Alternate Energy Sources

[MCD1]

Trying to better understand NEC 705.

Scenario: You have a 200A fused feeder to a double-tub panelboard with a 250A rated bus and someone adds two 2-pole, 60A input circuits from two wind turbines.

705.12.D.2 states 'sum of ampere ratings of overcurrent devices in circuits supplying power to busbar or conductor shall not exceed 120 percent of the rating of busbar or conductor.

705.12.D.7 states 'unless the panelboard is rated not less than the sum of the ampere ratings of all overcurrent devices supplying it, a connection in a panelboard shall be positioned at the opposite (load) end from the input feeder location or main circuit location. The bus or conductor rating shall be sized for the loads connected in accordance with Article 220. In systems with panelboards connected in series, the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter(s) shall be used in the calculations for all busbars and conductors. A permenent warning label shall be applied to the distribution equipment with the following or equivalent wording: WARNING INVERTER OUTPUT CONNECTION DO NOT RELOCATE THIS OVERCURRENT DEVICE

Does 705.12.D.7 allow you to circumvent 705.12.D.2 if you locate the inverter input circuits at the opposite end of the panelboard from the incoming feeder connection?

 

[don_resqcapt19]

You have to comply with all of the parts of 705.12(D). The only thing (D)(7) does for you is to permit the breakers from the other sources to be located anywhere in the panel, if the panel bus has an ampacity that is equal to or exceeds the total rating of all of the breakers that can feed power to the bus. In your case, this would require a panel with a bus rating of 320 amps.
With a 250 amp bus and a 200 amp main, the maximum sum of any other breakers that supply power to the panel would be 100 amps and these breakers would have to be located at the opposite end of the bus from the main.