Common problems with circuit breakers

Update date:2018-08-24 Source:MAXGE

Common problems with circuit breakers

How to choose the model of the circuit breaker? What is the difference between 1p, 2p, etc. of the circuit breaker? How do families choose circuit breakers? Many people have many similar problems. This article will answer your questions. MAXGE is a professional manufacturer of circuit breakers.

1 What is the difference between the miniature circuit breakers 1P, 1P+N, and 2P?

For miniature circuit breakers, 1P+N.1P.2P is generally used as the on-off control of single-phase electrical appliances, but the effect is different.

1P-----Single-pole circuit breaker with thermal magnetic tripping function, only control the live line (phase line), modulus 18mm; 1P+N---monopole + N circuit breaker, while controlling the live line, neutral line, But only the hot wire has a thermomagnetic tripping function: the modulus is also 18mm:

2P-----single-phase 2-pole circuit breaker, which controls the live wire and neutral wire at the same time, and both have thermal magnetic tripping function, the modulus is 2*18mm=36mm.

Therefore, the following conclusions can be drawn:

1 In order to reduce the cost, 1P can be used, but the upper circuit breaker must have the leakage trip function. In order to prevent fire and zero confusion during maintenance, the upper power supply must be cut off.

2, for avoiding one problem during maintenance, 1P+N (ie DPN) can be used:

3. Reason for using 2P: For the circuit breaker case which is also 18mm modulus, there is a difference between the internal 1P and the 1P+N. The former "limit breaking capacity" in the short-circuit accident state is definitely higher than that. After all, space is an important factor affecting the ability to break. Therefore, it is more important. It is better to use 2P (higher cost) for maintenance and operation, and it is easy to fault.

4. With 1P, the premise is that the lighting distribution box must have the leakage trip function, at least the incoming line (or the upper level of the outgoing line) should use the leakage circuit breaker.

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Detailed explanation of 2:1P, 1P+N, 2P, 3P, 3P+N, 4P?

1P, 2P.3P, and 4P are pole numbers, indicating that several lines can be segmented. Now +N, all N lines are broken, but there is no trip device on the N line. Only when the phase line is broken, the N line is cut off. For example, for a 4P 16A circuit breaker, if the N-line current is greater than 16A, or greater than 20A, in theory, the circuit breaker will trip. But the 3P+N circuit breaker, N line current 160A, will not jump. The premise is that the phase current does not exceed the rated value.


What appliances are used in 31P, 2P, and 3P? What is the difference between them?


1P.2P single-phase equipment, lighting can use 1P; socket should be 2P; 3P is used in three-phase equipment, and there is a place for three-phase electricity to enter the household.

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4 Is the lighting circuit using 1P or IP+N?

1. 1P for lighting, traditional practice, nothing bad. There is also 1P+N, which is not necessary. Lighting does not leak,

2. Its practical 1P+N is good, like DPN switch, and 1P switch modulus

3. Lighting generally uses 1P. The residential standard mentions that residential bathroom lighting should be protected by leakage, so the bathroom lighting circuit can be protected by 1P+N with leakage. General lighting uses Ip.


5In the residential single-phase distribution box incoming line should be 1P or 2P? (In civil residential buildings, single-phase outlets are used when wiring from the meter box to the indoor distribution box, why is the distribution box using 2P instead of 1P? ? The switch has no leakage?

1.2P, easy to repair, safe!

2. Civil Building Design Specification 25.3/11 When each household adopts single power supply, the miniature circuit breaker of the household should adopt two poles; when three-phase power supply is adopted, the miniature circuit breaker of the household should adopt three poles. And should be set up self-resetting over and under voltage protector.


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