<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:p="urn:schemas-microsoft-com:office:powerpoint" xmlns:a="urn:schemas-microsoft-com:office:access" xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882" xmlns:s="uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882" xmlns:rs="urn:schemas-microsoft-com:rowset" xmlns:z="#RowsetSchema" xmlns:b="urn:schemas-microsoft-com:office:publisher" xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet" xmlns:c="urn:schemas-microsoft-com:office:component:spreadsheet" xmlns:odc="urn:schemas-microsoft-com:office:odc" xmlns:oa="urn:schemas-microsoft-com:office:activation" xmlns:html="http://www.w3.org/TR/REC-html40" xmlns:q="http://schemas.xmlsoap.org/soap/envelope/" xmlns:rtc="http://microsoft.com/officenet/conferencing" xmlns:D="DAV:" xmlns:Repl="http://schemas.microsoft.com/repl/" xmlns:mt="http://schemas.microsoft.com/sharepoint/soap/meetings/" xmlns:x2="http://schemas.microsoft.com/office/excel/2003/xml" xmlns:ppda="http://www.passport.com/NameSpace.xsd" xmlns:ois="http://schemas.microsoft.com/sharepoint/soap/ois/" xmlns:dir="http://schemas.microsoft.com/sharepoint/soap/directory/" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:dsp="http://schemas.microsoft.com/sharepoint/dsp" xmlns:udc="http://schemas.microsoft.com/data/udc" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:sub="http://schemas.microsoft.com/sharepoint/soap/2002/1/alerts/" xmlns:ec="http://www.w3.org/2001/04/xmlenc#" xmlns:sp="http://schemas.microsoft.com/sharepoint/" xmlns:sps="http://schemas.microsoft.com/sharepoint/soap/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:udcs="http://schemas.microsoft.com/data/udc/soap" xmlns:udcxf="http://schemas.microsoft.com/data/udc/xmlfile" xmlns:udcp2p="http://schemas.microsoft.com/data/udc/parttopart" xmlns:wf="http://schemas.microsoft.com/sharepoint/soap/workflow/" xmlns:dsss="http://schemas.microsoft.com/office/2006/digsig-setup" xmlns:dssi="http://schemas.microsoft.com/office/2006/digsig" xmlns:mdssi="http://schemas.openxmlformats.org/package/2006/digital-signature" xmlns:mver="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns:mrels="http://schemas.openxmlformats.org/package/2006/relationships" xmlns:spwp="http://microsoft.com/sharepoint/webpartpages" xmlns:ex12t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:ex12m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:pptsl="http://schemas.microsoft.com/sharepoint/soap/SlideLibrary/" xmlns:spsl="http://microsoft.com/webservices/SharePointPortalServer/PublishedLinksService" xmlns:Z="urn:schemas-microsoft-com:" xmlns:st="" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv=Content-Type content="text/html; charset=us-ascii">
<meta name=Generator content="Microsoft Word 12 (filtered medium)">
<title>Re: [RE-wrenches] Square D DC disconnects</title>
<style>
<!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:Consolas;
panose-1:2 11 6 9 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page Section1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.Section1
{page:Section1;}
-->
</style>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang=EN-US link=blue vlink=purple>
<div class=Section1>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>David,<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'>The state by the Eaton guy at SPI shows that person’s lack
of understanding. The person I talked to was adamant that all disconnects had
to be tested to the disconnect standard that assumes a high (10,000-amp)
current source behind any fault. Switch openings are also tested based on the
inductance in the circuit since that has a major impact on the size and
duration of the arc—especially in ac systems.<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'>Square D did an evaluation based on the limited fault currents
and inductance in PV system circuit that has no batteries. I believe their
evaluation is valid. The issue is that there is no specific test at UL yet—that’s
why UL did not list it (I’m pretty sure they were involved at some level,
but that is impossible to prove). It will probably be added to UL1741. Perhaps
that was what the Eaton rep was referring—we’ll give him the
benefit of the doubt.<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'>I still use my basic rule similar to the rule for politicians—how
do you know if a marketing guy is lying?== his lips are moving.<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'>Bill.<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>
<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"'>
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> Monday, January 11, 2010 3:41 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Cc:</b> 'Tim Townsend'<br>
<b>Subject:</b> Re: [RE-wrenches] Square D DC disconnects<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:11.0pt;
font-family:"Calibri","sans-serif"'>Thanks, Bill.<br>
<br>
Glad to hear you think the HU series is still a good option.<br>
<br>
When I was making the rounds at SPI, I stopped by the Eaton booth and got the
sense that they were gunning for Square D. They made light of Square D’s
self-certification of the HU series discos. The rep also made a statement about
the new Eaton dc discos being the only ones designed to meet UL1741
requirements. When I got home, the first thing I looked up was 690.4(D). This
doesn’t say anything about dc disconnects needing to be listed to some
special PV standard. <br>
<br>
