My mission for today.... My main breaker keeps tripping, and it's really hard to turn off/on/reset. I suspect it's bad. Can you replace one of these without shutting off power to the box? I've installed many breakers, but never the main one. Off to check it out. If I do not return, you'll know it didn't go well..... Disclaimer: Do not try this at home. Over9five is a professional, and has done this thousands of times.