What is the allowable ampacity of each 350 KCMIL XHHW aluminum conductor in an underground raceway at 105 degrees Fahrenheit?

The allowable ampacity of conductors is determined by the National Electrical Code (NEC) and is influenced by various factors such as the size of the conductor, the type of insulation, the ambient temperature, and the installation method. For a 350 KCMIL XHHW aluminum conductor, the ampacity must be evaluated based on the temperature rating and the specific conditions of installation.

At an ambient temperature of 105 degrees Fahrenheit, it's essential to refer to the NEC tables for the thermal adjustment factors. XHHW insulation allows for a relatively high maximum operating temperature, which is typically rated at 90 degrees Celsius (194 degrees Fahrenheit) in dry locations. However, when conducting ampacity calculations, if the ambient temperature exceeds the standard reference temperature of 86 degrees Fahrenheit (30 degrees Celsius), you would apply adjustment factors to account for the increased temperature, which can reduce the allowable ampacity.

When looking at the ampacity charts for 350 KCMIL XHHW aluminum conductors, at 105 degrees Fahrenheit the adjusted ampacity is typically around 164 amps. This value considers the reduction due to the ambient temperature exceeding 86 degrees Fahrenheit, making it the most suitable choice amongst the options provided.

Understanding and applying the NEC standards regarding conductor