I think Table 310.16 would have to be used for quadruplex cable. I'm really not 100 percent certain. Table 310.17 is for single conductors. Table 310.16 would require 4/0 conductors if the terminals at the disconnect and the main breaker in the panelboard in the dairy barn are rated for 90 deg. In the area where I live it is not unusual for the Power Company to install triplex or quadruplex service drop conductors of a smaller size than the Contractors service conductors. They are not required to comply with the NEC for such an installation. However, for feeder conductors whether indoors or outdoors Table 310.16 should be used. Just my opinion....


Frank (cinkerf)