Re: [RE-wrenches] Inverter Output Circuit OCPD Meltdown

[August Goers]

Hi Jason -

It certainly appears that there was some sort of surge or short. We've had
a few cases where microinverter branch circuit end termination caps were
left off or fell off and shorted out during rain storms. You might want to
double check that those are all in place. We've also had cases were
microinvers themselves developed internal shorts. This third comment is
only anecdotal - I've been in touch with a couple of other installers that
have had back-fed breaker issues specifically with Eaton brand breakers
burning up the bus stabs. Our company has had one unexplained issue where
the inverter output breaker bus stabs were burned up with Eaton breakers. I
have no idea whether the breakers were faulty or what, but thought I'd just
mention it in case there is a pattern.

Best, August
Luminalt


On Tue, Jan 21, 2020 at 9:10 AM Jason Szumlanski <
ja...@floridasolardesigngroup.com> wrote:

> (System installed by another contractor...)
>
> I have been tasked with assisting in the investigation of damage in a
> subpanel used to combine inverter output circuits (5 strings of
> microinverters). There appears to be no damage to conductors or other
> system components. It looks like the damage started at the stabs of the bus
> bar where the breakers connect. Picture attached. Here are a few clues:
>
>- Monitoring indicates that damage occurred overnight a few weeks ago.
>That night we had rain as a winter front came through Florida, possibly
>lightning. The prior day everything was fine.
>- The next morning, only 2 of 5 strings started producing power, but 4
>of 5 strings were reporting data to the Envoy. The two strings that were
>reporting but not producing power reported 0Vac and Voc on the DC side of
>the microinverters.
>- A couple of weeks later, 1 of the 2 strings that was producing power
>quit doing so, but continued reporting data.
>- Customer discovered damage yesterday.
>- About a week before the initial damage apparently manifested itself,
>another contractor installed a whole house generator transfer switch on the
>line side of the PV interconnection. The generator has never been run
>(there is not even a LP fuel source on site yet). I pointed out that the
>solar interconnection, which was previously on the supply side, would need
>to be moved to the supply side of the generator transfer switch's main
>breaker before operation. During the transfer switch installation, the
>contractor also switched line 1 and line 2, but that shouldn't
>really matter, except for Enphase consumption monitoring, which was messed
>up by the swapping of the lines.
>
> So I'm looking for ideas. I'm wondering if the OCPD would be a likely
> place for lightning damage to manifest itself. I can't visually detect any
> other damage anywhere else. I can't imagine that the transfer switch
> installation would have anything to do with it, but the timing is
> interesting. Other than replacing the subpanel and OCPD and firing it back
> up (no pun intended), I'm not sure how to approach further investigation.
>
> Jason Szumlanski
> Florida Solar Design Group
>
>
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Re: [RE-wrenches] Inverter Output Circuit OCPD Meltdown

[Dave Tedeyan]

Hi Jason,
I have had an experience servicing other's arrays where they used PVC on
the roof. The LB cover does not hold up over time and then water and snow
were getting into the conduit, which came straight down into the top of
that same kind of Eaton panel. Corrosion caused at least one breaker in
there to fail.
Another thing I've seen burn marks on a breaker like that just due to loose
connection (is what it appeared to be, anyway) arcing over time.
Good luck,
Dave

*Dave Tedeyan, PE*
Senior Engineer | Taitem Engineering, PC

110 South Albany Street | Ithaca, NY 14850
o. *607.277.1118 x121*  f. 607.277.2119
www.taitem.com

Solar • Sustainability • Energy • Design
Certified B-Corporation since 2013


On Tue, Jan 21, 2020 at 12:40 PM August Goers  wrote:

> Hi Jason -
>
> It certainly appears that there was some sort of surge or short. We've had
> a few cases where microinverter branch circuit end termination caps were
> left off or fell off and shorted out during rain storms. You might want to
> double check that those are all in place. We've also had cases were
> microinvers themselves developed internal shorts. This third comment is
> only anecdotal - I've been in touch with a couple of other installers that
> have had back-fed breaker issues specifically with Eaton brand breakers
> burning up the bus stabs. Our company has had one unexplained issue where
> the inverter output breaker bus stabs were burned up with Eaton breakers. I
> have no idea whether the breakers were faulty or what, but thought I'd just
> mention it in case there is a pattern.
>
> Best, August
> Luminalt
>
>
> On Tue, Jan 21, 2020 at 9:10 AM Jason Szumlanski <
> ja...@floridasolardesigngroup.com> wrote:
>
>> (System installed by another contractor...)
>>
>> I have been tasked with assisting in the investigation of damage in a
>> subpanel used to combine inverter output circuits (5 strings of
>> microinverters). There appears to be no damage to conductors or other
>> system components. It looks like the damage started at the stabs of the bus
>> bar where the breakers connect. Picture attached. Here are a few clues:
>>
>>- Monitoring indicates that damage occurred overnight a few weeks
>>ago. That night we had rain as a winter front came through Florida,
>>possibly lightning. The prior day everything was fine.
>>- The next morning, only 2 of 5 strings started producing power, but
>>4 of 5 strings were reporting data to the Envoy. The two strings that were
>>reporting but not producing power reported 0Vac and Voc on the DC side of
>>the microinverters.
>>- A couple of weeks later, 1 of the 2 strings that was producing
>>power quit doing so, but continued reporting data.
>>- Customer discovered damage yesterday.
>>- About a week before the initial damage apparently manifested
>>itself, another contractor installed a whole house generator transfer
>>switch on the line side of the PV interconnection. The generator has never
>>been run (there is not even a LP fuel source on site yet). I pointed out
>>that the solar interconnection, which was previously on the supply side,
>>would need to be moved to the supply side of the generator transfer
>>switch's main breaker before operation. During the transfer switch
>>installation, the contractor also switched line 1 and line 2, but that
>>shouldn't really matter, except for Enphase consumption monitoring, which
>>was messed up by the swapping of the lines.
>>
>> So I'm looking for ideas. I'm wondering if the OCPD would be a likely
>> place for lightning damage to manifest itself. I can't visually detect any
>> other damage anywhere else. I can't imagine that the transfer switch
>> installation would have anything to do with it, but the timing is
>> interesting. Other than replacing the subpanel and OCPD and firing it back
>> up (no pun intended), I'm not sure how to approach further investigation.
>>
>> Jason Szumlanski
>> Florida Solar Design Group
>>
>>
>> ___
>> List sponsored by Redwood Alliance
>>
>> List Address: RE-wrenches@lists.re-wrenches.org
>>
>> Change listserver email address & settings:
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Re: [RE-wrenches] Inverter Output Circuit OCPD Meltdown

