Positive Energy On Mar 4, 2011 12:22 PM, Mick Abraham m...@abrahamsolar.com wrote: Hello, we mounted some PV onesy modules as high as we could reach without a man-lift, but an enterprising thief could reach just as high. The side of pole mounts hold the bolt heads captive so I bought some aluminum breakaway nuts. However the nuts have a big diameter which would not fit inside the Kyocera PV frames. Has anyone tried spot welding the PV frames direct to the aluminum rails to which they are mounted? Would this over stress the glass laminate or cause other problems? I realize this would void the Kyo warranty but nothing voids system performance like a stolen PV module. Happy Friday, Mick Abraham, Proprietor www.abrahamsolar.com Voice: 970-731-4675 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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] Spot welding PV's to rails for theft prevention: bad idea?
The BP oil company installed a ton of solar arrays for cathodic protection in the desert near Bakerfield in the 80s and 90s. They used Arco and Kyocera modules at ~50 watts each. They had a terrible time with theft, so they began welding the modules to the racks and the racks to the steel structures. However, the thieves persisted, by cutting the steel substructures with torches to get the modules. Eventually, BP brought in the utility power. Too bad. The good thing was that I got to buy the remaining 600 used modules for a good price. Nick Soleil Project Manager Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953 Cell: 707-321-2937 Office: 707-789-9537 Fax:707-769-9037 From: Allan Sindelar al...@positiveenergysolar.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Fri, March 4, 2011 4:06:53 PM Subject: Re: [RE-wrenches] Spot welding PV's to rails for theft prevention: bad idea? Mick, Direct Power did this some years ago on a piece of Interstate roadside art. I think it worked quite well to discourage theft. You might want to call DPW for info; I'd talk with Jeff. Allan at Positive Energy On Mar 4, 2011 12:22 PM, Mick Abraham m...@abrahamsolar.com wrote: Hello, we mounted some PV onesy modules as high as we could reach without a man-lift, but an enterprising thief could reach just as high. The side of pole mounts hold the bolt heads captive so I bought some aluminum breakaway nuts. However the nuts have a big diameter which would not fit inside the Kyocera PV frames. Has anyone tried spot welding the PV frames direct to the aluminum rails to which they are mounted? Would this over stress the glass laminate or cause other problems? I realize this would void the Kyo warranty but nothing voids system performance like a stolen PV module. Happy Friday, Mick Abraham, Proprietor www.abrahamsolar.com Voice: 970-731-4675 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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] grounding the Enphase inverter
Hi Mark, Ray, and wrenches: I agree that the grounding requirements can be onerous, but I have to interject that most generator manufacturers do specify a dedicated grounding electrode conductor. Also, I do not feel that a #8 ground is too big. Probably unnecessary 99% of the time, but with all the shorts and arced connections that I have found in j-boxes, I feel good about running a larger grounding conductor. With regard to the Enphase grounded with WEEB; which I have done many times, I would recommend spelling out the exact grounding method for the micro-inverters on the permit package. We should have this issue resolved before installation begins. Nick Soleil Project Manager Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953 Cell: 707-321-2937 Office: 707-789-9537 Fax:707-769-9037 From: Mark Frye ma...@berkeleysolar.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Fri, March 4, 2011 10:53:46 AM Subject: Re: [RE-wrenches] grounding the Enphase inverter Yes, but that comes from the assumption that the inverter constitutes a seperately derived system. But if the only purpose or use of the DC power derived from the DC system is to drive the AC side of the inverter, how closely does it realy resemble a classic seperately derived system. As opposed to having the DC power source actually run DC utilization equipment such as motors and appliances. It is interesting that the very language in the code descibes the inverter as utility interactive. Is it really correct to describe a UL174 inverter operating only in parrallel with the utility as a seperately derived system? To what degree has the Code failed to reflect the evolution of technology? Yes, battery-based inverter systems capable of powering a facility in the absense of a utility power souce do in fact become a seperately derived system which need to have a GEC. But to impose the same requirement on an inverter which cannot possibly deliver power to anything other than a system that already has a GEC seems to me to be a crude cookie cutter response to a far more complex situation. We have put the complexity into the inverters. Recogonizing this we see that we don't need the complexity in wiring? Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 www.berkeleysolar.com -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Bill Brooks Sent: Friday, March 04, 2011 9:51 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter System grounding requirements. -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Frye Sent: Friday, March 04, 2011 7:51 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter The interesting thing to me is the underlying assumption in the Code that a GEC is requried for grid-tied inverters at all. Why isn't EG sufficient for function and safety. Which of the following common electrical equipment has the same requirement: UPS Motors with regenerative energy disipators DC power supplies Standby generators ?? Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 www.berkeleysolar.com -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Bill Brooks Sent: Thursday, March 03, 2011 10:48 PM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter All, While there is ambiguity in the 2008 NEC in 690.47(C) on the requirements for system grounding of PV systems, the 2011 NEC in 690.47(C) clarifies the intent. While an application note from Enphase may state that WEEBs can be used as part of the grounding electrode system, I disagree with this concept and do not believe it meets the requirements or intent of the NEC as clarified in the 2011 NEC. The problem with a grounded PV inverter is that it requires a grounding electrode conductor (GEC) from the grounding point (on the inverter) to the grounding electrode. The 2008 and 2011 NEC allows for that connection to be terminated at the grounding bar in the service panel supplying the micro-inverters. There is no problem with using the WEEB to bond the rails to the modules and then to the Enphase Micro-inverter. From the micro-inverter, a bare 6AWG could be run to pick up each micro-inveter in each row of micro-inverters with splices made to a single bare 6AWG made with irreversible splices. At the rooftop junction box, the GEC could be irreversibly spliced to an 8AWG green insulated conductor to run unbroken to the grounding busbar in the service equipment. While this may not be in agreement with the Enphase application note, I believe it meets the intent and letter of the
Re: [RE-wrenches] grounding the Enphase inverter
The better question is why is there a solid ground in the inverter. As I stated before-we are talking about system grounding-with 100+ years of electrical history and precedent to back it up. System grounding rules are not open to a lot of discussion. That is why my recommendation since before they released their first product was to go ungrounded. Just because it is a pain, and we think there is no technical reason, does not mean we can ignore the rules. As I said in my post, this is not really a safety issue, but it is very much a compliance issue. System grounding is so much a part of our electrical culture, that tiny electrical supplies like PV microinverters were never really considered. Any installer can use the don't ask, don't tell method of installation, but once we start down that path, the ability of the human mind to justify actions is limitless. We have to go back to why we ground systems in the first place. It is to prevent the voltage on the system conductors from wondering too far from ground potential. There are other ways to prevent this, but in the U.S. we mostly use conductors (not a variety of conductive materials without clear ratings). The advent of the WEEB, with all its great benefits, does not fundamentally change system grounding. The sooner we get PV systems ungrounded, or resistively grounded, the better the whole U.S. PV industry will be. To that end, everyone should move to PV Cable/Wire and modules with PV Cable/Wire so we are using better products than USE-2 and we can easily transition to ungrounded inverters as they become more available. We already have several so now is not a bad time to start thinking about it. Bill. From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of William Miller Sent: Friday, March 04, 2011 9:58 AM To: RE-wrenches Subject: Re: [RE-wrenches] grounding the Enphase inverter Bill: Other than complying just because this is a rule that has to be followed, is there any logical foundation to the requirement to provide a #8 ground to a circuit with OC protection at 20 amps? If there is a valid safety reason, then let's all get behind it and become adept at providing this GEC. If the rule makes no sense, let's advocate that it be changed. What is the reason for providing this GEC to an inverter? Thanks in advance. William Miller At 09:51 AM 3/4/2011, you wrote: System grounding requirements. -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Frye Sent: Friday, March 04, 2011 7:51 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] grounding the Enphase inverter The interesting thing to me is the underlying assumption in the Code that a GEC is requried for grid-tied inverters at all. Why isn't EG sufficient for function and safety. Which of the following common electrical equipment has the same requirement: UPS Motors with regenerative energy disipators DC power supplies Standby generators ?? Mark Frye ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options 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
