What it is and what it does
The Siemens 3VM1125-3GE42-0AA0 is a 4-pole IEC frame 160 molded-case circuit breaker rated 25 A continuous, with a 25 kA breaking capacity at 415 V (class N). That Icu rating means it can safely interrupt a fault up to 25 kA without welding or rupturing — critical for panel selectivity studies where the upstream device must see the fault and trip first. The TM220 thermal-magnetic trip unit gives you adjustable overload protection (Ir = 18…25 A) and a fixed short-circuit pickup at 12.8 x In (320 A), so it's sized for general distribution or motor branch circuits where the inrush won't nuisance-trip. This is a product class C item — manufactured to order, not a stocked shelf good. That means it ships on your order, not from a bin, and it's non-returnable once produced. Plan your BOM quantities accordingly; no swapping out an extra unit later.