Axial Flux turbine up and running at 10,000'

hi Wbuffetjr1 
had a look at you video, turbine is looking very good.
i am building one myself, but need a little help with determining the power output, form what i read on your video description your turbine is rated at 4kw, can you please explain how you calculated this ?
from my understanding:
 u mention you used 15 gauge wire, the maximum current a 15 gauge wire can carry is 4.7 amps meaning that the 5 coils in series per phase cannot exceed 4.7 amps , since the voltage is 48v per phase, the power output per phase will be 4.7 x 48 = 225 watts, multiply that by 3, equals to 765 watts, a long way from 4000 watts. can you please explain what im doing wrong and the the correct way to do the calculation. 
thank you