[RE-wrenches] Remote battery disconnects
Ray Walters
ray at solarray.com
Mon Jan 30 10:16:50 PST 2023
Another point is that the tougher the code requirements, the more DIY
folks will just do it on their own with little regard for the code at
all. Already in Colorado, most solar companies won't even touch off
grid because of the code complications. That just puts more folks off
grid with horribly dangerous systems that don't have disconnects at all,
much less remote accessible disconnects.
The 2nd thing that happens, is that many of those potential off grid
customers may then decide to go On grid because of the overly
complicated requirements. Those power lines being extended into remote
areas, cause many of the forest fires devastating California and
Colorado. I think if the NFPA pulled back to consider the overall fire
safety of the entire country, they would realize that off grid systems
are better than extending the grid. I think an off grid system wired to
NEC 2008 is a reasonable combination of safety requirements.
We need reasonable exceptions to these rules, and we need the code to
quit changing so dramatically every cycle.
Ray Walters
Remote Solar
On 1/30/2023 4:46 AM, Christopher Warfel via RE-wrenches wrote:
>
> I don't think the discussion has forked at all. A solution to this
> problem, and it is the best solution all things considered, including
> firefighter exposure to 10 ft of conductors that I have a hard time
> imaging them being exposed to, is for the NEC to issue a memo
> IMMEDIATELY indicating that this section of the code is no longer to
> be considered a requirement and that the next Code cycle will
> eliminate this requirement.
>
> The other solutions discussed would only work for a few configurations
> realistically and would introduce more danger. Chris
>
>
>
> On 1/29/2023 2:41 PM, William Miller via RE-wrenches wrote:
>>
>> James, Brian and others:
>>
>> Thank you all for the lively discussion. I am always interested in
>> my colleague’s perspectives and this has been illuminating.
>>
>> It appears to me the discussion has forked: One topic is how to deal
>> with the reality of the new code regarding a very narrow scenario:
>> ESS inside of a residence. The other topic is: has the NEC evolved
>> to be overly restrictive without factual basis?
>>
>> Regarding the first topic, it’s in black and white that we must
>> provide battery disconnecting means for energy storage systems
>> located in one or two family homes if the battery voltage exceeds 60
>> VDC. There are very few areas that do not adopt the NEC. If you
>> install ESS you will eventually have to deal with this code
>> requirement one way or another.
>>
>> Due to lax enforcement or unfamiliarity on the part of local building
>> departments, some of you may be able to skirt this requirement. This
>> is great until something happens. If your non-compliant installation
>> causes a loss, you will end up in the defendants chair, not the
>> building inspector.
>>
>> Here is how I approach these compliance conundrums: If I could argue
>> the code does not apply or there is a good reason to waive the
>> requirement; if the building official agrees; if I feel the
>> installation is really and truly safe without meeting the
>> requirement—only then could I proceed without the disconnect.
>> Otherwise I am going to have to find a way to comply.
>>
>> As contractors, each of you makes those decisions every day: What is
>> safe enough for my clients? If any of you think you know more than
>> the people who write the codes, then install what you can get away
>> with and keep your fingers crossed. I am not willing to live like that.
>>
>> Regarding the second topic: Are we being picked on by an overly
>> scare-mongering NFPA?
>>
>> What is interesting here is that while most electrical codes are
>> trying to prevent house fires, this particular section is trying to
>> protect fire fighters after a fire starts (or an earthquake happens
>> or a dump truck runs into your house, etc.).
>>
>> When California first adopted roof clearances for fire fighters, I
>> got my feelings hurt because I was losing business and I did not
>> understand what it takes to fight a house fire. I spoke with a few
>> fire fighters and learned about roof and wall venting and how it is
>> affected by prevailing winds. I came around to appreciate there is a
>> real need for rooftop fire setbacks.
>>
>> It is self-evident why firefighters would not want to cut into a wall
>> with a demo saw if there are energized, high amperage conductors in
>> or on that wall. This code requirement for battery disconnecting
>> means is fundamentally sensible. That ends the discussion for me.
>>
>> Oh, yeah, the charge controller blowing up thing: Does anyone have
>> any factual data to share on this? Regardless of that, does it
>> really matter if the charge controller is saved but the house burns down?
>>
>> The islanding thing: To be compliant, all ungrounded battery
>> conductors need to be disconnected. This includes the charge
>> controller circuit(s). With the charge controllers and inverters
>> disconnected from the batteries and from each other there cannot be
>> DC “islanding”.
