[RE-wrenches] DC Rating of Disconnects

[Kent Osterberg]

Peter,

Many general duty safety switches, such as the Siemens GNF321R, are 
rated for 250 volts dc.  They usually require the use of two switch poles.

Kent Osterberg
Blue Mountain Solar



Peter Parrish wrote:
>  
> 
>  
> 
> Peter T. Parrish, Ph.D., President
> California Solar Engineering, Inc.
> 820 Cynthia Ave., Los Angeles, CA 90065
> Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885
> CA Lic. 854779, NABCEP Cert. 031806-26
> peter.parrish at calsolareng.com
> 
> ------------------------------------------------------------------------
> 
> *From:* Peter Parrish [mailto:peter.parrish at calsolareng.com]
> *Sent:* Friday, November 21, 2008 9:10 AM
> *To:* 'RE-wrenches'
> *Cc:* 'Peter Parrish'
> *Subject:* DC Rating of Disconnects
> 
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> I am looking into using the PV Powered PVP2000 inverter for some small, 
> low voltage designs. The string Voc will be around 200 Vdc, worst case.
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> Since the PVP2000 doesn’t come with a DC disconnect, I am wondered what 
> other wrenches who install the PVP2000 have been doing about this. I 
> hate to spend $150 on a 600 V AC/DC disco such as the SD HU361RB to 
> provide the means of disconnection. I believe that the 240 V AC discos 
> such as the SD DU221RB have no DC rating.
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>  From an academic point of view, I wonder why the smaller discos are not 
> dual rated, since we all know that the real-time voltage difference in a 
> 240 V AC system can be 41% greater than 240 V.
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> In any event, any Code-compliant solutions would be greatly appreciated.
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> - Peter
> 
> Peter T. Parrish, President
> California Solar Engineering, Inc.
> 820 Cynthia Ave., Los Angeles, CA 90065
> Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885
> CA Lic. 854779, NABCEP Cert. 031806-26
> peter.parrish at calsolareng.com