Re: [RE-wrenches] NEC 230.46 spliced and tapped conductors

[Jeff Clearwater via RE-wrenches]

We've transitioned from using supply-side taps to using Feeder taps re: 
705.12(B) almost exclusively.


The advantages are numerous - and you just added one more - not needing 
line side listing on your tap hardware.


One of the most dangerous things I see looming in the present code is 
the fact that supply side taps can be safe for backfeeding up to 160 
Amps of PV on a standard 200 Amps service IF you are only grid-tie and 
the current is canceling incoming current.


But as soon as you add hybrid inverters and batteries.  Now you are 
adding significant battery charging amperage  to the NEC 220 load calcs 
that the service entrance connectors are based on..  Given that many 
residences utilized the downsize table for service entrance conductors 
you can quickly end up with a situation where your supply side tap is 
overloading your service entrance conductors if pulling the inverters 
full capability for battery charging and adding that to your normal 
house loads.


Feeder taps take care of this vulnerability in the present code.  By 
having a main 200 Amp breaker on both sides of the tap as per 705.122 B 
- all conductors are protected for both the increased loads due to 
battery charging as well as being able to still use the full 160 Amps 
available for backfeed.  And you don't have to shut down the utility to 
install.


Now you also add not needing to list your taps for supply side and you 
can use the venerable ILscos again . . .


Hope that helps!

Best,

Jeff


Brian Mehalic via RE-wrenches 
February 1, 2023 at 7:18 PM
The requirements for power distribution blocks (PDB) to be marked 
“*suitable for use on the line side*…” when installed connected in 
that manner in wireways (Art. 376) and pull/junction boxes (Art. 314) 
have been in the NEC® for quite a few cycles.


It looks like the additions to 230.46 in the 2020 NEC® (PDBs and 
splices/pressure connectors connected to service conductors must be 
marked “suitable for use…”) coincided with this explicit requirement 
being removed from 314 (though it remains in 376); this makes sense - 
if you’re using a PDB on the line side, well you’re connecting to some 
type of service conductors, so why not cover it in Art. 230 (maybe 
it’ll also be removed from 376 in 2026).


UL 1953 allows for PDBs (UL product code QPQS) to be listed for 
connection on the line side, load side, or both, with those that can 
connect on the line side having the marking mentioned above. Note that 
many have an SCCR of 10 kA unless combined with 
the manufacturer-specified fuse type and size (or smaller), and have 
minimum enclosure sizes that must be followed as well. I have had a 
difficult time finding PDBs that are marked for use on the line side 
while just using the internet (and have been too lazy to pick up the 
phone thus far...plus it doesn't help that all PDBs have a line and 
load side of the device regardless of whether or not they are being 
connected on the line or load side of the service!).


Of course many folks are not going to want to use PDBs due to 
re-routing conductors to them (if even possible) and having to shut 
down the utility supply to install them. Enter pressure connectors, 
and the seemingly industry-fave insulation-piercing style; 
unfortunately I'm not aware of any that are available *yet* with the 
proper listing and markings as required by 230.46.


A colleague that works for a large electrical product manufacturer 
passed this along:


/“No test existed for qualifying single polarity connectors suitable 
for line side use when this was added to the 2020 code with the 
January 1, 2023 date for enforcement.  A strategy and test procedure 
needed to be developed and adopted by the UL CSDS working group.  Not 
a speedy process.  Long story short, after developing a strategy, 
public comment period and voting the *standard wasn’t published until 
August of last year.*  On average the testing requirements take about 
90 days.  To further complicate matters, I was recently told that UL 
is still developing the submittal process.


I know that there are a lot of companies currently testing products 
but until the UL submittal process catches up, no one will be 
official.  The *UL product code is ZMWW*; as companies become 
qualified they should show up in the ZMWW search.  As of today, no one 
is listed.  This leaves power distribution blocks as the lone 
connector product rated for line side use.  I know that Bussmann has 
some PDBs rated for line side use."


So this begs the question of whether or not NEC® 90.4(D) can be 
invoked (new products not yet available at the time the Code is 
adopted...); PDBs already exist, so no dice there, and it is likely 
that since they exist, an argument using 90.4(D) in regards to 
pressure connectors/splices will fall on deaf ears because, well, use 
PDBs."/


Ugh.

Brian Mehalic
NABCEP Certified Solar PV Installation Professional™ R031508-59
National 

Re: [RE-wrenches] Remote battery disconnects

[bob--- via RE-wrenches]

 SPDs or (MOVs) on the PV input side of a charge controller are not 
wired to snub excessive PV voltage.


They are wired from PV+ to GND and the other from PV- to GND and only 
the two in series, at double the

MOV clamp voltage would have any effect on clamping the PV+/PV- voltage.
SPDs are wired to keep the charge controller's insulation system to 
below the Hi-Pot voltage the unit is
tested with.  i.e.  They are wired for common-mode and not 
differential.  That voltage is much higher

than maximum controller or inverter input voltage.

What *IS* in place that might help limit PV voltage is the PV array 
itself.  Any PV voltage that would try go
go above the array's  Voc  would be clamped across the array.  This 
would be during the day or at night and
of course that Voc is determined mainly by PV cell temperature. Solar 
panels are just a bunch of diodes
in series so will be forward-biased when Voc is exceeded by an inverter 
or charge controller.

  PV modules make great space heaters and can even melt snow, ya know. 

