Re: [RE-wrenches] Starting fires for fun with string wiring
Jeff, In my limited knowledge of this issue, there is no doubt DC arcs have the capacity to burn and are difficult to extinguish, and good wiring practices are essential at these elevated voltages. However, you need to distinguish between high temperature arcs which can burn, and Arc-Flash risks which require special PPE and procedures. In order for the there to be a serious risk of Arc-Flash, there has to be both a high voltage such as 480V and a very high source current, in the order of 65,000 Symmetrical Amperes, such as you find near a HT/LT transformer. The extremely high current is what creates the explosive heating of the air. Solar PV, being current limited, has high enough DC voltages but does not have anywhere near the current capacity and cannot cause arc flash. Chris ___ 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] Starting fires for fun with string wiring
The Midnite Classic controllers come with arc-fault protection built in. -- Dan Fink, Executive Director; Otherpower Buckville Energy Consulting Buckville Publications LLC NABCEP / IREC accredited Continuing Education Providers 970.672.4342 (voicemail) On Mon, Mar 12, 2012 at 10:09 AM, JRQ quackkc...@yahoo.com wrote: I've been wondering about this since I read over the 2011 code: Are there any listed DC arc-flash products on the market yet, or scheduled to come to market within the next year? Also: will arc-flash protection come in the form of breakers that need to be installed externally, or will it be something internal to the inverters or charge controllers to which source circuits are wired? Will they need to be installed on each string, or can they function on a combined circuit? Do systems with DC optimizers or with micro-inverters have arc-fault protection at the module level? Jeffrey Quackenbush NABCEP Certified PV Installer Peripatetic Solar Technician ___ 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] Need info resource re wind hail damage
Hi Allen For what it is worth I had a house in Puerto Rico with two modules on the roof. Hurricane Marilyn blew the roof off of the house but the panels stayed on for the ride. The roof landed upside down pinning the modules under the debris. These the UniSolar UPM880 (non glass) and they survived with minor cosmetic damage and still measured full output after they were salvaged. In Florida we were hit hard again by Hurricane Charlie, with 145 mph winds reported nearby our home. This time the roof stayed on and again so did the pv panels. We were the only place with power that first night since all the grid was blown down. So, modules can survive some of the big winds if fixed well enough and if you lucky. I have been lucky since none of our family or friends were (physically) hurt in these storms. Steve McCarney Solar Electric Light Fund On Thu, Mar 8, 2012 at 11:13 PM, Allan Sindelar al...@positiveenergysolar.com wrote: ** Fellow Wrenches, We have an engineer-type whose wife wants badly to do a PV system, but he puts up barriers. In her words: Well, I don't know how long ago it was, surely old technology by now, but some experimental solar panels at Sandia Labs were shattered by hail and it caused a big controversy. My husband says it turned him off solar.It comes up every time I talk to him. Either he is complaining about the wind or the hail or whatever. I get to respond to this, and am seeking specific assistance: Can anyone send me a link to any formal standards, or reports of aggregated field experiences, indicating that wind and hail (not to leave out whatever) are not issues of concern when PV modules are installed correctly? Anything that came from Sandia Labs would be ideal, but it just has to be reputable enough to satisfy a grouchy retired national lab engineer. Web links, reports, product warranties, etc. - all good. Thank you in advance. Allan -- *Allan Sindelar* *al...@positiveenergysolar.com* al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician *Positive Energy, Inc.* 3201 Calle Marie Santa Fe, New Mexico 87507 *505 424-1112* *www.positiveenergysolar.com* http://www.positiveenergysolar.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] Starting fires for fun with string wiring
SMA will have AFCI protection built into the inverters. It is integrated into the inside of the inverter, so there are no extra components to install. They work off of the combined circuit to offer the AFCI protection. The units are listed but, won't be available for another couple of months. We are in the field testing stage now. Thanks SMA America, LLC Steve Jefferson Sr. Technical Service Specialist, Sunny Family 6020 West Oaks Blvd, Suite 300 Rocklin, CA 95765 - 3714 U.S.A. Tel: +1 916 625 0870 Fax: +1 916 624-2445 Service Line +1 877 697 6283 (Toll Free) Email: steve.jeffer...@sma-america.com www.SMA-America.comhttp://www.sma-america.com/ This email and any attachments thereto may contain SMA America, LLC confidential, privileged and private material for the sole use of the intended recipient. Any review, copying, or distribution of this email (or any attachments thereto) by others is strictly prohibited. If you are not the intended recipient, please contact the sender immediately and permanently delete the original and any copies of this email and any attachments thereto. Thank you. From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of JRQ Sent: Monday, March 12, 2012 9:09 AM To: RE-wrenches Subject: Re: [RE-wrenches] Starting fires for fun with string wiring I've been wondering about this since I read over the 2011 code: Are there any listed DC arc-flash products on the market yet, or scheduled to come to market within the next year? Also: will arc-flash protection come in the form of breakers that need to be installed externally, or will it be something internal to the inverters or charge controllers to which source circuits are wired? Will they need to be installed on each string, or can they function on a combined circuit? Do systems with DC optimizers or with micro-inverters have arc-fault protection at the module level? Jeffrey Quackenbush NABCEP Certified PV Installer Peripatetic Solar Technician From: b...@midnitesolar.com b...@midnitesolar.