Conditions and causes of electric shock. Causes of electric shock and basic protection measures. Electrical Safety Common Causes of Electric Shock

Statistics show that electric shocks are commonly encountered in everyday life and at work. How to protect yourself and what to do in case of exposure to current?

What is an electrical injury?

Cases of electric shock are rare, but at the same time they are among the most dangerous injuries. With such a lesion, a fatal outcome is possible - statistics show that it occurs on average in 10% of injuries. This phenomenon is associated with the effect of electric current on the body. Therefore, representatives of professions related to electricians can be attributed to the risk group, but they are not excluded among people who accidentally encountered the action of current in everyday life or on sections of power lines. As a rule, the cause of such a defeat is technical problems or non-compliance with safety regulations.

Types of electric shock

The nature of the impact on the body and its degree can be different. The classification of the lesion is based precisely on these features.

Electrical burn

Electric shock is one of the most common injuries. There are several variants of such an injury. First of all, it should be noted the contact form, when an electric current passes through the body upon contact with a source. An arc lesion is also distinguished, in which the current itself does not pass directly through the body. The pathological effect is associated with an electric arc. If there is a combination of the forms described above, such a lesion is called mixed.

Electrophthalmia

An electric arc leads not only to a burn, but also to irradiation of the eyes (it is a source of UV rays). As a result of such exposure, inflammation of the conjunctiva occurs, the treatment of which can take a long time. In order to avoid such a phenomenon, special protection against electric shock and compliance with the rules for working with its sources are necessary.

Metallization

Among the types of skin lesions, metallization of the skin stands out with its clinical features, which occurs due to the penetration of metal particles melted under the action of an electric current. They are the smallest in size, penetrate into the surface layers of the epithelium of open areas. Pathology is not fatal. Clinical manifestations soon disappear, the skin acquires a physiological color, and pain stops.

electrical signs

Thermal and chemical action leads to the formation of specific signs. They have sharp contours and color from gray to yellowish. The shape of the signs can be oval or round, as well as resemble lines and dots. The skin in this area is characterized by the occurrence of necrosis. It becomes hardened due to the necrosis of the surface layers. Due to cell death in the post-traumatic period, there are no complaints among complaints. The lesions disappear after some time due to regeneration processes, while the skin acquires a natural color and elasticity. This type of injury is very common and usually non-fatal.

Mechanical damage

They occur with prolonged exposure to current. Mechanical injuries are characterized by ruptures of muscles and ligaments, which occurs due to muscle tension. In addition, the neurovascular bundle is additionally damaged, and such severe injuries as fractures and complete dislocations are also possible. More serious and highly qualified assistance is required in case of electric shock with such a clinic. In case of untimely assistance or too long exposure, a fatal outcome is possible.

As a rule, these types do not occur separately, but are combined. This factor makes it difficult to provide first aid and further treatment.

What determines the degree of electric shock?

This indicator depends not only on the strength, duration of action and the nature of the current, but also on the resistance of the body. The skin and bones have a high resistance index, while the liver and spleen, on the contrary, have a low resistance index. Fatigue contributes to a decrease in resistance, and therefore, in such cases, a fatal outcome is most likely. Wet skin also contributes to this. Clothes and shoes made of leather, silk, wool and rubber will help protect the body from harmful effects, as they will act as an insulator. It is these factors that affect the risk of electric shock.

Effects

Electrical current causes multiple damage. First of all, it acts on the nervous system, due to which motor activity and sensitivity worsen. In addition, there are, for example, severe convulsions and loss of consciousness can cause death due to respiratory arrest. After saving the victim, deep lesions of the central nervous system are sometimes noted. The main ones lead to this.

Impact on the heart can also lead to death, as the current leads to impaired contractility and causes fibrillation. Cardiomyocytes begin to work inconsistently, as a result of which the pumping function is lost, and the tissues do not receive the necessary amount of oxygen from the blood. This leads to the development of hypoxia. Another formidable complication is rupture of blood vessels, which can lead to death from blood loss.

