The Siemens 5SU1356-6KV25 is a combined residual current device and miniature circuit breaker (RCBO) — an FI/LS protector in Siemens' own naming. It's a Type A unit rated at 30 mA earth leakage sensitivity and 6 kA breaking capacity, with a 1+N-pole form factor and a B-curve 25 A overcurrent trip. The 'PSE/SSF' marking indicates it meets the Swedish PSE and Swiss SSF utility requirements, so it's already cleared for those national grids.
What the ratings mean for fit
Type A detection means this RCBO trips on AC sinusoidal residual currents plus pulsating DC residuals — the kind a half-wave rectifier load (like a washing machine or a single-phase VFD) can produce. The 30 mA IΔn is the standard for personal protection against direct contact; it's the same threshold used in domestic and light commercial distribution boards across Europe. The 6 kA breaking capacity (Icn) is sized for a typical sub-distribution board where the prospective short-circuit current at the busbar stays under 6 kA — common in TN and TT systems with a 25 A upstream fuse or MCB. The B-curve (3-5 In) means it holds through inrush from resistive and small motor loads but trips fast on a hard short.
Panel integration
The 70 mm depth (D=70MM) is the dimension from the DIN-rail mounting plane to the front of the housing — standard for Siemens 5SU series RCBOs. It clips onto a 35 mm DIN rail and occupies a single modular width (1+N pole). The neutral is switched and protected internally, so no separate neutral bar connection is needed downstream. The tunnel terminals accept up to 25 mm² conductor for the incoming supply.