In my experience, you will have appropriate isolation features between the safety and non-safety portion of your system (e.g., two safety-related fuses). If the modification is occurring entirely "downstream" of your isolation features and does not require changes to the design of the safety portion (I.e., no changes to the characteristics of the load that require your safety-related uninterruptable power system to be modified), then your changes should be non-safety-related.
Your local licensing engineer who is cognizant for Chapter 8 of your FSAR should also be able to help you make the call.