What the 25 kA breaking capacity means for your panel
The Siemens 5SP3720-2KK02 is a SENTRON main miniature circuit breaker — 1-pole, rated 25 kA breaking capacity per EN 60898 at 230 V AC, 50 Hz. In a residential or infrastructure meter panel where the utility-side fault current can hit 25 kA, this breaker holds the line; anything lower and you risk the breaker failing to clear a bolted fault, which cascades upstream. The E tripping characteristic (E20A L2 per the description) means it's a selective (time-delayed) curve — it rides through short-duration inrush from downstream loads without nuisance tripping, coordinating with branch MCBs so only the faulted circuit opens.
Mounting and integration in the meter panel
Fastens directly onto a 40-mm busbar system per DIN 43870 Part 2 — the standard grid in European meter cabinets. Occupies 1.5 modular width units, so it needs one and a half 18 mm slots on the DIN rail. The outgoing feeder uses a spring-loaded terminal; infeed is via box terminal. Enclosure depth is 76.3 mm; overall depth with the breaker body is 89.5 mm, which fits standard meter-panel enclosures. IP40 with connected conductors — fine for indoor meter boards, not for washdown areas.
Environmental and mechanical margins
Shock tested to 30 g, 11 ms half-sine, 3 impacts per axis; vibration per IEC 60068-2-6 at 2 g, 5–150 Hz, 20 frequency cycles. Mechanical life 20 000 operating cycles typical.
Locking and seal options
Sealable via locking slide accepting a padlock, additional wire seal, cable ties, or Antilux sealing wire. Switch position indicator shows OFF = green, ON = red for quick visual status. Infeed position is stipulated for the lower section of the meter panel per the design.