>>
>> The house flooding thing: At the surface, it appears you have a
>> choice of disasters: flood or fire. I submit that fire is more
>> destructive (I don’t think many people have died from a ruptured
>> water pipe). I don’t think it has to be either or: Find a way to
>> provide emergency power to freeze protection devices with that
>> disconnect waived or under key in cooperation with the fire
>> department. This may mean the batteries need to remain connected.
>> Put those leads in metal raceway and mark their locations from the
>> outside. Work with building and fire officials. Limit your liability.
>>
>> Thanks again to all of you for the discussion. I know what I need to do.
>>
>> William Miller
>>
>> Miller Solar
>>
>> 17395 Oak Road, Atascadero, CA 93422
>>
>> 805-438-5600
>>
>> www.millersolar.com <http://www.millersolar.com/>
>>
>> CA Lic. 773985
>>
>> *From:*James Jarvis [mailto:jj at aprsworld.com]
>> *Sent:* Saturday, January 28, 2023 7:03 PM
>> *To:* Brian Mehalic
>> *Cc:* RE-wrenches; william at millersolar.com
>> *Subject:* Re: [RE-wrenches] Remote battery disconnects
>>
>> Brian and William,
>>
>> With all due respect, I think your geographical location of
>> California may be limiting in your understanding of the implications
>> of local power security.
>>
>> Where I am in Minnesota and where I work in Alaska, loss of power and
>> backup power can have very expensive consequences. When it is -30F
>> outside and howling wind, buildings only have a matter of hours
>> before their interiors will drop below freezing. A few hours after
>> that pipes start to freeze and break. Pressurized water then starts
>> to spray everywhere and then things can very quickly run into
>> six-figure dollars amounts of damage. So one way of reducing this
>> risk is by installing an ESS.
>>
>> Around here, prior to the latest NEC, we didn't have exterior
>> disconnects available for anyone to shut off power. We still don't
>> for businesses.
>>
>> My point is that NEC is mandating that there be zero security of a
>> buildings electrical systems by requiring publicly accessible
>> disconnects on backup systems. And if NEC wasn't so prescriptive,
>> there could be slightly more secure alternatives such as a KNOXBOX or
>> access controlled disconnects.
>>
>> William: I also disagree with your premise that you'll test the
>> battery disconnect system after dark. That's not a test; that's just
>> cheating. You had a knowledge person tell you that the MPPT
>> controllers can and do blow up when they lose their voltage reference
>> (battery) under load. And removing the battery from the circuit does
>> allow the charge controllers to island with the inverter and DC loads
>> and do other damage. I know of a telecom customer that had hundreds
>> of thousands of dollars of damage when their battery became
>> disconnected. If you are unwilling to test it at full load, I'd guess
>> you know that the whole concept is a dumb idea.
>>
>>
>> -James Jefferson Jarvis
>> APRS World, LLC
>> +1-507-454-2727
>>
>> http://www.aprsworld.com/
>>
>> On Sat, Jan 28, 2023 at 7:35 PM Brian Mehalic <brian at solarenergy.org>
>> wrote:
>>
>> Every single house I’ve looked at in my town has a breaker panel
>> with a main service disconnect on the outside of the house
>> already. So in many cases we are well beyond worrying about
>> someone “flicking your switch!”
>>
>> In fact, in addition to the emergency disconnect requirement for
>> stationary standby batteries [480.7(B)] and ESS [706.15(B)] in
>> one- and two-family dwellings, also added in 2020 was the
>> requirement for an emergency disconnect for services on those
>> same one- and two-family dwellings [230.85].
>>
>> Brian Mehalic
>>
>>
>>
>> On Jan 28, 2023, at 5:58 PM, James Jarvis via RE-wrenches
>> <re-wrenches at lists.re-wrenches.org> wrote:
>>
>>
>>
>> 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 <http://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
>> <http://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 <tel:805-438-5600>
>>
>> www.millersolar.com
>> <http://www.millersolar.com/>
>>
>> CA Lic. 773985
>>
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>>
>> William Miller
>> Miller Solar.com
>> 895-438-5600
>> www.millersolar.com <http://www.millersolar.com>
>>
>> _______________________________________________
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> --
> Christopher Warfel
> ENTECH Engineering, Inc.
> PO Box 871, Block Island, RI 02807
> 401-466-8978
> <http://entech-engineering.com>
>
>
>
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