What it is and what it does
The Siemens 5SL3263-7MB is a 2-pole SENTRON miniature circuit breaker with a C-curve trip characteristic, rated 63 A at 400 V AC. It interrupts faults up to 4.5 kA per EN 60898, which is the standard for overcurrent protection in residential and light commercial distribution boards. The C-curve means it trips between 5 and 10 times rated current — a good fit for inductive loads like small motors or transformers that draw a moderate inrush.
Key ratings and what they mean for fit
Rated 63 A at 400 V AC, this breaker handles a 63 A continuous load on a 2-pole circuit. The 4.5 kA breaking capacity per EN 60898 is sufficient for most residential and light commercial service entrances where the prospective fault current stays under that level. If your installation requires a higher interrupting rating (e.g., 10 kA), you would step up to the 3-pole 5SL4363-7, which carries 10 kA per both EN 60898 and IEC 60947-2. The 2-pole design (2 MW units, 36 mm wide) breaks both phase and neutral on a single-phase supply. For a 3-phase circuit you would need the 3-pole variant. The C-curve is specified for general-purpose and moderate inductive loads; if your load is purely resistive (heating, lighting) a B-curve would avoid nuisance trips, and for high-inrush loads (large transformers) a D-curve is standard. Ambient temperature range from -40 °C to 75 °C covers indoor and outdoor enclosures in most climates. The IP20 rating (with connected conductors) means it is protected against solid objects larger than 12 mm but not against moisture — it belongs inside a distribution board or panel, not in a wet location.
Panel integration and mounting
Snap-on mounting to DIN rail EN 60715. The 36 mm width (2 MW units) is standard for a 2-pole MCB. Installation depth is 70 mm; overall depth is 76 mm. Mounting position is any — no derating for horizontal or inverted orientation. Sealable design allows locking the breaker in the ON or OFF position for safety lockout/tagout. Supplementary devices (auxiliary switches, shunt trips, undervoltage releases) can be installed on the right side using the SENTRON accessory system. Power loss is 4.4 W per pole at rated current in hot state — account for this heat inside the enclosure when calculating thermal rise.