电（1）电缆的额定电压要大于或等于安装点供电系统的额定电压； (1) the rated voltage of the cable should be greater than or equal to the rated voltage of the power supply system at the installation point. （2）电缆持续容许电流应等于或大于供电负载的最大持续电流； (2) the continuous permissible current of the cable should be equal to or greater than the maximum continuous current of the power supply load; （3）线芯截面要满足供电系统短路时的稳定性的要求； (3) the cross section of the wire core should meet the requirements of the stability of the power supply system short circuit. （4）根据电缆长度验算电压降是否符合要求； (4) checking the voltage drop according to the cable length is in line with the requirements. （5）线路末端的最小短路电流应能使保护装置可靠的动作。 (5) the minimum short-circuit current at the end of the line should be able to make a reliable action of the protective device.