What this combination starter delivers
The Siemens 3RA1125-0JA23-1BW4 is a nonreversing combination starter from the SIRIUS S0 frame series, rated for 0.7-1 A with a 48 VDC control voltage. It integrates a motor starter protector (MSP) and a contactor in one DIN-rail or panel-mount package, saving panel space and wiring time on IEC motor control circuits. The auxiliary side carries one SPDT NO/NC contact on the MSP plus one NO front-mounted auxiliary contact on the contactor — enough for a feedback signal and a status lamp without adding a separate aux block.
UL recognition and approvals
The 3RA1125-0JA23-1BW4 holds UL File E156943 in Volume 1, Section 14, confirming its listing for the US and Canadian markets. That file covers the combination starter assembly, so the entire unit — MSP and contactor — is UL-recognized as a single component, simplifying panel certification for UL 508A shops.
Control voltage and auxiliary contact configuration
The 48 VDC control coil is fixed — this is a DC-rated solenoid, not an AC coil with a rectifier. If your panel runs 24 VDC control, this part will not pick; you would need the 24 VDC variant of the same S0 frame starter. The MSP auxiliary provides one SPDT (NO/NC) contact, and the contactor adds one NO front-mounted auxiliary — two isolated signal paths total, both rated for the same switching duty as the main contactor.