Electronic transformers are slowly becoming the standard in low voltage lighting.
Its low profile design allows for space saving design while electronic circuitry ensures a noise free environment.
HOW TO SELECT YOUR TRANSFORMER:
Add the total lamp wattage of each output circuit in your application, make sure that the total lamp wattage would not exceed the maximum wattage of the transformer you plan to use.
For example: If the transformer you plan to use is rated 300W and you have two output circuits each with three 50 watt lamps, your total wattage would be: 3 lamps x 2 circuits=6 lamps x 50 watts (each)=300 watts - exactly the rated wattage of your transformer.
If the total lamp wattage is more, you have to select another transformer which rated close to your total wattage but never less.
Please be aware that sometimes its better to use two small transformers instead of a high rated one, this is in the event that you don't want to light all the lamps together.