> > 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
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