What this frame is and where it sits
The Schneider Electric C125N4FM is a basic frame from the ComPacT NS630b...1600 new generation range — a 4-pole, manually operated air circuit breaker frame rated 1250 A at 50 °C, designed for fixed backplate mounting. It carries an N breaking capacity code: 50 kA Icu at 415 V AC, 50/60 Hz, certified to IEC 60947-2. This is the bare frame without a control unit or protection module; you add the trip unit separately to define the protection curve.
Impulse withstand (Uimp) is 8 kV, which covers overvoltage category III installations. The integral instant protection is set at 40 kA, a fixed magnetic threshold that acts as backup protection if the trip unit fails.
Physical integration and panel fit
Fixed backplate mounting, 4-pole, neutral on the left. Dimensions: 280 mm wide, 224 mm high, 147 mm deep. Connection pitch is 70 mm — standard for busbar or cable lug termination at this frame size. Power losses are 44 W at rated current, which factors into enclosure ventilation sizing. Mechanical durability is 10,000 cycles; electrical durability varies by voltage and current — 2,000 cycles at 690 V AC at In, up to 5,000 cycles at 440 V AC at In/2. Storage temperature range -50 to 85 °C; operating -25 to 70 °C.