Re: nec
The code would cover the required branch-circuit rating of any particular equipment. Article 424 would cover this topic. The OCD can be sized per Article 210.
Ohm's Law: 15,000 / 240 / 1.732 = 36-amp
424.3(B): 36 x 125% = 45-amp = #8, 75 degree 310.16
210.20(A): 36 x 125% = 45-amp OCD.
See 424.22(A) if applicable.