The Siemens 5SY4214-7 is a 2-pole SENTRON miniature circuit breaker with a C tripping characteristic, rated at 0.3 A at AC. It carries a dual breaking capacity rating: 10 kA per IEC/EN 60898-1 for standard branch-circuit protection, and 35 kA per IEC 60947-2 / UL1077 for industrial panel applications where higher fault current is expected. That 35 kA figure is the one that matters when the breaker sits downstream of a large transformer or in a high-SCCR distribution board — the 10 kA rating is for residential or light commercial duty where the available fault current is lower.
What the ratings mean for fit
The C-curve (magnetic trip between 5 and 10 times In) makes this a good fit for moderate inrush loads like small motors, transformers, or capacitor banks — not for pure resistive heaters (B-curve territory) or high-inrush drives (D-curve). At 0.3 A, this is a low-current branch or control-circuit protector, not a main feeder breaker. Temperature derating is published: at 40 °C ambient the breaker is rated 0.28 A, at 50 °C it drops to 0.26 A, and at 60 °C it's 0.24 A. If the panel runs hot, the actual continuous current the breaker can carry without nuisance tripping is lower than the 35 °C nameplate value. The 2-pole design (2 MW, 36 mm wide) protects both line and neutral in single-phase circuits, or two phases in three-phase control circuits. It snaps onto a DIN rail via the quick-assembly system and can be mounted in any position — useful when panel layout is tight and the rail is vertical. IP20 with connected conductors means it's protected against finger contact but not against moisture — standard for enclosed distribution boards. Pollution degree 3 (conductive pollution or dry non-conductive pollution that becomes conductive due to condensation) is typical for industrial control panels.
Panel integration notes
Depth is 76 mm, width 36 mm (2 modular units), height 90 mm. Installation depth (behind the panel face) is 70 mm. Combined top and bottom terminals accept the same conductor range — no special ordering for line vs. load side. Sealable, halogen-free, silicon-free. Rated for ambient temperatures from -40 °C to 75 °C, which covers unheated electrical rooms and outdoor-rated enclosures in most climates. The storage temperature range is wider than the operating range — the -40 °C low end is a storage/survival spec, not a switching spec at that temperature.