What this SIRIUS load feeder is
The Siemens 3RA1125-1JL16-4BB4 is a SIRIUS non-fused load feeder in size S0, configured as a direct starter with bimetal motor protection and a circuit-breaker for short-circuit protection. It ships as a pre-assembled unit containing a 3RT1016-1BB41 contactor, a 3RV1021-1JA15 circuit-breaker, and a 3RA1921-1BA00 link module — one order code, one assembly, one BOM line.
Snap-on mounting onto a DIN rail, with a vertical mounting surface that can be rotated ±90° or tilted ±22.5° front-to-back. Dimensions are 45 mm wide, 205 mm high, and 154 mm deep — the S0 footprint common across the SIRIUS feeder range, so it fits existing panel layouts without re-drilling. Clearance requirements: 30 mm upward, 10 mm forward, 9 mm backward, 0 mm downward, and 30 mm at the side (0 mm when side-by-side mounted). IP20 on the front — protected against finger contact, suitable for enclosed panel installation where the front face is the only accessible surface.
Environmental and electrical ratings
Shock resistance of 12.5g and pollution degree 3 mean it withstands the vibration and conductive-dust conditions typical of machine-mounted panels. Rated insulation voltage 690 V, surge voltage resistance 6 kV — coordination class for standard 400 V line supplies with adequate overvoltage protection upstream. The electromechanical switching contact design supports a no-load switching frequency of 15 operations per second, though the motor-start duty cycle will be lower.