Only you can tell. Take a meter and measure the total current in Amps. Multiply by the voltage (use 15 Volts as an example) The answer is the power being consumed in Watts. A ZW will supply around 200 Watts on a good day in a cool room. This is the simple method to get a rough idea of the power being consumed.
If you don't have an ammeter that will measure up to and beyond 10 Amps, measure each train by itself and add them up.
If you divide 200 by 20 (Watts by Volts) you get 10 Amps. I don't know what the rating of the circuit breaker is, so you need to look it up or ask someone who might know. If your total power exceeds 200 Watts, I would imagine that the cb is doing its job. I would not suggest using a cb that is rated for higher current.