As for charge controllers blowing up when charging hard and then 
disconnecting,  I am very anal in
designing in safe guards to keep this from happening on the MidNite 
Classic at least.  That was done

several years ago now.

But even then, electronics, especially power  electronics, break once in 
a while and it is sometimes very

hard to know why it happened.

With our new HV MPPT controllers,  their E-Panels also include 
remote-trip PV breakers, triggered by the controller's
hardware in order to reduce   battery side  over-voltage in case 
something goes wrong.


So, I understand that we have a remote battery disconnect device 
basically done but have held off due to
not knowing how important it would actually be.  300 amps from an 
external switch closure or open.
Our older BD module basically went away with the bird house and bird 
next shut down system.


There are NEC requirements that are not enforced and some installers 
don't  worry about including,
but from this discussion, it sounds like this battery disconnect better 
be finished sooner than later.


Now we know.  Thanks !

boB  MidNite Solar




On 2/1/2023 2:49 PM, Brian Mehalic via RE-wrenches wrote:
Most firefighters are not electrical engineers; nor are most insurance 
agents. However both of those groups are stakeholders with influence 
over codes and standards. Some may say too much influence, but the 
fact of the matter is that code making is a group/consensus process, 
and very often none of the groups get exactly what they want (in fact 
sometimes a group accepts exactly what it doesn't want to leverage 
that for something they do; yes it often smacks of politics). I would 
appeal to y'all to submit a proposal for the 2026 NEC® - they are due 
by September of this year. Better yet would be to circulate language 
that this, or some other, group can work on, agree on, write a solid 
technical justification for, and sign their names to and submit - the 
more stakeholders that support a proposal the more weight it has.


It seems that the PV Industry Forum, or another similar body, may 
again begin work to develop PV and storage industry 
stakeholder-consensus PIs to submit; in the past this was a very 
successful endeavor. I'll post on this list if and when that happens 
so that anyone that is interested can get involved, but don't let that 
possibility keep you from submitting any PIs on your own.


Maybe in the meantime, a control system that shuts off the PV, and 
then the batteries, would be worth designing.


Brian Mehalic




On Wed, Feb 1, 2023 at 2:10 PM James Jefferson Jarvis via RE-wrenches 
 wrote:




On 2/1/2023 2:58 PM, Starlight via RE-wrenches wrote:
> Have you (or any) installed surge suppression on the PV input
side to
> clamp the open circuit voltage surge?

That's not where the issue is and isn't really a solution. As I
explained in my previous e-mail, the issue is the open circuit on the
output leaves no where for the energy in the MPPT controllers
inductor
to go and the only option is for the voltage to rise until it finds
somewhere to go.

Surge suppressors, such as sold by Midnite Solar, are nothing more
than
Metal Oxide Varistors. Or in the case of Delta, they are pieces of
wire
in sand. They require large rise in voltage before they conduct.

MOVs are sometimes found on the battery side of inverters and charge
controllers, but their clamp time and voltage before clamping
requires
additional circuitry that works faster to protect fragile
semiconductors.


If you are proposing using a surge supressor to regulate the
voltage of
an island between a charge controller and an inverter when the
battery
is disconnected, that's also a no go. Once the MOV clamps, it stays
clamped until voltage goes essentially to zero or until it blows up.
It's not a regulator.

-

To further 

Re: [RE-wrenches] NEC 230.46 spliced and tapped conductors

[Brian Mehalic via RE-wrenches]

The requirements for power distribution blocks (PDB) to be marked “*suitable
for use on the line side*…” when installed connected in that manner in
wireways (Art. 376) and pull/junction boxes (Art. 314) have been in the
NEC® for quite a few cycles.

It looks like the additions to 230.46 in the 2020 NEC® (PDBs and
splices/pressure connectors connected to service conductors must be marked
“suitable for use…”) coincided with this explicit requirement being removed
from 314 (though it remains in 376); this makes sense - if you’re using a
PDB on the line side, well you’re connecting to some type of service
conductors, so why not cover it in Art. 230 (maybe it’ll also be removed
from 376 in 2026).

UL 1953 allows for PDBs (UL product code QPQS) to be listed for connection
on the line side, load side, or both, with those that can connect on the
line side having the marking mentioned above. Note that many have an SCCR
of 10 kA unless combined with the manufacturer-specified fuse type and size
(or smaller), and have minimum enclosure sizes that must be followed as
well. I have had a difficult time finding PDBs that are marked for use on
the line side while just using the internet (and have been too lazy to pick
up the phone thus far...plus it doesn't help that all PDBs have a line and
load side of the device regardless of whether or not they are being
connected on the line or load side of the service!).

Of course many folks are not going to want to use PDBs due to re-routing
conductors to them (if even possible) and having to shut down the utility
supply to install them. Enter pressure connectors, and the seemingly
industry-fave insulation-piercing style; unfortunately I'm not aware of any
that are available *yet* with the proper listing and markings as required
by 230.46.

