What it is and what it does
The Siemens 5SL4420-7CC is a 4-pole (4P) miniature circuit breaker from the SENTRON 5SL series, rated 20 A with a C tripping characteristic. It is designed for AC circuits at 400 V and provides a 10 kA breaking capacity per EN 60898 — enough for most residential and light commercial distribution boards where the prospective fault current stays under that threshold. The C-curve means it trips between 5 and 10 times rated current, which suits moderate inrush loads like small motors, lighting banks, and transformer primaries without nuisance tripping.
Key ratings and what they mean for fit
The 20 A rating governs the continuous load it can carry — size the downstream cable and load to stay under this. The 10 kA breaking capacity is the maximum fault current it can safely interrupt at 400 V AC; if your panel's available fault current exceeds this, you need a current-limiting upstream device or a higher-rated breaker. The 4-pole configuration switches all three phases plus neutral (though the neutral pole is not switched — confirms no neutral conductor switching, so it's a switched-neutral type for TN systems where the neutral is not broken). The C-curve is the standard choice for general-purpose branch circuits in European-style distribution.
Mounting and integration
Snaps onto standard 35 mm DIN rail. At 4 modular width units (72 mm wide,), it occupies four 18 mm slots in the enclosure. Installation depth is 70 mm, and mounting position is any — no derating needed for horizontal or upside-down orientation. The IP20 rating means it's protected against finger contact but not moisture; install inside a closed panel or distribution board. Terminal touch protection is provided.
Environmental and compliance
Rated for ambient temperatures from -40 °C to +75 °C, with a note that at +55 °C and 95% humidity the breaker still operates within spec. Halogen-free and silicon-free construction matters for clean-room or sensitive electronics environments where outgassing can cause contact corrosion. Sealable — the toggle can be locked in the off position with a padlock hasp for lockout/tagout. Vibration resistance tested to 50 m/s² at 25–150 Hz per IEC 60068-2-6, so it holds up on machinery panels subject to continuous vibration.