Slow throw 50a breaker?? regular HD ok??

I asked Square D if their QO series of breakers which are very common were all HACR rated since I had seen some marked as such and some not. They said they all were. HACR stands for Heating, Air Conditioning and Refrigeration I think which means they are made to tolerate the high startup currents that such devices require. I would consider this similar to Slo-Blo but I am not going to get into any arguments about it. I would guess that the other popular manufacturers breakers may be the same.

I have a Miller 225A stick welder that I run off a 40A breaker and have never had it trip. Most of the time I am under 140A but I have run it flat out without problem for a short period. Miller says I should have a 50-60A breaker for it. The breaker powering the welder is a Federal Pioneer Stablok not a Square-D QO. One thing about using high-currents you don't stick the rod down as easily! Billh

Ask an electrical inspector in your area. Here, the code recognizes that welding is an intermittent operation and allows a 60AMP breaker to be used with #8 wire.

Ted