How to wire the circuit breaker

1、 Preparation before wiring
Confirm the type and specifications of the Circuit Breaker
Type: Distinguish between single pole (1P, control live wire), double pole (2P, control live wire+neutral wire), three pole (3P, three-phase live wire), with leakage protection (RCD), etc.
Parameters: rated voltage (such as 220V/380V), rated current (such as 16A/32A), trip characteristics (such as C-type for lighting and D-type for motors).
Power off inspection
Disconnect the previous power supply (such as the main switch), use a multimeter to confirm that there is no voltage at the incoming terminal, and ensure safe operation.

2、 Core wiring steps
（1） Single phase circuit (220V, taking 1P+N residual current circuit breaker as an example)

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(Note: The actual wiring is subject to the product identification. Some brands' neutral wire terminals are fixed incoming wires and cannot be reversed.)
Incoming end
L (live wire): Connect the power input live wire (usually red or brown) and insert it into the terminal with switch of the circuit breaker (marked as "L" or "live wire").
N (neutral wire): Connect the power supply incoming neutral wire (usually blue or black), insert it into the circuit breaker neutral wire terminal (marked as "N", some are fixed holes, cannot be reversed).
Outgoing terminal
L (live wire): Connect the load live wire (such as the live wire end of a lamp or socket).
N (neutral wire): Connect the load neutral wire (independent of the incoming neutral wire and cannot be mixed).
Ground wire (PE)
If it is a socket circuit, a separate grounding wire (yellow green dual color wire) must be connected to the socket grounding hole, and a circuit breaker must not be connected.
（2） Three phase circuit (380V, taking 3P circuit breaker as an example)

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Incoming end
L1/L2/L3 (live line): Connect the three-phase power supply incoming lines (yellow, green, red) respectively, corresponding to terminals 1/2/3 of the circuit breaker (marked as "L1/L2/L3").
Neutral wire (N): If it is a three-phase four wire system, the neutral wire is directly connected to the neutral wire busbar of the distribution box without passing through a circuit breaker (the circuit breaker only controls three live wires).
Outgoing terminal
L1/L2/L3 (live wire): Connect three-phase loads (such as motors and three-phase equipment), with corresponding terminals consistent with the incoming wire.
3、 Precautions
Wiring direction
Circuit breakers follow the principle of "upward and downward": the incoming end is on the top and the outgoing end is on the bottom. If connected in reverse, it may lead to a decrease in arc extinguishing ability and affect safety.
Terminal fastening
The insulation layer of the wire needs to be stripped of a suitable length (about 1cm), and after inserting the terminal, it should be tightened with a screwdriver to ensure good contact and avoid faults caused by loose heating.
Special requirements for residual current circuit breakers
The neutral wire shall not be repeatedly grounded: The neutral wire of the residual current circuit breaker shall be separately led out from its terminal. If mixed with the neutral wire of other circuits, it may cause the leakage protection to malfunction.
Test button: After wiring, press the "TEST" button to check if the trip is sensitive (regular testing is required every month).
Circuit matching
Lighting, sockets, air conditioning and other circuits need to be separately equipped with circuit breakers to avoid overload. For example:
General lighting: 10-16A single pole circuit breaker;
Socket (with leakage): 16-20A bipolar or 1P+N leakage circuit breaker;
Air conditioner/water heater: 20-32A single or double pole circuit breaker.
4、 Wiring Examples and Error Avoidance
Correct Example
Single phase lighting circuit: 1P circuit breaker controls the live wire, the neutral wire is directly connected to the neutral wire busbar, and the ground wire is connected to the metal casing of the lamp (if any).
Socket circuit: 1P+N residual current circuit breaker, with the live and neutral wires connected to the corresponding terminals, and the ground wire connected to the PE hole of the socket.
fault signaling 
Connecting the neutral wire to the live terminal of the circuit breaker may cause a short circuit or switch failure.
Mixing ground and neutral wires: violating safety regulations and may pose a risk of electric shock.
Overload wiring: If a 16A circuit breaker is used to connect a 3000W water heater (current ≈ 13.6A, although not overloaded, a margin needs to be left, it is recommended to use 20A).
5、 Functional testing and acceptance
Closing test
Slowly close the switch and observe for sparks or abnormal noises. If it trips, it may be a short circuit or leakage in the circuit, and the fault needs to be investigated.
Load Testing
Connect to normal load, run for 30 minutes, touch the surface of the circuit breaker to check for overheating (slight heating is normal, if it is hot, check for excessive contact or load).
Leakage test
Circuit breakers with leakage protection require a leakage tester to simulate leakage scenarios and test whether they trip within 0.1 seconds.
prompt
Non professionals are not allowed to operate high voltage or complex circuits!
If it involves scenarios such as forward and reverse rotation of three-phase motors, dual power switching, etc., it is necessary to cooperate with components such as contactors and relays. It is recommended that the wiring diagram be designed by an electrician.
When replacing circuit breakers in old distribution boxes, it is necessary to check whether the insulation layer of the wires is aging, and if necessary, replace the wires synchronously.