Potter is using a 400w HPS, just like me. and no, the bulbs are twice the size of any normal bulb outlet. you will need to get a ballast which supports those higher watt lights and will come with a bigger bulb outlet thing if you want to use one of those.
its called a mogul socket when its the big fat one... regular bulbs are called medium base all mogul socket bulbs require special high power wattage specific ballasts.