I'm not a superstitious person, but I don't like to mess with Main Breakers. If they are working, I say leave them alone. Breakers aren't like switches, and if you turn the Main Breaker off, it might not come back on.
Just saying. And it happened again today at a Dental Office. A compressor breaker was tripping and for safety, the staff thought it would be a good idea to turn off the main breaker until a service tech could come. Guess what happened? The main breaker now couldn't be reset. It would stay on for a while and then "trip." Great. It's freezing cold at night, they don't make this old breaker anymore, and it won't reset.
Once on site, we found the Main Breaker halfway over from the off position. At first attempt, the lever seemed frozen and couldn't be moved. We took the cover off and got a picture of the breaker itself in case we needed the part number for an order. While shutting off the individual circuit breakers, we saw one of the circuit breakers below in the the tripped position. Probably the compressor. With the cover off and my safety glasses on, I got serious about moving that handle over. Something about a pair of pliers and a screwdriver, but there were no witnesses. I figured if it died in the process of being resuscitated it wouldn't be my first patient. But it lived, and when the handle got all the way over to it's stop position, it held. Probably didn't want the old hammer and chisel routine again. More likely it held because it was now fully reset whereas before it had not been. Either way, still a win.
Not every story like this has a happy ending. In the past I have been called out on these problems to find that the main had been somehow turned off, couldn't be reset, and now had to be replaced. Or the whole panel replaced because the breaker is unavailable or outdated. Don't do that. Don't be that guy!
Hey, we found the reason those compressors were tripping. Overloaded circuit. Splitting up the load to nearby outlets got that fixed. We then came up with a plan for turning them off and on at night. Worked great. Wrapped up, cleaned up, and headed out. Happy ending, right? Well...
Here's hoping that breaker holds. Kinda feel guilty about how I mistreated it. But it was me or him you see, and I hate messing with the Main Breaker.