The Siemens 5SP3720-2KK03 is a SENTRON main miniature circuit breaker (SHU) — a 1-pole, E-characteristic device rated for 230 V AC supply voltage with a 25 kA breaking capacity per EN 60898. This is a main breaker intended for the incoming feed in residential or infrastructure meter panels, not a branch-circuit MCB.
The insulation voltage (Ui) is rated at 690 V, and surge voltage resistance is 6 kV, overvoltage category IV — meaning it's built for the utility-side of the meter, not downstream branch protection. Mechanical service life is 20,000 operating cycles typical. That's the expected life of the mechanism under normal switching — not the number of fault interruptions, which is much lower. For a main breaker that cycles only on panel shutdown, this is ample. The enclosure depth is 76.3 mm, overall depth 89.5 mm, height 151.3 mm — fits standard meter-panel cutouts. Mounts on a 40-mm busbar system per DIN 43870 Part 2, or via busbar fastening. Infeed is at the box terminal; outgoing feeder uses spring-loaded terminals. Conductor range: 2.5 to 50 mm² solid or stranded. IP40 with connected conductors, pollution degree 3, vibration resistance 2 g per IEC 60068-2-6, shock resistance 30 g at 11 ms. Sealable with locking slide, wire seal, cable ties, or Antilux — important for utility-locked meter cabinets.
Integration and deployment context
In a meter panel, the supply cord position is stipulated for the lower section — meaning the incoming feed enters at the bottom, outgoing at the top via spring-loaded terminals. The switch position indicator shows OFF = green, ON = red, a standard visual cue for panel walk-downs.