What is the advantage of using 240v single phase lighting vs. 120v lighting. The wattage is still the same if you use P=IE. On the 240v circuit, the voltage is higher and the current is lower. But, you are still limited to 2000 watts on a 20 amp breaker and 1500 watts on a 15 amp breaker. So you really haven't gained anything. Is there any advantage that I am missing? I am involved in a job where 10 400 watt metal halide lights are going to be hung and we are trying to decide on what voltage to use. Thanks!