Human body’s safe voltage and current
The voltage and current level of pure electric vehicles are relatively high. The power voltage is generally 300-400 V (DC), and the current can reach several hundred amps in an instant. The safe voltage value that the human body can withstand depends on the current allowed by the human body and the resistance of the human body. Relevant studies have shown that the resistance of the human body is generally 1000-3000 Ω. The human skin resistance is related to the state of the skin and can be as high as tens of thousands of ohms when dry, clean and undamaged, while the resistance of wet skin, especially when subjected to manipulation, may drop below 1 000 Ω. Since the safety voltage in my country is mostly 36 V, it is roughly equivalent to the situation that the human body allows the current to be 30 mA and the human body resistance is 1 200 Ω. Therefore, it is required that the voltage of any two live parts of an electric vehicle that can be touched by the human body should be less than 36 V. According to the requirements of international electrical standards, the current safety threshold for the human body without any feeling is 2 mA, which requires that when the human body directly contacts any part of the electrical system, the current flowing through the human body should be less than 2 mA before the vehicle is considered qualified for insulation.