Siemens 5SP3220-3 SENTRON Miniature Circuit Breaker – 20 A, 2-Pole, Type E, 25 kA
The Siemens 5SP3220-3 is a 2-pole SENTRON miniature circuit breaker (MCB) rated at 20 A with a 25 kA breaking capacity at 400 V AC, per EN 60898. Its Type E tripping characteristic is designed for residential and infrastructure applications where a delayed magnetic trip is needed to avoid nuisance tripping from inrush currents — common on transformer or long-cable circuits. Rated insulation voltage (Ui) is 690 V, with surge voltage resistance rated at 6 kV and overvoltage category IV — suitable for main incoming panels where transient energy is highest.
Occupies 3 modular width units (each 18 mm wide, so 54 mm total). The enclosure depth is 76.3 mm; height is 128 mm. The locking slide is integrated and accepts a padlock, wire seal, or cable tie for lockout/tagout compliance. Shock resistance is rated at 30 g for at least 3 impacts of 11 ms duration, so it survives shipping and panel vibration without tripping.
Temperature Derating and Wire Range
Rated 20 A at 30 °C ambient. Derate to 19 A at 40 °C, 18.5 A at 45 °C, 18 A at 50 °C, and 17.5 A at 55 °C — important for panels with high internal heat rise or summer ambient conditions. The wide wire range (2.5 to 50 mm²) covers everything from small control circuits to main feeder tails.