Schneider Acti9 C120N 125A Miniature Circuit Breaker

The C120N belongs to the Acti9 series high-current miniature circuit breaker (MCB). It is an upgraded high-current variant of the standard C65N, with a maximum rated current of 125A and isolation function. Widely used for power distribution in industrial and building terminals, as well as outgoing circuits in power cabinets.

1. Model Definition

C120: Product series, high-current MCB (63~125A)

N: Breaking capacity class, Icn=10kA @ 400V AC

125A: Rated working current In=125A (reference temperature: 30℃)

Full model requires additional [pole number + tripping curve]

C-curve: Instantaneous tripping at 5~10In, for general power distribution, lighting and resistive loads (Part No. A9N18359 / A9N18363 / A9N18369)

D-curve: Instantaneous tripping at 10~14In, for loads with inrush current such as motors and transformers (Part No. A9N18389)

2. Core Electrical Specifications

3. Wiring Specifications

Solid copper cable: Max. 50mm²

Flexible copper cable: Max. 35mm²

Optional aluminum terminal: For 16~50mm² aluminum cables

4. Application Scenarios
5. High-current outgoing circuits in factory buildings, computer rooms and building distribution cabinets
6. Main power incoming, fan and water pump circuits (D-curve recommended)
7. Alternative to small-frame moulded case circuit breakers to save cabinet space

Optional accessories: Vigi C120 residual current module, auxiliary contact, fault alarm contact, shunt release

5. Selection Guidelines & Alternative Products

Selection Notes

1. Derating is required when ambient temperature exceeds 30℃;
2. D-curve is preferred for motor loads; C-curve for general distribution;
3. C120N with 10kA breaking capacity; select C120H (15kA) / C120L (25kA) for circuits with higher short-circuit current.

Domestic Alternatives

Chint: NM1-125 compact MCCB / NB1-125 MCB

Delixi: CDB2 125 series miniature circuit breaker

6. Common Troubleshooting
7. Trips immediately after closing: Short circuit on downstream side, check cable insulation and load earth fault;
8. Trips after period of loaded operation: Overload, actual load exceeds 125A, or high ambient temperature causes derating;
9. Cannot close, handle stuck: Damaged internal mechanism, or Vigi residual current module triggered;
10. Green indicator does not appear: Main contacts are not fully disconnected. Maintenance on downstream circuits is prohibited.
11. HS Code Reference

85362000 Low-voltage circuit breaker (for customs declaration reference only, subject to customs verification)

Schneider Acti9 C120N 125A Product Manual (Compiled from Original Datasheet)

Series: Acti9 C120N High-current Miniature Circuit Breaker (MCB)

Rated current: 125A (reference at 30℃)

Breaking capacity: Icn=10kA @400V AC

Reference part numbers:

2P C-curve: A9N18363

3P C-curve: A9N18369

4P C-curve: A9N18376

3P D-curve: A9N18389

The C120N is part of Schneider Acti9 high-current MCB family covering 63~125A. It features isolation function. The green contact indicator provides direct visual confirmation that main contacts are open, meeting maintenance safety requirements. It provides thermal-magnetic protection against overload and short-circuit for high-current power distribution in industrial and building distribution cabinets. Compatible with add-on accessories including Vigi C120 residual current module, auxiliary contacts, alarm contacts and shunt releases.

Standards: GB10963.1, IEC/EN60898-1, IEC/EN60947-2; CCC, CE certified

2. Electrical Specifications

3. Mechanical & Wiring Specifications
4. Mounting: 35mm standard DIN rail, snap-in type, mountable in any orientation
5. Protection class: IP20 (front terminals)
6. Wiring capacity

Solid copper cable: Max.50mm²

Flexible copper cable (with cable lug): Max.35mm²

Optional aluminum terminals: For 16~50mm² aluminum cables

4. Tightening torque: 3.5 N·m
5. Overall dimensions (18mm per pole)

2P: 36mm width; 3P: 54mm width; 4P:72mm width

6. Operating environment

Ambient temperature: -25℃ ~ +70℃; derating required above 30℃

Storage temperature: -40℃ ~ +85℃

Altitude: No derating ≤2000m; derating required above 2000m

Relative humidity: 5~95%, non-condensing

4. Tripping Characteristics
5. Thermal overload trip (inverse time)

1.13In: No tripping within 1h (cold state)

1.45In: Tripping within 1h

2. Magnetic instantaneous trip

C-curve:5~10In, power distribution, lighting, resistive loads

D-curve:10~14In, motors, transformers, capacitor loads with inrush current

5. Optional Accessories
6. Vigi C120: Add-on residual current protection module, forms RCD+MCB combination
7. OF Auxiliary contact: Circuit ON/OFF status signal
8. SD Fault alarm contact: Tripping signal for short-circuit / overload
9. MX Shunt release: Remote electrical trip
10. MN Undervoltage release: Loss-of-voltage protection
11. Busbar: Comb-type busbar for multi-pole parallel incoming connection
12. Installation & Operation Notes
13. Derating: Derate rated current when ambient temperature >30℃. Derating also required for multiple devices installed side by side inside enclosed cabinets.
14. Isolation verification: When handle is set to OFF position, the green indicator visible confirms main contacts are fully open before downstream maintenance. Handle position alone cannot be used as isolation confirmation.
15. Wiring: Top-in or bottom-in wiring is acceptable. Cable lugs are recommended. Tightening torque 3.5N·m to prevent overheating.
16. Model differentiation

C120N:10kA; C120H:15kA; C120L:25kA. Select H/L version for circuits with high short-circuit current.

7. Troubleshooting
8. Trips immediately after closing: Short circuit or earth fault on downstream side. Test breaker separately after disconnecting load to verify breaker integrity.
9. Trips after loaded operation: Actual load exceeds rated current, or high ambient temperature causes derating.
10. Cannot close, handle stuck: Damaged mechanism or locked residual current module.
11. Overheating when closed: Insufficient terminal torque, undersized cable, oxidized terminals.
12. Model Selection Table (C120N 125A)

Schneider Acti9 C120N 125A Overall & Mounting Dimensions (Original Datasheet)

Reference: Height H=81mm, Depth D=73mm, height and depth are consistent for all pole types; width varies with pole count

Mounting rail: 35mm standard symmetrical DIN rail, snap-in installation

Common model: 3P C120N 125A (A9N18369): 81(W) × 81(H) ×73(D) mm

Related Mounting Dimensions

1. Cable stripping length: 15 mm
2. Terminal tightening torque: 3.5 N·m
3. Max terminal wiring: Solid wire 50mm² / Flexible wire 35mm²
4. Cabinet clearance: ≥20mm wiring space reserved at top and bottom terminals; keep heat dissipation gap for side-by-side installation at high temperature (derating)

Supplementary Notes

Depth 73mm: Total depth from DIN rail backplate to front handle of breaker body; cabinet door cutout needs clearance allowance

Height 81mm: Overall vertical height of device body, excluding cable bending allowance

If Vigi C120 residual current module is fitted, overall depth increases, refer to separate accessory datasheet for dimension