Most homeowners believe that once they move into their homes and as long as they had a home inspection where the electrical system passed they are completely safe. I had a situation just yesterday doing a bathroom remodel where I had to shut off a circuit in order to work on it. I inadvertantly shorted the branch circuit feed to the side of the metal electrical box (PLEASE DON'T TRY THIS AT HOME BOYS AND GIRLS !!!) and the breaker took about 2 seconds to trip. Upon further investigation I found the breakers were the Square D QO type (probably one of the best breakers on the market) but also probably haven't been changed out since their original installation some 25-30 years ago. Does anyone know what the expected life is of circuit breakers in general and how often they should be changed out ?