[Chris Sparadeo]

Jason,

Have you calculated your back-fed amapacity allowance to confirm it
complies with the 120% busbar rule as per 705.12?

Best,
Chris

On Tue, Jan 21, 2020 at 12:40 PM August Goers  wrote:

> Hi Jason -
>
> It certainly appears that there was some sort of surge or short. We've had
> a few cases where microinverter branch circuit end termination caps were
> left off or fell off and shorted out during rain storms. You might want to
> double check that those are all in place. We've also had cases were
> microinvers themselves developed internal shorts. This third comment is
> only anecdotal - I've been in touch with a couple of other installers that
> have had back-fed breaker issues specifically with Eaton brand breakers
> burning up the bus stabs. Our company has had one unexplained issue where
> the inverter output breaker bus stabs were burned up with Eaton breakers. I
> have no idea whether the breakers were faulty or what, but thought I'd just
> mention it in case there is a pattern.
>
> Best, August
> Luminalt
>
>
> On Tue, Jan 21, 2020 at 9:10 AM Jason Szumlanski <
> ja...@floridasolardesigngroup.com> wrote:
>
>> (System installed by another contractor...)
>>
>> I have been tasked with assisting in the investigation of damage in a
>> subpanel used to combine inverter output circuits (5 strings of
>> microinverters). There appears to be no damage to conductors or other
>> system components. It looks like the damage started at the stabs of the bus
>> bar where the breakers connect. Picture attached. Here are a few clues:
>>
>>- Monitoring indicates that damage occurred overnight a few weeks
>>ago. That night we had rain as a winter front came through Florida,
>>possibly lightning. The prior day everything was fine.
>>- The next morning, only 2 of 5 strings started producing power, but
>>4 of 5 strings were reporting data to the Envoy. The two strings that were
>>reporting but not producing power reported 0Vac and Voc on the DC side of
>>the microinverters.
>>- A couple of weeks later, 1 of the 2 strings that was producing
>>power quit doing so, but continued reporting data.
>>- Customer discovered damage yesterday.
>>- About a week before the initial damage apparently manifested
>>itself, another contractor installed a whole house generator transfer
>>switch on the line side of the PV interconnection. The generator has never
>>been run (there is not even a LP fuel source on site yet). I pointed out
>>that the solar interconnection, which was previously on the supply side,
>>would need to be moved to the supply side of the generator transfer
>>switch's main breaker before operation. During the transfer switch
>>installation, the contractor also switched line 1 and line 2, but that
>>shouldn't really matter, except for Enphase consumption monitoring, which
>>was messed up by the swapping of the lines.
>>
>> So I'm looking for ideas. I'm wondering if the OCPD would be a likely
>> place for lightning damage to manifest itself. I can't visually detect any
>> other damage anywhere else. I can't imagine that the transfer switch
>> installation would have anything to do with it, but the timing is
>> interesting. Other than replacing the subpanel and OCPD and firing it back
>> up (no pun intended), I'm not sure how to approach further investigation.
>>
>> Jason Szumlanski
>> Florida Solar Design Group
>>
>>
>> ___
>> List sponsored by Redwood Alliance
>>
>> List Address: RE-wrenches@lists.re-wrenches.org
>>
>> Change listserver email address & settings:
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-- 
Chris Sparadeo


C_802-369-4458
H_802-728-3059
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Re: [RE-wrenches] Inverter Output Circuit OCPD Meltdown

[Jason Szumlanski]

Yes - It's only 56A total inverter output rating on a 125A bus. Max string
is 13A inverter output rating on 20A OCPD.