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Monday, March 12, 2012 12:37 AM Subject: Re: [RE-wrenches] Starting fires for fun with string wiring On 3/11/2012 9:26 PM, Kent Osterberg wrote: boB, Most local codes, have granted a delay on implementing arc fault protection. Also, the code only requires series faults to be cleared. I mentioned this because arc fault is already in the 2011 NEC whether it is adopted or not. I have a feeling that Jeff was referring to some of the changes that are in the works for 2014. As far as I understand, the code cannot be required unless there are products that fill the requirement. Also, the UL spec was not quite complete, but that didn't stop many of us from starting to work on it before even 2011 code was out, even releasing something, even if it did not have a spec to test to yet. This code is going to get interesting for sure. It's also going to make installations more expensive so it's good that PV prices are falling some to help make up for it ! boB Kent Osterberg Blue Mountain Solar, Inc. www.bluemountainsolar.comhttp://www.bluemountainsolar.com t: 541-568-4882 On 3/11/2012 8:28 PM, b...@midnitesolar.commailto:b...@midnitesolar.com wrote: On 3/11/2012 7:35 PM, Jeff Yago wrote: I just sent a post about people not understanding the dangers of fire in the array strings between the modules and before the combiner because its high voltage DC and there are no fuses or circuit breakers to shut down the power source (at least not until the next code requires arc-fault sensing!). Jeff, Arc fault was required as of NEC2011. boB Anyway, we have a 3 string, 4-module per string off-grid test system behind the shop wired for 88 volts peak into a charge controller and 24 volt battery bank. Last week as a test I temporarily disconnected the charge controller and re-wired the 3 strings together into a single string of 12 modules with a 264 volt open circuit voltage DC output at about 7 amps at dead short. When compared with most grid-tie systems, this is not that high a voltage or current, so what happened next would be far worse for a larger voltage array. I took a 2 x 4 and attached USE-2 single conductor wires using wire staples with the (+) and (-) cables routed side by side and down the 2 x 4. At the lower wire staple, I deliberately nailed through the wire insulation which nicked the insulation but did not cut the wires. After routing the array power through these test wires nothing happened since the wire staple was not making a very good contact with the bare wire at the insulation nick. I then moved the wires slowly from side to side by hand, which could have been caused in a real installation from wind, temperature expansion/contraction, somebody pulling on them, or just the action of age on the nicked wire insulation. Anyway,
Re: [RE-wrenches] Starting fires for fun with string wiring
Just a point of clarification since this can be a danger to installers. Chris Mason correctly pointed out that arc-flash and arc-fault are different and my post may not have made this clear. However, he stated that arc-flash requires at least 480 volts which I strongly disagree. I had an arc-flash inside a Kohler 240 VAC transfer switch happen when I started to remove the cover and a small metal shaving fell down across the buss bars inside. The explosion bowed out the cover and the sound was like a shotgun. I then went through some arc-flash training by the military before inspecting several hundred electrical panels on a military base and was told this can happen at much lower voltages than the generally accepted 480 volts. To all, regardless of high voltage AC or DC, arc-faults and arc-flash are still not generally understood by some electricians working on these higher voltage systems and there are safety equipment made to protect hands and faces which can receive some really bad burns. Please review proper safety procedures for working on this equipment. Jeff yago ___ 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] Starting fires for fun with string wiring
I didn't mean to suggest arc flash could only happen at 480V, just that it is less likely to be very serious at lower voltages. The PPE needed for work on 480V switchgear looks like the person is in the hot part of a nuclear reactor. Scary stuff. -- Chris Mason ___ 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] solar accumulation panel
Nick, I don't see that name (or an alternate term) in the report on proposals (do a search for 120% or 4-375a). http://www.nfpa.org/Assets/files/AboutTheCodes/70/70_A2013_NEC-P04_ROPballot.pdf On 2012/3/9 16:45, Nick Vida wrote: Hello, I was wondering if any of you wise wrenches know if 'solar accumulation panel' is still the name proposed to be used in the NEC. I think I remember Bill Brooks mentioning that they couldn't get it in for 2011, but that it will probably be good for 2014. I was wondering because here in Los Angeles they are revising the standard plan and they have an unusualname for the device, so as it is still a draft, I would us like to align with the future, if at all possible. Thanks wrenches! Nick Vida ___ 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] Starting fires for fun with string wiring
MidNite also offers AFCI protection in their disconnecting combiner boxes. The switches can also be hard-wired to the MidNite Birdhouse which allows ground-level personnel to remotely disconnect the PV output circuit at the combiner. http://www.midnitesolar.com/pdfs/multi1_inside_outside.pdf For a brighter energy future, Andrew Truitt MSc., LEED GA NABCEP Certified PV Installer™ (ID# 032407-66) Principal Truitt Renewable Energy Consulting (202) 486-7507 http://www.linkedin.com/pub/andrew-truitt/8/622/713 Don't get me wrong: I love nuclear energy! It's just that I prefer fusion to fission. And it just so happens that there's an enormous fusion reactor safely banked a few million miles from us. It delivers more than we could ever use in just about 8 minutes. And it's wireless! ~William McDonough On Mon, Mar 12, 2012 at 9:13 AM, Dan Fink danbo...@gmail.com wrote: The Midnite Classic controllers come with arc-fault protection built in. -- Dan Fink, Executive Director; Otherpower Buckville Energy Consulting Buckville Publications LLC NABCEP / IREC accredited Continuing Education Providers 970.672.4342 (voicemail) On Mon, Mar 12, 2012 at 10:09 AM, JRQ quackkc...@yahoo.com wrote: I've been wondering about this since I read over the 2011 code: Are there any listed DC arc-flash products on the market yet, or scheduled to come to market within the next year? Also: will arc-flash protection come in the form of breakers that need to be installed externally, or will it be something internal to the inverters or charge controllers to which source circuits are wired? Will they need to be installed on each string, or can they function on a combined circuit? Do systems with DC optimizers or with micro-inverters have arc-fault protection at the module level? Jeffrey Quackenbush NABCEP Certified PV Installer Peripatetic Solar Technician ___ 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