A colleague that works for a large electrical product manufacturer passed
this along:





*“No test existed for qualifying single polarity connectors suitable for
line side use when this was added to the 2020 code with the January 1, 2023
date for enforcement.  A strategy and test procedure needed to be developed
and adopted by the UL CSDS working group.  Not a speedy process.  Long
story short, after developing a strategy, public comment period and voting
the standard wasn’t published until August of last year.  On average the
testing requirements take about 90 days.  To further complicate matters, I
was recently told that UL is still developing the submittal process.   I
know that there are a lot of companies currently testing products but until
the UL submittal process catches up, no one will be official.  The UL
product code is ZMWW; as companies become qualified they should show up in
the ZMWW search.  As of today, no one is listed.  This leaves power
distribution blocks as the lone connector product rated for line side use.
I know that Bussmann has some PDBs rated for line side use."So this begs
the question of whether or not NEC® 90.4(D) can be invoked (new products
not yet available at the time the Code is adopted...); PDBs already exist,
so no dice there, and it is likely that since they exist, an argument using
90.4(D) in regards to pressure connectors/splices will fall on deaf ears
because, well, use PDBs."*

Ugh.

Brian Mehalic
NABCEP Certified Solar PV Installation Professional™ R031508-59
National Electrical Code® CMP-4 Member
(520) 204-6639

Solar Energy International
http://www.solarenergy.org



On Wed, Feb 1, 2023 at 4:26 PM Jason Szumlanski via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

> As someone who does 75%+ supply-side interconnections, this kind of
> terrifies me. We have another year of NEC 2017 here, so I have time to
> prepare, but I'm watching this closely.
>
> Meter disconnects/reconnects here are difficult due to the lack of good
> utility company cooperation and the requirement for an inspection prior to
> reconnection, which leaves homeowners without power for many hours at
> times. Otherwise, I would just pop in a 200A main disconnect between the
> meter and main distribution panel and do a feeder tap for the inverter
> output between the new service disconnect and the existing distribution
> equipment. Unfortunately, that usually means bringing grounding electrodes
> and conductors up to current standards, but that's how we would be forced
> to comply if this splice/tap rule comes into effect here and there are no
> suitable products available.
>
> Side note: 200A 2-pole fusible disconnects are all but impossible to get
> here. Even 200A main breaker enclosures are very hard to find. Hurricane
> Ian didn't help that with thousands of people who had their service
> equipment under water... It has been a challenge.
>
>
> Jason Szumlanski
> Principal Solar Designer | Florida Solar Design Group
> NABCEP Certified Solar Professional (PVIP)
> Florida State Certified Solar Contractor CVC56956
>
>
> On Tue, Jan 31, 2023 at 7:56 PM August Goers via RE-wrenches <
> re-wrenches@lists.re-wrenches.org> 

Re: [RE-wrenches] NEC 230.46 spliced and tapped conductors

[Jason Szumlanski via RE-wrenches]

As someone who does 75%+ supply-side interconnections, this kind of
terrifies me. We have another year of NEC 2017 here, so I have time to
prepare, but I'm watching this closely.

Meter disconnects/reconnects here are difficult due to the lack of good
utility company cooperation and the requirement for an inspection prior to
reconnection, which leaves homeowners without power for many hours at
times. Otherwise, I would just pop in a 200A main disconnect between the
meter and main distribution panel and do a feeder tap for the inverter
output between the new service disconnect and the existing distribution
equipment. Unfortunately, that usually means bringing grounding electrodes
and conductors up to current standards, but that's how we would be forced
to comply if this splice/tap rule comes into effect here and there are no
suitable products available.

Side note: 200A 2-pole fusible disconnects are all but impossible to get
here. Even 200A main breaker enclosures are very hard to find. Hurricane
Ian didn't help that with thousands of people who had their service
equipment under water... It has been a challenge.


Jason Szumlanski
Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956


On Tue, Jan 31, 2023 at 7:56 PM August Goers via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

> Hi Wrenches -
>
> Occasionally we will do supply side connection for our PV systems. As of
> 1/1/2023 in CA, we follow the 2020 NEC 705.11 Supply-Side Source
> Connections section. Recently, an inspector asked us to comply with the
> following:
>
> 230.46 Spliced and Tapped Conductors
> Service-entrance conductors shall be permitted to be spliced or tapped in
> accordance with 110.14, 300.5(E), 300.13, and 300.15. Power distribution
> blocks, pressure connectors, and devices for splices and taps shall be
> listed. Power distribution blocks installed on service conductors shall be
> marked "suitable for use on the line side of the service equipment" or
> equivalent.
> Effective January 1, 2023, pressure connectors and devices for splices and
> taps installed on service conductors shall be marked "suitable for use on
> the line side of the service equipment" or equivalent.
>
>
>
> When we reached out to one supplier of insulation piercing connectors
> (ILSCO), they responded: "We are still in testing, I just checked and from
> what I see there are no products listed for this new requirement yet by any
> manufacturer."
>
> Has anyone bumped into this before and/or have any proposed solutions?
>
> Best, August
> Luminalt
> ___
>
>
___
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Re: [RE-wrenches] Remote battery disconnects

[Jason Szumlanski via RE-wrenches]

I have been following this discussion intently. I hate to say it, but it
all sounds like a major case being made for AC-coupled system architecture,
and even integrated "AC Batteries" like Powerwalls and Encharge
that integrate the battery and inverter into listed Energy Storage Systems.
As someone who keeps exploring getting back to DC Coupled systems for some
significant reasons, the complexity and lack of standardization makes that
a big leap.

