I'msticking with my electrical theme this week so here is another about circuit breakers and replacing them because of age.
According to most manufactures, circuit breakers should be replaced every 20-30 years depending on exposure. The US Government recommends replacement after 30 years. Over the past few years I have seen many electrical contractors trying to up sell clients on circuit breaker replacement. As an licensed electrical contractor with over 25 years experience, my opinion is go with the manufacture recommendation and begin to think about replacement after 20 years. Breaker panels with west side exposure in hot dusty parts of the country may require more frequent replacement, closer to 20 years rather than 30.
The reason for replacement is two fold. First, circuit breakers generally mount to the buss bar (the metal bar they plug into for the power) via spring steel. Over the years, as the metal heats and cools from use the metal tends to loose a great deal of it's spring which causes a poor connection. Once a poor connection is created it can create an arc, which in return can damage both the busing and the breaker itself. Damaged bus-sing is the number one reason for panel replacement.
In the Phoenix market, panel replacement runs from $1,200 to about $4,000 depending on the amount of work involved sometimes this is the less expensive way to go. Replacing most circuit breakers (Brands Zinsco and FPE I just recommend replacing the entire panel) can be done for about $10-30 per breaker plus the cost of the main. In some cases those costs can be even lower depending on the breaker manufacture.