(in civil residential buildings, the outgoing line from the meter box to the indoor distribution box is a single-phase outgoing line. Why does the incoming line of the distribution box use 2p instead of 1p? The switch has no leakage?)

Answer: 1 2p, convenient and safe maintenance!

2. Code for electrical design of civil buildings 25.3/11 when single-phase power supply is adopted for each house, the miniature circuit breaker entering the house shall adopt two poles; When three-phase power supply is adopted, the miniature circuit breaker entering the house shall adopt three poles. Self resetting overvoltage and undervoltage protectors shall be set.