The Siemens 5SU1356-0DA25 is an FI/LS protector (RCBO) combining overcurrent protection and residual current detection in a single 1+N-pole module. It is rated B-curve 25A for overcurrent, with a residual sensitivity of 30mA (Type AC) and a breaking capacity of 6kA. The 70mm width and pigtail connection suit standard distribution board layouts where space is allocated per DIN rail module count.
What the Ratings Mean for Fit
The B-curve 25A rating means the unit trips magnetically at 3 to 5 times rated current (75–125A) — appropriate for resistive and general-purpose loads, but not for high-inrush motor circuits where a C- or D-curve would be needed. The 30mA Type AC residual sensitivity detects sinusoidal AC fault currents only; it does not cover pulsating DC or smooth DC faults, so it is suited for standard final circuits (lighting, socket outlets) but not for equipment with rectifiers or variable-speed drives. The 6kA breaking capacity (Icn) is adequate for domestic and light commercial distribution boards with a prospective short-circuit current under 6kA at the point of installation.