Can anyone tell me how to tell the difference in screw in sockets. Medium base, mogule base? Is there a messurement? Im using a Hamilton Tech. Fixture it has 150w screw in bulbs. I just built a new mag ballast for it. The ballasts are 250w each. Its up and running great but now I want to pick out some new bulbs. I do not know witch socket is in the fixture. Are they all the same, 150,175,250 watt bulb sockets? Is there a way to messure the base of the bulb to know?