Re: [RE-wrenches] 1987 NEC

[Kent Osterberg]

Thanks, Hans. The part about shorting the array was abandoned, I'm not sure but it may be have been removed for the 1993 code. It's item two on this list that I've been trying to backtrack to. It is pretty much the same as in the current code: "open the grounded conductor". It is also not the way things are actually done. The GFP fuse, circuit breaker, or PTC (Positive Temperature Coefficient) in inverters and now in some charge controllers opens the system bond (As described by John Wiles) not the grounded PV array conductor. Not openning the PV array grounded conductor means that not only is the normally grounded conductor in the PV array possibly energized (that can't be avoided), but everything else it is attached to is possibly energized. For battery based systems that includes: the battery negative terminal, battery vent fan wiring, and all dc loads. The fact that all dc loads may be energized to the potential of the PV array is troubling. Especially with the possibility now of a 600-volt PV array charging a battery system. Kent Osterberg Blue Mountain Solar Hans Frederickson wrote: Kent, I'm not a geezer yet, but thanks to my dad I do have a copy of the 1987 NEC. 690-5 (Ground Fault Detection and Interruption) was added in the 1990 NEC. There is no 690-5 or mention of ground fault detection/interruption in the 1987 NEC.   In the 1990 NEC, section 690-5 is very small compared to 690.5 in the 2011 NEC. Here's the complete text from 1990:   "690-5. Ground Fault Detection and Interruption.  Roof-mounted photovoltaic arrays located on dwellings shall be provided with ground-fault protection to reduce fire hazard. The ground-fault protection circuit shall be capable of detecting a ground fault, interrupting the fault path, and disabling the array."   The handbook for 1990 goes on to say that the gfp device must: 1) detect the ground fault 2) open the grounded conductor to interrupt the ground fault 3) open the ungrounded conductors and short the photoltaic array source to disable it   For some reason, I've never heard of item #3, specifically the part about shorting the array. Can anyone shed light on this?   Regards, -Hans From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Kent Osterberg Sent: Monday, July 18, 2011 10:07 PM To: g...@icarussolarservices.com; RE-wrenches Subject: Re: [RE-wrenches] 1987 NEC Gary, No one else has come up with a 1987 NEC. If you can get a copy of 1987 section 690.5 (I think it was 690-5 back then), I'd appreciate it. Kent Osterberg Blue Mountain Solar Gary Willett wrote: Kent: I am a member of the International Association of Electrical Inspectors (IAEI), and they're headquartered here in the Dallas area. If you aren't successful getting the info from a Wrench with the 1987 code book, let me know and I am sure I can request a FAXed copy of 1987 section 690.5. Regards, Gary Willett, PE g...@icarussolarservices.com On 7/15/2011 4:30 PM, Kent Osterberg wrote: I'm looking for the text of 1987 NEC 690.5 to compare with 2011 version. If any of you geezers have kept copies that old, please contact me off list. Thanks. Kent Osterberg Blue Mountain Solar _______________________________________________ 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 _______________________________________________ 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 _______________________________________________ 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

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