I have no idea, how to deal with question, any thoughts ?

[Naveen Kumar]

The following figure depicts a load side interconnection of a PV system via a 300 A breaker to a 1,200 A switchboard with a 1,200 A main breaker. Please indicate how this system meets or does not meet the requirements of NEC 705.12(B).

 

[don_resqcapt19]

Have you read the section? It seems pretty clear in providing the information needed to answer the question. There is a second level subdivision for busbar.

 

[Naveen Kumar]

Have you read the section? It seems pretty clear in providing the information needed to answer the question. There is a second level subdivision for busbar.

I am confused to use between

705.12(B)(1)The sum of 125 percent of the power source(s) output circuit current and the rating of the overcurrent device protecting the busbar shall not exceed the busbar ampere rating. Informational Note: This general rule assumes no limitation in the number of loads or sources applied to busbars or their locations.

or


705.12(B)(2)Where two sources, one a primary power source and the other another power source, are located at opposite ends of a busbar that contains loads, the sum of 125 percent of the power-source(s) output circuit current and the rating of the overcurrent device protecting the busbar shall not exceed 120 percent of the busbar ampere rating.

 

[winnie]

You have 2 possibilities, B(1) or B(2). Decide which applies.

B(1) says take the main OCPD + 1.25*PV circuit current. Must be less than bus bar rating.


B(2) says take the main OCPD + 1.25*PV circuit current. Must be less than 1.2 * bus bar rating.

Note that it says '125 percent of the power-source(s) output circuit current' not OCPD rating.

Jon

 

[Naveen Kumar]

THanks a lot @winnie

 

[jaggedben]

Hmm. There's also a (B)(3), and more, and the question didn't provide enough information to answer definitively.

 

[shortcircuit2]

Does that service have Ground-Fault Protection?

 

[JakeX]

2023 NEC 705.12(B)(2) applies. Basically, the sum of the rating of the input breakers cannot exceed 120% of the bus rating. 1200A (MCB) + 300A (PV CB) is greater than 1200A*1.2, so the installation does not meet the requirement.