What is the allowable ampacity for a 4 AWG aluminum conductor under 90°C insulation?

To determine the allowable ampacity for a 4 AWG aluminum conductor, it is essential to reference the National Electrical Code (NEC) tables, specifically Table 310.16, which provides the ampacity ratings based on conductor size, material, type of insulation, and ambient temperature.

For a 4 AWG aluminum conductor with 90°C insulation, the maximum ampacity listed in the NEC is typically higher than that for the same conductor with 75°C insulation. When considering the derating and conditions mentioned, the ampacity is generally interpreted to be around 100 amperes.

However, the selection of the correct answer is crucial based on the application and wiring method. If ampacity ratings were being adjusted for specific conditions like continuous loads or ambient temperature adjustments, these factors can lead to different allowable ampacities.

In this case, selecting the correct allowable ampacity reflects the understanding of how to apply the correct NEC tables and adjust for insulation types. Confirming that a 4 AWG aluminum conductor typically can handle 100 amps ensures proper installation that adheres to electrical safety standards.

Thus, the correct answer should reflect that the ampacity for a 4 AWG aluminum conductor under 90°C insulation is in fact **100