Muscle contraction often reaches such a force that a fracture of the spine is possible, and, consequently, damage to the spinal cord. On the part of the sense organs, there is a violation of tactile sensitivity, tinnitus, hearing loss, damage to the eardrum and elements of the middle ear.

Complications do not always appear immediately. Even with a short exposure, electrical injury can make itself felt in the future. Long-term effects - arrhythmias, endarteritis, atherosclerosis. From the side of the nervous system, neuritis, vegetative pathologies and encephalopathy can occur. In addition, contractures are possible. That is why means of protection against electric shock are important.

The reasons

The main etiological factor is the action of the current. Additional conditions are the state of the body and the presence or absence of any protection. Electrical shock is usually caused by improper use or lack of protection when working with wiring. The risk group includes professions related to working with current. However, electrical injury can happen to anyone. Cases of defeat in everyday life are not uncommon, but they mostly end favorably. In addition, episodes of contact with such lesions are frequent. Attention and knowledge of safety precautions will protect against such phenomena.

Clinical manifestations of electrical injury

Symptoms depend on the type of lesion, while their complex is based on a combination of manifestations of the described types of injuries. Also, the clinic depends on the severity. It should be noted that the most dangerous functional deviations of the respiratory, nervous and cardiovascular systems. The victim is in severe pain. A characteristic suffering expression appears on the face, and the skin becomes pale. Under the action of current, muscle contraction occurs, the duration of which depends on the preservation of their integrity. All this can cause loss of consciousness, and in a more severe case - death. Protecting against electric shock will help prevent this condition.

The effect of current on the body

The changes that occur in the body under the influence of current are associated with the versatility of its effects. It has a thermal effect by converting electrical energy into thermal energy due to tissue resistance. This is due to the formation of burns and marks. Thermal action adversely affects the body, as it inevitably leads to the destruction of tissues.

Electrochemical action mainly affects the circulatory system. This leads to a change in the charge of many molecules, and also sticks together blood cells, thickening the blood and promoting the formation of blood clots.

The biological effect is associated with a violation of organs and systems - the effect on muscle tissue, the respiratory system, and nerve cells.

The multiple effect of the current on the body aggravates the condition of the victim, increasing the risk of death. The combined factors of electric shock can lead to a different outcome. Even the action of 220 volts on the body will cause irreversible damage.

First aid

All types of electric shock require otherwise a fatal outcome is possible. First of all, it is necessary to stop the effect of current on the victim, that is, turn it off from the circuit. To do this, the rescuer should definitely protect himself with insulating materials and only after that pull the victim away from the source. After you need to call an ambulance team and start providing first aid. These activities are carried out before the arrival of specialists. A person exposed to current does not tolerate cold, so it must be transferred to a warm, dry surface. First aid is aimed at restoring vital functions - breathing and blood circulation. This requires cardiopulmonary resuscitation. Every person should be trained in it or have at least the slightest idea. Resuscitation is carried out on a hard surface. The rescuer combines artificial respiration and cardiac massage. It is required to observe the ratio - 2 breaths and 30 clicks. Salvation begins with a massage, since the restoration of blood circulation is a priority. It is performed with straight arms, placing the palms on top of each other (pressure is applied to the area of ​​the wrist on the lower part of the sternum). The recommended frequency is 100 compressions per minute (the chest should move 5 cm). After the oral cavity is cleaned of secretions and artificial respiration is carried out. To protect the rescuer, it is recommended to manipulate through a handkerchief. Resuscitation can be carried out by two rescuers, while maintaining the ratio of 2 breaths and 15 clicks. When one person takes a breath, the second is contraindicated to touch the chest. When inhaling, the chest of the victim must necessarily rise - this indicates the correctness of the procedure.

Treatment

Electric shock requires prompt resuscitation and subsequent treatment. The therapy is carried out in a hospital. Even if the victim feels satisfactory, and the damage is minor, preventive monitoring is required to help avoid complications.

Treatment is aimed at the speedy healing of skin lesions, as well as the elimination of other disorders associated with the harmful effects of current. Observation in the hospital is carried out until complete recovery.

