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The un-controlled conductor could be up to 15 feet, 10 on the roof
and 5 in the building?<br>
<br>
Mark Frye<br>
Berkeley Solar Electric Systems<br>
<br>
<div class="moz-cite-prefix">On 1/15/2014 2:02 PM, Daniel Young
wrote:<br>
</div>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Here
is a link for a video where Mike Holt helps with an
explanation to your question.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><a
moz-do-not-send="true"
href="https://www.youtube.com/watch?v=sUXShMZJorQ">https://www.youtube.com/watch?v=sUXShMZJorQ</a><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Essentially,
the rapid shutdown needs to keep the energized length of
conductors to within 10’ of the array if on the roof (this
rule is only for arrays on buildings) or within 5’ of
building penetration. I would assume that if you are 9’ on
the roof, you then only have 1’ in the building before you
need the shutdown device.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">So
micro inverters and some DC-DC optimizers should comply with
the standard as is (since they prevent wires from being
energized with <u>DC voltage</u> before they even leave the
array). But string inverter systems will need to get
creative with how they address this. Midnite solar disco
combiners with the birdhouse seem to be a possible solution,
but they add a lot of cost to some smaller systems that
didn’t even need combiners before, let alone disconnect
combiners with power supply cards and separate control
boxes...<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hopefully
a better solution for small string inverters is on the
horizon. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">With
Regards,<o:p></o:p></span></p>
<div>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Daniel
Young, <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">NABCEP
Certified PV Installation Professional<sup>TM</sup>: Cert
#031508-90<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">NABCEP
Certified Solar Heating Installer<sup>TM</sup>: Cert
#SH031409-13<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif";color:#92D050">
<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><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 class="moz-txt-link-abbreviated" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>
[<a class="moz-txt-link-freetext" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">mailto:re-wrenches-bounces@lists.re-wrenches.org</a>] <b>On
Behalf Of </b>Jeffrey Quackenbush<br>
<b>Sent:</b> Tuesday, January 07, 2014 10:46 AM<br>
<b>To:</b> 'RE-wrenches'<br>
<b>Subject:</b> [RE-wrenches] NEC 2014 690.12 Rapid
Shutdown<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal" style="background:white"><span
style="font-size:13.5pt;font-family:"Helvetica","sans-serif";color:black">I've
been going through the new Code book (which is in effect
now in Massachusetts) and found myself somewhat puzzled
by the intent of the new "rapid shutdown" requirement in
690.12. Does anyone have insight into how this is
supposed to be interpreted and implemented? I've put
together a list of my own questions, given below (the
numbers reference the new 690.12 text). <span
class="apple-style-span">Thanks!</span></span><span
style="font-family:"Helvetica","sans-serif";color:black"><o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p>
</div>
<div>
<div>
<p class="MsoNormal"><b><span
style="font-size:13.5pt;font-family:"Times","serif";color:black">690.12
Rapid Shutdown</span></b><span
style="font-size:9.0pt;font-family:"Times","serif";color:black"><o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:13.5pt;font-family:"Times","serif";color:black">1.
Where should the rapid shutdown switch be located? (1)
only says that the shutdown function should be
installed if the circuit is longer than 10’ or goes
more than 5’ into a building. If this condition is
fulfilled, it says nothing about where the switch
should be located. (2) says that controlled conductors
should be limited to 30V, 240W, which will only be the
case downline from the switch, so this may mean that
it should be located close to the source, i.e. on the
roof. But this is just an inference, and one that
doesn’t have clear boundaries; every source conductor
for a series connected PV circuit (that is not Solar
Edge, Enphase , etc.) will have a higher voltage and
wattage potential when the sun is shining <i>somewhere</i>
along its length, even if the disconnect is located
very close to the array. Or does this requirement mean
that all systems will need to have some kind of
“smart” junction box, module DC-DC converter or module
level AC inverter? Furthermore, individual modules
often have higher voltages & wattages these days
and there is no way to impose limits on their
electrical characteristics in any field wired
configurations. A listed AC module that sees the
module leads as internal would be the only scenario
that would be exempt.</span><span
style="font-size:9.0pt;font-family:"Times","serif";color:black"><o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:9.0pt;font-family:"Times","serif";color:black"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:13.5pt;font-family:"Times","serif";color:black">2.
(5) asks that equipment performing the shutdown should
be listed and identified. Does that mean listed and
identified for the purpose of this specific
requirement? Or just listed and identified to limit
voltage and wattage in 10 seconds? Does a specific UL
standard exist for the function they have in mind?
Does any equipment exist that has such listing and
identification yet?</span><span
style="font-size:9.0pt;font-family:"Times","serif";color:black"><o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:9.0pt;font-family:"Times","serif";color:black"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:13.5pt;font-family:"Times","serif";color:black">3.
Is the rapid shutdown intended to be automatic or
manual? If automatic, what are the parameters that
would trigger the shutdown? If manual, are there any
accessibility requirements?</span><span
style="font-size:9.0pt;font-family:"Times","serif";color:black"><o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:9.0pt;font-family:"Times","serif";color:black"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:13.5pt;font-family:"Times","serif";color:black">4.
Rapid shutdown seems more like a disconnect
requirement than a circuit requirement. Why limit
circuits to 30V, 240W, instead of just requiring a
shutdown? Why 10 seconds, when all the disconnecting
functions (i.e. manual disconnects, and internal AFCI,
GFCI & UL 1740 disconnects) happen in less than a
second? (It hardly seems like a “rapid” shutdown). Why
write this article into section II rather than section
III?</span><span
style="font-size:9.0pt;font-family:"Times","serif";color:black"><o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p>
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