What should you use to select the size of motor branch circuit conductors based on voltage drop?

To determine the appropriate size of motor branch circuit conductors based on voltage drop, the most accurate method involves using the actual nameplate Full Load Amperage (FLA) of the motor. The nameplate FLA is critical as it represents the maximum current that the motor will draw under full load conditions. This information allows you to calculate the voltage drop accurately, as voltage drop is a function of current, conductor length, and conductor size.

Using the actual wire type may not provide a reliable measure for calculating voltage drop since different wire materials (like copper or aluminum) have distinct conductivity properties. While considering the type of wire is essential for other aspects of installation, it doesn't play as direct a role in voltage drop calculation compared to knowing the FLA.

Thus, utilizing the actual nameplate FLA enables a precise selection of conductor size, ensuring that the voltage drop remains within acceptable limits for efficient motor operation.