2014 NEC 705.12(D)2 - Utility Interactive Inverter Bus/Conductor Ampere Rating

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djr3203

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I am tasked to design a PV system for a building that will connect to the load side of the building main circuit breaker disconnect. An adjacent building will subfeed this new building with the PV system (both buildings under same ownership). Would the bus of the main switchboard in the adjacent building, subfeeding the new building with PV connected to the feeder, be subject to the bus sizing requirements of 705.12(D)(2)(3)? Or am I only subject to follow the feeder sizing rule of 705.12(D)(2)(1)(b)?

As always, I appreciate any insight.

Thanks,

DJR
 
djr3203 said:
I am tasked to design a PV system for a building that will connect to the load side of the building main circuit breaker disconnect. An adjacent building will subfeed this new building with the PV system (both buildings under same ownership). Would the bus of the main switchboard in the adjacent building, subfeeding the new building with PV connected to the feeder, be subject to the bus sizing requirements of 705.12(D)(2)(3)? Or am I only subject to follow the feeder sizing rule of 705.12(D)(2)(1)(b)?

As always, I appreciate any insight.

Thanks,

DJR
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If you interconnect at a subpanel, assume worst case scenario the possibility that all of its local loads diminish to zero. Thus, apply it to every panelboard busbar from the point of interconnection all the way to the service point.

Because of NEC2014's change in language, all that matters is the calculation that sizes the interconnection OCPD, rather than the OCPD itself. I.e. 125% of the total inverter output current. So if you interconnect 32A (which becomes a 40A breaker) at a 200A panel, which itself is fed from a 400A panel, only the 40A matters. It is irrelevant that a 200A breaker feeds the subpanel off of the 400A main panel.
 
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