What this RCBO brings to the panel
The Siemens 5SU1324-6FN20 is a 2-pole RCBO from the SENTRON family, combining overcurrent protection and residual current detection in a single 36 mm wide module (2 MW). It is rated 20 A with a B tripping curve and 30 mA Type A residual sensitivity, breaking capacity 10 kA per EN 60898. The B curve means it trips between 3 and 5 times rated current — suited for resistive and general-purpose loads where inrush is modest, not for high-starting-current motors or transformers. Type A residual detects sinusoidal AC and pulsating DC fault currents, covering most domestic and light commercial circuits. The 10 kA SCCR at 400 V (per EN 60898) means it safely interrupts faults up to that level without cascading upstream — a standard rating for final subcircuits in a distribution board.
Derating and environmental limits
Rated 20 A at 30 °C ambient; derates to 19.5 A at 40 °C, 19.2 A at 45 °C, 18.9 A at 50 °C, 18.7 A at 55 °C, and 18.4 A at 60 °C. If the panel ambient runs above 40 °C, factor the derated value into the load schedule — a 20 A circuit at 50 °C is effectively an 18.9 A circuit. The RCBO is rated for pollution degree 3 (conductive pollution or dry non-conductive that becomes conductive) and overvoltage category III (equipment in fixed installations). Operating temperature range -40 °C to 70 °C, mounting position any. Insulation voltage Ui 500 V, surge voltage resistance 4 kV.
Panel fit and integration
Snap-on DIN rail mount, 2 MW wide (36 mm), depth 72 mm, installation depth 70 mm. Supply can enter from top or bottom. IP20 with connected conductors in an installed distribution board — not rated for washdown or outdoor exposure. The halogen-free designation is No, so if the specification requires halogen-free materials (e.g., for rail or marine), this part does not meet it.