What it is and what it does
The Siemens 5SV3314-6BA is a SENTRON 5SV3-series residual current circuit breaker (RCCB) — instantaneous type, 2-pole, rated 40 A at 230 V AC. Its 30 mA trip threshold and Type A fault-current detection (pulsating DC and sinusoidal AC) make it the standard choice for general-purpose shock protection in residential and light commercial distribution boards. The 10 kA short-circuit current rating (SCCR) means it can safely interrupt fault currents up to that level without upstream fuses needing to clear first — a key spec for panel coordination.
Mounting and integration
Snaps onto DIN rail (REG) and occupies 2 width units (36 mm). Depth is 70 mm, height 90 mm — fits standard 18-module enclosures with room for gland plates. Conductor cross-section accepts 0.75 to 35 mm² solid or stranded; supply can enter from top or bottom. Mounting position is any, so no derating for horizontal or inverted installation. IP20 with the distribution board installed and conductors connected.
Thermal derating — the real-world current limit
The 40 A rating is at 40 °C ambient. At 45 °C it drops to 38.1 A, at 50 °C to 35.59 A, and at 55 °C to 32.29 A. At 65 °C you are down to 23.3 A; at 70 °C only 17.62 A. If the distribution board runs hot — say, a packed enclosure with multiple breakers — the effective current capacity shrinks fast. Plan the load per the ambient curve, not the nameplate.