Hey folks - love the Code, hate it, don’t care about it or follow it: it doesn’t matter to me. But if you want to change it you have to realize it is a process with rules and procedures, and posting on this list that “the NEC” should immediately “issue a memo” to do what you want or change what you don’t like has ZERO effect.
Brian On Jan 30, 2023, at 4:47 AM, Christopher Warfel via RE-wrenches <[email protected]> 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
CA
Lic. 773985
From:
James Jarvis [mailto:[email protected]]
Sent: Saturday, January 28, 2023 7:03 PM
To: Brian Mehalic
Cc: RE-wrenches; [email protected]
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.
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].
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.
On Sat, Jan 28, 2023 at
6:22 PM William Miller via RE-wrenches <[email protected]>
wrote:
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.
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 <[email protected]>
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:[email protected]]
On Behalf Of Jeremy
Rodriguez via
RE-wrenches
Sent: Saturday,
January 28, 2023 10:12
AM
To: [email protected];
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.
Sent by
Jeremy's iPhone.
Sorry for typos
and shorthand.
On
Jan 28, 2023, at 7:28 AM,
Christopher Warfel via
RE-wrenches <[email protected]>
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:[email protected]]
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.
Sent
from my
'smart'phone,
so please
excuse typos
and spelling
errors.
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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