Thanks Dave, I think I was thinking about "on" in the wrong way. -N
On Tue, Apr 15, 2014 at 11:18 AM, Dave Click <davecl...@fsec.ucf.edu> wrote: > Nathan, 690.12 only applies to "PV system circuits installed on or in > buildings" so that might be your answer. You'd only be affected by 690.12 > if you're running to an interior inverter. So- your strategy of exterior > conduit to wall-mounted inverters on the exterior of a building won't be > subjected to the 690.12 requirement. > > On 2014/4/15, 11:09, Nathan Charles wrote: > > Hi All, > > I have a follow up to this discussion. What's the proper way to think > through this regarding ground mounts? It seems to me that if the goal is > to protect firefighters then running a conduit underground and coming up to > outdoor wall mounted inverters is keeping in the spirit of things, but I'm > not sure if the language of 690.12 supports this. Am I mistaken? Do you > have any best practice advice for this scenario? > > Best regards, > -N > > > On Tue, Jan 21, 2014 at 12:36 PM, Drake < > drake.chamber...@redwoodalliance.org> wrote: > >> >> Bill, >> >> It is good to see that energized conductors are going to be disconnected >> near the arrays. I've been an advocate of disconnecting these conductors by >> ground fault sensing equipment since ground fault detection was first >> implemented in the code. If contactors are to be installed on roofs, it >> likely won't be long before both ground faults and arc faults are >> automatically cleared. >> >> When the requirement for AC arc fault branch circuit protection was first >> put in the NEC, it was postdated to allow time for the electrical industry >> to adapt. This new remote disconnecting requirement does not provide any >> lead time. >> >> As the 2014 NEC is adopted in various jurisdictions, inspectors may feel >> that it is necessary to disallow systems without the newly required >> disconnect feature. This may result in serious problems for solar companies >> and customers, as well as manufacturers. >> >> The protection of firefighters is essential. The implementation of >> renewables is essential also. Insurance claims for weather related, global >> warming-triggered climatic disasters are rising exponentially. Extreme >> weather related events result in major loss of life and billions of dollars >> in property damage. Atmospheric CO2 levels continue to climb from the >> burning of fossil fuels. This is a crisis of global proportions. >> >> My request for code writers is to please take into account the effect >> that inserting new rules into the NEC may have on the stability of >> renewable energy, and implement new requirements in a way that will allow >> for a smooth interface. >> >> Thank you, >> >> Drake >> >> Drake Chamberlin >> >> >> >> >> >> *Athens Electric LLC OH License 44810 CO License 3773 NABCEP Certified >> Solar PV 740-448-7328 <740-448-7328> *http://athens-electric.com/ >> >> >> At 12:45 PM 1/16/2014, you wrote: >> >> Content-Type: multipart/alternative; >> boundary="----=_NextPart_000_0F94_01CF129F.BCC65BD0" >> Content-Language: en-us >> >> >> Jeffrey, >> >> Sounds like you need to get involved in the code making process since you >> have so many good ideas on how to improve the language. I like >> confrontational discussions as long as they lead to a better understanding >> and constructive outcomes. >> >> About 30 people worked on this language, so it is definitely not perfect. >> However, I don’t think it is quite as bad as you make it out to be. I >> wanted to jump in since some of your conclusions were not correct. >> >> This is a circuit requirement, not a disconnecting means requirement, >> since it has to do with shock hazard of PV circuits in and around a >> building. This is for firefighter safety. 30V is the international standard >> for touch safe in a wet location. 240VA is to set a limit on the available >> power on a circuit. Contactor combiners, which would be part of a compliant >> solution, have 24V control circuits. The other reasoning for 240VA is that >> internally, 72-Cell PV modules can be divided into segments of this power >> level for the foreseeable future (more on that another day). >> >> If the conductors stay outside, you have 10’ from the array to place your >> shutdown device. On large central systems, this would likely be a contactor >> combinermost manufacturers sell these. If the conductors are going >> immediately into the building, as with residential and integrated systems, >> a shutdown device would have to be within 5’ of entering the building. If >> goes outside for a while, then inside the building, the total length could >> be no more than 10’ and no more than 5’ inside the buildingthis is not >> additive. Remember, all this is for firefighter safety. >> >> As Brian Mehalic and others have pointed out, the language does not >> specify where the shutdown initiating device is to be located. The lack of >> detail is more for flexibility than it is to give an AHJ license to make an >> installer do anything they want. >> >> With grid-tie only systems (no battery backup), it would be most >> convenient and cost effective to have a system that initiates the shutdown >> on loss of utility. In this way, a firefighter can do what they normally >> do, shut down utility power to the building, and the rapid shutdown would >> automatically initiate. This does not necessitate an additional >> disconnecting means for a load-side PV connection. The main breaker could >> be the initiating device. For a supply-side connection, the NEC already >> requires that the PV disconnect switch be located adjacent to the service >> disconnecting means (article 230). >> >> The biggest issue with string inverters (central inverters) is that there >> is a need to shutdown the capacitor input side of the inverter since that >> stays energized for 5 minutes or more. The 10 seconds was to provide a >> means to rapidly discharge the capacitors rather than requiring a relay or >> tripping device. Doing something other than a relay will require a test >> laboratory to evaluate the functionguess what?we don’t have a standard >> yet to evaluate those products. Sounds like you might want to work on that >> committee. >> >> It is more complicated for battery backup systems. Midnite Solar’s >> birdhouse products are the best I have seen so far to address this concern. >> Since dc and ac circuits are not differentiated, battery backup systems >> need to have a shutdown process that works independently of a utility >> outage for obvious reasons, and it must shutdown both the dc circuits and >> the backup ac circuits. A separate switch, like the birdhouse, would be >> necessary that only controls these functions in an emergency situation. >> >> Is the language not detailedpossibly. This was done to provide >> flexibility rather than create problems. Fire departments have been >> requiring rooftop disconnects for years in California. These disconnects >> are nearly worthless from a shock prevention point of view since capacitors >> in the inverter stay charged or there are multiple disconnecting means >> feeding each other. We have been trying to hold the fire community off of >> rooftop disconnect requirements so we could work on a solution that >> actually does what they want it to do. There is a long discussion on this >> in the appendix of my “Understanding the CalFire Guidelines” document on >> the SolarABCs website. >> >> The 2014 NEC language was a compromise worked out with the solar industry >> (yes string inverter companies as well) in response to the first version of >> the proposal which was to require module-level shutdown. This is not >> module-level shutdown, it is PV output circuit shutdown (combiner box >> shutdown is another way to look at it). However, the 2017 NEC cycle is this >> year and there was a lot of talk about requiring module-level shutdown this >> time around. >> >> I hope this helps. I will be writing articles for IAEI journal and other >> periodicals on this subject since it was a very far-reaching and >> potentially confusing new requirement in the NEC. Thanks for your interest >> and let’s keep the constructive dialogue going on the subject. It is time >> to get involved in the NEC update process again. >> >> Bill Brooks. >> >> *From:* re-wrenches-boun...@lists.re-wrenches.org >> [mailto:re-wrenches-boun...@lists.re-wrenches.org<re-wrenches-boun...@lists.re-wrenches.org>] >> *On Behalf Of *Jeffrey Quackenbush >> *Sent:* Thursday, January 16, 2014 1:09 AM >> *To:* RE-wrenches >> *Subject:* Re: [RE-wrenches] NEC 2014 690.12 Rapid Shutdown >> >> Wrenches, >> >> There is no guidance in the Code text for where the shutdown should take >> place. (1) says: "Requirements for controlled conductors shall apply only >> to PV system conductors of more than 1.5m (5') in length inside a building, >> or more than 3m (10') from a PV array." >> >> >> So, the provisions *apply if* the circuit 10' from the array and 5' >> inside a building, but no mention is made of where the shutdown actually >> needs take place in the circuit. In the video Bill Brooks suggests that the >> shutdown mechanism should also be placed within this 10'/5' boundary but >> that is just an inference -- nowhere in the text is this actually >> specified. If that was the intent of the Code committee, then they've done >> a poor job actually expressing it in English. >> >> I'm concerned that some AHJs will interpret this to exclude all central >> inverter systems (without the addition of cost-inducing secondary DC-DC >> converters like Tigo) because the combiner or junction box can be many feet >> from the actual beginning of a home run under the array. Alternately, >> permissive AHJs could allow this function to be fulfilled anywhere, meaning >> that the implementation won't meet the intent of the writers. >> >> I'm also concerned, as Isaac mentioned, that there are no requirements >> for how the shutdown be initiated, or that it contains of the accessibility >> and grouping requirements that are always included for disconnects. I >> really think this should be treated and categorized as a disconnect >> requirement, not a circuit requirement, because that is the ultimate >> function that's intended. >> >> I'm surprised none of the inverter manufacturers have chosen to comment >> here, as this could dramatically impact the sales of central inverters. >> >> Jeffrey Quackenbush >> >> >> >> ------------------------------ >> [image: []] <http://www.avast.com/> <http://www.avast.com/> >> >> This email is free from viruses and malware because avast! >> Antivirus<http://www.avast.com/>protection is active. >> >> _______________________________________________ >> 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 >> >> >> > > > -- > Nathan Charles > Engineer > NABCEP Certified PV Installation Professional #042013-20 > Paradise Energy Solutions > (717) 283-2021 direct > > > _______________________________________________ > 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 > > > -- Nathan Charles Engineer NABCEP Certified PV Installation Professional #042013-20 Paradise Energy Solutions (717) 283-2021 direct
_______________________________________________ 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
