Are you sure it is a hps bulb? I have a 150 that has a bigger socket. AND YES ALL HPS NEED A BALLAST. sOME HAVE THEM BUILT INTO THE UNIT GROW LIGHTS HAVE EXTERNAL ONES.
Yeah it always needs a ballast man. Any sort of sodium bulb. it can have a built in unit ballast. But it would be obvious and clear on the packaging and instructions. These ones also take like 5 to 10minutes to start than the proper ballasts. But always need a ballast man.