point of connection [RE-wrenches]

[Bill Brooks]

William,

Article 230, referred to in 690.64 (A) is entitled "SERVICES".

Bill.

-----Original Message-----
From: William Miller [mailto:wrmiller at charter.net] 
Sent: Friday, May 02, 2008 4:56 PM
To: RE-wrenches at topica.com
Subject: RE: point of connection [RE-wrenches]


Bill:

Your message raises some questions:

1. What do you mean by "60-amps on the low side if the supply is connected 
to a building."

2. This sentence does not make any sense to me:  "If the array is 
ground-mounted, then it is possible that at 30-amp or 40-amp
service."

3. Where in the code does it specify that a supply side PV interconnection 
be considered a "new service?"

Thanks,

William Miller


At 12:49 PM 5/2/2008, you wrote:

>William,
>
>My understanding is that the "tap rule" does not apply to supply side
>service connections. There is a limitation on the supply side and that is
>the service conductor size on the high side and 60-amps on the low side if
>the supply is connected to a building. I try be careful to not use the term
>"tap" when referring to anything on the Supply side of the service
>disconnect. The NEC considers this connection a new service.
>
>If the array is ground-mounted, then it is possible that at 30-amp or
40-amp
>service. Article 230.82 is referenced in 690.64(A). John Wiles and a
>contractor from Colorado put together a good write-up on the subject. I'm
>sure you can get it off of the SWTDI at the New Mexico State University
>website.
>
>Bill.
>
>-----Original Message-----
>From: William Miller [mailto:wrmiller at charter.net]
>Sent: Friday, May 02, 2008 11:28 AM
>To: RE-wrenches at topica.com
>Subject: Re: point of connection [RE-wrenches]
>
>
>Larry:
>
>There is no inherent limitation on the supply-side option.  As you have
>correctly surmised, the 2 SB5000 inverters create an output that exceeds
>the allowance in 690.64B.  The breaker rating is not the factor, the Max AC
>amps rating (20.8 AAC) from the manufacturer is.
>
>Section 690.64A allows a supply side connection.  This point of connection
>must be between the meter and the service disconnecting means.  This is not
>always easily accomplished.  When accomplished, we use the tap rule
>(430.28).  When designing this, choose a breaker panel to combine your
>inverter AC feeds that has a large enough bus rating and connect it to the
>tap with over-current protection that is less than the bus rating.  This
>gives you the allowance to connect your inverters.
>
>Our web site has a spreadsheet you can use to check your
>calculations:  http://mpandc.com/resources/resources.html
>
>Thanks,
>
>William Miller
>
>PS:  I am not sure what you mean by a "feed through" panel.  Could you
>describe this device?
>
>WM
>
>At 10:12 AM 5/2/2008, you wrote:
>
> >Wrenches,
> >
> >We are doing an installation with 2 Sunny Boy 5000 inverters each
> >requiring a 30 amp 2 pole breaker.  The closest point of
> >interconnection is outside the house on the supply side of the main
> >service disconnect near the customer side of the utility meter.
> >According to 690.64B on the load side we are limited to 120% of the
> >busbar rating, which means we could not put 2- 30 amp backfeed
> >breakers in the main 200 amp service panel.  But 690.64A does not
> >state a limitation  of 120% .  So we are considering a 200 amp feed
> >through panel, also recommended by our local electrical inspector,
> >and then putting our 2-30 amp 2 pole breakers in this feed thru
> >panel. Anyone have any comments on this method? What other methods
> >are people using to make a supply side interconnection?
> >
> >Larry Brown
> >Sun Mountain
>
>
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