I have a rather large fluorescent fixture. Not industrial large, but like basement workshop large, larger than a kitchen size. I am out of 3 prong cords to ravage, and I only have a 2 prong cord, slithly larger gauge than your common household cord. No idea what it went to, a heater maybe. 

ANyway, my question is, can I hook this fluorescent light up with the two prong cord and leave it ungrounded? I'm sure it will work, I just don't know if there is some kind of circuit pattern with fluorescent lights if they wont turn on unless grounded or what?

It will work, for testing purposes, but it really should be grounded if it's going into service for two reasons, safety, and as a starting aid for the tubes.. Computer cords for the most part are all three prong, and in the thrift stores they are like a dime a dozen just cut the end that plugs in the computer in and wire it up safely and ground it..

It will work, for testing purposes, but it really should be grounded if it's going into service for two reasons, safety, and as a starting aid for the tubes.. Computer cords for the most part are all three prong, and in the thrift stores they are like a dime a dozen just cut the end that plugs in the computer in and wire it up safely and ground it..

I know that, I just didn't want to have to go out again.

For a TEST you can connect the luminaire enclosure together with the Neutral. This is dangerous, far more dangerous than leaving it non Earthed at all from an electrical safety standpoint. But you can place it on something isolating and avoid touching it. The Neutral will provide the same lamp starting aid as an Earth

Even thoguh it is Neutral, in the time when you are inserting or removing the plug there may be a brief moment when the Phase is connected and the Neutral is not, at this moment the luminaire body will be at 120V throught the ballast. Besides that, the luminaire body will become at 120V in any case if the plug (or wall receptacle wiring) is reversed or the Neutral wire breaks, and that is why this setup is dangerous