The voltage of 220 V "enters" into any modern apartment, and then diverges through outlets. Consequently, people in apartments always have a risk of electric shock. However, the current in the outlet is always variable, and its direction of electron flow changes 100 times per second, that is, the plus and minus poles change places. In most cases, a person is shocked by a variable type. Direct current is necessary for the operation of any household appliances in the house, and it becomes constant after transformation in the power supply. Let's see if the current is dangerous - AC or DC.
Research result
Thanks to an in-depth study of electrical injuries, scientists were able to find out whether the current is dangerous - alternating or constant. In the course of laboratory experiments on dogs, scientists of the Academy of Sciences of Kyrgyzstan were able to obtain new data on the hazard ratio of direct and alternating current at voltages of 12, 36, 120 V.
It turned out that in the standard situation, when the electrodes are on the human limbs, the danger of damage at a voltage of 120 V DC is equal to the risk of damage at a voltage of 42 V AC. Also, direct current in a network with a voltage of 108 V can affect a person, as well as a current in a network with a voltage of 36 V.
All this allows us to understand whether the current is dangerous - AC or DC. Both types can be harmful to humans, only in the case of direct current the voltage in the network should be higher. Therefore, the chance of getting a burn or other DC damage is much lower.
Electrode Arrangement
However, as far back as 1903, it was established that the danger is more dependent on the poles of a direct current source. In those cases when an electrode with a negative pole is connected to the upper part of the human body, and an electrode with a positive pole is connected to the lower, the danger of damage is much higher than with a reverse arrangement. The scientist Azhibaev developed this statement, and his studies on dogs confirmed that fibrillation occurs earlier precisely when the electrode with the negative pole is at the top. However, the reaction in different animals can manifest itself in different ways.
In 1970-1972 Gudersky's studies were conducted, which consisted of comparing the evaluation of the effect of direct current of industrial frequency. During the study, scientists gradually increased the voltage from zero, as a result, the severity of damage to animals at constant current was much lower (several times) compared to the severity of damage to AC (the frequency was 50-60 Hz). This once again makes it clear which current is more dangerous - alternating and constant.
Short voltage supply
If voltage of both types of currents is applied for a short time, the differences in the effect will be very significant. This allows scientists to argue that the opinion about the lower dangers of direct current is erroneous, at least for the moment of formation of an electric circuit passing through the human body, that is, for the moment of “turning on”.
Convulsive reactions
Scientists Gudersky and Teresyak made attempts to explain the difference in the effects on humans of alternating and direct current. They came to the conclusion that the latter does not cause convulsive reactions, which necessarily occur when a person is affected by alternating current. There are also no limit values for constant non-releasing current and there are no biophysical justifications for the formation of protective measures to protect a person from damage by direct current. However, even the so-called non-releasing current can cause paresis of the muscles of the hands.
It would seem that it is now extremely clear which current is more dangerous. Variable and constant have different harmful effects on humans. And although direct current can cause a seizure, the mains voltage should be so high that it is simply impossible to provide a set of protective measures. If the DC power is very high, then there is another danger - the victim's rejection from the leading parts that are under voltage. Such a feature with alternating current is extremely rare. As a result, the discarded person may even receive physical injury, which, depending on the conditions of the person’s fall, may prove fatal. This completely confuses people and does not make it possible to determine exactly which current is dangerous - alternating or constant.
It is also worth noting that when touching live parts (for example, on the rectifier), where there is a ripple current, it can even lead to convulsive reactions, since there is a variable component.
AC is more dangerous
Unfortunately, scientists still can’t answer exactly which current is dangerous - AC or DC, and why. This problem has not been solved enough today, but attempts are being made to study it, because the elimination of this gap will allow a deeper study of the biophysics of electrical trauma, and it will be more effective to treat it further, not to mention the possibility of creating protective measures to prevent a person from being struck by direct current.
However, we can safely say that with a smooth increase in voltage, the danger of direct current for a person is much less. A shock from it can be obtained with a voltage of at least 120 V, while alternating current can harm a person only with a voltage of 42 V. The scientists also came to the conclusion that the probability of the formation of a dangerous electric circuit in the body a person is higher with an AC shock.
Finally
Now we understand why and what kind of current is dangerous - alternating or constant. However, direct current causes less harm only in domestic conditions (at home), and a person being struck by direct current at very high voltage can simply throw him away, which causes mechanical injury.