Re: [RE-wrenches] Remote battery disconnects

[Christopher Warfel via RE-wrenches]

I think California is the first place that I realized external MSP and 
breakers are common. Not so in the northeast and many other parts of the 
country. It doesn't matter with respect to battery systems in any case.

As for getting involved in writing the Code, that is a pretty rotten 
things to say.  Brian, why don't you post the schedule for the next two 
Code cycles as best you can that says when: 1) Open for receiving 
recommendations for revised language, 2) How to submit, and 3) reference 
to the process for how this works?

I, and many other people I know, have submitted language for 
consideration. Not one suggestion for twenty years has made it. And it's 
not as though they were bad ideas.  I stopped once I saw how it didn't 
work. The CMP have made solar increasingly more convoluted and less safe 
instead of the other direction. I've had it with cloistered processes 
infiltrated by special interests. It's like lobbyists writing bills.

This discussion is an example.  I am familiar with 480.7. It is an 
example of Not seeing the trees for the forest. It is using a sledge 
hammer with a bad handle to address an issue that a tack hammer could 
solve.

Not too long ago I was part of a team that trained about 10,000 fire 
fighters/first responders in solar systems.  To not second guess them 
would be wrong.  Many had a very bad understanding of pv (thanks again 
to those great ex fire fighters turned solar experts making lots of 
money providing incomplete information on this technology).  Fire 
fighters need better education.  This battery disconnect requirement to 
control 10 feet of conductors is nonsensical and counterproductive and 
should not be enforced. NEC should issue a memo stating that it is a 
mistake and serves no material purpose immediately. Would someone please 
explain stepwise how this requirement is better protection than an ac 
conductor disconnect on the battery supplied panel.  Step wise, cost 
wise, performance wise???

At a time when we are engaged in an international struggle where energy 
is being used as a weapon against those who stand for representative 
governments, freedom of speech, etc. to have language such as this has 
always been suspect, but now shows up as really glaringly wrong.  We 
need distributed energy storage systems. We need greater use of our 
renewable energy resources to reduce ours, and our allies dependence 
upon energy sources from countries who are hostile to our way of life 
and freedom.  This NEC language just plays into the hands of those that 
would like to harm the free world.


Chris





On 1/28/2023 10:08 PM, Brian Mehalic via RE-wrenches wrote:
Easy buddy. First off you are wrong about where I live. And secondly 
your whining about being cold will win you no sympathy; old folks die 
in heat waves when the air conditioning fails!

And if it such a big deal to you then don’t just complain - get 
involved in the process, since I’m sure your ideas are the absolute 
best and we’d all be better off if you wrote the Code.

Brian

On Jan 28, 2023, at 8:02 PM, James Jarvis <j...@aprsworld.com> wrote:


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 <br...@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@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@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
        <wlbr...@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@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]
                *On Behalf Of *Jeremy Rodriguez via RE-wrenches
                *Sent:* Saturday, January 28, 2023 10:12 AM
                *To:* 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> 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]
                        *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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Christopher Warfel, PE
Entech Engineering, Inc.
POB 871 Block Island, RI 02807
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