UL listed interchangeable rating plugs are used to establish or change the long time trip point of the circuit breaker. The key advantage of the rating plug is the flexibility of interchangeable rating plugs across the permissible current ratings of a given circuit breaker frame. Since the installed rating plug establishes the ampere rating of the breaker, the installer must verify the adequacy of the connected cable and/or bus bar ampacity. The National Electric Code allows cable size to be matched to the ampere rating established by the rating plug.