[RE-wrenches] Remote battery disconnects
Christopher Warfel
cwarfel at entech-engineering.com
Sun Jan 29 04:22:24 PST 2023
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 <jj at 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 <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>
>>> _______________________________________________
>>> List sponsored by Redwood Alliance
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--
Christopher Warfel, PE
Entech Engineering, Inc.
POB 871 Block Island, RI 02807
401-466-8978
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