What it is and what it does
The Siemens SENTRON 5SV3357-6 is a 4-pole residual current circuit breaker (RCCB) — instantaneous type, 80 A rated current, 30 mA trip threshold, Type A waveform sensitivity. That 30 mA trip is the standard for personnel protection in most IEC-based residential and light commercial panels; Type A means it catches pulsating DC faults on top of sinusoidal AC, which covers modern electronics and single-phase rectified loads. The instantaneous design (no intentional delay) clears fast on a fault, but it also means no selectivity against downstream RCCBs — every device on the same circuit sees the fault at the same time.
Mounting and panel fit
Snaps onto standard DIN rail (REG profile). Occupies 4 modular width units — that's 72 mm of rail space, so it eats four 18 mm slots in a typical distribution board. Depth is 70 mm, which matches the standard 70 mm installation depth for this class; the height is 90 mm. Mounting position is unrestricted — horizontal, vertical, upside-down, the trip mechanism works the same. Supply can land on top or bottom terminals; no polarity restriction. IP20 with conductors connected and the board closed — that's the usual for enclosed distribution gear, not for open-panel washdown zones.
Thermal derating — the real-world current
The 80 A rating holds at 40 °C ambient. At 45 °C it drops to 77.57 A; at 50 °C to 74.59 A; at 55 °C to 70.22 A; at 60 °C to 64.47 A; at 65 °C to 57.35 A; at 70 °C to 48.8 A. If the panel runs hot — say a packed enclosure near a furnace line or a roof-mounted board in summer — the actual continuous current the device can carry is what the derating curve says, not the label. The operating ambient range is -25 °C to 45 °C; storage range is -40 °C to 75 °C.
Fault ratings and coordination
Short-circuit current rating (SCCR) is 10 kA per IEC 61008-1. That's the standard for most residential and light commercial panels; if the prospective fault current at the installation point exceeds 10 kA, this device isn't the right choice without an upstream current-limiting breaker. The let-through energy (I²t) is rated at 110,000 A²·s — that's the energy the device lets pass before it clears. Surge current resistance is 1 kA (8/20 μs waveform), which means it survives lightning-induced or switching surges up to that peak without nuisance tripping. Overvoltage category III — suitable for fixed installations downstream of the main distribution board.