I started out with Heart 12V inverters and moved toward Xantrex SW and
moved on to Outback GFX and dabbled in other brands before changing
businesses and going basically all grid tie with Enphase, later with some
Powerwalls and then back into battery backup exclusively with Enphase. In
the last three years, I've dabbled with Sol-Ark and done service on a bunch
of DC coupled brands (begrudgingly usually). The Enphase system is so
limited in terms of max battery capacity, but in terms of design simplicity
and safety, I can't think of a better option for consumers right now. The
problem of dealing with high ampacity DC circuits keeps me from wanting to
jump back into DC Coupled systems despite the advantages of cost, capacity
and efficiency for off-grid applications and backup.

So from what I'm reading here, the DC charge control is an issue when DC
batteries are abruptly disconnected. It seems like an AC-coupled PV system
is the answer to that, but it still leaves some DC battery disconnect
issues to be considered, especially the remote disconnect issue that can
come up.

My pipe dream is for Enphase to drastically cut their price and drastically
increase their battery capacity, and then get rid of all of the ridiculous
communication issues that frustrate me endlessly. Their unique AC coupling
that parallels generator output to PV via the System Controller is a novel
approach, albeit limited in flexibility. Absent my dreams coming true,
maybe someone will come along with an integrated answer that solves some of
these DC coupling issues. I'm not holding my breath that standards will be
developed. We're more likely to have a slow march toward AC coupling as
codes make it harder and harder to comply with the DC issues.

Jason Szumlanski
Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956


On Wed, Feb 1, 2023 at 4:50 PM Brian Mehalic via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

> Most firefighters are not electrical engineers; nor are most insurance
> agents. However both of those groups are stakeholders with influence over
> codes and standards. Some may say too much influence, but the fact of the
> matter is that code making is a group/consensus process, and very often
> none of the groups get exactly what they want (in fact sometimes a group
> accepts exactly what it doesn't want to leverage that for something they
> do; yes it often smacks of politics). I would appeal to y'all to submit a
> proposal for the 2026 NEC® - they are due by September of this year. Better
> yet would be to circulate language that this, or some other, group can work
> on, agree on, write a solid technical justification for, and sign their
> names to and submit - the more stakeholders that support a proposal the
> more weight it has.
>
> It seems that the PV Industry Forum, or another similar body, may again
> begin work to develop PV and storage industry stakeholder-consensus PIs to
> submit; in the past this was a very successful endeavor. I'll post on this
> list if and when that happens so that anyone that is interested can get
> involved, but don't let that possibility keep you from submitting any PIs
> on your own.
>
> Maybe in the meantime, a control system that shuts off the PV, and then
> the batteries, would be worth designing.
>
> Brian Mehalic
>
>
>
>
> On Wed, Feb 1, 2023 at 2:10 PM James Jefferson Jarvis via RE-wrenches <
> re-wrenches@lists.re-wrenches.org> wrote:
>
>>
>>
>> On 2/1/2023 2:58 PM, Starlight via RE-wrenches wrote:
>> > Have you (or any) installed surge suppression on the PV input side to
>> > clamp the open circuit voltage surge?
>>
>> That's not where the issue is and isn't really a solution. As I
>> explained in my previous e-mail, the issue is the open circuit on the
>> output leaves no where for the energy in the MPPT controllers inductor
>> to go and the only option is for the voltage to rise until it finds
>> somewhere to go.
>>
>> Surge suppressors, such as sold by Midnite Solar, are nothing more than
>> Metal Oxide Varistors. Or in the case of Delta, they are pieces of wire
>> in sand. They require large rise in voltage before they conduct.
>>
>> MOVs are sometimes found on the battery side of inverters and charge
>> controllers, but their clamp time and voltage before clamping requires
>> additional circuitry that works faster to protect fragile semiconductors.
>>
>>
>> If you are proposing using a surge supressor to regulate the voltage of

Re: [RE-wrenches] Remote battery disconnects

[Brian Mehalic via RE-wrenches]

Most firefighters are not electrical engineers; nor are most insurance
agents. However both of those groups are stakeholders with influence over
codes and standards. Some may say too much influence, but the fact of the
matter is that code making is a group/consensus process, and very often
none of the groups get exactly what they want (in fact sometimes a group
accepts exactly what it doesn't want to leverage that for something they
do; yes it often smacks of politics). I would appeal to y'all to submit a
proposal for the 2026 NEC® - they are due by September of this year. Better
yet would be to circulate language that this, or some other, group can work
on, agree on, write a solid technical justification for, and sign their
names to and submit - the more stakeholders that support a proposal the
more weight it has.

It seems that the PV Industry Forum, or another similar body, may again
begin work to develop PV and storage industry stakeholder-consensus PIs to
submit; in the past this was a very successful endeavor. I'll post on this
list if and when that happens so that anyone that is interested can get
involved, but don't let that possibility keep you from submitting any PIs
on your own.

Maybe in the meantime, a control system that shuts off the PV, and then the
batteries, would be worth designing.

