[RE-wrenches] Target fire

Mon Oct 18 16:07:36 PDT 2010

Hi Nick,

Technically, I sent my message a half an hour before the timestamp on yours.
I've had a few messages take quite some time to actually show up on the list
lately. Technically speaking, I think Michael has me on the "review before
publishing" list at the moment. Was it something I wrote? ;)

Regarding "why I believe there was probably a fault, on the array side of
the combiner, before the coupling fire":  There were 14 blown fuses in the
affected combiner, for starters. I've seen this racking system and the piss
poor way that wires are pulled in it. I've personally seen fault currents in
this racking system. I've been lucky to do lots of post-mortems on failures
in PV systems over the years. Large and small failures. I'm finding it hard
to believe that the arcing at the coupling somehow induced enough current to
ignite the string wiring and modules on the other side of that combiner...
Unless the wiring or a module was already compromised. Even the honorable
electrical inspector and esteemed Mr. Wiles concluded that a "low level
fault" in the array was likely (top of page 6 in the report). I agree with
this aspect of the report.

Regarding "the fuse protecting that one string should open and elimate that
string from the array":  Yeah. Sort of. But only if the fault is in the
fused conductor. Since this was a Xanthrax project, it was negatively
grounded. Meaning that the positive conductors are fused. If you short the
positive conductor of a string somewhere in that sharp-edged racking, you
will most likely blow a fuse in the string combiner. Which still leaves the
negative conductor of that string connected to the rest of the array. Which
means that the module and the positive conductor are also connected to the
rest of the array. Until something burns completely in two, that is. But
what about a negative to ground fault? No combiner fuse is going to blow
there. Not only is the negative very solidly connected to the rest of the
array, the positive is, too. If you introduce a catastrophic failure, like
the flaming coupling, once the ground-fault fuse opens up, have a nice day!

I think that trying to hang the electrician for using an expansion fitting
that wasn't listed for EMT is bullsomethingsmelly, by the way. Not using
enough of them or not leaving room to move in the straps, that's a different
story.

I also think that it's probable that the EMT was never fully inserted in the
coupling and that the coupling was never tightened in the first place. I
think "expansion and contraction" wasn't as much a factor as they make it
out to be. On top of that, the original installation was finished in March.
A year later, in April, the fires broke out. The temperature difference
between March and April is not super-significant in Bakersfield. Let's just
say Fire Day was 20 degrees warmer than Pipe Installation Day for the sake
of discussion. The math they did in the report regarding range of expansion
relates to comparing the extreme low temp to the extreme high temp. A total
of 3.7" calculated over 113 degree differential. I don't buy that the pipe
contracted 2" when the differential was a positive 20 degrees. Which is what
would have had to happen if the pipe was fully inserted into the coupling
originally. This tells me that it was probably never fully inserted and the
coupling was never tightened. Even if it was fully inserted, but the
coupling not tightened, it most likely pulled back when they pulled the
wire. Which could very possibly have compromised the insulation at that
time. Over the course of a year, it would have moved a little, eventually
wearing thru the insulation on one of the conductors and initiating an arc.
Which quickly heated up, involving the other conductors and the full wrath
of the entire array. 

The bottom line is several important quality control measures were missed.
Accident or negligence? I have my thoughts on the matter. One of them is
that I'm glad nobody got hurt. This time.

$0.02001

Solar "Don't Call Me Negligent" Janitor

PS - FYI to everyone. These are just my observations, based on the various
types and sources of information I have. I wasn't there. I didn't get to
inspect the thing after the cooking was done. Personally, I would like to
have the monitoring data and service records on this site. And a snapshot of
the inverter brain so we have some idea how many ground-faults there had
been since day 1. The whole intent behind my comments is to PREVENT THIS
KIND OF THING FROM HAPPENING IN THE FUTURE. That's all. 
  _____  

From: Nick Soleil [mailto:nicksoleilsolar at yahoo.com] 
Sent: Monday, October 18, 2010 2:09 PM
To: gilligan06 at gmail.com; RE-wrenches
Subject: Re: [RE-wrenches] Target fire

Hi Matt:
    I saw you chimed in after I had sent my posting.  It appears that the
fire was caused by just the one fault at the loose 2" EMT connector.  If one
of the module strings was faulted, then the fuse protecting that one string
should open, and thus eliminating that string from the array.  Why do you
think that the module level wiring contributed?

Nick Soleil
Project Manager
Advanced Alternative Energy Solutions, LLC
PO Box 657
Petaluma, CA 94953
Cell: 707-321-2937
Office: 707-789-9537
Fax: 707-769-9037 

  _____  

From: Matt Lafferty <gilligan06 at gmail.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Mon, October 18, 2010 1:12:34 PM
Subject: Re: [RE-wrenches] Target fire

Andrew,

The General/Prime Contractor on the job was SunPower vis a vis Powerlight.
As per standard operating procedures there, the actual installation was
subbed out. I don't recall which subs they used on this job, but there was
more than one. Per their normal routine, one sub installs the racking,
modules, and wiring from the modules to the combiners. This sub can have any
one of several different license classifications. They use an electrical sub
to install the combiners, homeruns, inverters, interconnection. The
electrical sub is responsible for terminations.

