For a 220V (240V) dryer, the appropriate wire size depends on the dryer's electrical requirements and the length of the wiring run. Most dryers in the United States typically require a 30-amp circuit, though some larger or more powerful models may need a 40-amp circuit.
The National Electrical Code (NEC) provides guidelines for selecting the proper wire gauge based on the current (amps) and the length of the wiring run. For a 30-amp circuit, you would generally use 10 AWG (American Wire Gauge) copper wire. For a 40-amp circuit, you would need 8 AWG copper wire.
If the wiring run is particularly long or there are other factors that could cause voltage drop, it might be necessary to use a larger wire gauge to compensate and ensure the dryer receives the proper voltage.
It's crucial to follow local electrical codes and regulations when installing the wiring for a dryer. Additionally, for safety and compliance, it is recommended to consult a licensed electrician for proper installation and to determine the appropriate wire size based on the specific requirements of your dryer and your electrical system.