HI William B, That is a good point. And even beyond the potential CC damage, since your now potentially powering the inverter it could actually stay alive ( I’ve seen this happen ) or it can cause a voltage spike from the CC which can damage the inverter which I”ve also seen.
I don’t know what that section of the code is trying to do, but its doing it extremely poorly. jay > On Jan 28, 2023, at 3:32 PM, William Bryce via RE-wrenches > <re-wrenches@lists.re-wrenches.org> wrote: > > All > > One thing that no one is talking about is what happens to the MPPT charge > controllers when the Battery Disconnect trips when the charge controllers are > under full load. > Many will blow up. Try turning off the battery breaker on a SolaArk when the > charge controllers are maxed, and see if you get lucky. > > On Sat, Jan 28, 2023 at 3:27 PM William Miller via RE-wrenches > <re-wrenches@lists.re-wrenches.org > <mailto:re-wrenches@lists.re-wrenches.org>> wrote: > Jeremy: > > > Thanks for posting the code references for those that had never looked them > up. > > > Chris: > > > What do you mean by “a disconnect for AC wiring, not specific to which or > both panel types”? > > > All: > > > Code references are handy when receiving edicts from building officials, but > not required, IMHO, for two reasons: The contractor should already be versed > in the codes and, building departments can mandate their own requirements > above and beyond the code. > > > It may seem redundant to require an AC disconnect for premise wiring as well > as a DC battery disconnect. In most cases if you disconnect the inverter > from the batteries the AC power goes off. However if the generator is > running at the time, some battery inverters can operate when disconnected > from batteries. So to completely de-energize all components of an off-grid > home you need to disconnect the generator and the battery leads. > > > In this case the home is required to have fire sprinklers. There is pressure > pump to provide flow to these fire sprinklers-- said pump being powered by > the inverter/battery system. I am going to apply for a waiver to remove the > DC disconnect requirement on the grounds that the pressure pump is essential > fire suppression equipment. Instead I will propose to supply an AC > disconnect (meeting all requirements for accessibility and marking) that will > disconnect all premise wiring except the pressure pump. > > > By the way, I will of course be trying to apply the logic that the voltage > specification is for nominal battery voltage and this project having a > nominal 48 volt bank does not require the battery disconnect. > > > I will let the group know what response I receive. Regardless of how this > works in this jurisdiction, I think these are both valid arguments worth > trying in any jurisdiction requiring the battery disconnect. Some officials > are amenable to dialog and negotiation and some are less so. > > > > William Miller > > > Miller Solar > > 17395 Oak Road, Atascadero, CA 93422 > > 805-438-5600 > > www.millersolar.com <http://www.millersolar.com/> > CA Lic. 773985 > > > > From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org > <mailto:re-wrenches-boun...@lists.re-wrenches.org>] On Behalf Of Jeremy > Rodriguez via RE-wrenches > Sent: Saturday, January 28, 2023 10:12 AM > To: cwar...@entech-engineering.com <mailto:cwar...@entech-engineering.com>; > RE-wrenches > Cc: Jeremy Rodriguez > Subject: Re: [RE-wrenches] Remote battery disconnects > > > > > 2020 Code Language: > > 480.7 DC Disconnect Methods. > > (A) Disconnecting Means. A disconnecting means shall be provided for all > ungrounded conductors derived from a stationary battery system with a voltage > over 60 volts dc. A disconnecting means shall be readily accessible and > located within sight of the battery system. > > N (B) Emergency Disconnect. For one-family and two-family dwellings, a > disconnecting means or its remote control for a stationary battery system > shall be located at a readily accessible location outside the building for > emergency use. The disconnect shall be labeled “EMERGENCY DISCONNECT”. > > N (C) Disconnection of Series Battery Circuits. Battery circuits exceeding > 240 volts dc nominal between conductors or to ground and subject to field > servicing shall have provisions to disconnect the series-connected strings > into segments not exceeding 240 volts dc nominal for maintenance by qualified > persons. Non-load-break bolted or plug-in disconnects shall be permitted. > > > Jeremy Rodriguez > > Solar Installation / Design > > All Solar, Inc. > > 1453 M St. > > Penrose