Brian Mehalic




On Wed, Feb 1, 2023 at 2:10 PM James Jefferson Jarvis via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

>
>
> On 2/1/2023 2:58 PM, Starlight via RE-wrenches wrote:
> > Have you (or any) installed surge suppression on the PV input side to
> > clamp the open circuit voltage surge?
>
> That's not where the issue is and isn't really a solution. As I
> explained in my previous e-mail, the issue is the open circuit on the
> output leaves no where for the energy in the MPPT controllers inductor
> to go and the only option is for the voltage to rise until it finds
> somewhere to go.
>
> Surge suppressors, such as sold by Midnite Solar, are nothing more than
> Metal Oxide Varistors. Or in the case of Delta, they are pieces of wire
> in sand. They require large rise in voltage before they conduct.
>
> MOVs are sometimes found on the battery side of inverters and charge
> controllers, but their clamp time and voltage before clamping requires
> additional circuitry that works faster to protect fragile semiconductors.
>
>
> If you are proposing using a surge supressor to regulate the voltage of
> an island between a charge controller and an inverter when the battery
> is disconnected, that's also a no go. Once the MOV clamps, it stays
> clamped until voltage goes essentially to zero or until it blows up.
> It's not a regulator.
>
> -
>
> To further stir the pot, it is definitely possible to design electronics
> that can deal with load dumps and survive most anything. Aerospace
> electronics come pretty close. But all that costs money and takes space
> to do. Are we comfortable with requiring $16,000 charge controllers so
> they can handle load dumps reliably from a poorly thought out NEC
> requirement? I think the fossil fuel industry would be very happy with
> the cost of renewable energy electronics being an order of magnitude
> more expensive.
>
>
>
>
> >
> > Larry Crutcher
> > Starlight Solar Power Systems
> >
> >
> >
> > On Feb 1, 2023, at 1:23 PM, William Bryce via RE-wrenches
> >  > > wrote:
> >
> > I can also backup what Jim has said, and have seen the same gear
> > destroyed by removing the battery abruptly when the controller is under
> > heavy load. They can die, and sometimes die spectacularly.
> >
> > Have seen SolArk inverters integrated MPPT controllers blow up when
> > lithium battery BMS disconnects. Not a field fixable issue.
> >
> > Just flip off the breaker when the solar is working hard and and the
> > SolArk will give up the smoke.
> >
> > Like I originally said, it’s the non talked about issue that is a big
> > issue depending on what gear your using.
> >
> > On Wed, Feb 1, 2023 at 2:49 PM James Jefferson Jarvis via RE-wrenches
> >  > > wrote:
> >
> >
> >
> > On 2/1/2023 12:25 PM, Alex MeVay via RE-wrenches wrote:
> >  > Although our controllers are probably smaller than what you would
> be
> >  > considering in this discussion, surviving a load dump (suddenly
> >  > disconnected battery) is an engineering requirement for us, and
> > likely
> >  > would be for other responsible MFG's on this list (boB?).  The
> charge
> >  > controller can either handle full input voltage on the output, or
> >  > there is a comparator that will shut the controller down instantly
> >  > when the output voltage gets too high.
> >
> > So that's part of the picture.
> >
> > The other part of the picture is the rest of the system. The
> discussion
> > and what NEC is mandating is that the battery be disconnected. As
> > far as
> > I can tell, there 

Re: [RE-wrenches] Remote battery disconnects

[James Jefferson Jarvis via RE-wrenches]

On 2/1/2023 2:58 PM, Starlight via RE-wrenches wrote:
Have you (or any) installed surge suppression on the PV input side to 
clamp the open circuit voltage surge?


That's not where the issue is and isn't really a solution. As I 
explained in my previous e-mail, the issue is the open circuit on the 
output leaves no where for the energy in the MPPT controllers inductor 
to go and the only option is for the voltage to rise until it finds 
somewhere to go.


Surge suppressors, such as sold by Midnite Solar, are nothing more than 
Metal Oxide Varistors. Or in the case of Delta, they are pieces of wire 
in sand. They require large rise in voltage before they conduct.


MOVs are sometimes found on the battery side of inverters and charge 
controllers, but their clamp time and voltage before clamping requires 
additional circuitry that works faster to protect fragile semiconductors.



If you are proposing using a surge supressor to regulate the voltage of 
an island between a charge controller and an inverter when the battery 
is disconnected, that's also a no go. Once the MOV clamps, it stays 
clamped until voltage goes essentially to zero or until it blows up. 
It's not a regulator.


-

To further stir the pot, it is definitely possible to design electronics 
that can deal with load dumps and survive most anything. Aerospace 
electronics come pretty close. But all that costs money and takes space 
to do. Are we comfortable with requiring $16,000 charge controllers so 
they can handle load dumps reliably from a poorly thought out NEC 
requirement? I think the fossil fuel industry would be very happy with 
the cost of renewable energy electronics being an order of magnitude 
more expensive.







Larry Crutcher
Starlight Solar Power Systems



On Feb 1, 2023, at 1:23 PM, William Bryce via RE-wrenches 
> wrote:


I can also backup what Jim has said, and have seen the same gear 
destroyed by removing the battery abruptly when the controller is under 
heavy load. They can die, and sometimes die spectacularly.


Have seen SolArk inverters integrated MPPT controllers blow up when 
lithium battery BMS disconnects. Not a field fixable issue.


Just flip off the breaker when the solar is working hard and and the 
SolArk will give up the smoke.


Like I originally said, it’s the non talked about issue that is a big 
issue depending on what gear your using.


On Wed, Feb 1, 2023 at 2:49 PM James Jefferson Jarvis via RE-wrenches 
> wrote:




On 2/1/2023 12:25 PM, Alex MeVay via RE-wrenches wrote:
 > Although our controllers are probably smaller than what you would be
 > considering in this discussion, surviving a load dump (suddenly
 > disconnected battery) is an engineering requirement for us, and
likely
 > would be for other responsible MFG's on this list (boB?).  The charge
 > controller can either handle full input voltage on the output, or
 > there is a comparator that will shut the controller down instantly
 > when the output voltage gets too high.