On Tue, Jan 21, 2020 at 12:58 PM Chris Sparadeo 
wrote:

> Jason,
>
> Have you calculated your back-fed amapacity allowance to confirm it
> complies with the 120% busbar rule as per 705.12?
>
> Best,
> Chris
>
> On Tue, Jan 21, 2020 at 12:40 PM August Goers  wrote:
>
>> Hi Jason -
>>
>> It certainly appears that there was some sort of surge or short. We've
>> had a few cases where microinverter branch circuit end termination caps
>> were left off or fell off and shorted out during rain storms. You might
>> want to double check that those are all in place. We've also had cases were
>> microinvers themselves developed internal shorts. This third comment is
>> only anecdotal - I've been in touch with a couple of other installers that
>> have had back-fed breaker issues specifically with Eaton brand breakers
>> burning up the bus stabs. Our company has had one unexplained issue where
>> the inverter output breaker bus stabs were burned up with Eaton breakers. I
>> have no idea whether the breakers were faulty or what, but thought I'd just
>> mention it in case there is a pattern.
>>
>> Best, August
>> Luminalt
>>
>>
>> On Tue, Jan 21, 2020 at 9:10 AM Jason Szumlanski <
>> ja...@floridasolardesigngroup.com> wrote:
>>
>>> (System installed by another contractor...)
>>>
>>> I have been tasked with assisting in the investigation of damage in a
>>> subpanel used to combine inverter output circuits (5 strings of
>>> microinverters). There appears to be no damage to conductors or other
>>> system components. It looks like the damage started at the stabs of the bus
>>> bar where the breakers connect. Picture attached. Here are a few clues:
>>>
>>>- Monitoring indicates that damage occurred overnight a few weeks
>>>ago. That night we had rain as a winter front came through Florida,
>>>possibly lightning. The prior day everything was fine.
>>>- The next morning, only 2 of 5 strings started producing power, but
>>>4 of 5 strings were reporting data to the Envoy. The two strings that 
>>> were
>>>reporting but not producing power reported 0Vac and Voc on the DC side of
>>>the microinverters.
>>>- A couple of weeks later, 1 of the 2 strings that was producing
>>>power quit doing so, but continued reporting data.
>>>- Customer discovered damage yesterday.
>>>- About a week before the initial damage apparently manifested
>>>itself, another contractor installed a whole house generator transfer
>>>switch on the line side of the PV interconnection. The generator has 
>>> never
>>>been run (there is not even a LP fuel source on site yet). I pointed out
>>>that the solar interconnection, which was previously on the supply side,
>>>would need to be moved to the supply side of the generator transfer
>>>switch's main breaker before operation. During the transfer switch
>>>installation, the contractor also switched line 1 and line 2, but that
>>>shouldn't really matter, except for Enphase consumption monitoring, which
>>>was messed up by the swapping of the lines.
>>>
>>> So I'm looking for ideas. I'm wondering if the OCPD would be a likely
>>> place for lightning damage to manifest itself. I can't visually detect any
>>> other damage anywhere else. I can't imagine that the transfer switch
>>> installation would have anything to do with it, but the timing is
>>> interesting. Other than replacing the subpanel and OCPD and firing it back
>>> up (no pun intended), I'm not sure how to approach further investigation.
>>>
>>> Jason Szumlanski
>>> Florida Solar Design Group
>>>
>>>
>>> ___
>>> List sponsored by Redwood Alliance
>>>
>>> List Address: RE-wrenches@lists.re-wrenches.org
>>>
>>> Change listserver email address & settings:
>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>>>
>>> List-Archive:
>>> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
>>>
>>> List rules & etiquette:
>>> www.re-wrenches.org/etiquette.htm
>>>
>>> Check out or update participant bios:
>>> www.members.re-wrenches.org
>>>
>>> ___
>> List sponsored by Redwood Alliance
>>
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>
> --
> Chris Sparadeo
>
>
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> H_802-728-3059
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Re: [RE-wrenches] Inverter Output Circuit OCPD Meltdown

[Jason Szumlanski]

I just remembered this... There was a tripping breaker here almost
immediately after installation. We investigated the string and found no
issues, including checking the termination cap (on all strings). We reset
the breaker a few times and it would run for days without issue, then trip.
Then we went back once to reset the breaker and heard a huge pop and smoke
was billowing out of a microinverter. It was replaced under warranty. The
system ran for months without issue after that.

Now I'm suspecting that that incident compromised the breaker and it has
been arcing for a while and just manifested itself much later down the line.

The last thing I want to do is have this subpanel and breakers changed out
and then have the incident reoccur. We will double check for water, loose
connections, termination caps, etc, but if there is an internal fault in
cabling or a microinverter, it's kinda hard to nail down these issues
without replacing a whole lot of components.

Jason



On Tue, Jan 21, 2020 at 12:40 PM August Goers  wrote:

