For a three-conductor 8 AWG Type NM cable at 94°F, what is the ampacity of the copper circuit conductors?

The ampacity of conductors is defined based on several factors including the material (copper in this case), the size of the conductors (8 AWG), and the insulation type. For Type NM (non-metallic sheathed) cable, the ampacity values are specified in the National Electrical Code (NEC) Table 310.16.

At a temperature of 94°F, we refer to the base ampacity for 8 AWG copper conductors, which is typically rated at 40 amps at 30°C (86°F). Since 94°F is above this temperature, adjustments may need to be considered for the temperature rating. However, for simplicity and in most scenarios involving typical residential wiring, the ampacity for 8 AWG copper in NM cable remains at 40 amps, as it is acceptable to consider the ampacity table values unless otherwise affected by additional factors such as a higher ambient temperature or derating due to multiple conductors installed together.

Therefore, the choice of 40 amps reflects the standard ampacity for a three-conductor 8 AWG Type NM cable under normal operating conditions at 94°F.