What is the ampacity of two 4 AWG XHHW-2 aluminum conductors in rigid metal conduit at an ambient temperature of 50°C?

To determine the correct ampacity of two 4 AWG XHHW-2 aluminum conductors in rigid metal conduit at an ambient temperature of 50°C, it is essential to refer to the National Electrical Code (NEC) tables or an equivalent source that outlines ampacity ratings based on wire gauge, type, and installation conditions.

For XHHW-2 aluminum conductors, the ampacity for 4 AWG conductors is typically listed in standard NEC tables at a base temperature of 30°C. At this base temperature, a 4 AWG aluminum conductor generally has an ampacity of around 70 A. However, when the ambient temperature rises to 50°C, adjustments must be made due to the increased thermal conditions affecting conductor performance.

To account for this increase in temperature, a correction factor is applied. The NEC provides correction factors that apply as temperatures increase above 30°C, resulting in a decrease in the allowable ampacity. The applicable correction factor typically reduces the ampacity at elevated temperatures, which results in the rating being adjusted to 62 A for two conductors. The adjustment accounts for both the increased ambient temperature and the fact that multiple conductors in a conduit can generate more heat, which influences the overall amp