So that's part of the picture.

The other part of the picture is the rest of the system. The discussion
and what NEC is mandating is that the battery be disconnected. As
far as
I can tell, there isn't an explicit requirement in all cases that
all of
the power inputs into the system are all going to go away at exactly
the
same time  or ever. This leaves things like charge controllers
getting input power potentially from PV or wind or grid or generator or
something else. And nothing in the NEC, as far as I can tell, is
mandating that all of the DC loads be disconnected. So the loads are
online. Now the regulation circuit (switching power supply in the case
of a MPPT controller) is regulating variable loads and nothing is
providing substantial resistance to change. Normally the battery is
acting like a very very very big capacitor. But without the battery,
there isn't enough damping in the control loops and voltage stability
will suffer. This is where you get 250 volts on your normally 48 volt
battery bus. Or 3 volts. Or -80 volts. Or all of those in a fraction of
second. This sort of thing is hard on electronics and will cause
failures.


Alex's comment about Genasun's controllers handling full input voltage
on the output is probably unique to their niche product. Looking at
their biggest controller, it appears to support VOC of 34 volts. At 34
volts, he can use 50V or 100V rated components on his output. For a
150V
input controller, you probably can. But you wouldn't because it
would be
too expensive. But on a 600V or 1000V controller, there's just no way
that you do that because 1000V rated components are big and expensive
and their spacing requirements are huge compared 100V level sort of
stuff. So the way bigger 

Re: [RE-wrenches] Remote battery disconnects

[Starlight via RE-wrenches]

Have you (or any) installed surge suppression on the PV input side to clamp the 
open circuit voltage surge? 

Larry Crutcher
Starlight Solar Power Systems



On Feb 1, 2023, at 1:23 PM, William Bryce via RE-wrenches 
 wrote:

I can also backup what Jim has said, and have seen the same gear destroyed by 
removing the battery abruptly when the controller is under heavy load. They can 
die, and sometimes die spectacularly.

Have seen SolArk inverters integrated MPPT controllers blow up when lithium 
battery BMS disconnects. Not a field fixable issue.

Just flip off the breaker when the solar is working hard and and the SolArk 
will give up the smoke. 

Like I originally said, it’s the non talked about issue that is a big issue 
depending on what gear your using.

On Wed, Feb 1, 2023 at 2:49 PM James Jefferson Jarvis via RE-wrenches 
mailto:re-wrenches@lists.re-wrenches.org>> 
wrote:


On 2/1/2023 12:25 PM, Alex MeVay via RE-wrenches wrote:
> Although our controllers are probably smaller than what you would be
> considering in this discussion, surviving a load dump (suddenly
> disconnected battery) is an engineering requirement for us, and likely
> would be for other responsible MFG's on this list (boB?).  The charge
> controller can either handle full input voltage on the output, or
> there is a comparator that will shut the controller down instantly
> when the output voltage gets too high.

So that's part of the picture.

The other part of the picture is the rest of the system. The discussion 
and what NEC is mandating is that the battery be disconnected. As far as 
I can tell, there isn't an explicit requirement in all cases that all of 
the power inputs into the system are all going to go away at exactly the 
same time  or ever. This leaves things like charge controllers 
getting input power potentially from PV or wind or grid or generator or 
something else. And nothing in the NEC, as far as I can tell, is 
mandating that all of the DC loads be disconnected. So the loads are 
online. Now the regulation circuit (switching power supply in the case 
of a MPPT controller) is regulating variable loads and nothing is 
providing substantial resistance to change. Normally the battery is 
acting like a very very very big capacitor. But without the battery, 
there isn't enough damping in the control loops and voltage stability 
will suffer. This is where you get 250 volts on your normally 48 volt 
battery bus. Or 3 volts. Or -80 volts. Or all of those in a fraction of 
second. This sort of thing is hard on electronics and will cause failures.


Alex's comment about Genasun's controllers handling full input voltage 
on the output is probably unique to their niche product. Looking at 
their biggest controller, it appears to support VOC of 34 volts. At 34 
volts, he can use 50V or 100V rated components on his output. For a 150V 
input controller, you probably can. But you wouldn't because it would be 
too expensive. But on a 600V or 1000V controller, there's just no way 
that you do that because 1000V rated components are big and expensive 
and their spacing requirements are huge compared 100V level sort of 
stuff. So the way bigger MPPT controllers deal with load dump is with 
transient voltage supression or other diodes to handle the voltage spike 
caused by the inductor when the load goes away. When operated in 
parameters, these parts don't wear out. But it can be interesting to 
size them adequately to account for inductance elsewhere in the system 
adding to voltage and energy that has to be absorbed.


There is a very simple experiment that anybody can perform to see how 
equipment handles a load dump: Simply wait for a sunny day and turn off 
the battery breaker. If no magic smoke was released, turn back on 
battery breaker. If still no magic smoke was released, then great, your 
system survived a load dump.

If you are at all uncomfortable doing this and/or your system gets 
destroyed in the process, think back to my earlier security comments 
about having a self destruct switch on the outside of your building 
allowing anyone walking by to do this experiment for you.

I have personally destroyed Outback, Midnite, and Morningstar 
controllers inadvertently or intentionally doing load dumps by shutting 
off their output breaker. Typically the TVS diodes short out and 
secondary over current protection (circuit breaker) trips before things 
catch on fire. Usuaully the UL94V0 rating on the circuit board and the 
box the circuit board is in prevents fire from spreading when things do 
get wild.

