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How to select household circuit breakers?

Views: 13     Author: Site Editor     Publish Time: 2022-11-30      Origin: zhihu

1. How to calculate and choose miniature circuit breaker according to the power of home appliances?

1 horse=735W≈750w;

1.5 horsepower=1.5*750W=1125W;

2 horses=2*750W=1500W;

Calculation method and so on.

Case 1:

Q: How many amps of circuit breaker should be selected for a 3-horsepower air conditioner?

A: (220V voltage) 3 horsepower * 750W = 2250W * 3 times (impact current) = 6750W/220≈30.68A≈32A

Case 2:

Q: How many amps of miniature circuit breaker should be selected for 5 horsepower air conditioner?

A: (380V voltage) 5 hp*750W=3750W*3 times (impulse current)=11250W/380≈29.6≈32A (summary: power/voltage=ampere)


In the case of understanding the principle and function of earth leakage circuit breaker and miniature circuit breaker, the principle of small lighting, medium socket and large air conditioner should be followed. You can make a flexible power distribution plan according to your own requirements and decoration personality, combined with the actual situation.


circuit breaker switch

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2. What do the 1P and 2P on the circuit breaker mean? What is the difference between an miniature circuit breaker and an earth leakage circuit breaker?

1P is also called single-pole, there is only one terminal, and only one phase wire can be disconnected. This switch is suitable for controlling one-phase live wire.

2P is also called two-pole, There are two terminals, one connected to the phase line and the other connected to the neutral line. This circuit breaker switch is suitable for controlling one phase and one zero.

3P is also called three-pole, there are three terminals, and all three are connected to the live wire. This switch is suitable for controlling three-phase 380V voltage lines.

4P is also called four-pole. There are four terminals, three of which are connected to the live wire and one to the neutral wire. This switch is suitable for controlling three-phase four-wire lines.

The leakage protector is used for the control of the main switch. In addition to the original overload and short circuit protection functions of the miniature circuit breaker, the leakage protection function is added.


Earth Leakage Circuit Breaker

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3. How to choose household miniature circuit breakers and earth leakage circuit breaker?

Modern household electricity should be installed with lighting circuits, power socket circuits, and air-conditioning circuits, and separate wiring. When one of the circuits (such as the socket circuit) fails, the other circuits can still supply power normally.

The socket circuit must be equipped with a leakage protection device to prevent personal electric shock accidents caused by electrical leakage of household appliances.

The main switch of the household distribution box generally chooses a 32A-63A miniature circuit breaker that can be disconnected at the same time, with or without leakage.

The lighting circuit generally chooses a 10A-16A small circuit breaker, the socket circuit generally chooses a 16A-20A leakage protection circuit breaker.

In the air-conditioning circuit, the air-conditioning circuit of 1-1.2 horses generally chooses a small circuit breaker of 16-25A.

The cabinet machine of 3-5 horses needs a small circuit breaker of 25A-32A.

The central air conditioner of about 10 horses needs an independent 2P 40A miniature circuit breakers.

When a double-pole or 1P+N circuit breaker is used, the phase line and neutral line of the power supply will be cut off when there is a short circuit or leakage fault in the line to ensure the safety of personal safety and electrical equipment.


The above selections are for reference only. The actual electrical appliances used by each household are different. The specific selection should be based on the design of the electrician.




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