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How to Calculate Power Requirements for Model Trains

Model trains contain small electric motors that power the wheels; they may also power small electric lights and sound effects. The voltage applied to a train set is stipulated by the manufacturer -- typically 12 volts, as specified by the National Model Railroad Association (NMRA). The wattage of the train motors and the number of trains simultaneously running on the layout determine the total power requirements.

Things You'll Need

Calculator

Instructions

- 1
  Establish the wattage of the train motor. You can find this information printed on the underside of the train and in the manufacturer's literature that accompanied the model.
- 2
  Divide the wattage by the voltage supplied to the track; the result is the current drawn by the train. For example, if the motor has a 10-watt rating and the voltage is 12 volts, the current is 0.83 amps (as 10 watts / 12 volts = 0.833 amps).
- 3
  Round up the current value to the nearest full amp; the result is the power requirement for the model train. In the example used previously, the train requires a power supply capable of delivering 12 volts and a minimum current of 1 amp.

Model Railroads