Siemens 5SJ4210-7HG42 Miniature Circuit Breaker

Siemens Sentron 5SJ4210-7HG42 is a two-pole miniature circuit breaker (NSJ family) that protects branch circuits in 480Y/277 VAC, 50/60 Hz systems with a nominal current rating of 10 A. It uses a thermal-magnetic trip mechanism with a C-curve characteristic, delivering reliable overload and short-circuit protection; it mounts on a 35 mm DIN rail in control panels and distribution boards. Key electrical ratings include Ui 440 V and a rated voltage of 480/277 VAC, with an interrupting capacity cited as 14 kA in some listings, and 10 kA per EN 60898 and 15 kA per IEC 60947-2 depending on standard. The unit complies with UL 489 and CSA 22.2 No. 5-02 and IEC 60947-2, aligning with common safety requirements for industrial electrical installations. Power loss is about 1.4 W per pole in hot operating state, and the device is rated for roughly 10,000 mechanical operating cycles. When used in industrial feeders or panel boards, it provides simultaneous disconnection of both conductors and dependable protection for sensitive circuits while preserving compact form factor on the DIN rail.