The Siemens SIRIUS 3RV1948-1K is a terminal block designed for increased air clearances and creepage distances, incorporating phase barriers for circuit breaker Size S3. It is designated Type E per UL, which means the terminal block provides enhanced isolation spacing between conductors — critical for maintaining insulation integrity in higher-voltage or polluted environments where standard spacing would risk tracking or flashover.
This part is marked as a phased-out product. The official replacement (3RV2948-1K) should be validated for fit — same Size S3 footprint and UL Type E designation, so the mechanical and clearance requirements carry over, but verify any control-wiring or accessory compatibility before committing the revision.
What the UL Type E designation means for fit
The Type E acc. to UL designation means this terminal block is built to meet UL's spacing requirements for increased air clearances and creepage distances. In practice, this matters when the breaker is installed in a panel where phase-to-phase or phase-to-ground clearance is tight — the integrated phase barriers prevent arc tracking between terminals. The Size S3 designation ties it to Siemens 3RV2 circuit breakers in that frame size; it mounts directly onto the breaker's terminals, so no additional DIN-rail space is consumed. For a panel OEM wiring a Size S3 motor-protective breaker, this block is the correct accessory to maintain the UL listing of the assembly.