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<DIV dir=ltr align=left><SPAN class=407242320-19072011><FONT face=Arial
color=#0000ff size=2>David,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=407242320-19072011><FONT face=Arial
color=#0000ff size=2>Thanks for the interesting history on GFPDs. My copy of the
1987 NEC does not have 690-5, and it's not missing any pages. Either my
code book is an incomplete printing or perhaps John Wiles was
referring to a 1987 proposal that didn't make it into the code
until the 1990 NEC. </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=407242320-19072011><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=407242320-19072011><FONT face=Arial
color=#0000ff size=2>Regards,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=407242320-19072011><FONT face=Arial
color=#0000ff size=2>-Hans</FONT> </SPAN></DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
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<FONT face=Tahoma size=2><B>From:</B> re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <B>On Behalf Of </B>David
Brearley<BR><B>Sent:</B> Tuesday, July 19, 2011 12:57 PM<BR><B>To:</B>
RE-wrenches<BR><B>Subject:</B> Re: [RE-wrenches] 1987 NEC<BR></FONT><BR></DIV>
<DIV></DIV><FONT face="Calibri, Verdana, Helvetica, Arial"><SPAN
style="FONT-SIZE: 11pt">Hans,<BR><BR>John Wiles described the evolution of this
standard for a Home Power article that we referenced later in a SolarPro on PV
System Ground Faults:<BR><BR><A
href="http://solarprofessional.com/article/?file=SP2_5_pg60_Mync">http://solarprofessional.com/article/?file=SP2_5_pg60_Mync</A><BR><BR>“</SPAN></FONT><FONT
size=1><FONT face=Arial><SPAN style="FONT-SIZE: 9pt">As described by John Wiles,
program manager for the Institute for the Energy and the Environment, in the
February/ March 2008 Home Power article "Ground-Fault Protection Is Expanding,"
Article 690.5 was added to the <I>NEC</I> in 1987. One of Wiles’ first
projects in the PV industry was to develop “prototype hardware” to meet the
new <I>Code</I> requirement. "The basic concept (of the original GFPD
prototype)," writes Wiles, "was to insert a 0.5- or 1-amp circuit breaker in the
dc system-bonding conductor." This small circuit breaker senses any current
between the grounded current-carrying conductor and the grounding system,
tripping if current exceeds the 0.5 A or 1 A rating. By mechanically linking
this smaller breaker to larger capacity breakers that are installed inline with
the ungrounded current-carrying array conductors, it is possible to detect,
interrupt and indicate that a ground fault has occurred, and to disconnect the
fault.<BR><BR>These early GFPDs were manufactured for 48 V or lower PV systems.
According to Wiles, “As higher voltage, utility-interactive PV inverters became
available in the late 1990s, using a 0.5- or 1-amp fuse as the sensing element
and the inverter’s control electronics to monitor the fuse was more cost
effective.” While the sensing equipment may have changed, in general the role of
the modern GFPD remains the same as it was in 1987:<BR><BR>1. Detect ground
faults in PV arrays. <BR>2. Interrupt the fault current. <BR>3.
Indicate that a ground fault has occurred. <BR>4. Disconnect the faulted
part of the array.<BR><BR>These four GFPD requirements for grounded PV arrays
are spelled out in <I>NEC</I> 690.5(A) and 690.5(B). The former
requires ground-fault detection and interruption (GFDI), which includes the
provision to indicate the presence of a ground fault. The latter requires that
faulted circuits be isolated either by disconnecting the ungrounded conductors
of the faulted circuit or by shutting down power to the output power circuits of
the inverter or charge controller.<BR><BR>A final GFPD requirement is found in
Article 960.5(C), which calls for a visible warning in the proximity of the
ground-fault indicator. The warning could be an LED, an LCD or both. In general,
the manufacturer provides this electric shock hazard warning as part of the
listed grid-tied inverter or charge controller. However, where a PV system
includes batteries, the installer must apply a duplicate warning label near the
batteries, stating:<BR></SPAN></FONT></FONT>
<P align=center><FONT size=1><FONT face=Arial><SPAN