Colorado 81240 > > > Sent by Jeremy's iPhone. Sorry for typos and shorthand. > > > > > On Jan 28, 2023, at 7:28 AM, Christopher Warfel via RE-wrenches > <re-wrenches@lists.re-wrenches.org > <mailto:re-wrenches@lists.re-wrenches.org>> wrote: > > > > Seems confusing that the AHJ is requiring a disconnect for AC wiring, not > specific to which or both panel types, and then a dc disconnect with no code > reference. Was trying to convey a reasonable, safe approach. A lot of bad > information from fire department solar consultants making a lot of money fear > mongering, which has led to this type of situation. Chris > > On 1/27/2023 3:35 PM, William Miller via RE-wrenches wrote: > > Glenn: > > > As I wrote, a DC disconnect is required. Here is an excerpt from the Q&A > with the building official: > > > 4. Will you be requiring an external disconnect to disconnect the AC output > of the inverter system from premise wiring? > > Yes, as required per 230.85 > > 5. Will you be requiring an external disconnect to disconnect batteries > from the inverters? > > Yes > > > If the DC disconnect was not required I would not be wasting everyone’s time > with my post. I try to be careful about that, researching on my own before > posting and trying to make my questions very clear. I also try not to > embarrass myself with dumb questions, but that does happen occasionally… > > > William > > > Miller Solar > > 17395 Oak Road, Atascadero, CA 93422 > > 805-438-5600 > > www.millersolar.com <http://www.millersolar.com/> > CA Lic. 773985 > > > > From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org > <mailto:re-wrenches-boun...@lists.re-wrenches.org>] On Behalf Of Glenn Burt > via RE-wrenches > Sent: Friday, January 27, 2023 11:46 AM > To: William Miller via RE-wrenches > Cc: Glenn Burt > Subject: Re: [RE-wrenches] Remote battery disconnects > > > Does the AHJ really want the batteries disconnected from conductors, or does > he really just want the inverters to stop operating and producing AC within > the house? > > Obviously there is a big difference here and it may be changing as the code > evolves. > > > -Glenn > > Sent from my 'smart'phone, so please excuse typos and spelling errors. > > > ------ Original message------ > > From: William Miller via RE-wrenches > > Date: Fri, Jan 27, 2023 2:26 PM > > To: RE-wrenches; > > Cc: William Miller; > > Subject:[RE-wrenches] Remote battery disconnects > > > Friends: > > > We have a large-ish residential off-grid system install coming up. The AHJ > has said they will require a remote battery disconnect. I suspect there will > be fire sprinkler controls and a pressure pump that would become inoperable > if this system were engaged. In this case we will apply for a waiver. > > > The last time this was discussed here as far as I can find was October of > 2020. At that time no one suggested any specific battery disconnect > equipment. > > > To further clarify my needs: There will be 4 or 5 Radian 8048 inverters (5 > or 6 4/0 battery circuits, ~350A each) and two 175 amp PV recombiner outputs. > That is 6 poles of high amperage DC disconnects. > > > The battery array will be either a UnigyII VRLA or a lithium of a brand yet > to be determined. In the case of lithium we will look for a system that can > remotely enable a BMS shutdown. In the case of a VRLA lead-acid, we will not > have that luxury. > > > I have done some considerable research and have not found viable, high > amperage, remotely activated shutdown equipment. > > > I am wondering what hardware others may be using to achieve remote battery > disconnecting in these types of cases.. > > > William > > > Miller Solar > > 17395 Oak Road, Atascadero, CA 93422 > > 805-438-5600 <tel:805-438-5600> > www.millersolar.com <http://www.millersolar.com/> > CA Lic. 773985 > > > > > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > <http://re-wrenches.org/> > > List Address: RE-wrenches@lists.re-wrenches.org > <mailto:RE-wrenches@lists.re-wrenches.org> > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > <http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org> > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > <https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/> > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org> > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > <http://www.re-wrenches.org/etiquette.htm> > > Check out or update participant bios: > http://www.members.re-wrenches.org <http://www.members.re-wrenches.org/> > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. 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