To be clear, 10ga wire can be used for more than 30A. 30A is the rating for regular residential wiring, there are other ratings for wire in other conditions such as in free air. Further codes allow wiring to electric welders to be undersized based on the duty rating of the welder.

At 40' up I expect very good ventilation even on a 5mph wind day.

Where do I find zinc stick? I haven't heard if that but it sounds good if I can weld, chip and get the stick on while still hot. Might be a bit difficult 40' up a tower bur perhaps I can get a helper up too.

I find myself faced with an interesting repair project, repairing a failed weld on a tower lattice rung. The tower is solid construction with 7/8" verticals and 1/2" rung latice, 18" face width and in a 70' self supporting gonfiguration (no guys). When doing some work on the tower the...