The Siemens 5SL4420-7RC is a SENTRON miniature circuit breaker (MCB) with four poles, C-curve tripping characteristic, and a 20 A rated current. It interrupts fault currents up to 10 kA at 415 V AC per EN 60898, making it a standard choice for final subcircuit protection in residential and light commercial distribution boards. The 4-pole configuration switches all three phases plus neutral, though the neutral pole is not switched internally — it remains solidly connected.
What the ratings mean for fit
The C-curve means the magnetic trip threshold is 5–10× rated current — suitable for loads with moderate inrush like small motors, lighting banks, and general-purpose circuits where you want to avoid nuisance trips from startup current. The 20 A rating at 30 °C ambient sets the continuous load limit; derate for higher panel temperatures. The 10 kA breaking capacity is the maximum prospective fault current the breaker can safely clear at its rated voltage — sufficient for most residential and light commercial service entrances where the utility transformer impedance keeps fault levels below that. The 415 V AC rated voltage matches standard three-phase distribution voltages across much of Europe and Asia; the breaker also carries a 440 V maximum for multi-phase operation and a 250 V single-phase rating.
Panel integration and mounting
Snap-on mounting to 35 mm DIN rail per EN 60715. The 18 mm width occupies one modular unit, so a 4-pole breaker takes four modules of rail space. Depth is 76 mm, installation depth 70 mm — fits standard distribution board enclosures. IP20 protection with connected conductors means it's touch-safe for panel interiors but not rated for wet or dusty environments. Mount in any position, which simplifies layout in tight enclosures. Pollution degree 2 and overvoltage category III suit fixed-installation mains distribution.
Halogen-free and silicon-free construction — relevant for installations where off-gassing during a fault event must not corrode nearby contacts or sensitive electronics. Sealable means the breaker can be locked in the OFF position for lockout/tagout. Mechanical service life is 10,000 switching cycles typical, which is standard for an MCB used for overcurrent protection rather than frequent switching duty. Temperature range spans -40 °C to 75 °C, covering unheated utility rooms and outdoor enclosures in most climates.