For a 3-phase, 480-volt circuit with a calculated load of 98 amperes, which copper conductor size is required for the insulation types according to Table 310.16?

To determine the proper conductor size for a 3-phase, 480-volt circuit with a load of 98 amperes, it's essential to refer to Table 310.16, which outlines the allowable ampacities for different sizes and types of conductors based on their insulation rating.

Considering the specified load of 98 amperes, the conductor size must be calculated based on the insulation type you are using. For example, if you are using THHN insulation, which is common, you'll find that a 3 AWG copper conductor has an ampacity of 100 amperes under typical conditions. This means that it can safely carry the 98 amperes required by the circuit without exceeding its rated capacity.

Using a 1 AWG or 2 AWG conductor would provide more capacity than needed, which may not be cost-effective, while a 4 AWG conductor would present a risk of overheating because its ampacity is below the circuit's requirement. Therefore, 3 AWG is the correct choice as it meets the demand without being oversized, ensuring safety and efficiency in the installation.

In summary, the selection of the 3 AWG conductor aligns perfectly with the load requirement as specified and falls within the permissible limits set out in