Was welding on some steel tubing this morning and finished up and headed for some aluminum angle that I was going to practice on. Switched over to AC adjusted my AC balance to about 50% and Frequency to about the middle of adjustment just to get a feel for things. Laid a bead down and was working on my puddle control without filler and it was looking pretty good. Picked up my filler and cleaned up a new area.....stainless brush wipedown with acetone and let dry. Stepped on the pedal and noticed that my arc really wasn't wanting to start very well. Before I could let off the pedal KABOOM from the machine and the breaker tripped. This is a 40amp breaker and a thin piece of angle so wasn't real sure what happened. Turned off the unit immediately and unplugged from the outlet. Let it sit and scratched my head a minute. Good ground contact..wasn't on DC....Argon flowing and plenty in tank. Turned breaker back on and checked the outlet and all looked well. Plugged machine in no problem. Turned on power switch and KABOOM again. Shut down and unplugged and headed to computer. I'm afraid to turn anything on for fear of damaging the machine or other equipment. Any Ideas or is it back to Everlast to test the warranty service. This is a brand new machine probably used for less than 1hour total. Im wondering if the contact points have closed up completely but not cracking this thing open yet.