The Siemens 5SU9304-7KK16 is a SENTRON RCBO — an RCD-operated circuit breaker combining overcurrent and residual-current protection in a single 1-module-wide (18 mm) package. It's rated 16 A with a C-curve tripping characteristic, 30 mA type A residual-current sensitivity, and a 10 kA breaking capacity per EN 60898 and IEC 60947-2. The supply can enter from either top or bottom, and the unit includes a 600 mm pigtail for the neutral connection.
What the ratings mean for fit
The C-curve means the magnetic trip activates at 5 to 10 times rated current — suited for circuits with moderate inrush, like lighting banks or small motor loads, where a B-curve might nuisance-trip but a D-curve would be too slow. The 30 mA type A residual-current element detects both sinusoidal AC faults and pulsating DC faults, which covers most modern electronics and variable-speed drives downstream. The 10 kA breaking capacity is the standard domestic and light-commercial SCCR for final subcircuits in most European installations — it safely interrupts a bolted fault up to that level without upstream cascading. The 1P+N design protects only the phase conductor; the neutral is switched but not protected. This is the common arrangement for single-phase final circuits in TN and TT systems where the neutral is solidly earthed and does not require overcurrent protection. The solid N pigtail simplifies wiring in distribution boards — the neutral bar connection is factory-terminated, reducing installation time. At 18 mm width and 77 mm depth, it occupies a single modular unit on a DIN rail. The IP20 rating is standard for enclosed distribution boards — the protection is only complete once the board cover is fitted and conductors are connected.