| However, it is unclear to me how I would rewire a single phase 220V to the | canadian 2 phase 220v connector. If memory served me correctly the canadian | and usa oven plugs have 4 wires (2 hot, neutral and ground) , whereas europe | 220V is 1 hot 220V, a neutral and a ground.
The only risk that exists is if the French welder assumes one of the wires at 230 volts is grounded, and uses it in some way relative to ground. Such a design would have its hazards regardless, so this should not normally be done.
In North America, the 2 pole 1 phase system has 240 volts between the
2 poles, with ground in the middle. If the transformer primary is connected to the 2 wires and nothing else is connected, it will be fine. If it is rated 50/60 Hz, it is very likely expected by its manufacturer to be used on any power system in the world (at the proper voltage, which should be fine anywhere from 200 to 240 volts).
Added electrical "smarts" might be another story. But again, since it is rated for 50/60 Hz, they probably considered the issue.
I wish more American products would be designed to work on 2-wire only electrical power at the 240 volt range.