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--></style></head><body lang="EN-US" link="blue" vlink="purple"><div class="WordSection1"><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Wrenches:</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Here is a question that has bothered me for some time: If one is using a GFD (ground fault detection) breaker on a PV feeder(s) to a battery inverter system, the state of the industry is to use a breaker with an extra 0.5 or 1 amp pole. This section of the breaker connects, or bonds the DC negative, or grounded conductor, to the grounding system.</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">In order for the GFD breaker to work one needs to isolate the grounded bus bar (negative). If there is a ground fault the breaker opens and breaks the bond.</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">This goes very much against my conceptualization of how a bonding system should work. The bond should never be broken, particularly when there is a fault in the system. When this breaker opens, either manually or by an overcurrent condition on any pole, the DC bond is removed for all portions of the DC system.</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">There is a prominent personality in the industry that often presents academic opinions on solar related electrical issues in articles and in seminars. This person claimed to have invented this GFD system, but when pressed to comment on the concerns mentioned above, changed the subject.</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">I believe ground fault protection is important. I just don\u2019t believe the method the industry has offered is really effective in solving the issues presented in a ground fault scenario. </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">I believe similar issues present on non-battery PV systems with the simple fuse in the ground system found on many inverters. I know some troubleshooting guides warn of energized parts in ground fault conditions.</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Have any of you thought about these concerns? Are my concerns valid? What are your policies on this subject?</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">Thanks in advance for any insight.</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif"">William Miller</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Verdana","sans-serif""> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial","sans-serif"">Miller Solar</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial","sans-serif"">17395 Oak Road, Atascadero, CA 93422</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial","sans-serif"">805-438-5600</span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial","sans-serif""><a href="http://www.millersolar.com/">www.millersolar.com</a></span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial","sans-serif"">CA Lic. 773985</span></p><p class="MsoNormal"> </p><p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Arial","sans-serif"">Quote of the month: \u201cAs they age, batteries transition from energy </span></p><p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Arial","sans-serif"">storage devices to energy consuming devices.\u201c W. Miller</span></p><p class="MsoNormal"> </p></div></body></html>