> Hi Jason -
>
> It certainly appears that there was some sort of surge or short. We've had
> a few cases where microinverter branch circuit end termination caps were
> left off or fell off and shorted out during rain storms. You might want to
> double check that those are all in place. We've also had cases were
> microinvers themselves developed internal shorts. This third comment is
> only anecdotal - I've been in touch with a couple of other installers that
> have had back-fed breaker issues specifically with Eaton brand breakers
> burning up the bus stabs. Our company has had one unexplained issue where
> the inverter output breaker bus stabs were burned up with Eaton breakers. I
> have no idea whether the breakers were faulty or what, but thought I'd just
> mention it in case there is a pattern.
>
> Best, August
> Luminalt
>
>
> On Tue, Jan 21, 2020 at 9:10 AM Jason Szumlanski <
> ja...@floridasolardesigngroup.com> wrote:
>
>> (System installed by another contractor...)
>>
>> I have been tasked with assisting in the investigation of damage in a
>> subpanel used to combine inverter output circuits (5 strings of
>> microinverters). There appears to be no damage to conductors or other
>> system components. It looks like the damage started at the stabs of the bus
>> bar where the breakers connect. Picture attached. Here are a few clues:
>>
>>- Monitoring indicates that damage occurred overnight a few weeks
>>ago. That night we had rain as a winter front came through Florida,
>>possibly lightning. The prior day everything was fine.
>>- The next morning, only 2 of 5 strings started producing power, but
>>4 of 5 strings were reporting data to the Envoy. The two strings that were
>>reporting but not producing power reported 0Vac and Voc on the DC side of
>>the microinverters.
>>- A couple of weeks later, 1 of the 2 strings that was producing
>>power quit doing so, but continued reporting data.
>>- Customer discovered damage yesterday.
>>- About a week before the initial damage apparently manifested
>>itself, another contractor installed a whole house generator transfer
>>switch on the line side of the PV interconnection. The generator has never
>>been run (there is not even a LP fuel source on site yet). I pointed out
>>that the solar interconnection, which was previously on the supply side,
>>would need to be moved to the supply side of the generator transfer
>>switch's main breaker before operation. During the transfer switch
>>installation, the contractor also switched line 1 and line 2, but that
>>shouldn't really matter, except for Enphase consumption monitoring, which
>>was messed up by the swapping of the lines.
>>
>> So I'm looking for ideas. I'm wondering if the OCPD would be a likely
>> place for lightning damage to manifest itself. I can't visually detect any
>> other damage anywhere else. I can't imagine that the transfer switch
>> installation would have anything to do with it, but the timing is
>> interesting. Other than replacing the subpanel and OCPD and firing it back
>> up (no pun intended), I'm not sure how to approach further investigation.
>>
>> Jason Szumlanski
>> Florida Solar Design Group
>>
>>
>> ___
>> List sponsored by Redwood Alliance
>>
>> List Address: RE-wrenches@lists.re-wrenches.org
>>
>> Change listserver email address & settings:
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Re: [RE-wrenches] Inverter Output Circuit OCPD Meltdown

[Jerry Shafer]

Wrenches
Cant tell anymore but l had a buss failure due to water getting on buss and
pealing the tin off the buss and the aluminum base will light up real quick.
Jerry

On Tue, Jan 21, 2020, 9:10 AM Jason Szumlanski <
ja...@floridasolardesigngroup.com> wrote:

> (System installed by another contractor...)
>
> I have been tasked with assisting in the investigation of damage in a
> subpanel used to combine inverter output circuits (5 strings of
> microinverters). There appears to be no damage to conductors or other
> system components. It looks like the damage started at the stabs of the bus
> bar where the breakers connect. Picture attached. Here are a few clues:
>
>- Monitoring indicates that damage occurred overnight a few weeks ago.
>That night we had rain as a winter front came through Florida, possibly
>lightning. The prior day everything was fine.
>- The next morning, only 2 of 5 strings started producing power, but 4
>of 5 strings were reporting data to the Envoy. The two strings that were
>reporting but not producing power reported 0Vac and Voc on the DC side of
>the microinverters.
>- A couple of weeks later, 1 of the 2 strings that was producing power
>quit doing so, but continued reporting data.
>- Customer discovered damage yesterday.
>- About a week before the initial damage apparently manifested itself,
>another contractor installed a whole house generator transfer switch on the
>line side of the PV interconnection. The generator has never been run
>(there is not even a LP fuel source on site yet). I pointed out that the
>solar interconnection, which was previously on the supply side, would need
>to be moved to the supply side of the generator transfer switch's main
>breaker before operation. During the transfer switch installation, the
>contractor also switched line 1 and line 2, but that shouldn't
>really matter, except for Enphase consumption monitoring, which was messed
>up by the swapping of the lines.
>
> So I'm looking for ideas. I'm wondering if the OCPD would be a likely
> place for lightning damage to manifest itself. I can't visually detect any
> other damage anywhere else. I can't imagine that the transfer switch
> installation would have anything to do with it, but the timing is
> interesting. Other than replacing the subpanel and OCPD and firing it back
> up (no pun intended), I'm not sure how to approach further investigation.
>
> Jason Szumlanski
> Florida Solar Design Group
>
>
> ___
> List sponsored by Redwood Alliance
>
> List Address: RE-wrenches@lists.re-wrenches.org
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Re: [RE-wrenches] Inverter Output Circuit OCPD Meltdown

[Ray]

Almost every meltdown I've looked at was not due to lightning, but heat 
from a high resistance connection.  A lug not torqued can cause 
surrounding plastic to melt.  If the wrong breakers are used with the 
buss bar, they might snap on and work, but not be able to take the 
current over time.  Coupled with high humidity, you can start getting 
corrosion going which further increases the resistance.  Eventually, if 
its gets bad enough, the resistance can cause glowing red hot metal, and 
attached insulator plastic starts melting.


Its also possible that someone knocked a wire or breaker loose? Or 
possibly shorted the buss doing something wrong, corrected the error, 
but didn't realize the buss had been damaged.    Lots of guessing, but 
that's how you figure it out.


If it was lightning, there would be lots of related damage: Enphase 
inverters and other electronics cooked.


