Final answer:
To determine the maximum ampacity of a 10 AWG copper conductor with Type THW insulation in 40ºC ambient temperature, NEC tables and correction factors must be used. The standard ampacity is typically reduced by a correction factor because of the increased ambient temperature, resulting in an approximate maximum ampacity of 27.3 A in free air.
Step-by-step explanation:
A student has asked: What is the maximum ampacity of a 10 AWG copper conductor with Type THW insulation if it is to be run in free air and the ambient air temperature is 40ºC? To answer this, the National Electrical Code (NEC) ampacity tables need to be referenced. According to the NEC, a 10 AWG copper conductor with THW insulation typically has an ampacity of 30 amperes at an ambient temperature of 30ºC. However, for ambient temperatures other than 30ºC, ampacity correction factors provided in the NEC must be applied. For an ambient temperature of 40ºC, the correction factor is typically around 0.91. Therefore, the maximum ampacity of the conductor would be calculated as follows:
Maximum Ampacity = Standard Ampacity × Correction Factor
Maximum Ampacity = 30 A × 0.91
Maximum Ampacity ≈ 27.3 A
It's important to note that for precise guidelines, the latest version of the NEC and local amendments should always be checked, as regulations may vary.