The effect of electric current on the human body. Occupational Safety and Health

OCCUPATIONAL SAFETY AND HEALTH
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The effect of electric current on the human body. Occupational Safety and Health

Occupational Safety and Health

Occupational Safety and Health / electrical safety

Electric current, acting on the human body, can lead to various injuries: electric shock, burns, skin metallization, electric sign, mechanical damage, electrophthalmia (Table 1).

Table 1. Characteristics of the impact on a person of electric current of various strengths

Current, mA	AC 50 - 60 Hz	D.C
0,6 - 1,5	Slight trembling of the fingers	Not felt
2 - 3	Strong trembling of the fingers	Not felt
5 - 7	Cramps in the hands	3d. Feeling warm
8 - 10	Hands with difficulty, but still can be torn off the electrodes. Severe pain in the arms, especially in the hands and fingers	Heating boost
20 - 25	Hands are paralyzed immediately, it is impossible to tear them off the electrodes. Very severe pain. Difficulty breathing	Even greater increase in heating, slight contraction of the muscles of the hands
50 - 80	Respiratory paralysis. Beginning of ventricular flutter	Strong feeling of warmth. Contraction of the muscles of the hands. Seizures. Difficulty breathing
90 - 100	Paralysis of breathing and heart when exposed to more than 0,1 s.	Respiratory paralysis

electric shock leads to the excitation of living tissues; Depending on the pathological processes caused by electric shock, the following classification of the severity of electrical injuries during electric shock is accepted:

electrical injury of the XNUMXst degree - convulsive muscle contraction without loss of consciousness;
electrical injury II degree - convulsive muscle contraction with loss of consciousness, "
electrical injury of the III degree - loss of consciousness and impaired functions of cardiac activity or respiration (both are not excluded);
electrical injury IV degree - clinical death.

The severity of electrical damage depends on many factors: the resistance of the body, the magnitude, duration of action, the type and frequency of the current, its path in the body, environmental conditions.

The outcome of electrocution also depends on the physical condition of the person. If he is sick, tired or in a state of intoxication, mental depression, then the action of the current is especially dangerous. Alternating current up to 10 mA and direct current up to 50 mA are considered safe for humans.

Electric burn various degrees - a consequence of short circuits - in electrical installations and the stay of the body (usually hands) in the sphere of light (ultraviolet) and thermal (infrared) influence of an electric arc; III and IV degree burns with a severe outcome - when a person comes into contact (directly or through an electric arc) with current-carrying parts with a voltage of over 1000 V.

electrical sign (current mark) - specific lesions caused by mechanical, chemical or their combined effects of current. The affected area of the skin is practically painless, there are no inflammatory processes around it. Over time, it hardens and superficial tissues die off. Electrosigns usually heal quickly.

Leather plating - the so-called impregnation of the skin with the smallest vaporous or molten metal particles under the influence of mechanical or chemical action of the current. The affected area of the skin acquires a hard surface and a peculiar color. In most cases, plating heals without leaving marks on the skin. Electrophthalmia is damage to the eyes by ultraviolet rays, the source of which is a voltaic arc. As a result of electrophthalmia, an inflammatory process occurs after a few hours, which disappears if the necessary treatment measures are taken.

In production conditions, electric shock is most often the result of people touching live parts that are under dangerous voltage.

Rice. 1. Two-phase inclusion in the current circuit

There are two options for such touches with varying degrees of danger. The first, most dangerous, is simultaneous contact with two linear wires and the second, less dangerous (there are more such cases) - touching one phase (Fig. 1, 2).

Rice. 2. Single-phase inclusion in the current circuit: a) with a grounded neutral; b) with isolated neutral

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