What it is and what it does
The Siemens 3RV2323-4AC10 is a SIRIUS circuit breaker in the S0 frame size, designed specifically for starter combinations — meaning it integrates into a motor starter assembly, combining branch-circuit protection with a contactor. It mounts onto a 35 mm DIN rail per DIN EN 60715 using either screws or a snap-on latch, and accepts any mounting position. The 97 by 45 by 97 mm footprint fits the standard S0 cutout, so it drops into panels already laid out for that frame size without re-drilling.
Key ratings and what they mean for fit
This breaker is rated 16 A at both 480 V and 600 V, which tells you the thermal-magnetic trip holds that continuous current across North American line voltages. At 230 V it carries a 2 hp motor load; at 460/480 V that rises to 10 hp — so it is sized for fractional- to medium-horsepower three-phase motors. The interrupting capacity at 690 V AC is 4 kA, and the backup fuse coordination is specified: gG 63 A at 400 V, gG 50 A at 500 V, gG 40 A at 690 V. That means if a fault exceeds the breaker's own breaking capacity, the upstream gG fuse clears it before the breaker ruptures. No ground-fault or phase-failure detection is built in — those functions, if needed, must come from an external module or the downstream overload relay.
Clearance and wiring constraints
Clearance requirements are tight: zero mm forwards and backwards from the mounting surface, 50 mm above and below, 30 mm to the sides. That means you can butt-mount this breaker against a panel backplate or a busbar — no breathing gap needed front or rear. The main circuit terminals are M4 screws, accepting 2x 1 to 2.5 mm² or 2x 2.5 to 10 mm² solid or stranded wire. Use a Pozidriv size 2 tip with a 5 to 6 mm shaft diameter for the terminal screws. Operating temperature range is -20 to +60 °C; storage and transport go from -50 to +80 °C.