240 Volt Wiring
I recently purchased a 240 volt mig welder. It has a three wire cord, two black(hot) and one yellow-green ground. I read somewhere all new 240 volt appliances have to have a four wire hook up. Two hot, a neutral and a ground. I guess the welder is not considered an appliance. Anyway my barn where the welder is going does not have a ground wire going back to the main panel in the garage. It has two #8 hot wires for 240 volt, and a neutral for 120. I found two copper ground stakes used for the system ground. All outlets are GFI protected and grounded to the stakes. I know you shall NOT use the neutral as a ground even though they are electrically connected at the main panel.
My question is whether or not this is a safe system to run my welder? Should I get 240 volt GFI protection for the welder? I assume there is such a thing. Should I run a separate ground wire back to the garage panel?