The Siemens 5SU1654-1RC20 is a 2-pole RCBO (residual current circuit breaker with overcurrent protection) rated at 20 A with a C characteristic and Type AC 300 mA residual current sensitivity. It occupies 2 module spaces on a DIN rail, making it a compact choice for a final-circuit protective device in a distribution board.
What the Ratings Mean for Fit
The 20 A rating with a C characteristic means the device is designed to trip instantaneously at 5 to 10 times the rated current (100 to 200 A), which suits loads with moderate inrush, such as small motor circuits or lighting banks. The Type AC residual current detection at 300 mA handles sinusoidal AC fault currents only — it is not rated for pulsed DC or smooth DC faults, so it fits standard domestic or commercial final circuits where the load is predominantly resistive or inductive AC. The 2-pole, 2-module form factor snaps onto a DIN rail in a consumer unit or sub-distribution board, occupying the same width as two single-pole MCBs.
Deployment Context
Mounts on a standard 35 mm DIN rail inside a distribution board or enclosure. The 2-module width (approx. 36 mm) means it fits alongside other modular devices in a row; plan for adequate heat dissipation when grouping multiple RCBOs — the manufacturer's derating guidelines apply above 40 °C ambient.