Can I wire my mig/plasma together and use a common ground clamp?
 

I'm setting up my new shop and I want to use a new longer power cord to attach both my mig and plasma cutter to the outlet. I'll run both on the same cart so everything is on and ready. Since I am now going to only have one cart for the pair I figured I could share a common ground cable as well but I do not know what that will do to my equipment. Any problems with running it like this? I know there are many places that share a common ground clamp between machines but I don't know if sharing the power cord at the same time will mess something up. I'm sure it won't but I wanted to at least see if someone who knows more than jack sh*t like me thought it would be ok. Thanks!

Yes especially if you don't run them at the same time.

I will probably power both up but only "activate" (squeeze the trigger) one at a time. I can't see me ever cutting a seam with one hand and stitching it back up with the other.

OK, now that is settled I just need to design a new welding cart to hold them both. More than likely I will just modify one of my cheap HF carts (add a shelf) to hold the mig above the plasma.

OK, I started with my mig and plasma on separate cheap blue HF welding carts. I modified one to hold both machines and then purchased a metal junction box with a top and cable clamps. I wired both the plasma/mig together using wire nuts. I've turned both on at the same time but have only used the mig for a brief time. I kept separate work cables (which I was incorrectly calling ground cables before). The plasma uses a (-) on the clamp but the mig with gas uses the clamp as (+). This ended up being a fairly good solution. My machines take up half the work space they used to and I got rid of one cable/outlet. The 30' long heavy cable is pretty nice.

I am happy...