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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><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> 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> 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 href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a> [<a 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></body></html>