[RE-wrenches] Remote battery disconnects

Sat Jan 28 16:58:27 PST 2023

It would be nice if the decision was up to the owner / occupant of the
property. I, for one, do not want any random person to be able to turn off
my house or business with the flick of a switch. I feel strongly that there
is far too much fear mongering in NEC with relation to renewable energy.

-James Jefferson Jarvis
APRS World, LLC
+1-507-454-2727
http://www.aprsworld.com/

On Sat, Jan 28, 2023 at 6:22 PM William Miller via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Esteemed wrenches:
>
> Well if my house is on fire and the entry of fire responders is delayed
> for lack of a disconnect, I choose having the disconnect. I can worry about
> the charge controllers later.
>
> Others may prioritize their charge controller over their homes…
>
> Put a cable-tie lock in the closed position to discourage kids from
> messing with it. Test it only after dark.
>
> William
>
> On Sat, Jan 28, 2023 at 2:32 PM William Bryce <
> wlbryce at pineridgeproducts.com> 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> 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
>>>
>>> CA Lic. 773985
>>>
>>>
>>>
>>>
>>>
>>> *From:* RE-wrenches [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; 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> 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
>>>
>>> CA Lic. 773985
>>>
>>>
>>>
>>>
>>>
>>> *From:* RE-wrenches [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
>>>
>>> www.millersolar.com
>>>
>>> CA Lic. 773985
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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>>> --
>
> William Miller
> Miller Solar.com
> 895-438-5600
> www.millersolar.com
> _______________________________________________
> List sponsored by Redwood Alliance
>
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