Depends on the combined wattage of all of your lamps and the length of your wire runs. Ideally, the total load on your transformer should be no more than 80% of the transformer’s wattage. For instance, for a 300W transformer, the total combined wattage of all of your fixture lamps should be no more than 240W. That could be 120 2W fixtures or eighty 3w fixtures or sixty 4W fixtures and so on. If you’re planning any long lighting runs, you should also factor that into your decision making. HTH
