I think the issue here is 690.32 deals just with 'fittings and connectors', not
the actual wire or cable.
I believe you meant to reference 690.31 which says 'all raceway and cable
wiring methods included in this codeshall be permitted'.
But you still have to comply with 690.31E which says it
Thanks Ray, you're correct, I meant to refer to 690.31(E). and thanks
also
for your perspective . dbDan BrownPresidentFoxfire Energy Corp.Renewable Energy Systems(802)-483-2564www.Foxfire-Energy.comNABCEP #092907-44
Original Message
Subject: Re: [RE-wrenches] 690.32(E) + MC?
Fr
Hi William,
Thanks for responding. We have three long rows of modules, with rails
attached every other rafter, every 4'. The inspector's argument is that two
attachments for one row might be fine, but that the wind load for the entire
array theoretically could be born by one rafter, and therefore
HI Allan,
Here is an interesting way that statistics can make bad results.
It might be that 64% of all solar batteries are VRLA, but I would guess that
most of the those "systems" are single battery ones.
Such as road call boxes, lighting etc which number in the 10's of thousands of
systems but
I believe that in a Code Corner back in the '05 era, John Wiles had said
that MC cable was OK to use, then in a later Code Corner he says that it
isn't; I thought it was because part of the reason for a metal raceway
is physical protection, and EMT/FMC would be sturdier than MC. But then
I look
Rebecca,
With three rows and six lags in every other rafter there is a
tremendous force on each of the rafters. Unirac has excellent
information in their installation manual that shows all
the engineering info needed for ASCE-7, which is meets the
requirements for most building departments.
There have been many posts about modules pros and cons, with several had a side mention as to frame construction, but I don't remember anything that specifically addressed the strongest feames. I have had a few modules in the 200w size range over the years that just seemed flimsy to me compared t
We are starting to get much larger grid tie systems above 100 kW and I still remember very clearly that Target melt down related to conduit that shorted out a bundle of string runs between the array and inverters due to improper allowance for expansion and contraction in the long above roof conduit
I have always wondered about that statistic, and figured it had to be
something wrong with the survey - that pretty much confirms it.
It makes sense, but to add another skew to it: From Jan 2008 until now, we
have sold around $1.6 million in batteries. Of those, not a single one was
purchased
Something that may help with the inspector would be to alternate
trusses. If your array spanned ten trusses, which I'll call A-J, and you
have three rows of six rails:
Rail #1, 3, 5: attach to A, C, E, G, I, J
Rail #2, 4, 6: attach to A, B, D, F, H, J
It's not helping his concern on the end tr
Rebecca,
We have encountered this a few years back on an inspector issue [ known by
most of the early solar manufacturers as that SOB in CO] that he claimed the
issue was subject to AHJ [...@#$%^ Having Jurisdiction] .
I went over my inspectors head to his supervisor who saw my logic. The
insp
Allan, thank you for this important information.
Tom Hund, Bob Hammond, and others at the DOE brought scientific discipline
to our work, but they lacked the field experience that Wrenches have. John
Wiles, Ward Bower, Bill Brooks and others are better grounded in the
real-world and make valuab
http://www.ecmag.com/?fa=article&articleID=10827
Do any of you have any comments on the efficacy of these types of products?___
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Jeff
EMT is fine on the roof. Rigid will add weight to the roof, as well as increase
your labor costs to install it.
My take away from the Target project after reading the report was they did not
use the correct fittings. Coupled with long conduit runs and perhaps not using
junction boxes and
One thing we've had to do here is stagger the connections to the rafters
from row to row thus each rafter is secured to, not every other one. This is
easy enough to do, and just adds one extra standoff or Quick Mount in your
case on the staggered row. (we are in a high snow load area and the idea
Assume 3 parallel battery stings, with identical batteries of internal
resistance r.
Assume identical wire leads of resistance R.
Then when the batteries have the same state of charge and their internal
resistances are equal, one can solve for the current in each string.
I1 = I3
I2 = I1 r / (r+R
Sorry for mis-statement as I was not trying to place blame on the designer or installer of the Target failure which I do not have any first hand knowledge.
My point was that regardless of who did what, the conduit did came loose at a fitting, most likely due to expansion and contraction in a lo
Antony Tersol wrote:
Assume 3 parallel battery stings, with identical batteries of internal
resistance r.
Assume identical wire leads of resistance R.
Then when the batteries have the same state of charge and their
internal resistances are equal, one can solve for the current in each
string.
Call unirac; find a structural engineer who is green in the good sense
(not cents); get specs from the truss manufacturer; speak with his boss.
Sent from my iPhone
On Dec 4, 2009, at 5:55 PM, Rebecca Lundberg > wrote:
Solar is somewhat 'new technology' where I live. :-) I have a
building i
Hi Rebecca..when necessary we often locate the truss company thru the
builder or the homeowner and have had very good luck with their engineers
giving the their stamp to their own trusses as being capable of having a
solar array of the requested size installed on that set of trusses.
Typica
Rebecca:
I am not a structural engineer, nor would I second guess a structural
engineer's findings. The audacity here is that your inspector posture's
him/herself as knowing more than a licensed engineer and is imposing unfair
demands. Your maximum responsibility ends with an engineer's proj
This comment comes from a physicist, so I may be more critical that the
average bear.
To begin with, antireflective coatings have been around for a long time. The
trick with antireflective coatings is as follows:
(1) Even if the material (e.g. low iron glass) absorbs ~1% of the light
in
This also assumes all the identical batteries are at identical temperature, and
it one is slightly warmer or can not lose heat as fast, if being charged it
will get warmer. the warmer battery will do what? have a lower vltage, have
higher current and receive more heat, and get warmer, this is s
Remember target had two fires. one caused by the conduit cutting insulation and
the other by the ground current passing through small module ground leads. Had
the grounded conductor not been grounded this other fire would not have
happened. We need to move to ungrounded systems.
Darryl
Darryl:
You make an important and valid point. This is why I am interested in
Aurora Inverters. They use ungrounded PV arrays. Here is a link to the
manual.
http://www.power-one.com/resources/products/appnote/AlternativeEnergy/manual4.2us.pdf
Check out section 2.4.2. Here is the manufactu
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