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Bill:<br><br>
I have to disagree with you on this one. We can not abandoned a
tried and true practice just because some practitioners don't do it
right. I don't know how one can justify saying that encapsulating
high voltage conductors in a conduit is less safe than exposed in a
flimsy basket. Consider snow and ice and falling objects.<br><br>
Too many installers entered the PV field without first acquiring the
necessary skills as journeymen or women electricians. I don't see
the benefit of rewriting the code to accommodate a lack of skills in the
industry.<br><br>
Respectfully,<br><br>
William Miller<br><br>
PS: The temperature adders always encourage us to enter the
building envelope at the first appropriate location to avoid adding
them. Thoughtful installers will do the same.<br><br>
Wm<br><br>
<br>
At 10:15 PM 3/25/2013, you wrote:<br>
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William,<br>
<br>
I would strongly disagree that conduit is tried and true on rooftops. I
have rarely seen good conduit runs on rooftops. Most electricians have no
clue how to work with expansion joints. Conduit on rooftops is a bad idea
in general. Most conduit runs in big buildings are all done indoors for
good reason. We are the crazy people doing things on the roof. <br>
<br>
The sooner we get away from conduitparticularly for long feeder runsthe
better.<br>
<br>
In Europe they don’t have problems with their rooftop wiring systems
because everything is in tray.<br>
<br>
For those that don’t allow cable tray for anything less than 1/0, just
remember that if it isn’t called cable tray, then 392 doesn’t apply. The
NEC would allow us to use treated lumber in place of cable tray. This
makes no sense.<br>
<br>
We did some research on the origin of the 1/0 requirement, and it is
ancient and no longer relevant. Just because it is in the code, does not
mean it is correct. That’s why we try to fix it every three years.<br>
<br>
Bill.<br>
<br>
<br>
<b>From:</b> re-wrenches-bounces@lists.re-wrenches.org
[<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" eudora="autourl">mailto:re-wrenches-bounces@lists.re-wrenches.org</a>]
<b>On Behalf Of </b>William Miller<br>
<b>Sent:</b> Monday, March 25, 2013 9:30 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] Cable tray<br>
<br>
David:<br><br>
Of course, I understand that you are not saying we can willfully
disregard the Code in anticipation of future clarification. I was
just extrapolating on your idea. <br><br>
If we want an exception based on a predicted update in the code, we are
at the mercy of the AHJ who may or may not be convinced. I think
most AHJs are willing to diverge from the Code in a more strict
interpretation, but not the reverse. Right now, as I read it, unless the
leads are 1/0 or larger, we are forbade.<br><br>
I treat PV systems like rooftop AC units. The voltages and currents
are similar, if not more severe. I don't believe you could or
should run power to a rooftop AC unit in cable tray. Conduit is a
tried and true practice and I recommend it.<br><br>
William Miller<br><br>
<br>
At 06:01 PM 3/25/2013, you wrote:<br><br>
Ouch. I promise I'm not advocating for anything like that. What I may be
missing is the Code reference that says "no cable tray on
roofs" or similar. <br><br>
There is so much room for improvement in wire management practices, that
being able to use cable tray seems like a step forward. I understand some
jurisdictions do not allow it, but it appears as though Code changes were
made specifically to address this. It's boring stuff, but you can read
the explanation of the Code changes in the ROP and ROC documents.
<br><br>
The Code changes a lot with regards to PV system, and Article 690 is more
fluid than other articles. Some of this is the Code trying to keep up
with technology. In other cases the Code evolves based on new
applications for existing products. Often it changes because some areas
of the Code are confusing for electricians and inspectors alike. If the
new Code language is more clear in its intent than previous versions,
some inspectors are willing to let installers build to the most current
standard.<br><br>
That's all I'm advocating for: Trying to understand how the minimum
requirements outlined in Code evolve over time so that you can have a
friendly and informed conversation with your AHJ over a donut. <br><br>
<br><br>
<br>
On Mar 25, 2013, at 6:26 PM, William Miller wrote:<br><br>
<br>
David:<br><br>
This is great news. Now, whenever I want to do something that is
prohibited by code, I can just say that the Code Making Panel is gonna
correct that pesky code section (<i>insert your problem citation
here</i>) any day now, so I might as well be allowed to do whatever it
was I was fixin' to do anyway. Unless I am missing
something...<br><br>
Thanks!<br><br>
William Miller<br><br>
PS: Just kidding. Hope no offense is taken.<br><br>
wm<br><br>
<br>
At 03:46 PM 3/25/2013, you wrote:<br><br>
<br>
So if you ever get called on 392.10(B)(2), I think you can point out that
the Code Making Panels have been busy clarifying that cable tray is okay
for source circuit conductors. Unless I'm missing something....<br>
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