What conductor size is required for connecting a motor feeder in a three-phase 240-volt system?

In a three-phase 240-volt system, the conductor size required for connecting a motor feeder is determined by several factors, including the motor's full-load current, the allowable ampacity of the conductor, and any applicable adjustments for temperature and installation conditions.

When dealing with motor feeders, the National Electrical Code (NEC) provides guidelines on ampacity and conductor sizing based on the motor's horsepower (HP) rating. For many common motor sizes in a three-phase system, it is typical to reference the NEC tables to find the appropriate conductor size for the specific current draw of the motor.

Choosing a conductor size of 6 AWG is often appropriate for motors that do not draw excessive current and fit within certain HP ranges at the specified voltage. This gauge provides sufficient current-carrying capacity while ensuring minimal voltage drop over the distance the feeder runs. It balances the need for safety, efficiency, and compliance with electrical codes, making it a sound choice for connecting motor feeders in a three-phase 240-volt system.

It's also essential to consider that larger gauges (like 3 or 2 AWG) might be used for larger motors to ensure they can handle the load without overheating, while smaller gauges (like 4 AWG)