A 15 AMP electric circuit can safely handle 1800 watts at 120 Volts before the breaker trips to prevent overheating of the electrical wire.
Most new homes today are wired for 20 AMPS though for the electric outlet circuits and 20 AMP circuits can handle a total of 2400 watts before it trips the breaker to prevent the electric wire from overheating.
15 AMP wire and circuits are okay for lightning needs but really it's best to use 20 AMPS for electrical outlets to allow for more amperage being plugged in today.