What is the minimum wire gauge required for a 3 hp, 1Ø motor at 208-V?

The minimum wire gauge required for a 3 hp, single-phase motor operating at 208 volts can be determined using the National Electrical Code (NEC) tables, which specify the appropriate wire sizes based on the current carrying capacity and the motor's power requirements.

For a 3 hp motor, the full-load current at 208 volts typically falls around 15 amps. When sizing conductors for motor applications, it is important to consider not only the full-load current but also potential overloads, voltage drop, and the installation conditions. Generally, a larger gauge conductor, which offers less resistance and handles more current safely, is advised.

In this case, using the NEC’s ampacity tables and considering that a 3 hp motor under these conditions would indeed require #6 AWG copper wire to handle the current safely and efficiently, especially when factoring in potential voltage drops over long runs or the need for future capacity. Wire gauge 6 is sufficient to offer both the necessary safety margin and ensures that the conductor can handle the operational demands without overheating or voltage drops that could impair motor performance.

Therefore, the requirement for a #6 wire gauge for a 3 hp, 1Ø motor at 208-V is well supported by the NEC and ensures