Is 36V a safe voltage? It’s okay to touch it? Wrong! 12V can also kill a person

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“Life is more important than anything else; safety is of utmost importance. ”We often hear people say, “36V is a safe voltage” and “It’s completely safe for humans to come into contact with 36V; nothing will happen.” Is that really the case? In fact, this statement is not precise. 36V is a safe voltage; that statement is correct! But in some cases, voltages of 36V or even 12V can be deadly! Safe voltage level: Safe voltage refers to a voltage that does not cause immediate death or disability in humans. The \"safe ultra-low voltage\" that can be subjected to continuous contact under normal environmental conditions is 36V. According to the **standard document ‘Safe Voltage’ (GB3805—83), safe voltages in China are divided into 5 levels: 42V, 36V, 24V, 12V, and 6V. Depending on the respective production environments and work sites, the appropriate level of safe voltage is used. Specifically, as shown above, the safe voltage varies depending on the environment. Under normal conditions, 36V is safe, but in particularly humid environments or those with conductive metal dust, it can be fatal. The basis for the level of safe voltage: Why is the safe voltage different in various environments? This requires analysis from two aspects: the electric current causing the shock and the human body’s resistance. Electric shock refers to the tissue damage and functional disorders caused by electric current flowing through the body when it comes into direct contact with a live electrical conductor, and it can even lead to cardiac and respiratory arrest. The greater the current passing through the human body, the greater the danger ； The longer the current flows through the body, the greater the likelihood of death. Relevant studies show that when the current passing through the human body reaches 0.7 mA, it can cause sensations in a person ； When the current passing through the human body reaches 10mA, it may become impossible to free oneself voluntarily ； When the current passing through the human body reaches 50mA, a fatal danger can occur within a short period of time (1 second). So, what factors are related to the magnitude of the electric current passing through the human body? According to Ohm’s law (I=U/R), the magnitude of the current flowing through the human body is related to the applied voltage and the resistance of the body. When the current remains constant, the greater the resistance of the human body, the higher the safe voltage it can withstand. Human body resistance is divided into internal resistance and external resistance. Since the human body is primarily composed of water, the resistance within it is essentially equal, at around 500Ω. Intrinsic resistance is related to the skin, such as: the contact area between the skin and the charged object, the degree of dryness, sweating, the presence of conductive dust or oils on the skin, as well as wounds, and so on. In a dry environment, the human body resistance is relatively high, generally around 1000-2000Ω. However, when the human body sweats or the skin becomes moist, the resistance drops significantly ； If there are wounds on the skin, the external resistance can even drop to zero. In addition to the person’s own resistance, the resistance of external items such as clothes, shoes, and pants also needs to be taken into account when considering human body resistance; factors like moisture and dirt on clothes, shoes, and socks play a role in this. In summary, the resistance of the human body varies under different conditions, and it is impossible to calculate or measure the magnitude of the current flowing through the body. To ensure personal safety in different environments, safety voltages corresponding to each environment have been specified. In summary, electric shock occurs when electricity affects the human body, and voltage is merely one factor that influences the magnitude of the current. Since there are too many factors that affect the electric shock current, the lowest voltage is used to ensure personal safety in various environments. Safety is no trivial matter; we should approach it with a more rigorous attitude. To claim that a 36V voltage is safe regardless of environmental factors is simply nonsense. When discussing safe voltage, we must mention environmental factors.