What this RCCB is and what it does
The Siemens 5SV3414-6KL is a SENTRON 5SV3 series residual current circuit breaker (RCCB) — 2-pole, Type A, rated 40 A at 40 °C, for 230/400 V AC 50 Hz systems. Type A means it detects sinusoidal AC fault currents plus pulsating DC fault currents up to 1 kHz, covering most modern electronic loads (switched-mode supplies, variable-speed drives, LED drivers) that a plain AC-type RCCB would miss. The 10 kA short-circuit current rating (SCCR) means it can safely interrupt a fault up to that level without upstream damage, assuming the installation's prospective short-circuit current is within that limit. Mounts on DIN rail (REG), occupies 2 width units (36 mm), and is rated IP20 with conductors connected — standard for enclosed distribution boards.
Thermal derating and conductor sizing
The 40 A rating holds only up to 40 °C ambient. Above that, the continuous current must be derated: 38.1 A at 45 °C, 35.59 A at 50 °C, 32.29 A at 55 °C, 28.19 A at 60 °C, 23.3 A at 65 °C, and 17.62 A at 70 °C. If the panel ambient runs hot, size the upstream protective device and conductor for the derated value, not the nominal 40 A. The terminals accept solid or stranded copper from 0.75 mm² up to 35 mm² — enough for the full 40 A circuit without pigtailing.
Panel integration notes
Mounts on DIN rail in any position. Depth is 70 mm, height 90 mm — fits standard 2-module-wide cutouts in distribution boards. Supply can enter from top or bottom. The design is instantaneous (no short-time delay), so it trips within milliseconds on a fault. Overvoltage category III, pollution degree 2 suitable for fixed-installation panels. Finger and back-of-hand safe to IP20 with conductors connected.