**Legal safety voltage standards

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**Legal safety voltage standards: Safety voltage refers to a range of voltages from specific power sources that are used to prevent electric shock accidents. Its power supply requires isolation between the output and input circuits, as well as isolation from other electrical systems. The upper limit of this voltage range shall not exceed 50 volts RMS for alternating current (50–500 Hz) between any two conductors or between either conductor and ground, under normal as well as fault conditions. Depending on the characteristics of the location, one can use the safe AC voltage levels specified by China’s safety voltage standards: 1, 42 volts (with an upper limit of less than or equal to 50 volts when unloaded), which can be utilized in areas where there is a risk of electric shock, such as for handheld power tools ； 2. 36 volts (with an no-load maximum of 43 volts); suitable for use in applications such as headlamps in mines or environments with conductive dust ； 3. Three voltage levels – 24 volts, 12 volts, and 6 volts (with no-load limits of less than or equal to 29 volts, 15 volts, and 8 volts respectively) – are available for devices whose live parts may be accidentally touched by humans. When working inside large boilers, metal containers, or generators, it is essential to use low-voltage lamps of 12 volts or 6 volts to ensure personal safety. When electrical equipment uses a safe voltage of 24 volts or higher, measures must be taken to prevent direct contact with live parts. Its circuit must be insulated from the ground. The safe voltage is determined based on the product of the allowable current for the human body and the resistance of the human body.