The choice of household circuit breakers

Update date:2018-03-16 Source:MAXGE

The choice of household circuit breakers

1. Trip type: refers to the type of the circuit breaker disconnection time and the current through the circuit breaker; Type B is basically not used (more use in electronic products, instantaneous operating current multiple is low), C type is generally used for non-impact Type of load (such as: general lighting, instantaneous operating current of circuit breaker switch is generally 5-10 rated current In); D type is generally used for impact load (such as: motor start, transformer and other inductive load); in fact, as long as understand, home The type C trip type is generally selected.


2. Rated current: The current value of the circuit breaker that can carry continuous operation for a long time. The value of current that can be used for a long time, do not exceed this current value when the household appliance is used.The number of poles: According to the modularization of points, here is a circuit breaker width of 18mm as a module. One pole represents one module.

3. Rated voltage: The voltage used in domestic power supply is 380V/220V. The rated voltage refers to the optimal voltage when the electrical equipment is working for a long time. The rated voltage is also called the nominal voltage. When the operating voltage of the electrical equipment is higher than the rated voltage, it is easy to damage the equipment, and when it is lower than the rated voltage, it will not work normally (such as the lamp does not emit light normally, and the motor does not operate normally).


4. Rated breaking capacity: The breaking capacity of the circuit breaker refers to the ability of the circuit breaker to safely cut off the fault current (fault current: the current generated when the two electric wires of the socket are broken together and broken together). Usually 3kA or more is enough for home use.  The more controversial in the selection of circuit breakers is the location of the leakage circuit breakers. Individual engineers will put the leakage circuit breakers in the position of the master switch at the time of design, and each branch switch will not be provided with ordinary circuit breakers for leakage.


Of course, this design can minimize the cost. However, there are two uncontrollable designs of this kind:

1. The leakage occurred in a single branch, but its leakage value is relatively small. The circuit breaker cannot reach the tripping work value and the circuit leakage will not trip. This is especially true for a water heater, which is related to human life safety.

2. When there is a leakage on one of the roads, the entire domestic circuit will be disconnected, causing all control loops to black out.


The appropriate choice is to install a switch-disconnector 63A or more at the main switch position (the switch-disconnector is used for inspections with a clear disconnection point) followed by a 2P C 40A circuit breaker and a 1P C 16A breaker in the bedroom. (If the room has more internal lamps or there are many floors, you can use a 1P circuit breaker on each floor or branch.) The kitchen and bathroom use leakage circuit breaker 1P+NC 16A alone, and the leakage current is 30mA. Each room outlet is controlled by a 2P C 25A leakage circuit breaker. The leakage current is selected to be 30mA. Air conditioners and water heater outlets are controlled by a 2P C 25A leakage circuit breaker. The 10mA leakage current is recommended for the water heater to better protect personal safety.

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