[RE-wrenches] Square D DC disconnects

[Kirpal Khalsa]

>
> Hi All......



> I recently came across a revised technical bulletin from square D (
> http://ecatalog.squared.com/pubs/Electrical%20Distribution/Safety%20Switches/Heavy%20Duty/3110DB0401.pdf )......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?



> 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.
>
> 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.


On a side note............Are there any other manufacturers making
*listed*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?



> --
> Sunny Regards,
> Kirpal Khalsa
> NABCEP Certified Solar PV Installer
> Renewable Energy Systems
> www.oregonsolarworks.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20100109/0cb8c821/attachment-0002.html>