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<div class=Section1>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Mark,<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Although this exception is allowed, I think it is bad practice
in the field. We will probably see the NEC revoke this exception within the
next few cycles, and it may be revoked for PV systems much sooner. Relying on
box connections to carry the low fault currents inherent in PV systems is a
really bad idea. The NEC is a minimum standard.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Bill.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><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"'> re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>Mark
Frye<br>
<b>Sent:</b> Friday, October 09, 2009 3:42 PM<br>
<b>To:</b> 'RE-wrenches'<br>
<b>Subject:</b> Re: [RE-wrenches] Rooftop wiring methods between multiple
subarrays<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>Hey Folks,</span><o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>I don't want to dicourage anyone from doing good work that meets or
exceeds Code requirements. But I am a little quizzical about the how we
all seem to be ignoring what the Code actual says about this.</span><o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>"250.97 Bonding for Over 250V Volts....</span><o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>Exception: Where oversized, concentric, or eccentric knockouts are
not encountered....the following methods shall be permitted:...(3) Fittings
with shoulders that seat firmly against the box or cabinet, such as electrical
metallic tubing connectors..."</span><o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>This tells me that if I run PV source conductors in EMT from one
metal box to another, I don't nessecarily need to bond the EMT as if it were
part of a service.</span><o:p></o:p></p>
<p class=MsoNormal> <br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Mark Frye</span>
<br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Berkeley Solar
Electric Systems</span> <br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>303 Redbud Way</span>
<br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Nevada
City, CA 95959</span> <br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>(530) 401-8024</span>
<br>
<a href="http://www.berkeleysolar.com/"><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>www.berkeleysolar.com</span></a><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span> <o:p></o:p></p>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<div class=MsoNormal align=center style='text-align:center'>
<hr size=2 width="100%" align=center>
</div>
<p class=MsoNormal style='margin-bottom:12.0pt'><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"'> re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>August
Goers<br>
<b>Sent:</b> Friday, October 09, 2009 12:57 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] Rooftop wiring methods between multiple
subarrays</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>All –<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>PVC doesn’t hold up well in the Bay Area – Here’s a photo of
some ~4 year old PVC browned PVC from Marin County:<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><img border=0 width=341 height=150 id="Picture_x0020_0"
src="cid:image001.jpg@01CA48FC.58ED0FD0" alt="PVC (Small).jpg"><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>You can see that the straps melted resulting in the conduit
sliding down. Thank goodness we didn’t install this. PCV seems like a good
option for shaded areas. <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>As Bill pointed out, if we use EMT we need to bond both ends of
the conduit to comply with NEC 250.97. My issue is that it is hard to find
outdoor rated bonding bushings – that’s why we’ve just been installing cast
metal boxes with threaded connections (complies with NEC 250.92(B)(2)).<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>As William point out, EMT is robust and reliable. I still think
that there must be more efficient way to go between arrays. Maybe that’s why
commercial low profile racking systems are often fully integrated systems with
built in wire raceways.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>-August<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>August Goers<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Luminalt Energy Corporation<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>O: 415.564.7652<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>M: 415.559.1525<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>F: 650.244.9167<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>august@luminalt.com<o:p></o:p></span></p>
</div>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><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"'>
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>William
Miller<br>
<b>Sent:</b> Friday, October 09, 2009 12:07 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] Rooftop wiring methods between multiple
subarrays<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'>Ray:<br>
<br>
Good question. We do use PVC in coastal zones to avoid corrosion.
We try to keep it in the shade, paint it where exposed to UV and support it in
close intervals.<br>
<br>
William<br>
<br>
<br>
At 10:57 AM 10/9/2009, you wrote:<o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'>Except for coastal
installations.... where EMT is NOT recommended outdoors, PVC browns
out and warps, and we should therefore use product X???<br>
<br>
R. Walters<br>
<a href="mailto:ray@solarray.com">ray@solarray.com</a><br>
Solar Engineer<br>
<br>
<br>
<br>
<br>
On Oct 9, 2009, at 11:38 AM, William Miller wrote:<br>
<br>
<o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'>August:<br>
<br>
I suggest the use of EMT with proper fittings to protect high voltage, high
amperage DC Wiring on rooftops. Sure it is time consuming, but high
quality, reliable craftsmanship will always be thus.<br>
<br>
William Miller<br>
<br>
<br>
<o:p></o:p></p>
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