Ray Walters
Remote Solar
303 505-8760

On 1/21/20 12:51 PM, Jerry Shafer wrote:

Wrenches
Cant tell anymore but l had a buss failure due to water getting on 
buss and pealing the tin off the buss and the aluminum base will light 
up real quick.

Jerry

On Tue, Jan 21, 2020, 9:10 AM Jason Szumlanski 
> wrote:


(System installed by another contractor...)

I have been tasked with assisting in the investigation of damage
in a subpanel used to combine inverter output circuits (5 strings
of microinverters). There appears to be no damage to conductors or
other system components. It looks like the damage started at the
stabs of the bus bar where the breakers connect. Picture attached.
Here are a few clues:

  * Monitoring indicates that damage occurred overnight a few
weeks ago. That night we had rain as a winter front came
through Florida, possibly lightning. The prior day everything
was fine.
  * The next morning, only 2 of 5 strings started producing power,
but 4 of 5 strings were reporting data to the Envoy. The two
strings that were reporting but not producing power reported
0Vac and Voc on the DC side of the microinverters.
  * A couple of weeks later, 1 of the 2 strings that was producing
power quit doing so, but continued reporting data.
  * Customer discovered damage yesterday.
  * About a week before the initial damage apparently manifested
itself, another contractor installed a whole house generator
transfer switch on the line side of the PV interconnection.
The generator has never been run (there is not even a LP fuel
source on site yet). I pointed out that the solar
interconnection, which was previously on the supply side,
would need to be moved to the supply side of the generator
transfer switch's main breaker before operation. During the
transfer switch installation, the contractor also switched
line 1 and line 2, but that shouldn't really matter, except
for Enphase consumption monitoring, which was messed up by the
swapping of the lines.

So I'm looking for ideas. I'm wondering if the OCPD would be a
likely place for lightning damage to manifest itself. I can't
visually detect any other damage anywhere else. I can't imagine
that the transfer switch installation would have anything to do
with it, but the timing is interesting. Other than replacing the
subpanel and OCPD and firing it back up (no pun intended), I'm not
sure how to approach further investigation.

Jason Szumlanski
Florida Solar Design Group

*

*
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Re: [RE-wrenches] Inverter Output Circuit OCPD Meltdown

[Jason Szumlanski]

I discovered the issue I believe, so I thought I'd update all of you who
gave me ideas on what to look for (thank you).

And this is something that I stress the importance of all the time...

The branch circuit pairs were not properly paired up! All of the L1
conductors went to L1 on the bus and all of the L2 to L2. However, for
example, circuit 1 L1 and circuit 2 L2 were on a single 2-pole breaker. And
circuit 2 L1 and circuit 1 L2 were on another breaker. Everything worked
because it was electrically connected to the right bus bar. However, when
there was a previous fault one of the breakers probably didn't trip when it
should have as a result of the improper pairings. It was reset a few times
and just kept heating up and heating up.

This isn't conclusive, but it sure makes sense. It wasn't fun tracking this
down with 5 strings and 5 junction boxes on the roof, but once we started
continuity testing and finding strange results, it became clear.

Jason Szumlanski



On Tue, Jan 21, 2020 at 12:10 PM Jason Szumlanski <
ja...@floridasolardesigngroup.com> wrote:

> (System installed by another contractor...)
>
> I have been tasked with assisting in the investigation of damage in a
> subpanel used to combine inverter output circuits (5 strings of
> microinverters). There appears to be no damage to conductors or other
> system components. It looks like the damage started at the stabs of the bus
> bar where the breakers connect. Picture attached. Here are a few clues:
>
>- Monitoring indicates that damage occurred overnight a few weeks ago.
>That night we had rain as a winter front came through Florida, possibly
>lightning. The prior day everything was fine.
>- The next morning, only 2 of 5 strings started producing power, but 4
>of 5 strings were reporting data to the Envoy. The two strings that were
>reporting but not producing power reported 0Vac and Voc on the DC side of
>the microinverters.
>- A couple of weeks later, 1 of the 2 strings that was producing power
>quit doing so, but continued reporting data.
>- Customer discovered damage yesterday.
>- About a week before the initial damage apparently manifested itself,
>another contractor installed a whole house generator transfer switch on the
>line side of the PV interconnection. The generator has never been run
>(there is not even a LP fuel source on site yet). I pointed out that the
>solar interconnection, which was previously on the supply side, would need
>to be moved to the supply side of the generator transfer switch's main
>breaker before operation. During the transfer switch installation, the
>contractor also switched line 1 and line 2, but that shouldn't
>really matter, except for Enphase consumption monitoring, which was messed
>up by the swapping of the lines.
>
> So I'm looking for ideas. I'm wondering if the OCPD would be a likely
> place for lightning damage to manifest itself. I can't visually detect any
> other damage anywhere else. I can't imagine that the transfer switch
> installation would have anything to do with it, but the timing is
> interesting. Other than replacing the subpanel and OCPD and firing it back
> up (no pun intended), I'm not sure how to approach further investigation.
>
> Jason Szumlanski
> Florida Solar Design Group
>
>
>
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Re: [RE-wrenches] Inverter Output Circuit OCPD Meltdown

[Blake Gleason]

Thanks for sharing, Jason.  That's an excellent cautionary tale...

