For a 3 hp motor supplied by a 120/240-V, 3-ph, 4-W panel, what minimum size SJ cord is required?

To determine the minimum size of the SJ cord required for a 3 hp motor, it is essential to consider the current draw of the motor and the relevant code guidelines.

A 3 hp motor, when operated at 240 volts, typically draws around 14 to 15 amps (depending on the efficiency and power factor). For cords, the National Electrical Code (NEC) provides guidelines for ampacity, which refers to the maximum amount of electric current a conductor or device can carry before sustaining immediate or progressive deterioration.

The SJ cord is a type of flexible cord that is often used for temporary wiring in a variety of applications, including motors. When choosing the wire size, one must ensure it can handle both the continuous load and any potential inrush current that may occur when the motor starts.

In this scenario, the appropriate SJ cord size for a 3 hp motor is 7. This size is selected based on its ampacity rating, which generally can handle the necessary current under normal conditions, ensuring safe operation without overheating or causing damage to the wire. Smaller sizes may not meet safety requirements or might lead to excessive voltage drop or overheating during operation, while larger sizes would be unnecessarily bulky and difficult to handle.

Overall, using a 7