Although I wasn't onsite to inspect the charcoal, I believe there were
multiple shorts, not just the separated coupling in the homerun. I suspect
there was at least one ground-fault in the array prior to whatever happened
at the coupling. If this was the case, then BOTH SUBCONTRACTORS FAILED. They
are both at least partially responsible for what happened there.

I have seen the racking system that was used on the Bakersfield project. The
vintage used there had SEVERE problems with wire management. Absolute crap!
Ground faults are common with that racking system. I have personally
witnessed a system running with 8 amps of current on the ground using the
same racking system. This was NOT on the Bakersfield site. Although I wasn't
permitted to troubleshoot the problem, I was told that they had been chasing
the ghost for several months. Ever since the initial installation. I have it
from reliable sources that this condition is common and a known flaw in the
design. At that time, their philosophy was that a ground fault is acceptable
as long as there isn't enough current to trip the inverter offline. Central
inverters commonly have up to a 10 amp GFP, so you can have one or more
strings directly shorted and keep running. 

The concept that they kept installing systems with a known flaw like this is
beyond acceptable. SunPower ultimately bears the greatest share of
responsibility here. I do not know whether they have corrected the crappy
wire management in that racking system since then or not. I certainly hope
they have either corrected it or stopped using the system altogether. 

A comprehensive commissioning process would identify these problems and
prevent the system from being placed into service. A visual inspection is
the beginning of any commissioning process. As I said, I have seen these
systems and they ain't pretty. Any schmuck can easily see numerous wires
pulled across sharp-edges of sheet metal at various points throughout the
array. Fail #1. Megger output jumpers... Fail #2.

The concept that any building department has signed one of these systems off
at all is mind-boggling. Another thing I find interesting... There was no
mention of this condition in the fire investigation report. Only a
recommendation to megger the remaining wires. What's up with that? How is it
that so many of these systems have been installed and passed inspection? How
many have caught fire that we haven't heard about? You know... Just a little
fire.

I would LOVE to know how much downtime has been logged because of this
dangerous problem. And how much money has been spent troubleshooting and
"fixing" faults caused by this problem. And how many "technicians" have been
shocked during installation or service? One thing I can guarantee you...
Unless you work inside the bowels of SunPower or this information comes out
in a lawsuit somewhere, we will never know. Maybe WikiLeaks will have
something on this someday. But I'm not holding my breath.

For the record, I'm not a SunPower hater. I do hate crappy workmanship. I
hate the practice of covering up crappy workmanship even more. You see, when
you cover it up, it's just gonna keep happening. At least until somebody
calls you on it.

$0.02001

Solar Janitor

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Andrew
Truitt
Sent: Monday, October 18, 2010 12:04 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Target fire

Thanks William.  That is the first place I looked but I didn't see it in
there.  But I love all the resources on your website!

- Andrew

On Mon, Oct 18, 2010 at 12:47 PM, William Miller <william at millersolar.com>
wrote:

Andrew:

It may be in the report:
http://mpandc.com/practices/Safety/safety_data.html

William 

At 11:30 AM 10/18/2010, you wrote:

Does anyone know who installed the infamous Bakersfield Target job?

Andrew Truitt
NABCEP Certified PV InstallerT (ID# 032407-66)
Truitt Renewable Energy Consulting
(202) 486-7507
http://www.linkedin.com/pub/andrew-truitt/8/622/713

"Don't get me wrong: I love nuclear energy! It's just that I prefer fusion
to fission. And it just so happens that there's an enormous fusion reactor
safely banked a few million miles from us. It delivers more than we could
ever use in just about 8 minutes. And it's wireless!"

~William McDonough

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Please note new e-mail address and domain:

William Miller 
Miller Solar
Voice :805-438-5600
email: william at millersolar.com
http://millersolar.com <http://millersolar.com/> 
License No. C-10-773985

____________________________________

Andrew Truitt
NABCEP Certified PV InstallerT (ID# 032407-66)
Truitt Renewable Energy Consulting
(202) 486-7507
http://www.linkedin.com/pub/andrew-
<http://www.linkedin.com/pub/andrew-truitt/8/622/713> truitt/8/622/713

"Don't get me wrong: I love nuclear energy! It's just that I prefer fusion
to fission. And it just so happens that there's an enormous fusion reactor
safely banked a few million miles from us. It delivers more than we could
ever use in just about 8 minutes. And it's wireless!"

~William McDonough

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