How much code compliance you need to do depends on the work being done and your local inspector. I replaced a panel that was rusted out (there was literally a

How much code compliance you need to do depends on the work being done and your local inspector. I replaced a panel that was rusted out (there was literally a hole rusted through in the back due to water intrusion in the wall) in a house that was built in the 1940's, re-wired with circuit breakers sometime in the 80's. The electrician said I didn't need to replace any breakers, just the panel. I asked the local inspector if I had to put AFCI's and GFCI's everywhere required by modern code, he confirmed that it was highly recommended, but not strictly required for existing circuits, only for new circuits. I also didn't need to install a cutoff before the panel. Since I was buying new breakers anyway, I ended up putting AFCI/GFCI's as required by code.