Answer: for micro circuit breaker, 1P+N and 2P are generally controlled by two lines, but the effect is different.

1P+N---- single pole +N circuit breaker, control fire line and zero line at the same time, but only the fire line has the function of thermal and magnetic release; the modulus is also 18mm.

2P------ single-phase 2 pole circuit breaker, at the same time control the fire line, zero line, and all have the function of thermal and magnetic release, the modulus is 2*18mm=36mm.

Therefore, we can draw the following conclusions:

1, in order to reduce the cost, 1P can be used, but the circuit breaker of the higher level must have the function of electric leakage tripping. If we want to prevent accidents caused by fire or zero, we must cut off the superior power supply.

2, in order to avoid 1 problems when overhauling, 1P+N (DPN) can be used.

3, 2P is for the same reason: circuit breaker shell 18mm module, installed 1P and 1P+N are different, the former in the short circuit accident under the "breaking capacity" must be higher than the latter, after all, space is an important factor that affects the breaking capacity. Therefore, for the more important, maintenance and operation of frequent, easy to failure of the electric circuit, it is best to use 2P (higher cost).

4, the 1P premise is that the lighting distribution box must have leakage and release function, at least the line (or the top of the line out) should use a leakage circuit breaker.