At what voltage above DC can it be fatal to be electrocuted?

It seems that the safe voltage is 36 volts! Any voltage above 36 volts poses a certain risk!

The human body generally does not feel power-frequency currents below 0.5 milliamps. Experimental data show that the minimum current required to produce a sensation varies among different individuals; it is approximately 1.01 milliamps for adult men and around 0.7 milliamps for adult women. This value is known as the perceptible current. At this time, the body feels a slight stinging sensation due to nerve stimulation. At the same time, the maximum current at which different people can free themselves from the power source after being electrocuted also varies; the average value is 16 milliamps for adult men and 10.5 milliamps for adult women. This value is known as the let-go current. Under normal circumstances, power-frequency currents of 8–10 milliamps or less, and direct-current currents of 50 milliamps or less can be considered safe currents that the human body can tolerate; however, it is still dangerous for these currents to flow through the body for extended periods of time. In situations equipped with protection against electric shock, the allowable frequency current for the human body is approximately 30 milliamps. In environments where serious secondary accidents could occur, the allowable frequency current for the human body should be 5 milliamps, to prevent severe muscle spasms. According to Ohm’s law (I = U/R), it can be seen that the magnitude of the current flowing through the human body is related to the applied voltage and the resistance of the human body. In addition to the human body’s own resistance, the resistance of clothing, shoes, pants, and other items worn by the person must also be taken into account. While the human body’s resistance is generally around 5000Ω, there are many factors that can affect it. Things such as moist or sweaty skin, the presence of conductive dust, an increased contact area and pressure with charged objects, as well as moisture and dirt on clothing, shoes, and socks, can all reduce the body’s resistance. Therefore, it is usually not possible to calculate in advance the magnitude of the current flowing through the human body. Therefore, to determine safety conditions, safety current is not typically used; instead, safety voltage is employed for estimation. Under normal circumstances, that is, in dry environments where the risk of electric shock is high, the safety voltage is set at 36V. In humid environments with a higher risk of electric shock (such as when welding or performing maintenance inside metal containers or pipes), the safety voltage is set at 12V. In this way, the current flowing through the human body in the event of an electric shock can be kept within limited levels, thereby ensuring personal safety to a certain extent.

To prevent accidents caused by electric shock to people, the specified voltage ranges are known as safe voltages; there are mainly five types: 42 volts, 36 volts, 24 volts, 12 volts, and 6 volts. The most commonly used ones are 36 volts and 12 volts.

The IEC standard sets the expected contact voltage limit for branches that can cause ventricular fibrillation at 120 V, as ventricular fibrillation can lead to death.

The safe voltage is 36 volts, a figure that results from various studies. Everyone’s sensitivity to electric current varies, but these factors were all taken into account before the standard was established.