I have three very nice 400 watt HPS lights that I acquired. The only problem is that they are set up to operate off 208 volts as oppossed to the 120 that my house current uses. I was wondering if I could replace the transformer in the light with one that has an input voltage of 120 instead of 208. I looked for something like that, and didn't find much. So then I thought, surely I can find a transformer that steps 120 volts up to 208. I looked and found nothing. I am fairly electrically knowledgable, so I figured I would buy some ferrite cores and make my own 120 to 208 transformer. The only thing is that I have never made a transformer to handle such high currents for such a period of time. Does anyone have any experience with these sort of things? Thanks.