At 240V, a 3,000 W baseboard heater draws 12.5 amps.(網上查來的）

Now, a 20-amp circuit can only handle devices that draw up to 20 amps. We can see that, if we have a 240V circuit, we can run a 3,000 W heater on a 20-amp circuit. That’s because it draws less than 20 amps; 12.5 amps, to be exact.

我的結論是大致能夠應付我的情況