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:j...@aprsworld.com]
*Sent:* Saturday, January 28, 2023 7:03 PM
*To:* Brian Mehalic
*Cc:* RE-wrenches; will...@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
<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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Miller Solar.com
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www.millersolar.com <http://www.millersolar.com>
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