Thanks for the description julmer. It raises a question about vorgath's welder. If that machine is set up with European wiring doesn't it expect European 220 coming into it (one wire carrying 220 volts rather than two wires carrying 110 each) and might it therefore have a "conversion box" somewhere inside it that converts the 220 to 110? I'm just wondering it it will work properly at all with just one 110 wire feeding into it (which the conversion box might not handle correctly).
The symptom vorgath describes (the rod sticking to the metal rather than striking a good arch) sounds like what happens if you try to run a U.S. made buzz box with only one side wired in (one 110 wire attached rather than two). The rod will just stick to the working surface.
I could be way off base here (due to my very limited knowledge of electronics)...just trying to piece together your description of European wiring and vorgath's symptoms.
Also, it sounds like you might have too much load on that breaker you are attempting to use, vorgath. If that one circuit is running everything in the garage and a few things in the house as well...it won't take much to trip it when you add the welder on. If you have room in your box, I'd try to add a dedicated breaker for the welder and the proper wiring to the garage.