Ray,
The reason I mentioned resistively grounded systems is that anything requires a ground, like SunPower, could use a resistive ground instead of being ungrounded. This solves SunPower polarization issue and is the way many of their systems are installed in Europe. Bill. From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R Ray Walters Sent: Tuesday, October 19, 2010 10:50 AM To: RE-wrenches Subject: Re: [RE-wrenches] BAKERSFIELD FIRE former "Target fire" R. Walters r...@solarray.com Solar Engineer HI Bill; Where do we sign your petition? I've advocated for ungrounded systems for over a decade. Besides Europe, electric vehicles and mobile systems are long standing examples that this is safe. It also solves IMHO some lightning issues, and is easier to work on (less accidental short circuits to frames and boxes) I've done numerous ungrounded systems, and never had any problems. (We still of course bonded all exposed metal to ground, with EGCs run with the conductors) My question is how do Sunpower modules behave ungrounded? I was under the impression that they had to have positive bonded to ground to function properly. Your proposed "Temporary Ground Lift" circuit would probably be the best way for Sunpower modules? Thanks for your always thorough education of us numb nuts in the field, Ray Walters Moving to ungrounded or resistively grounded arrays is relatively easy and the NEC covers the requirements in 690.35. We already have several transformerless designs from Power-One and SMA (new TL line in the U.S.), but there is nothing holding back larger inverters using transformers with ungrounded arrays. Existing arrays could be made much safer if they were to be retrofitted with a circuit at the inverter that would lift the grounded conductor each morning and test for ground faults on the grounded conductor prior to starting the inverter. While not quite as safe as "European-style" systems, it is a large improvement over where we are today. Don't be surprised if things change about how we do GFPs soon. If I have anything to do with it, it is going to happen. The current hazardous situation, and bad information about the Bakersfield fire, cannot continue. Bill. Bill Brooks, PE Principal Brooks Engineering 873 Kells Circle Vacaville, CA 95688 707-332-0761 (office and mobile) 707-451-7739 (fax) b...@brooksolar.com (email) www.brooksolar.com <http://www.brooksolar.com/> (web) _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org <http://www.members.re-wrenches.org/>
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