How do you wire a 4800 watt heater that's 240 volts?

This will pull 20 Amps continuous so you will need a 30 A breaker and 10 AWG wire. You would have Black, Red, White and Ground. The 240 V would be on the black and red connected to the output from a two pole 240 A breaker. White would be neutral and green or bare wire would be ground.