Is there a movement in this direction? Is there a UL1741 standard for dc discos
that is somehow different that the standard used for other dc disconnects?<br>
<br>
Best,<br>
<br>
David <br>
<br>
On 1/11/10 5:28 PM, "Bill Brooks" <<a href="billbrooks7@yahoo.com">billbrooks7@yahoo.com</a>>
wrote:</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>David and Kirpal,<br>
<br>
It is ultimately up to the AHJ whether or not they accept the Schneider/Square
D self certification. That is a judgment call the installer needs to clear with
the AHJ. That being said, having Square D behind the rating of a switch is a
whole lot more than any one of the smaller companies making equipment for the
PV industry. <br>
<br>
I will continue to use the 30, 60, and 100-amp versions in the way recommended
by the manufacturer because it is a huge saving in cost and they are well made
switches. I will also check with the local AHJ before installing them in case
they are not going to pass it. You have to remember you are working with one of
the largest electrical suppliers in the world. They have a huge reputation with
local jurisdictions.<br>
<br>
Eaton has been in the process of trying to make a big deal out of this issue
since they want a piece of the market. Fortunately, they are starting to build
products specifically for the PV industry, which I applaud. However, they need
to be given a hard time for the way they have tried to imply that all Square D
switches are not properly listed. They won’t admit to that because they
would end up in a legal battle, but that is essentially what they have been
doing. Square D still has the largest selection of dc-rated equipment on the
market. Eaton has a long way to go. <br>
<br>
In a recent project that I reviewed, the engineer pulled the Square D 400-amp
disconnect and replaced it with an Eaton disconnect at the insistence of the
Eaton rep. The Eaton product was not properly rated or listed for the voltage
while the Square D product was. This is the insanity that needs to stop.<br>
<br>
Bill.<br>
<br>
<br>
</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><br>
</span><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
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>David Brearley<br>
<b>Sent:</b> Monday, January 11, 2010 11:39 AM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] Square D DC disconnects<br>
</span><br>
<span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Kirpal,<br>
<br>
Have you checked out the SolarBOS disconnecting combiners? Their 28A version
might be ideal for large resi or small commercial applications. For larger
projects, Blue Oak PV Products and AMtec Solar also have disconnecting
combiners.<br>
<br>
Thanks for sharing the updated Square D tech note. I had no idea that the
Square D HU Series disconnects were not UL-listed when used as described in the
older tech notes. The fact that this is not a UL-listed use of the heavy duty
safety switch, pretty much means that it is not an option for integrators. As
far as I know, there is no other product that is listed for this use. <br>
<br>
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>
<br>
<br>
On 1/9/10 4:14 PM, "Kirpal Khalsa" <<a href="solarworks@gmail.com">solarworks@gmail.com</a>>
wrote:</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Hi
All......</span><o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:11.0pt;
font-family:"Calibri","sans-serif"'><br>
I recently came across a revised technical bulletin from square D ( <a
href="http://ecatalog.squared.com/pubs/Electrical%20Distribution/Safety%20Switches/Heavy%20Duty/3110DB0401.pdf">http://ecatalog.squared.com/pubs/Electrical%20Distribution/Safety%20Switches/Heavy%20Duty/3110DB0401.pdf</a>
)......we have for years been using the Square D DC Disconnect of various
amperages (30, 60, 100) as disconnects leading upto the inverter from the
array.....we have frequently wired one string to each of the three poles of the
disconnect......we have had this configuration inspected by inspectors
regularly with approval everytime......this new revision of the document from
Square D shows this is no longer a UL listed method.....they are now stating in
this document that they are "self certifying" this technique.......have
any of you come across this or know why Square D has back tracked? <br>
<br>
Something else I noticed is that they have raised the amperage rating on the
30A disconncect per pole by 2 amps from 18 to 20 which is good especially when
using higher amperage modules like Evergreen ES-A series which would not have
ben allowed to use the 30A disconnect as the short circuit current rating was
too high for the derated poles. <br>
<br>
This is not a huge concern as more and more of the inverters we are using these
days have an appropriate disconnect included with the inverter negating the
need for an additional stand alone disconnect. <br>
<br>
On a side note............Are there any other manufacturers making <u>listed</u>
muiti pole DC disconnects in which each pole can handle one string? Also there
is definately a need for roof mounted multi string (1-4 strings) combiner boxes
with integrated DC disconnects for residential applications that have a
reasonable price.......any one know if any?<br>
<br>
<br>
<br>
<br>
<br>
</span><o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:10.0pt;
font-family:Consolas'><br>
</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><br>
<br>
</span><o:p></o:p></p>
</div>
</body>
</html>