电缆芯数的选择 Selection of cable core number （1）电压1KV及以下的三相四线低压系统，若第四芯为PEN线时，应采用四芯 型电 缆而不得用三芯电缆加单芯电缆组合成的回路的方式。当PE线作为专用而与带 电导体N线分开时，则应用五芯型电缆。若无五芯型电缆时可用四芯电缆加单芯电缆电缆捆扎组合的方式；PE线也可利用电缆的护套，屏蔽层，铠装等金属外 护层等。分支单相回路带PE线时应采用三芯电缆。如果是三相三线制系统则采 用四芯电缆，第四芯为PE线。 补：(此段解说引入TN-S,TN-C-S解说) (1) the voltage 1KV and the following three phase four line low voltage system, if the fourth core is PEN line, should adopt the four core cable instead of the way of combination of three core cable and single core cable. When the PE line is dedicated and separated from the conductor N line, the five core cable is applied. If there is no five core cable, the four core cable can be combined with single core cable cable, and the PE line can also use the sheath of the cable, the shielding layer, the armour and so on. The three phase cable should be used when the branch single-phase loop is equipped with PE line. If it is three-phase three wire system, the four core cable and the fourth core are PE lines. Supplement: (this paragraph introduces TN-S, TN-C-S Commentary) (2) 3-35KV交流系统应采用三芯电缆. (2) three core cables should be used in the 3-35KV communication system. (3) 在水下或重要的较长线路中为避免或减少中间接头或单芯电缆比多芯电缆有较好的综合技术经济性时,可选用单芯电缆。但应注意用于交流系统的单芯电缆不 得采用钢带铠装，应采用经隔磁处理的钢丝铠装电缆。 (3) single core cable can be selected in order to avoid or reduce the intermediate or single core cable in an underwater or important long line to avoid or reduce the comprehensive technical and economical performance of the multi core cable. However, it should be noted that the single core cable used for the AC system should not be steel tape armour, and the steel wire armored cable should be treated by magnetic separation.