When specifying circuit breakers, it’s customary that breakers protecting down stream equipment and feeder conductors should be rated at no more than 80% of their maximum rated load current downstream at the bus voltage for the devices/feeders.
But I’ve come across applications where 100%-rated breakers are used/specified. These are usually in high voltage power distribution scenarios.
I understand that using 100% rated breakers permits the use of smaller downstream feeder conductors. But does anyone know where using such breakers makes sense? They are more expensive than regular breakers.