What is the minimum size circuit conductor for Motor #3 specified between the panel and the wireway?

The minimum size circuit conductor for a motor is determined based on several factors, including the motor's horsepower rating, the ambient temperature, and the specific application as outlined in the National Electrical Code (NEC). For most motors, particularly at common horsepower ratings, a 10 AWG conductor is suitable for carrying the necessary load if the motor is not heavily loaded and the conditions are standard.

Using a 10 AWG conductor typically accommodates the current draw of smaller motors and meets the NEC requirements for ampacity in typical residential and commercial applications. Additionally, the insulation type and installation environment can also affect the conductor sizing, but for the question posed, 10 AWG is generally the minimum standard size that ensures safe operation and compliance with code requirements.

Consideration of other choices reveals that 12 AWG might not be adequate for typical motor loads, which is why it may be ruled out. An 8 AWG or 6 AWG conductor would typically be used for larger motors or under specific conditions about temperature or installation methods, which might not be relevant in this scenario, making 10 AWG the most appropriate minimum size for the specified application.