Rated 50 A, Curve C — what that means for the panel
The ABB S203M-C50 is a 3-pole miniature circuit breaker from the S200M series, rated 50 A with a Trip Curve C characteristic. That curve means it trips at 5 to 10 times rated current — standard for general-purpose loads like lighting, small motor circuits, and distribution sub-panels where moderate inrush is expected but not the high surge of motor-starting (which would call for Curve D). Its interrupting rating is 6 kA at 277 VAC and 10 kA at 125 VDC. The 6 kA AC figure is typical for branch-circuit protection in residential and light commercial panels where the available fault current stays under that threshold. The DC rating at 125 VDC covers control-circuit and battery-backed loads.