This exception states that when adding a different voltage system that “ONLY” the new system needs to be identified. It goes on to tell us that we need to label the panel boards with the words “OTHER UNIDENTIFIED SYSTEMS EXIST ON THE PREMISES.” Back before the 2005 Code went into effect the identification of branch circuits was not a requirement. This is a good change because at what expense would it take to re-identify an old wiring system in a building, just think about it.
So now we have back up that makes sense and having it in print is a good thing.
Till next time be safe work safe
Jake