What this frame is and what it needs
The C40F4 is a ComPacT NSX400F basic frame — a 4-pole, 400 A rated (at 40 °C) air circuit breaker chassis that ships without a trip unit. You add the protection module (Micrologic electronic or thermal-magnetic) separately to set the overload and short-circuit curves. This is the standard way Schneider sells the NSX line above 100 A: the frame and the trip unit are separate line items so you match the protection to the load without swapping the whole breaker. Breaking capacity varies by voltage: 85 kA at 240 V AC (UL 508), 36 kA Icu at 380/415 V AC (IEC 60947-2), and 25 kA Icu at 500 V AC. At 690 V AC it still holds 10 kA Icu, enough for most industrial line-to-line faults.
Because it is a frame without a trip unit, stocking patterns vary — distributors often carry the frame and the trip units separately. The frame itself is a single mechanical assembly; the buying decision is pairing it with the right Micrologic or TM-D trip unit for your load.
Fixed-mount design for backplate installation. Front-connected both top and bottom, so cabling is accessible without reaching behind the panel. IP40 front face protection keeps dust and tools out of the mechanism; IK07 impact rating means it shrugs off accidental knocks during installation. Overvoltage category III suits fixed-installation distribution boards.
Certified to EN/IEC 60947-2 (low-voltage switchgear and controlgear — circuit breakers) and UL 60947-4-1 (motor-protective circuit breakers). The dual listing covers both IEC and UL installations, so the same frame works in a European panel or a North American motor control center. Rated insulation voltage 800 V AC, rated impulse withstand 8 kV. The Class II insulation on the front face means no protective earth connection is required for the operator interface — the toggle and escutcheon are double-insulated.