Final answer:
The ampacity of four #4/0THWN copper conductors in a raceway at 45℃ cannot be provided without consulting the NEC tables and applying temperature correction factors.
Step-by-step explanation:
The question asks about the ampacity (current-carrying capacity) of four #4/0THWN copper conductors in a raceway at an ambient temperature of 45℃. The ampacity depends on several factors, including the wire size, insulation type, and installation conditions. Copper conductors have different ampacities based on their gauge and the temperature rating of their insulation, which in this case is THWN insulation with a higher thermal rating at certain ambient temperatures. These data can be found in the National Electric Code (NEC) tables. Due to the raised ambient temperature higher than the presumed 30℃, ampacity correction factors must be applied to determine the correct ampacity for this scenario. Unfortunately, I cannot provide you with the exact value because the NEC table and correction factors are needed to answer this query accurately. For accurate results, one must consult the latest NEC codebook and apply the appropriate correction factors.