I need to make an extension cable for my welder but dont know what size or type of wire to use. I went to homo depot today and got the plugs but aparently knowing about wiring is not a prerequisit to working in the electrical department and none of the 'tards there could help. They had plenty of wire that was big but as expensive at is I want to do it right the first time. My welder is a millermatic 210 and the plugs that fit it say 250 volt 50 amp.