[Tom Line]

Bruce, we've got 4 cims, each on a 40, and you pop the 40's LONG before you should be popping the main breaker. In point of fact in 2008 we had 4 cims and 2 fisher price all drawing hard when we lifted a trackball and rounded the corner, and we STILL never popped our main breaker. That main breaker doesn't pop immediately at it's stated amperage - just like the snap-action breakers and have a small period of time where it can go over the rated amperage.

I'd be suspicious of your main breaker, or of some sort of short / wiring issue causing it to let go.

I've never heard of a team popping that main breaker simply through motor use (though I'm sure it's happened).