Help fitting hps in small grow cab

I just finished my first grow using CFL and had good results. I am helping a buddy make a grow cabinet and his is much larger than mine so I am thinking a HPS would be a much better idea than CFL's.

The cabinet is 3'x3' and 5' tall. Is this tall enough for an HPS?

Also, exactly what do you need to use an HPS bulb? Is it just the reflector and bulb? Thanks

that's plenty big for an HPS. 250W would probably be just about right, 400W if you want to crank it up.

you need a ballast, reflector and bulb. you want to get a ballast that is separate from the fixture/reflector, so that you can keep it - and the heat it produces - outside of the box.

You'll need a ballast to fire the bulb. With a cabinet of that size, you'll most likely need an air-cooled reflector or cooltube to maintain optimal temps with an HPS (you'll also need fans to ventilate cabinet & light).

the absolut best bet in my opinion in a box that size would be to get an external ballast and a cool tube reflector. People focus a lot on the heat from the bulb but ballasts actually give off quite a bit of heat as well, if you get an external ballast you can keep it outside of the box saving space and heat. Cooltube reflectors are the smallest air cooler reflectors you can get and so you will only be losing a few inches at the ceiling if you set up up right. With this set up you would maintain almost all of your height and could really grow some nice sized tomatoes or pumpkins or whatever you were planning on growing.