C25B3 — ComPacT NSX250B Basic Frame, 250 A, 25 kA
The C25B3 is a Schneider Electric ComPacT NSX250B basic frame — a 3-pole, 250 A frame rated at 40 °C, designed for distribution applications where you add your own trip unit. It carries a 25 kA Icu at 380/415 V AC 50/60 Hz (breaking capacity code B), with higher interrupting ratings at lower voltages: 40 kA at 220/240 V AC, 20 kA at 440 V AC, and 15 kA at 500 V AC, all conforming to IEC 60947-2. This is a fixed-mount, backplate-mounted frame with front-front connections (both line and load side). The toggle control gives a clear visual indication of contact position.
Rated operational voltage goes up to 690 V AC 50/60 Hz, with an insulation voltage of 800 V AC and an impulse withstand of 8 kV. Electrical durability is 10,000 cycles at rated current (440 V), 20,000 cycles at half-rated current. That's standard for a molded-case frame in this class — fine for most distribution and motor-circuit applications, but if you're switching a load multiple times per shift, you'll want to track cycles against the mechanical life.
Sourcing and lifecycle — active, but needs the trip unit
Standards compliance covers EN/IEC 60947-2 (circuit breakers) and UL 60947-4-1 (contactors/motor-starters) — so it's dual-certified for IEC and UL installations. The front face is Class II shock-protected. If you're working to a panel that needs an isolation switch, the 'suitability for isolation' mark (per EN/IEC 60947-2) covers that requirement.
Integration — mounting and connections
Fixed mount on a backplate (not DIN-rail). The 105 mm width, 161 mm height, and 86 mm depth fit the standard ComPacT NSX cutout — if you're retrofitting an older NS or NSJ frame, check the mounting hole pattern. Connection pitch is 35 mm between poles. Front-front connections mean both line and load terminations are accessible from the front of the panel, which simplifies wiring and maintenance access.