When deciding how many receptacles to add to a 20-amp circuit, consider what you are likely to plug into each one. For safety, the total draw on the circuit shouldn't exceed 16 amps at any one time, which translates to a maximum power draw of 1,920 watts on a conventional 120-volt circuit, even though the breaker won't trip until the power draw exceeds 2,400 watts. You should limit the number of receptacles on a circuit that will handle a power-hungry appliance. For example, most electric heaters draw 1,500 watts, so a circuit that powers one should have few other receptacles.