On Wed, Jan 22, 2020 at 2:58 PM Jason Szumlanski <
ja...@floridasolardesigngroup.com> wrote:

> I discovered the issue I believe, so I thought I'd update all of you who
> gave me ideas on what to look for (thank you).
>
> And this is something that I stress the importance of all the time...
>
> The branch circuit pairs were not properly paired up! All of the L1
> conductors went to L1 on the bus and all of the L2 to L2. However, for
> example, circuit 1 L1 and circuit 2 L2 were on a single 2-pole breaker. And
> circuit 2 L1 and circuit 1 L2 were on another breaker. Everything worked
> because it was electrically connected to the right bus bar. However, when
> there was a previous fault one of the breakers probably didn't trip when it
> should have as a result of the improper pairings. It was reset a few times
> and just kept heating up and heating up.
>
> This isn't conclusive, but it sure makes sense. It wasn't fun tracking
> this down with 5 strings and 5 junction boxes on the roof, but once we
> started continuity testing and finding strange results, it became clear.
>
> Jason Szumlanski
>
>
>
> On Tue, Jan 21, 2020 at 12:10 PM Jason Szumlanski <
> ja...@floridasolardesigngroup.com> wrote:
>
>> (System installed by another contractor...)
>>
>> I have been tasked with assisting in the investigation of damage in a
>> subpanel used to combine inverter output circuits (5 strings of
>> microinverters). There appears to be no damage to conductors or other
>> system components. It looks like the damage started at the stabs of the bus
>> bar where the breakers connect. Picture attached. Here are a few clues:
>>
>>- Monitoring indicates that damage occurred overnight a few weeks
>>ago. That night we had rain as a winter front came through Florida,
>>possibly lightning. The prior day everything was fine.
>>- The next morning, only 2 of 5 strings started producing power, but
>>4 of 5 strings were reporting data to the Envoy. The two strings that were
>>reporting but not producing power reported 0Vac and Voc on the DC side of
>>the microinverters.
>>- A couple of weeks later, 1 of the 2 strings that was producing
>>power quit doing so, but continued reporting data.
>>- Customer discovered damage yesterday.
>>- About a week before the initial damage apparently manifested
>>itself, another contractor installed a whole house generator transfer
>>switch on the line side of the PV interconnection. The generator has never
>>been run (there is not even a LP fuel source on site yet). I pointed out
>>that the solar interconnection, which was previously on the supply side,
>>would need to be moved to the supply side of the generator transfer
>>switch's main breaker before operation. During the transfer switch
>>installation, the contractor also switched line 1 and line 2, but that
>>shouldn't really matter, except for Enphase consumption monitoring, which
>>was messed up by the swapping of the lines.
>>
>> So I'm looking for ideas. I'm wondering if the OCPD would be a likely
>> place for lightning damage to manifest itself. I can't visually detect any
>> other damage anywhere else. I can't imagine that the transfer switch
>> installation would have anything to do with it, but the timing is
>> interesting. Other than replacing the subpanel and OCPD and firing it back
>> up (no pun intended), I'm not sure how to approach further investigation.
>>
>> Jason Szumlanski
>> Florida Solar Design Group
>>
>>
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Director of Innovation and Technical Excellence
O: 510-845-2997 x128
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Re: [RE-wrenches] Inverter Output Circuit OCPD Meltdown

[August Goers]

Jason -

Thanks for sharing - this is a good lesson for all Wrenches. Years ago we
had a dual string inverter installation where the DC positives and
negatives were mixed between the two interters. String 1 positive went to
inverter 1, string 1 negative went to inverter 2 and vice versa. The
inverters tested out and ran for about two weeks and then one of them
literally caught on fire. Since then, we implemented a policy of checking
wiring coming from the roof down individually. In the case of microinverter
branch circuits, this means checking each branch circuit voltage on the
roof with the other breakers off one branch at a time.

Not to get too far off on a tangent, but as we're installing more and more
energy storage with lots of onsite wiring work, it is clear that fully
testing wiring is of utmost importance. We have a procedure for checking
voltage at each piece of equipment (such as a backup loads panel, etc)
prior to turning on branch breakers. We've run into a couple of
scenarios where hots and neutrals were mixed up causing 240 v to go to a
120 v circuit. Not good.

August

On Wed, Jan 22, 2020 at 2:58 PM Jason Szumlanski <
ja...@floridasolardesigngroup.com> wrote:

