Thankyou WN The first ballast came in a pre-put-together unit from sunlight sheds. The metalhalide bulb worked fine in this ballast, and I did have the hps bulb in for a while ,then the bulb wouldn't work, so I took the bulb to hydrolite and he tested my bulb in his store and it worked fine. I then thought it must be the ballast and bought a ballast from the guy from hydo-lite and when I brought the ballast home took the old ballast off the light and hooked up the new ballast only to find out the new ballast would not fire up the hps bulb, however it ran the metal halide bulb no problem. So there you have it, does anybody know if metal halides use less power thanhps lights, if so maybe my normal everyday plugs won't power it. I read somebodies post about the thingermajigger may need to be pulled out inside the light socket and i did try that. (it didn't work) mammabear