series circuits for Sunny Boy [RE-wrenches]

[Travis Creswell, Ozark Solar]

Thanks for pointing that out Jeff.  I have used a truckload of them for 480
vac applications but never for DC applications over 48 vdc.  Hopefully, I
would have studied that a little closer before I did a battery less system. 
That's the great thing about this list.

I would still like to be able to use a handle to disconnect a system rather
than have to use tools to open a box (wasp home) and carefully remove a fuse
(buried under that wasp nest).

Travis
----------
>From: "Jeffrey Wolfe, Global Resources" <global at sover.net>
>To: "'RE-wrenches at topica.com'" <RE-wrenches at topica.com>
>Subject: RE: series circuits for Sunny Boy [RE-wrenches]
>Date: Sun, Dec 2, 2001, 11:48 PM
>

>Travis,
>
>One fine print note on using some of  the SqD disconnects. The 600VDC 
>rating on some of them depends upon breaking BOTH the hot and the negative, 
>using the outside poles of a three phase unit. The only unit I see in my 
>Grainger book that avoids this requirement is the 200A 4-wire switch, (but 
>it's not really clear it's listed for DC, and the Square D catalog does not 
>rate it for DC>)
>
>So you're into either multiple switches or ignoring the rating. The rating 
>is *probably* made in consideration of breaking the DC under load at a 
>level of 200A, but still and all, that's the rating.
>
>I'd stick with the combiner box.
>
>Jeff
>
>On Sunday, December 02, 2001 6:53 PM, Travis Creswell, Ozark Solar 
>[SMTP:ozsolar at ipa.net] wrote:
>> Check out page 458 of the Grainger No. 392 catalog.  You'll have to buy a 
>3
>> phase model and that will give you 3 sub arrays.  You can get a  Nema 3R
>> Rainproof ST/3P 600 VDC fusible disconnect (30 amp, Square D flavor) for
>> $401.75.
>>
>> Does the Trace Tech model have a handle or do you have to open the box 
>and
>> remove the fuses.
>>
>> And be ever so careful about trying to "educate inspectors".  Do want he
>> wants on this job with a big smile on your face then carefully challenge 
>him
>> next time.  Tell him how smart he is and thank him (for making life
>> difficult) and your life will be so much easier next time.  They are the
>> final authority so if they feel like it they can make your life very
>> difficult.
>>
>> Travis Creswell
>> Ozark Solar
>> ----------
>> From: "Mangelsdorf, Marco" <mmangelsdorf at hei.com>
>> To: RE-wrenches at topica.com
>> Subject: series circuits for Sunny Boy [RE-wrenches]
>> Date: Sun, Dec 2, 2001, 5:14 PM
>>
>>
>>
>> Aloha Wrenches,
>>
>> Does anyone know of a relatively low cost high voltage (up to 600 VDC)
>> combiner box that has, say, two or three fuse holders?
>>
>> We've finished the first Sunny Boy 2500U installation here in the islands
>> with two parallel series-wired sets of (10) BP 150-watt 24 VDC modules.
>> According to a reasonable interpretation of the NEC 690-9 (b), there is 
>no
>> need for fuse protection of each series circuit of modules.  So, in the
>> install, I have both sets of modules wired directly to a single pair of
>> #10CU conductors with no fuses.  The inspection did not pass last friday
>> with the notation being that there was no overcurrent protection on the
>> roof, i.e., no combiner box with separate fuses to protect each series
>> string.  I'm going to try and educate our local authorities tomorrow on 
>the
>> lack of need for fuses on the roof with a cover letter of my own and a
>> two-page letter that John Berdner of SMA-America has been kind enough to
>> supply me with.  BUT....in case I don't prevail in my education process, 
>I'm
>> looking for a low cost plan B.  I know that I can get a 10-circuit 
>combiner
>> from Trace Tech. that's rated at the high DC voltage.  But I'd like to 
>avoid
>> spending $400 or more bucks for it.
>>
>> Any ideas?
>>
>> thanks,
>> marco
>>
>> Marco Mangelsdorf, Ph.D.
>> Marketing and Sales
>> ProVision Technologies, Inc.
>> 69 Railroad Avenue, Suite A-7
>> Hilo, Hawaii 96720 USA
>> (808) 969-3281, fax 934-7462
>> www.provisiontechnologies.com - - - -
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