I've finally got my shop light fixtures finished and have four extra PC fans just sitting around. With overdriving the fixtures I want a fan to blow on the bulbs and one on each ballast. Figured I'd mount them off the fixture to make removal easier. Pleanty of room in the canopy.
How would I go about wiring this up? Any helpful topics/websites/quotes? I've searched but came up empty handed.
Those little fans are almost always 12 volt DC motors, so wiring them means connecting them to a 12 volt, preferably variable voltage, power supply. The fans will run clockwise with the wires hooked one way and if the wires are reversed they will run counterclockwise. That's about my total knowledge about them, and it has been sufficient to hook up a couple with no problems. The type of power supply needed is: RadioShack.com - Power & Batteries: Adapters: AC (Home) adapters: 3-12VDC/800mA Regulated AC-to-DC Adapter
Hoppy has it right. Only thing I'd add is that the fan runs fastest at 12V, and you can slow it down by running it at less than 12V. It's an obvious distinction that is only important if the fan is too loud. Running a fan at half speed will make it much quieter, just like a house fan.
they do make a 120v pc fan. That would make it easier then you could just usse the same feed wires that turn your ballast on. that way it will run whenever the lamps are on. If not then you can buy voltage transformers that will convert 120v AC to 12v DC. Besides the ones mentioned that actually plug unto the wall, you can buy some that will go inside the hood and wire up to the cord wiring. Its rather easy and if you have questions just send me a pm.
I like the DC fans because you can vary the voltage to get different speeds, as already mentioned. This is nice if you've got more fan than you need, since you can just throw a 9v transformer on a 12v fan for instance.
Or to get even more advanced, put a termistor on it and walla, you have a temperature-controlled fan that will blow harder or softer depending on the temperature in your hood.
How to wire PC fans to cool a light fixture? 
Linear Mode
