The Siemens 5SP3725-2KK02 is a 1-pole miniature circuit breaker from the SENTRON 5SP3 series, rated 25 A with an E tripping characteristic and a 25 kA breaking capacity per EN 60898. It mounts on a 40 mm busbar system per DIN 43870 Part 2, making it the standard fit for residential and infrastructure meter panels where the supply cord enters at the lower section of the enclosure. The E-curve (tripping characteristic E) means it holds through moderate inrush — typical for transformer or capacitor loads — while still tripping fast on a hard fault.
Both solid and stranded conductors from 2.5 mm² up to 50 mm² are accepted at the box terminal. The outgoing feeder uses a spring-loaded terminal — no tool needed for the load side, which speeds up panel wiring. Infeed is at the box terminal, so the line side lands on a fixed clamp. The breaker occupies 1.5 width units (roughly 27 mm) on the busbar. Depth is 89.5 mm overall; the enclosure itself is 76.3 mm deep, so the extra 13 mm is the terminal projection. Height is 151.3 mm. That footprint matches the standard 40 mm busbar spacing in DIN 43870 meter panels — no adapter needed.
Protection class IP40 with conductors connected — fine for indoor panel environments but not for washdown. Overvoltage category IV (mains-level) with a 6 kV surge voltage rating. Vibration resistance is 2 g per IEC 60068-2-6 (20 cycles, 5 to 150 Hz); shock resistance is 30 g for at least 3 impacts of 11 ms duration. The switch position indicator shows OFF = green, ON = red.
Locking and sealing
The breaker is sealable. The locking device uses a locking slide with a lock, plus provision for an additional wire seal, cable ties, and Antilux. This is typical for utility-meter compartments where tamper evidence is required.