:confused: hi I have a 3 year old house with 200 amp service and yesterday after turning central ac on for the 1st time this year the circuit breaker box buzzes when the unit kicks on and then doesn't buzz again until ac kicks on again, is this a bad breaker? And is it easy to change? Thank you for your help.

Most likely the breaker is weak or defective. Changing it is simple, it simply unplugs from the center of the panel. But if you are not familiar with working in a live panel, shut off the main before removing the cover, pull or pry the breaker gently at the center, and it will unplug form the bus bar.

Once the old breaker is unplugged inspect the bare metal the breaker plugs onto looking for any evidence of heat, discoloration or melted metal, just to be sure there will be a good connection for the new breaker.

Close up the panel and restore the power, and start the AC, the buzzing should be gone if the cause was the breaker. If the even slightest buzzing remains, then there is another mechanical problem in the panel and will need the attention of an electrician.