But I've also seen all of those brands survive a load dump.

I have multiple customer who have fielded lithium battery systems to 
cold locations and have had battery BMS disconnect the battery from the 
rest of the system. Ten's of thousands of dollars of equipment has been 
destroyed in these islanding events.


Some thoughts, for what they are worth.

-James Jarvis
APRS World, LLC

Re: [RE-wrenches] Remote battery disconnects

[William Bryce via RE-wrenches]

I can also backup what Jim has said, and have seen the same gear destroyed
by removing the battery abruptly when the controller is under heavy load.
They can die, and sometimes die spectacularly.

Have seen SolArk inverters integrated MPPT controllers blow up when lithium
battery BMS disconnects. Not a field fixable issue.

Just flip off the breaker when the solar is working hard and and the SolArk
will give up the smoke.

Like I originally said, it’s the non talked about issue that is a big issue
depending on what gear your using.

On Wed, Feb 1, 2023 at 2:49 PM James Jefferson Jarvis via RE-wrenches <
re-wrenches@lists.re-wrenches.org> wrote:

>
>
> On 2/1/2023 12:25 PM, Alex MeVay via RE-wrenches wrote:
> > Although our controllers are probably smaller than what you would be
> > considering in this discussion, surviving a load dump (suddenly
> > disconnected battery) is an engineering requirement for us, and likely
> > would be for other responsible MFG's on this list (boB?).  The charge
> > controller can either handle full input voltage on the output, or
> > there is a comparator that will shut the controller down instantly
> > when the output voltage gets too high.
>
> So that's part of the picture.
>
> The other part of the picture is the rest of the system. The discussion
> and what NEC is mandating is that the battery be disconnected. As far as
> I can tell, there isn't an explicit requirement in all cases that all of
> the power inputs into the system are all going to go away at exactly the
> same time  or ever. This leaves things like charge controllers
> getting input power potentially from PV or wind or grid or generator or
> something else. And nothing in the NEC, as far as I can tell, is
> mandating that all of the DC loads be disconnected. So the loads are
> online. Now the regulation circuit (switching power supply in the case
> of a MPPT controller) is regulating variable loads and nothing is
> providing substantial resistance to change. Normally the battery is
> acting like a very very very big capacitor. But without the battery,
> there isn't enough damping in the control loops and voltage stability
> will suffer. This is where you get 250 volts on your normally 48 volt
> battery bus. Or 3 volts. Or -80 volts. Or all of those in a fraction of
> second. This sort of thing is hard on electronics and will cause failures.
>
>
> Alex's comment about Genasun's controllers handling full input voltage
> on the output is probably unique to their niche product. Looking at
> their biggest controller, it appears to support VOC of 34 volts. At 34
> volts, he can use 50V or 100V rated components on his output. For a 150V
> input controller, you probably can. But you wouldn't because it would be
> too expensive. But on a 600V or 1000V controller, there's just no way
> that you do that because 1000V rated components are big and expensive
> and their spacing requirements are huge compared 100V level sort of
> stuff. So the way bigger MPPT controllers deal with load dump is with
> transient voltage supression or other diodes to handle the voltage spike
> caused by the inductor when the load goes away. When operated in
> parameters, these parts don't wear out. But it can be interesting to
> size them adequately to account for inductance elsewhere in the system
> adding to voltage and energy that has to be absorbed.
>
>
> There is a very simple experiment that anybody can perform to see how
> equipment handles a load dump: Simply wait for a sunny day and turn off
> the battery breaker. If no magic smoke was released, turn back on
> battery breaker. If still no magic smoke was released, then great, your
> system survived a load dump.
>
> If you are at all uncomfortable doing this and/or your system gets
> destroyed in the process, think back to my earlier security comments
> about having a self destruct switch on the outside of your building
> allowing anyone walking by to do this experiment for you.
>
> I have personally destroyed Outback, Midnite, and Morningstar
> controllers inadvertently or intentionally doing load dumps by shutting
> off their output breaker. Typically the TVS diodes short out and
> secondary over current protection (circuit breaker) trips before things
> catch on fire. Usuaully the UL94V0 rating on the circuit board and the
> box the circuit board is in prevents fire from spreading when things do
> get wild.
>
> But I've also seen all of those brands survive a load dump.
>
> I have multiple customer who have fielded lithium battery systems to
> cold locations and have had battery BMS disconnect the battery from the
> rest of the system. Ten's of thousands of dollars of equipment has been
> destroyed in these islanding events.
>
>
> Some thoughts, for what they are worth.
>
> -James Jarvis
> APRS World, LLC
>
>
> ___
> List sponsored by Redwood Alliance
>
> Pay optional member dues here: http://re-wrenches.org
>
> List Address: 

Re: [RE-wrenches] Remote battery disconnects

[James Jefferson Jarvis via RE-wrenches]

On 2/1/2023 12:25 PM, Alex MeVay via RE-wrenches wrote:

Although our controllers are probably smaller than what you would be
considering in this discussion, surviving a load dump (suddenly
disconnected battery) is an engineering requirement for us, and likely
would be for other responsible MFG's on this list (boB?).  The charge
controller can either handle full input voltage on the output, or
there is a comparator that will shut the controller down instantly
when the output voltage gets too high.


So that's part of the picture.

