Overview

Conductors, switches, and protection devices that supply electricity to motors are chosen based on the characteristics and requirements of the motor. While NEC Section 430.6 provided selection criteria for this equipment, there
was confusion regarding what could be determined from the NEC versus what could be determined from motor nameplates. The 2023 edition of NEC addressed this issue by allowing motor nameplate ratings to be used for determining conductor sizing, switch ratings, and protection device ratings for low-speed, high-torque, canned pumps, or multispeed motors. Additionally, it clarified that motor nameplate ratings could also be used for conductor sizing for large motors not covered in Part XIV.

Applying the 2023 Code

The electrical requirements of motors are influenced by their horsepower ratings, which directly affect the ratings of conductors, switches, and protective devices that supply power to them. As the horsepower of a motor increases, so does the amount of current it draws during operation. This increased current demand requires the use of larger conductor sizes, higher-rated switches, and overcurrent protection devices to safely provide the required power. Understanding these relationships between motor horsepower, current demands, and the corresponding ratings of conductors, switches, and protection devices is essential for designing reliable electrical systems.

NEC Section 430.6 offers guidelines for selecting conductors, switches, and overcurrent protection devices based on motor characteristics. In the 2023 edition of the NEC, a revision to 430.6(A)(2) introduced additional provisions for utilizing motor nameplate ratings to determine the feeding conductor ampacity, switch ratings, and overcurrent protection ratings. This update is particularly relevant for low-speed, high-torque, canned pumps, or multispeed motors. Furthermore, nameplate ratings are now permitted for determining conductor sizes for large motors exceeding the values given in Part XIV of NEC 2023. These changes simplify the determination of specific feeding circuit elements by allowing them to be based on nameplate ratings. Additionally, permitting conductor sizing for large motors not included in Part XIV enables end users to determine parameters not previously covered by NEC.

What’s New for the 2023 NEC?

The table below presents a comparison between the 2020 NEC and the 2023 NEC regarding Section 430.6.