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| According to experts the impact of current to 0.5 mA does not feel human. Notable current 0.5-1.5 mA does not hit people. However, its effect may be an indirect cause of the accident (for example, when working at heights). Therefore, although the exact value of the current sound is not set, it must be taken several times lower threshold current tangible (not exceeding 50 mA).
At a current of 10-15 mA in person cannot take his hands off the electrodes, cannot itself break the chain hitting it current. This current is called not - to release current. Current lower value is called letting go of shock.
The current in 50 mA affects the respiratory and cardiovascular system. At 100 mA fibrillation of the heart occurs, consisting in a chaotic, random contraction and relaxation of muscle fibers of the heart. Such a state of cardiac fibers disrupts the normal functioning of the heart, the heart stops, blood flow stops.
Current of 100 mA is a fatal. However, it should be borne in mind that the outcome (risk) of electric shock depends not only on the value of current flowing through the human body, but also the time of its impact. Prolonged exposure (several seconds), leads to a severe outcome. This is explained by the fact that with increasing exposure time the current decreases resistance of the human body (Fig. 1) arising from additional responses of the body (skin vasodilatation, sweating).
The current value is in turn dependent on the applied voltage and the resistance of all circuit elements on which the current passes, including the resistance of the body.
The resistance of the human body - vacillates. It is reduced by the impact - current and with increasing applied voltage to the body. Therefore, with increasing exposure time value of passing current through the human body to grow. The outcome of the shock depends also on the physical and mental condition of the person. The electrical resistance of the human body in a state of intoxication or nervous excitement as well as defects of the skin is less important than the resistance of the body healthy. Hence, other things being equal the current through the body will be more and more severe electric shock.
The resistance of the human body also depends on the environment in which the person is: humidity and ambient temperature, dust, fumes, etc.
The consequences of electric shock depend also on the staff. And, indeed, a person with sufficient knowledge and skills in electrical maintenance, finding himself in a dangerous situation, is able to quickly analyze the situation and take some effective measures for the liberation of the outflow itself, or his friend. |
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