The other part of the picture is the rest of the system. The discussion 
and what NEC is mandating is that the battery be disconnected. As far as 
I can tell, there isn't an explicit requirement in all cases that all of 
the power inputs into the system are all going to go away at exactly the 
same time  or ever. This leaves things like charge controllers 
getting input power potentially from PV or wind or grid or generator or 
something else. And nothing in the NEC, as far as I can tell, is 
mandating that all of the DC loads be disconnected. So the loads are 
online. Now the regulation circuit (switching power supply in the case 
of a MPPT controller) is regulating variable loads and nothing is 
providing substantial resistance to change. Normally the battery is 
acting like a very very very big capacitor. But without the battery, 
there isn't enough damping in the control loops and voltage stability 
will suffer. This is where you get 250 volts on your normally 48 volt 
battery bus. Or 3 volts. Or -80 volts. Or all of those in a fraction of 
second. This sort of thing is hard on electronics and will cause failures.



Alex's comment about Genasun's controllers handling full input voltage 
on the output is probably unique to their niche product. Looking at 
their biggest controller, it appears to support VOC of 34 volts. At 34 
volts, he can use 50V or 100V rated components on his output. For a 150V 
input controller, you probably can. But you wouldn't because it would be 
too expensive. But on a 600V or 1000V controller, there's just no way 
that you do that because 1000V rated components are big and expensive 
and their spacing requirements are huge compared 100V level sort of 
stuff. So the way bigger MPPT controllers deal with load dump is with 
transient voltage supression or other diodes to handle the voltage spike 
caused by the inductor when the load goes away. When operated in 
parameters, these parts don't wear out. But it can be interesting to 
size them adequately to account for inductance elsewhere in the system 
adding to voltage and energy that has to be absorbed.



There is a very simple experiment that anybody can perform to see how 
equipment handles a load dump: Simply wait for a sunny day and turn off 
the battery breaker. If no magic smoke was released, turn back on 
battery breaker. If still no magic smoke was released, then great, your 
system survived a load dump.


If you are at all uncomfortable doing this and/or your system gets 
destroyed in the process, think back to my earlier security comments 
about having a self destruct switch on the outside of your building 
allowing anyone walking by to do this experiment for you.


I have personally destroyed Outback, Midnite, and Morningstar 
controllers inadvertently or intentionally doing load dumps by shutting 
off their output breaker. Typically the TVS diodes short out and 
secondary over current protection (circuit breaker) trips before things 
catch on fire. Usuaully the UL94V0 rating on the circuit board and the 
box the circuit board is in prevents fire from spreading when things do 
get wild.


But I've also seen all of those brands survive a load dump.

I have multiple customer who have fielded lithium battery systems to 
cold locations and have had battery BMS disconnect the battery from the 
rest of the system. Ten's of thousands of dollars of equipment has been 
destroyed in these islanding events.



Some thoughts, for what they are worth.

-James Jarvis
APRS World, LLC


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Re: [RE-wrenches] Remote battery disconnects

[Jeff Clearwater via RE-wrenches]

Hi Esteemed Wrenchies,

Love this discussion.

It is clear to me after many years of watching this that the industry 
needs to have an Emergency Shutdown standard that includes an emergency 
shutdown of the BMS of every battery as well as the inverter's circuits 
including MPPTs if all all-in-one.


We are pushing now for all battery and inverter manufacturers to include 
this feature in their inverter communications so that if the inverter 
emergency shutdown pins are shorted -every battery shuts down.


This would avoid the ridiculous requirement of every battery cable being 
on a relay/contactor or bringing it to the outside of the house!





Jerry Shafer via RE-wrenches 
January 30, 2023 at 5:08 PM
Wrenches.
You might want to consider turning off the inverter as a solution to 
turning off the batteries, we have this feature as part of our 
installs with outback real simple then no chance of AC anywhere, Not 
going to pop a CC, no chance of run on and it has passed every time. 
Just a thought that's a safe solution. With Outback you just have to 
turn off the master nothing else.

"Fun time in a crazy world"



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Brian Mehalic via RE-wrenches 
January 30, 2023 at 10:54 AM
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 
 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 

Re: [RE-wrenches] Remote battery disconnects

[Alex MeVay via RE-wrenches]

> Oh, yeah, the charge controller blowing up thing:  Does anyone have any 
> factual data to share on this?

Although our controllers are probably smaller than what you would be
considering in this discussion, surviving a load dump (suddenly
disconnected battery) is an engineering requirement for us, and likely
would be for other responsible MFG's on this list (boB?).  The charge
controller can either handle full input voltage on the output, or
there is a comparator that will shut the controller down instantly
when the output voltage gets too high.

The only time we run into trouble during a load dump is if there is
another charger that is less well-behaved, such as an alternator,
running at the same time.  This most commonly happens on sailboats,
when someone turns off the ignominious battery switch with the engine
still running.  The alternator spikes the battery line from 12V up to
50-100V+ before the alternator regulator can respond, and the charge
controller (and other electronics aboard) might not survive.

Tangential to this conversation, it seems battery switches cause our
marine and RV customers way more problems than they solve.  It seems
important to have one, but I wish they were a little more towards the
break-glass-in-case-of-emergency end of the accessibility spectrum.

Thank as always, Wrenches, for the information you share and high
level of discourse.

Alex MeVay

Genasun * Blue Sky Energy * http://sunforgellc.com
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