70 A, 1-pole, Trip Curve K — what it means on your panel
The ABB S801U-K70 is a 1-pole miniature circuit breaker from the S800 series, rated 70 A at 240 VAC with a 25 kA interrupting capacity. Trip Curve K means it's designed for inductive and motor-starting loads — the magnetic trip point sits higher than a B or C curve, so it won't nuisance-trip on inrush.
Where it fits — and the one thing that trips people up
Curve K breakers are common in control panels feeding contactors, small transformers, or motor circuits where the starting surge exceeds what a C-curve would handle. The catch: a K-curve's magnetic trip is typically 8–12× rated current, so it's not for general-purpose lighting or resistive loads — use it where the load's inrush is known and repeatable.