> I discovered the issue I believe, so I thought I'd update all of you who
> gave me ideas on what to look for (thank you).
>
> And this is something that I stress the importance of all the time...
>
> The branch circuit pairs were not properly paired up! All of the L1
> conductors went to L1 on the bus and all of the L2 to L2. However, for
> example, circuit 1 L1 and circuit 2 L2 were on a single 2-pole breaker. And
> circuit 2 L1 and circuit 1 L2 were on another breaker. Everything worked
> because it was electrically connected to the right bus bar. However, when
> there was a previous fault one of the breakers probably didn't trip when it
> should have as a result of the improper pairings. It was reset a few times
> and just kept heating up and heating up.
>
> This isn't conclusive, but it sure makes sense. It wasn't fun tracking
> this down with 5 strings and 5 junction boxes on the roof, but once we
> started continuity testing and finding strange results, it became clear.
>
> Jason Szumlanski
>
>
>
> On Tue, Jan 21, 2020 at 12:10 PM Jason Szumlanski <
> ja...@floridasolardesigngroup.com> wrote:
>
>> (System installed by another contractor...)
>>
>> I have been tasked with assisting in the investigation of damage in a
>> subpanel used to combine inverter output circuits (5 strings of
>> microinverters). There appears to be no damage to conductors or other
>> system components. It looks like the damage started at the stabs of the bus
>> bar where the breakers connect. Picture attached. Here are a few clues:
>>
>>- Monitoring indicates that damage occurred overnight a few weeks
>>ago. That night we had rain as a winter front came through Florida,
>>possibly lightning. The prior day everything was fine.
>>- The next morning, only 2 of 5 strings started producing power, but
>>4 of 5 strings were reporting data to the Envoy. The two strings that were
>>reporting but not producing power reported 0Vac and Voc on the DC side of
>>the microinverters.
>>- A couple of weeks later, 1 of the 2 strings that was producing
>>power quit doing so, but continued reporting data.
>>- Customer discovered damage yesterday.
>>- About a week before the initial damage apparently manifested
>>itself, another contractor installed a whole house generator transfer
>>switch on the line side of the PV interconnection. The generator has never
>>been run (there is not even a LP fuel source on site yet). I pointed out
>>that the solar interconnection, which was previously on the supply side,
>>would need to be moved to the supply side of the generator transfer
>>switch's main breaker before operation. During the transfer switch
>>installation, the contractor also switched line 1 and line 2, but that
>>shouldn't really matter, except for Enphase consumption monitoring, which
>>was messed up by the swapping of the lines.
>>
>> So I'm looking for ideas. I'm wondering if the OCPD would be a likely
>> place for lightning damage to manifest itself. I can't visually detect any
>> other damage anywhere else. I can't imagine that the transfer switch
>> installation would have anything to do with it, but the timing is
>> interesting. Other than replacing the subpanel and OCPD and firing it back
>> up (no pun intended), I'm not sure how to approach further investigation.
>>
>> Jason Szumlanski
>> Florida Solar Design Group
>>
>>
>> ___
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> List Address: RE-wrenches@lists.re-wrenches.org
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Re: [RE-wrenches] Inverter Output Circuit OCPD Meltdown

[Jason Szumlanski]

What made this installation (again, by others) a bit more complicated was
that all branch circuit line conductors were black. I make it a point on my
installations to require black for L1 and red for L2 up to #6 wire size.
It's not a failsafe by any means but does reduce risk.




On Thu, Jan 23, 2020 at 2:41 PM August Goers  wrote:

> Jason -
>
> Thanks for sharing - this is a good lesson for all Wrenches. Years ago we
> had a dual string inverter installation where the DC positives and
> negatives were mixed between the two interters. String 1 positive went to
> inverter 1, string 1 negative went to inverter 2 and vice versa. The
> inverters tested out and ran for about two weeks and then one of them
> literally caught on fire. Since then, we implemented a policy of checking
> wiring coming from the roof down individually. In the case of microinverter
> branch circuits, this means checking each branch circuit voltage on the
> roof with the other breakers off one branch at a time.
>
> Not to get too far off on a tangent, but as we're installing more and more
> energy storage with lots of onsite wiring work, it is clear that fully
> testing wiring is of utmost importance. We have a procedure for checking
> voltage at each piece of equipment (such as a backup loads panel, etc)
> prior to turning on branch breakers. We've run into a couple of
> scenarios where hots and neutrals were mixed up causing 240 v to go to a
> 120 v circuit. Not good.
>
> August
>
> On Wed, Jan 22, 2020 at 2:58 PM Jason Szumlanski <
> ja...@floridasolardesigngroup.com> wrote:
>
>> I discovered the issue I believe, so I thought I'd update all of you who
>> gave me ideas on what to look for (thank you).
>>
>> And this is something that I stress the importance of all the time...
>>
>> The branch circuit pairs were not properly paired up! All of the L1
>> conductors went to L1 on the bus and all of the L2 to L2. However, for
>> example, circuit 1 L1 and circuit 2 L2 were on a single 2-pole breaker. And
>> circuit 2 L1 and circuit 1 L2 were on another breaker. Everything worked
>> because it was electrically connected to the right bus bar. However, when
>> there was a previous fault one of the breakers probably didn't trip when it
>> should have as a result of the improper pairings. It was reset a few times
>> and just kept heating up and heating up.
>>
>> This isn't conclusive, but it sure makes sense. It wasn't fun tracking
>> this down with 5 strings and 5 junction boxes on the roof, but once we
>> started continuity testing and finding strange results, it became clear.
>>
>> Jason Szumlanski
>>
>>
>>
>> On Tue, Jan 21, 2020 at 12:10 PM Jason Szumlanski <
>> ja...@floridasolardesigngroup.com> wrote:
>>
>>> (System installed by another contractor...)
>>>
>>> I have been tasked with assisting in the investigation of damage in a
>>> subpanel used to combine inverter output circuits (5 strings of
>>> microinverters). There appears to be no damage to conductors or other
>>> system components. It looks like the damage started at the stabs of the bus
>>> bar where the breakers connect. Picture attached. Here are a few clues:
>>>
>>>- Monitoring indicates that damage occurred overnight a few weeks
>>>ago. That night we had rain as a winter front came through Florida,
>>>possibly lightning. The prior day everything was fine.
>>>- The next morning, only 2 of 5 strings started producing power, but
>>>4 of 5 strings were reporting data to the Envoy. The two strings that 
>>> were
>>>reporting but not producing power reported 0Vac and Voc on the DC side of
>>>the microinverters.
>>>- A couple of weeks later, 1 of the 2 strings that was producing
>>>power quit doing so, but continued reporting data.
>>>- Customer discovered damage yesterday.
>>>- About a week before the initial damage apparently manifested
>>>itself, another contractor installed a whole house generator transfer
>>>switch on the line side of the PV interconnection. The generator has 
>>> never
>>>been run (there is not even a LP fuel source on site yet). I pointed out
>>>that the solar interconnection, which was previously on the supply side,
>>>would need to be moved to the supply side of the generator transfer
>>>switch's main breaker before operation. During the transfer switch
>>>installation, the contractor also switched line 1 and line 2, but that
>>>shouldn't really matter, except for Enphase consumption monitoring, which
>>>was messed up by the swapping of the lines.
>>>
>>> So I'm looking for ideas. I'm wondering if the OCPD would be a likely
>>> place for lightning damage to manifest itself. I can't visually detect any
>>> other damage anywhere else. I can't imagine that the transfer switch
>>> installation would have anything to do with it, but the timing is
>>> interesting. Other than replacing the subpanel and OCPD and firing it back
>>> up (no pun intended), I'm not sure how to approach furt

