I think that the calculation goes as follows:
(1) For residential PV systems, the bus can fed at 120% of its rated value:
1.2*225A=270A
(2) The main breaker limits the feed from the utility to 200A
(3) This leaves 70A for the PV system
- Peter
Peter T. Parrish, Ph.D., President
Wreches,
I have a system where we are tapping onto the bus bars of a 1200 amp panel fed
by a 1200 amp main breaker. The easy place to tap onto the bus bars is the
load side of the breaker using the existing bolts.
The inverter and utility fused disco are about 200 ft away, and the tap
Jerry:
At a recent John Wiles seminar, John declared that this scenario is not a
tap and is therefore not covered under the tap rule. This was news to me,
but Wiles is considered some sort of guru in compliance discussions.
William Miller
At 03:43 PM 12/5/2008, you wrote:
Wreches,
I
Jerry -
A line tap typically occurs between the utility meter and the main breaker -
not after the main breaker on the load side. It seems that you are describing a
load side tap which follows the 120% rule under 2008 NEC; I might be
misunderstanding the situation. Please clarify. There are
120% allowance is only ..For a dwelling unit.
Clearly this is a load side Point of Connection. If it is a dwelling unit
then the 120% allowance is applicable. If it is not a dwelling unit, then
there is no room to connect under NEC 2008.
Mark Frye
Berkeley Solar Electric Systems
303
Hi Mark,
Did you mean 2005 NEC? The language in the 2008 NEC, 690.64(B)(2)
doesn't differentiate between dwelling units and other cases, by my
reading. The same intent seems to be repeated in 705.12(D)(2). Or
perhaps I am missing something here...
Best,
Louis Woofenden
Mark Frye wrote:
Jerry,
As pointed out below, this is a load-side bus connection. It would follow
the 120% rule if using the 2008 NEC. Since the guy is buddies with the
inspector that should be no problem. However, you must follow the 2008 NEC
if you want to apply it (tap must be at the opposite end of the bus
Much Egg On My Own Face as Usual. Of couse I was refering to 2005 not 2008.
2008, 2005, 2011, who is counting.
Well actually I guess in California folks are using 2008 California which
references 2005 NECso, where is the job? Or does it really matter since
it all comes down to the
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