Re: residential upgrade
There could be local codes requiring everything to be upgraded. Here, if you are upgrading the service, then only the service equipment would have to be done.
One jurisdiction we work in has a "tenant minimum living standards" code. Once you upgrade the service, each unit has to be brought up to Code. The owner of the property wasn't happy, but he was stuck. The building had fuse panels, and his insurance carrier was not going to renew his policy unless he upgraded the system to circut breakers. He also couldn't find another insurance carrier to switch to that would accept the fuse system, so he had to upgrade. He then found out that he would have to have all units brought up to code. So he has to have a minimum of (2) small appliance circuts for Kitchen countertop, 3-ways added, AFCI breakers, etc...