Re: [RE-wrenches] Inverter Output Circuit OCPD Meltdown

[Ray]

We use this 3M wire numbering dispenser.  They don't stick as well as 
I'd like, but it can solve some very weird problems later.


3M STD Wire Marker Dispenser with #0-9 H-5223 - Uline

I'm also a fiend for color coding, and have had numerous discussion here 
on the list about the need to color code wire. Crossed wiring as Jason 
has illustrated to us, can be very dangerous and lead to issues none of 
us could have predicted. Once again,  this situation would have easily 
been prevented by good old labeling and color coding by the original 
installer  Every time I open a box and see unmarked black wires running 
every where, or inconsistent colors,  I know the entire installation is 
suspect.


Ray Walters
Remote Solar
303 505-8760

On 1/23/20 2:28 PM, Jason Szumlanski wrote:
What made this installation (again, by others) a bit more complicated 
was that all branch circuit line conductors were black. I make it a 
point on my installations to require black for L1 and red for L2 up to 
#6 wire size. It's not a failsafe by any means but does reduce risk.


*

*


On Thu, Jan 23, 2020 at 2:41 PM August Goers > wrote:


Jason -

Thanks for sharing - this is a good lesson for all Wrenches. Years
ago we had a dual string inverter installation where the DC
positives and negatives were mixed between the two interters.
String 1 positive went to inverter 1, string 1 negative went to
inverter 2 and vice versa. The inverters tested out and ran for
about two weeks and then one of them literally caught on fire.
Since then, we implemented a policy of checking wiring coming from
the roof down individually. In the case of microinverter branch
circuits, this means checking each branch circuit voltage on the
roof with the other breakers off one branch at a time.

Not to get too far off on a tangent, but as we're installing more
and more energy storage with lots of onsite wiring work, it is
clear that fully testing wiring is of utmost importance. We have a
procedure for checking voltage at each piece of equipment (such as
a backup loads panel, etc) prior to turning on branch breakers.
We've run into a couple of scenarios where hots and neutrals were
mixed up causing 240 v to go to a 120 v circuit. Not good.

August

On Wed, Jan 22, 2020 at 2:58 PM Jason Szumlanski
mailto:ja...@floridasolardesigngroup.com>> wrote:

I discovered the issue I believe, so I thought I'd update all
of you who gave me ideas on what to look for (thank you).

And this is something that I stress the importance of all the
time...

The branch circuit pairs were not properly paired up! All of
the L1 conductors went to L1 on the bus and all of the L2 to
L2. However, for example, circuit 1 L1 and circuit 2 L2 were
on a single 2-pole breaker. And circuit 2 L1 and circuit 1 L2
were on another breaker. Everything worked because it was
electrically connected to the right bus bar. However, when
there was a previous fault one of the breakers probably didn't
trip when it should have as a result of the improper pairings.
It was reset a few times and just kept heating up and heating up.

This isn't conclusive, but it sure makes sense. It wasn't fun
tracking this down with 5 strings and 5 junction boxes on the
roof, but once we started continuity testing and finding
strange results, it became clear.

Jason Szumlanski



On Tue, Jan 21, 2020 at 12:10 PM Jason Szumlanski
mailto:ja...@floridasolardesigngroup.com>> wrote:

(System installed by another contractor...)

I have been tasked with assisting in the investigation of
damage in a subpanel used to combine inverter output
circuits (5 strings of microinverters). There appears to
be no damage to conductors or other system components. It
looks like the damage started at the stabs of the bus bar
where the breakers connect. Picture attached. Here are a
few clues:

  * Monitoring indicates that damage occurred overnight a
few weeks ago. That night we had rain as a winter
front came through Florida, possibly lightning. The
prior day everything was fine.
  * The next morning, only 2 of 5 strings started
producing power, but 4 of 5 strings were reporting
data to the Envoy. The two strings that were reporting
but not producing power reported 0Vac and Voc on the
DC side of the microinverters.
  * A couple of weeks later, 1 of the 2 strings that was
producing power quit doing so, but continued reporting
data.
  * Customer discovered damage yesterday.
  * About a week b