A voltage greater than or equal to 1000 volts to ground is high voltage.
Low voltage is less than 1000 volts to ground. One of the safety voltage refers to the human body for a longer period of time without the risk of electric shock voltage. According to the national standard "GB3805-83" safety voltage provides for the prevention of electrocution accidents and the use of a specific power supply voltage series. China's industrial frequency safety voltage provides the following five levels, namely 42V, 36V, 24V, 12V and 6V.
Extended information
The ground voltage is one of the bases for determining the level of insulation of energized equipment or wires. If the insulating material cannot withstand the voltage to ground, it will cause a discharge, resulting in equipment failure and abnormal operation of the grid.
The zero line is generally connected to the earth, the fire line and the transformer is connected, the potential difference between them by the transformer ratio. General human contact with zero is not electrocuted, but not equal to the non-electrocution, when the zero line broken wire and other reasons, will cause the zero line charged. Ground is generally used in the three-phase five-wire system, is to do to prevent electric shock protection.
The fuse is made of lead and zinc all gold, the melting point is about three or four hundred degrees, when the current passes through, it will produce heat, and the conductor's overcurrent withstand capacity is directly proportional to its cross-sectional area, so the larger the diameter of the fuse, the larger the cross-sectional area, the greater the ability to withstand the overload current naturally the greater.
Baidu Encyclopedia - Voltage to Ground
Baidu Encyclopedia - Voltage