Final answer:
The maximum ampacity for a 6-AWG THHN conductor in an ambient temperature of 42° C is 65 amps.
Step-by-step explanation:
In order to determine the maximum ampacity for a 6-AWG THHN conductor in an ambient temperature of 42° C, we need to refer to the National Electric Code (NEC) table 310.15(B)(16). According to the table, a 6-AWG THHN conductor can carry a maximum ampacity of 65 amps in an ambient temperature of 42° C.