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<div class="moz-cite-prefix">I definitely think cable tray is a good
compromise between conduit and loose zip tie wiring; I primarily
question rodent protection.<br>
Even cable trays can go horribly wrong: I've seen them not
supported properly and bend or even fall over spilling cables onto
the roof or ground.<br>
<pre class="moz-signature" cols="72">R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760</pre>
On 11/14/2013 5:27 PM, Bill Brooks wrote:<br>
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<div class="WordSection1">
<p class="MsoNormal"><span style="color:#1F497D">William,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I know your
long-time stance on conduit. It has its place. This report
was about an integrated PV system that caught fire because
of a module failure—this was not a cable management issue.
We can all jump on our respective soap boxes and
pontificate—I have no problem with that.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I don’t think
you are correct on either reason for “lax wire standards”.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo3"><!--[if !supportLists]--><span
style="color:#1F497D"><span style="mso-list:Ignore">1.<span
style="font:7.0pt "Times New Roman""> </span></span></span><!--[endif]--><span
style="color:#1F497D">When 12- and 24-V systems were done,
they were all in conduit until post 2000 when cable and
connector systems began to be used. Not the reason for lax
standards.<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo3"><!--[if !supportLists]--><span
style="color:#1F497D"><span style="mso-list:Ignore">2.<span
style="font:7.0pt "Times New Roman""> </span></span></span><!--[endif]--><span
style="color:#1F497D">Cable management is not more lax in
Europe. You typical German electrician (far more competent
than your average American electrician), works with exterior
cabling systems all the time in ac wiring. They do beautiful
work in general—there are always exceptions to every
generalization, but we have a lot to learn from them.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Lastly—conduit
systems on large rooftop PV systems have proven to be very
problematic to the point where I would not recommend the use
of metallic conduit on feeders longer than 200-feet.
Everything should be in cable tray.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Down off my
soapbox—with all respect in the world to you. Hop up again
if you please.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Bill.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #E1E1E1
1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b>
<a class="moz-txt-link-abbreviated" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>
[<a class="moz-txt-link-freetext" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">mailto:re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On
Behalf Of </b>William Miller<br>
<b>Sent:</b> Wednesday, November 13, 2013 1:42 PM<br>
<b>To:</b> 'RE-wrenches'<br>
<b>Subject:</b> [RE-wrenches] PV Wiring methods<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black">Bill:<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black">I
respectfully disagree with your logic: Define “perfectly
installed.” If your connections are tight and permanent and
the conductors are protected from damage, you have a great
chance of a reliable, safe lifetime of service. How can you
guarantee that your leads will stay protected after the ties
fail? Studies show that even UV resistant wire ties will
fail well before the life expectancy of the system has
expired. When the ties fail, your PV leads are hanging on
the roof. Even before the ties fail, rodents can chew on
them. Conduit was invented for a reason and we should be
using it.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black">I
agree that arc-fault breakers will improve the situation,
but I don’t think any form of OCPD is a substitute for good
wiring practices. I think wire protection is just as
important on PV circuits as it is on any other high voltage
circuit. Try getting away with wiring a rooftop air
conditioning unit by tying the conductors to some metal
framework with plastic ties and see how long it takes to get
red-tagged by your local inspector.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black">I
suspect we’ve gotten to where we are on lax wire protection
standards for two reasons: <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l0 level1 lfo2"><!--[if !supportLists]--><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><span
style="mso-list:Ignore">1.<span style="font:7.0pt
"Times New Roman""> </span></span></span><!--[endif]--><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black">In
the early days, PV was low voltage, 12 to 24 volts, and was
treated as such, even though current capabilities exceeded
that of conventional low voltage thermostat, door-bell and
telephone wiring.<o:p></o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l0 level1 lfo2"><!--[if !supportLists]--><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><span
style="mso-list:Ignore">2.<span style="font:7.0pt
"Times New Roman""> </span></span></span><!--[endif]--><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black">It
is my understanding that PV wiring standards in Europe are
not stringent, and European demand drove the PV market for
many years. Products were built to satisfy the European
market and US standards had to work with the equipment
available.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black">Some
would say: “if it is under the array, it is protected.” We
have seen PV wire getting damaged under arrays and it is
possible to get damaged under BPIV components as well. I
believe that protecting PV wire is more important than
protecting conventional AC circuit wiring because PV
circuits are more prone to create and sustain arcing.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black">Some
say that protecting PV wire in conduits will add too much
expense to PV installations. Consider the cost of fires
and, inevitably, injuries and deaths. One news story about
an obscure, rarely used product is already causing many of
us headaches. Statistically, it is inevitable that more
accidents will happen. I don’t want that on my conscience.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black">I
would suggest that we need to expand the discussion beyond
fire hazards. I also worry about electrocution hazards in
high voltage PV circuits. Good wire protection is essential
in preventing contact with high voltages.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black">Unprotected
PV wiring is an irresponsible practice. I am fighting an
uphill battle to develops methods to protect PV wiring
because the industry is not helping at all. The trend has
been to make it harder to protect wiring. This trend will
result in accidents. I think we should do better.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black">Sincerely,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black">William
Miller<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
<a moz-do-not-send="true"
href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>
[<a moz-do-not-send="true"
href="mailto:re-wrenches-bounces@lists.re-wrenches.org">mailto:re-wrenches-bounces@lists.re-wrenches.org</a>]
<b>On Behalf Of </b>Bill Brooks<br>
<b>Sent:</b> Monday, November 11, 2013 3:38 PM<br>
<b>To:</b> 'RE-wrenches'<br>
<b>Subject:</b> Re: [RE-wrenches] RE-wrenches Digest,
Vol 6, Issue 423<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">William and
David,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">This particular
problem goes away with arc fault detection. The longer we
wait to introduce arc fault detection into our systems, the
more we will have opportunities for news reports such as the
one William brings forward. Wire ties are not the problem.
Could a wire tie cause a problem-sure, just like anything
improperly installed.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">At the end of
the day, you can a have a perfectly installed system, but if
it does not have arc fault detection and high resolution
ground fault detection, it can still catch on fire. You have
no control over product failures other than buying from
large companies that can actually insure their products in a
failure.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Fires are not
that common, but it didn’t take much to get all the viewers
of this news report up in arms did it?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Bill.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
</div>
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