The Siemens 5SM9343-0 is a SENTRON residual current (RC) unit designed as an electronic add-on for the 5SL4 miniature circuit breaker series. It is a 4-pole, type AC (sinusoidal AC residual currents only) device rated at 40 A and 400 V AC, 50 Hz, with a 30 mA trip threshold. This is the module that snaps onto the bottom of the 5SL4 MCB to create a combined RCBO function — the breaker handles overcurrent and short-circuit, the 5SM9343-0 handles earth leakage.
The 40 A rating matches the thermal capacity of the RC unit's own current path; the upstream MCB must be selected at or below this value to avoid nuisance tripping or damage.
Mounts via standard rail (DIN) snap-on, any position allowed. The supply connection feeds from the top, above the miniature circuit breaker. Occupies 3 modular width units (18 mm each = 54 mm total width). Depth is 70 mm, matching the standard 5SL4 footprint.