I'm not neglecting the second sentence of 215.2(A)(1). It tells me a need a minimum conductor SIZE of #1/0. The #2/0 that has the proper ampacity for the actual load is LARGER than the minimum conductor size of #1/0. You have to meet both requirements in 215.2(A)(1).

Not sure what differences in interpretation are but the misunderstanding has to be there.... Lets try this another way. Here's my understanding:

**Section 215.2 Minimum Rating and Size**

The minimum feeder-circuit conductor size (

*which we are trying to find*), before the application of any adjustment or correction factors (

*in this case 0.7 X 0.96 = 0.672*),

__shall have an allowable ampacity ____not less than the non-continuous load (42,400 VA) plus 125 percent of the continuous load (1.25 X 56,600 VA)__.

In other words, not less than 42,400 VA + 1.25 X 56,600 VA = 113,150 VA.

Which converts to: 113,150/3/277 = 136 A

So, the minimum feeder-circuit conductor size, before the application of any adjustment or correction factors (

*none applied yet*),

__shall have an allowable ampacity ____not less than 136 A__. This correlates to a 1/0 AWG conductor based on table 310.15(B)(16) 75 degree C column.

Feeder conductors shall have an ampacity not less than required to supply the load calculated in Parts III, IV, and V of article 220.

(No problem here since 42,400 VA + 56,600 VA = 99,000 VA and this converts to 119 A which can be carried by 1/0 AWG)

Now by applying adjustment and correction factors to 2/0 AWG (table 310.15(B)(16) 90 degree C column)... 0.672 X 195 A = 131 A

The ampacity of 131 A is NOT sufficient to carry 136 A.

Now by applying adjustment and correction factors to 3/0 AWG (table 310.15(B)(16) 90 degree C column)... 0.672 X 225 A = 151 A

The ampacity of 151 A is sufficient to carry 136 A.