[RE-wrenches] Remote battery disconnects
jay
jay.peltz at gmail.com
Sat Jan 28 15:20:51 PST 2023
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 at 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 at lists.re-wrenches.org <mailto:re-wrenches at 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-bounces at lists.re-wrenches.org <mailto:re-wrenches-bounces at lists.re-wrenches.org>] On Behalf Of Jeremy Rodriguez via RE-wrenches
> Sent: Saturday, January 28, 2023 10:12 AM
> To: cwarfel at entech-engineering.com <mailto:cwarfel at 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 at lists.re-wrenches.org <mailto:re-wrenches at 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-bounces at lists.re-wrenches.org <mailto:re-wrenches-bounces at 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
>
>
>
>
>
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