The ABB S204-C40 is a 4-pole miniature circuit breaker from the S200 series, rated at 40 A with a Trip Curve C characteristic and a 10 kA interrupting capacity at 277 V AC. It mounts on a standard DIN rail — straightforward to swap into an existing panel or drop into a new build without reworking the backplate.
Trip Curve C means the magnetic trip kicks in at 5 to 10 times rated current — good for moderate inrush loads like small motors, transformers, or lighting banks where you need some headroom against nuisance trips but still want fast fault clearing. The 10 kA SCCR at 277 V AC is enough for most commercial and light industrial distribution panels; it'll interrupt a bolted fault up to that level without upstream coordination issues.