For miniature circuit breakers, 1P, 1P+N, and 2P are typically employed as switching controls for single-phase electrical equipment.


1P Single-pole Circuit Breaker: Features a thermal release function, capable of controlling only the live wire (phase wire); module size is 18mm.

1P+N Single-pole + Neutral Circuit Breaker: Controls both live and neutral wires, but only the live wire has the thermal release function; module size remains 18mm.

2P Single-phase Two-pole Circuit Breaker: Controls both live and neutral wires, both possessing the thermal release function; module size is 2 * 18mm = 36mm.


To reduce costs, a 1P breaker can be used, but advanced breakers must possess an earth leakage tripping function. To prevent accidents caused by the confusion of live and neutral wires during maintenance, it is necessary to cut off the upstream power supply.

To circumvent this issue during maintenance, a 1PN breaker can be used.

Within the same 18mm module breaker housing, there are differences between the installation of 1P and 1PN. In the event of a short-circuit, the former must have a higher “ultimate breaking capacity” than the latter, as space is a crucial factor influencing breaking capacity.

Therefore, for more critical, frequently maintained, and operated power circuits prone to faults, it is preferable to use a 2P breaker (which is more expensive).

When employing a 1P breaker, the lighting distribution box must have an earth leakage tripping function, and at least the incoming line (or the upper layer of the outgoing line) should use a residual current circuit breaker.

For ordinary socket circuits, a 1P+N breaker is sufficient; however, if you require earth leakage protection, this will not suffice, as a 1P+N breaker cannot be assembled with earth leakage protection accessories and other electrical accessories.