Yesterday AEP Texas had a huge spike in our area and my shop has three phase. I had around 350 on the big leg and the requisite 115 or so on the other two. My shop was built in the 1950's and still has those big cylindrical fuses daisy chained between stations. Anyway, I had a big door motor go out, (I thought), then the air compressor (I thought) so when I turned on my Millermatic 350P, which is set to run on three phase, it blew a couple of those fuses. Long story short, AEP fixed the power spike, I replaced the blown cylindrical fuses and all of my three phase machines are working, except the Millermatic unit, which pretty much immediatly flips it's breaker. I rolled it across the shop to another outlet, same thing. I get a few lights, the MM350 comes up then pop, the breaker is out. My manual doesn't lead me to any internal circuit breakers or resets. I've yet to inspect my power cord but I think if I had an arc, then I wouldn't even get that far. Any further ideas from the members would be much needed and appreciated. JDMinerals