A 120/ 240 volt single phase residential panel board supplies 240 volt baseboard heaters: 2-1500 watt: 2-2000 watt: 2-2500 watt: 2-1500 watt: 2-2000 watt. Excluding exceptions, what size copper type TW grounded conductors are required?

A 120/ 240 volt single phase residential panel board supplies 240 volt baseboard heaters: 2-1500 watt: 2-2000 watt: 2-2500 watt: 2-1500 watt: 2-2000 watt. Excluding exceptions, what size copper type TW grounded conductors are required?