The Siemens 5SV3345-6 is an active-production 4-pole residual current circuit breaker (RCCB) from the RCCBs family. It is rated for 125 A continuous current with a 30 mA residual trip threshold on a 400 VAC system. The type A designation means it detects sinusoidal AC fault currents plus pulsating DC fault currents up to 6 mA — critical for modern variable-speed drives, LED lighting, and other electronics that generate smooth DC ripple on the line.
125 A / 30 mA — what that means for your panel
At 125 A this RCCB handles the full incoming feed for a sub-distribution board or a large single load like a commercial kitchen or a multi-machine cell. The 30 mA sensitivity is the standard for personal protection against direct contact (30 mA is the IEC threshold below which ventricular fibrillation is unlikely). On a 400 V three-phase system, the 4-pole design switches all three phases plus neutral — no neutral pole left unprotected. Type A is the right choice when the downstream loads include single-phase rectifiers, switched-mode power supplies, or VFDs with minimal DC-link filtering. Standard type AC RCCBs can blind to pulsating DC faults; type A catches them. If your line has 3-phase drives with active front ends or EV chargers, you need type B or B+ — but for general industrial and commercial panels with VFDs below about 7.5 kW, type A covers the majority of installations.
Panel integration — DIN-rail footprint
Packaging dimensions are 78 x 97 x 85 mm — standard 4-module width for a 4-pole RCCB on a 35 mm DIN rail. The 125 A rating means the incoming cable section will be at least 35 mm² Cu; verify the tunnel terminal accepts that size before wiring. Spring-cage or screw terminals? Not stated in the evidence — confirm termination type on the physical unit or the full datasheet before panel layout.