High voltage electricity refers to the electrical household lines with the AC voltage of distribution lines above 1000V or the DC voltage above 1500V. According to the definition 2.1 in GB/T 2900.50-2008, high voltage usually refers to the voltage level higher than 1000V (excluding); It refers to the voltage level of transmission in the power system under specific circumstances. Low voltage electricity refers to the electrical household line with the AC voltage of the distribution line below 1000V or the DC voltage below 1500V.

The safe voltage shall not exceed 36V AC and 50V DC. The AC voltage level of 1000KV and above in the power system is ultra-high voltage power supply, which is usually only used as a long-distance power transmission line for large power, because it can reduce the energy loss in the transmission process. In order to reduce the loss of electric energy in the transmission process, the current must be reduced, and the total power must be kept unchanged. The voltage must be appropriately increased, and it will finally reach the user's home after passing through the step-down substation.