3-pole, 4 A, Curve C — panel fit and trip coordination
The S203-C4 is a 3-pole miniature circuit breaker rated at 4 A with a Trip Curve C characteristic, meaning the magnetic trip threshold sits at 5 to 10 times rated current — the standard choice for moderate inrush loads like motor starters, contactor coils, and general-purpose branch circuits where you need to ride through the starting surge without nuisance tripping. Snaps onto standard DIN rail for panel integration; the 3-pole block handles three-phase loads or three independent single-phase circuits with a common trip bar.
Drop-in compatibility with the S203-C8
The S203-C8 is the same physical breaker — same 3-pole DIN-rail footprint, same 277 VAC rating, same 10 kA interrupting capacity — but rated at 8 A instead of 4 A. If a panel was built around the S203-C8, the C4 drops into the same mounting location without rewiring; the only change is the lower current rating, which reduces the load capacity of that branch.