[RE-wrenches] Congested Panel Problem

[Kirpal Khalsa]

Peter.....SMA makes a SB 4000US with a CL (current limited) marking.....you
would need to order this specifically.  They limit the max continuous output
to16A (16*1.25 =20) instad of 16.66 so that after adding your 1.25
multiplier you can still use a 20A breaker in a 100 amp panel and you are
then complying with the 20% rule for the 100A bus bar.
This does not cover your sub panel situation, but if your system design can
stand to be downsized then you can skip the subpanel situation all together.
 Of course if there is no space in the main panel than for a breaker than a
sub panel may still be required....
Cheers,
-- 
Sunny Regards,
Kirpal Khalsa
NABCEP Certified Solar PV Installer
Renewable Energy Systems
www.oregonsolarworks.com
541-218-0201 m
541-592-3958 o



Normally we pull two 20A/120V branch circuits out of the main panel into a
> subpanel, back feed the subpanel with the inverter output and feed the main
> panel from the subpanel.
>
> The inverter in question is a SMA SB4000. Minimum over current protection
> is
> 16.66A (e.g. 20A continuous duty breaker). Otherwise protection needs to be
> 20.83A (e.g. 25A regular breaker).
>
> So we installed a 100A subpanel, pulled in the two 20A circuits, backed
> this
> subpanel with the inverter via a 20A continuous duty breaker, and fed the
> main panel via #8 wire and a 40A breaker.
>
> The inspector has a problem with this approach. Doesn't have a problem with
> the 20A breaker in the subpanel, but he objects to the 40A breaker in the
> main panel. His reasoning includes applying NEC 790.64(B). I believe the
> last sentence of (B)(2) stipulates that the breaker back feeding the
> subpanel is the one that counts, not what eventually what breaker back
> feeds
> the main panel.
>
> This inspector also has a problem with the production meter we installed.
> He
> wanted to see the "UL Listing" on the meter. I called Austin International
> (our vendor) about the meter in question (Itron Centron C1S) and they said
> that UL doest test meters as they (normally) are not used on the customer
> side of the service. Is there another listing for meters that would satisfy
> a nit-picky inspector? To make matters worse, we now have in stock both
> Itron Centron C1S meters as well as Schlumberger Centron C1S meters. Did
> Schlumberger buy out Itron? Or vice versa?
>
> Any help on the main panel calculation and acceptable listings for meter
> would be greatly appreciated.
>
>
>
> Peter T. Parrish, Ph.D., President
> California Solar Engineering, Inc.
> 820 Cynthia Ave., Los Angeles, CA 90065
> CA Lic. 854779, NABCEP Cert. 031806-26
> peter.parrish at calsolareng.com
> Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885
>
>
>
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