Get a couple of good wirepeople to replace the existing (probably green) wire with a green/white pair and wire it right.
Otherwise you'll be on the hook for the next shock/fire that happens within 100 feet and/or five years.

 

If you open the door of your distribution panel and it says 120/208Y then you do in fact have a neutral.
Using the ground as a neutral (current carrying conductor) is a code violation, and if there are exceptions that are out there please give chapter/verse

 

Okay, so my panel reads 208y/120 ; 240; 240/120(delta). So as Gerty said, I should have a neutral and a ground in my distribution panel. Since the majority of my run from box to the twist lock is in conduit, I can add that 5th wire through it and connect it to the ground so I can have a L-L-L-N-G, and just change out the service cord to a 5 wire.

 

That would be the preferred and accepted method IMO.
Max.

 

Thanks to all you guys, that is exactly what I needed to know. I will try to have this done in the next week or 2. Thanks again!

 

here we have all machines bonded together, individual ground rods can cause ground loops which can be disasterous in fault situations. one common ground is the recomended way.

 

Here is a interesting couple of PDF's particularly the side-bar on ground rods.
Max.

 

Thanks to all you guys, that is exactly what I needed to know. I will try to have this done in the next week or 2. Thanks again!

Doing it right is always easier than explaining why you didn't...