style="FONT-SIZE: 9pt">WARNING <BR>ELECTRIC SHOCK HAZARD <BR>IF A
GROUND FAULT IS INDICATED, NORMALLY <BR>GROUNDED CONDUCTORS MAY BE
UNGROUNDED <BR>AND ENERGIZED </SPAN></FONT></FONT>
<P><FONT size=1><FONT face=Arial><SPAN style="FONT-SIZE: 9pt"><BR>One change in
the GFPD requirements introduced in 1987 is that it is no longer necessary to
short-circuit, or “crowbar,” the PV array in the event of a ground fault. This
added step had the effect of reducing the PV array voltage to zero, minimizing
shock hazard. The requirement was dropped in a
subsequent <I>Code</I> cycle, as leaving the array in a
short-circuited condition created several other
issues.”<BR><BR><BR></SPAN></FONT></FONT><FONT
face="Calibri, Verdana, Helvetica, Arial"><SPAN style="FONT-SIZE: 11pt">If
you’re a Home Power subscriber, you can access the original article in the HP
archives. If not, it is summarized above.<BR><BR>Best,<BR></SPAN></FONT><FONT
size=1><FONT face=Arial><SPAN
style="FONT-SIZE: 9pt"><BR></SPAN></FONT></FONT><FONT
face="Calibri, Verdana, Helvetica, Arial"><SPAN style="FONT-SIZE: 11pt">David
Brearley, Senior Technical Editor<BR><I>SolarPro</I> magazine <BR>NABCEP
Certified PV Installer ™<BR><A
href="david.brearley@solarprofessional.com">david.brearley@solarprofessional.com</A><BR>Direct:
541.261.6545<BR><BR><BR>On 7/19/11 2:19 PM, "Hans Frederickson" <<A
href="hans@fredelectric.com">hans@fredelectric.com</A>>
wrote:<BR><BR></SPAN></FONT>
<BLOCKQUOTE><SPAN style="FONT-SIZE: 11pt"><FONT color=#0000ff><FONT
face=Arial>Kent,<BR>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.<BR></FONT></FONT><FONT
face="Calibri, Verdana, Helvetica, Arial"><BR></FONT><FONT color=#0000ff><FONT
face=Arial>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:<BR></FONT></FONT><FONT
face="Calibri, Verdana, Helvetica, Arial"><BR></FONT><FONT color=#0000ff><FONT
face=Arial>"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."<BR></FONT></FONT><FONT
face="Calibri, Verdana, Helvetica, Arial"><BR></FONT><FONT color=#0000ff><FONT
face=Arial>The handbook for 1990 goes on to say that the gfp device
must:<BR>1) detect the ground fault<BR>2) open the grounded conductor to
interrupt the ground fault<BR>3) open the ungrounded conductors and short the
photoltaic array source to disable it<BR></FONT></FONT><FONT
face="Calibri, Verdana, Helvetica, Arial"><BR></FONT><FONT color=#0000ff><FONT
face=Arial>For some reason, I've never heard of item #3, specifically the part
about shorting the array. Can anyone shed light on
this?<BR></FONT></FONT><FONT
face="Calibri, Verdana, Helvetica, Arial"><BR></FONT><FONT color=#0000ff><FONT
face=Arial>Regards,<BR>-Hans<BR></FONT></FONT><FONT
face="Calibri, Verdana, Helvetica, Arial"><BR>
<HR align=center width="100%" SIZE=3>
</FONT><FONT face="Tahoma, Verdana, Helvetica, Arial"><B>From:</B> <A
href="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>Kent Osterberg<BR><B>Sent:</B> Monday, July 18, 2011 10:07
PM<BR><B>To:</B> <A
href="gary@icarussolarservices.com">gary@icarussolarservices.com</A>;
RE-wrenches<BR><B>Subject:</B> Re: [RE-wrenches] 1987 NEC<BR></FONT><FONT
face="Calibri, Verdana, Helvetica, Arial"><BR>Gary,<BR><BR>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.<BR><BR>Kent Osterberg<BR>Blue
Mountain Solar<BR><BR><BR><BR>Gary Willett wrote: <BR></FONT></SPAN>
<BLOCKQUOTE><FONT face="Calibri, Verdana, Helvetica, Arial"><FONT
size=4><SPAN style="FONT-SIZE: 14pt">Kent:<BR><BR>I am a member of the
International Association of Electrical Inspectors (IAEI), and they're
headquartered here in the Dallas area.<BR><BR>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.<BR><BR></SPAN></FONT><SPAN
style="FONT-SIZE: 11pt"><BR> <BR> <BR><BR></SPAN><FONT
size=2><SPAN style="FONT-SIZE: 10pt">Regards,<BR><BR>Gary Willett, PE<BR><A
href="Gary@IcarusSolarServices.com">Gary@IcarusSolarServices.com</A><BR></SPAN></FONT><SPAN
style="FONT-SIZE: 11pt"><BR>On 7/15/2011 4:30 PM, Kent Osterberg
wrote: <BR></SPAN></FONT>
<BLOCKQUOTE><FONT face="Calibri, Verdana, Helvetica, Arial"><SPAN
style="FONT-SIZE: 11pt">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. <BR><BR>Kent Osterberg
<BR>Blue Mountain Solar
<BR>_______________________________________________
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