Main Breaker failure?

[petersonra]

I think the chances are good you will never really know what went wrong. i would just replace the equipment and move on.

 

[norcal]

I don't know if it's called a "4-pole" breaker or not, but what he is describing is a typical 200A main breaker in some ITE panels. It's the size of four spaces, and in a backfeed configuration, with 2-pair of connections.

ITE was the first with that design breaker but GE, & Cutler-Hammer also used that style.