What it is and what it does
The Crabtree Starbreaker 5SU9306-6ES25 is an RCBO — a combined residual-current device and miniature circuit breaker in one 1-module-wide package. It protects a single-phase final subcircuit against both overload/short-circuit and earth leakage. The Type B tripping characteristic means the magnetic release operates between 3 and 5 times the rated current, per EN 60898, so it suits predominantly resistive loads with modest inrush — lighting, small heaters, socket outlets in domestic or light commercial distribution boards. Rated 25 A at 30 °C ambient, the device derates to 23.5 A at 40 °C, 22.75 A at 45 °C, 21.75 A at 50 °C, and 20.25 A at 55 °C. If the board runs warm — say, above 40 °C — the continuous load must be reduced accordingly. The breaking capacity is 6 kA per both EN 60898 and IEC 60947-2, which is the standard for domestic and light commercial final circuits in most European installations.
Mounting and integration
The unit occupies a single 18 mm modular width on a DIN rail. Installation depth is 70 mm; overall depth including the front is 77 mm. The IP20 rating applies only when the distribution board is installed and conductors are connected — this is not a standalone outdoor device. Supply is brought in from below per the manufacturer's marking. Mounting position is any, so the RCBO can be oriented horizontally or vertically inside the enclosure without affecting the ratings. The 1P+N design switches and protects only the line conductor; the neutral is switched but not protected. This is standard for single-phase RCBOs in TN or TT systems where the neutral is not fused. Overvoltage category III and pollution degree 2 confirm it is rated for fixed installation downstream of the utility meter, not for plug-in portable use.