PSPV as disconnect

Discussion about the Power System PV Combiner (PSPV)

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TNHunter
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PSPV as disconnect

Post by TNHunter » Tue May 25, 2004 2:09 am

Does the use of the PSPV for the combiner meet the requirement of the NEC as a means of disconnecting power from the array the the charge controller???

The reason I ask is that I thought the NEC required both current carrying wires to have a measn of disconnect. If the PSPV does not meet this requirement, how does Outback recommend accomplishing this? In your brochure for the MX-60, (which I am also using) you show the use of breakers on the input and output side of the controller, but only for the positive lead.

Can I use a switch with RK5 fuses to meet this requirement? HELP PLEASE> [img]images/smiles/icon_confused.gif[/img] [img]images/smiles/icon_confused.gif[/img] [img]images/smiles/icon_confused.gif[/img]

wd8cdh
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PSPV as disconnect

Post by wd8cdh » Tue May 25, 2004 5:39 am

The NEC does not require the grounded current carrying conductor to be disconnected with a switch or breaker. The NEC allows a bolted or terminal disconnecting means on the grounded conductor to allow maintenance or troubleshooting by qualified Personel. If you don't have a GFP, the NEC specifies that you SHALL NOT have a switch or breaker pole in the grounded conductor.

bbassett
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PSPV as disconnect

Post by bbassett » Tue May 25, 2004 8:04 am

The NEC also calls for less than 6 throws to switch everything off and that these switches all be grouped. If your combiner were close by your other disconnects and had only a couple of breakers in it it might fly. Yes, a switch with RK5 fuses is just fine so long as it's listed for the DC voltage you're using. Most are, and rated for 125vDC. I believe only Littelfuse fuses are listed for DC though (others may be mfg. rated but not UL listed).

Your DC negative is normally the grounded conductor (not the ground itself).

<small>[ May 25, 2004, 10:08 AM: Message edited by: Brad ]</small>

wd8cdh
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PSPV as disconnect

Post by wd8cdh » Tue May 25, 2004 10:42 pm

As Brad says, 6 throws is the limit. That is interpreted differently by different inspectors. Som say hou can turn off more than one breaker with the swipe of you hand and others think you can only use one finger at a time so you might need to use handle ties which are allowed by NEC.

Be carefull about selecting safety switches. Many are not DC rated. Some Murray/Seimans are 250VDC, Most GE are 250VDC, a few Square D are 600VDC, and most Cutler Hammer are NOT DC rated at all.

bbassett
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PSPV as disconnect

Post by bbassett » Wed May 26, 2004 10:24 pm

Generally the heavy duty grade of disconnects are DC rated at 250V, and general duty grade are often not, but a few are at 125VDC. All of the mfg's Ron mentions above, including C-H, make heavy duty switches some of which are rated for either 250v or 600v DC.

All of the switches rated for 600VDC, with one exception (Square D H361 series is listed for 13A up to 600V per pole for PV use only), require that the line be switched with TWO poles wired in series. Only the GE switches come pre-wired for this, and are a good price, but can take weeks to get.

<small>[ May 26, 2004, 12:27 PM: Message edited by: Brad ]</small>

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