Prevention

To prevent all types of electric shock will help compliance with safety regulations. Do not use electrical appliances that are defective. It is also contraindicated to touch them with wet hands, as this will improve the conduction of current. Working with electrical appliances and wiring requires the use of protective equipment against electric shock. These include gloves, special pads. Tools must have an insulated handle. Also, for prevention, the public should be informed about the possibility of such an injury. A special role is played by informing in the media, as well as conducting conversations with schoolchildren. This will reduce the risk of electric shock.

Electrical injuries are very dangerous, and their outcome depends on many factors. It is influenced not only by current indicators (voltage, duration), but also by the body's defenses. For example, a current of 220 volts, depending on the conditions of exposure, can lead to both non-fatal injuries and death. It is very important to observe safety precautions - this will help to avoid such defeats.

The main causes of electric shock to a person are:

Electric shock when using faulty household electrical appliances;

Connection to non-insulated parts of the electrical installation (contacts, wires, clamps, etc.);

Mistakenly applied voltage to the workplace;

The appearance of voltage on the body of the equipment, which under normal conditions is not energized;

Electric shock of a faulty power line (approaching a faulty power line at an unacceptable distance);

Classification of electric shocks. Consequences of electric shock.

Electric shocks according to the severity can be conditionally divided into several groups:

Electric shock without loss of consciousness, without violation of breathing and cardiac activity;

Electric shock, characterized by loss of consciousness, while breathing and heart activity are not disturbed;

An electric shock, in which a person loses consciousness, in addition, breathing and heart activity are disturbed;

Electric shock;

State of clinical death.

If a person has impaired cardiac activity and breathing, then it is necessary to immediately carry out resuscitation measures: artificial respiration (one of the methods: mouth to nose or mouth to mouth) and direct heart massage.

Electrical shock may result from electric shock. Electric shock is a severe, reflex reaction of the human body to electric shock. In this case, the person affected by the electric shock must be immediately taken to the nearest medical facility. The victim must be under the constant supervision of medical personnel, since the state of shock can last from one hour to a day. After this time, recovery of the victim or biological death may occur.

Methods and means of protection against electric shock

To protect against electric shock when touching parts of electrical equipment that are not normally energized, but which may become energized if the insulation is damaged or for other reasons, apply:

Insulating materials (rubber gloves, galoshes, rugs...),

grounding,

zeroing,

Safety shutdown...

Insulating agents are commonly used during the repair and maintenance of electrical installations and are not covered in this manual.

grounding

Grounding any part of an electrical installation or other installation is the intentional electrical connection of this part with a grounding device (ground electrode).

This connection is made with a conductor, which is called grounding.

The illustration below shows grounding: the computer case is connected to a grounding conductor (rail):

The grounding conductor is connected to a grounding conductor having a direct connection to the ground. If a phase is accidentally connected to an electrical equipment case, a short circuit will occur and the fuses will trip. Consequently, the electrical circuit will be de-energized and the danger of electric shock will disappear.

The illustration below shows what can happen when a phase is shorted to the case if there is neither grounding nor zeroing.

Zeroing

Protective zeroing of any part of an electrical installation or other installation is the intentional electrical connection of this part with a conductor, which is called a neutral, or zero protective conductor.

If a phase is accidentally connected to an electrical equipment case, a short circuit will occur and the fuses will trip. Therefore, in this case, the electrical circuit will be de-energized and the danger of electric shock will disappear.

Single-phase networks, made according to modern standards, are equipped with three-pin sockets, to which three conductors are connected:

Null,

Zeroing.

This neutral conductor is connected to the solidly grounded zero point (neutral) of the transformer in AC networks and to the solidly grounded midpoint of the power supply source in three-wire DC networks.

In the above illustration, the computer case is connected to the grounding contact of the socket:

Safety shutdown

A protective shutdown is a protection system that provides automatic shutdown by a high-speed device of all phases of the emergency section with a total shutdown time from the moment a single-phase short circuit occurs, no more than 0.2 s.

In other words, a safety shutdown is like a fast-acting fuse that blows when there is a danger of electric shock.

58) Classification of premises for electrical safety

The current rules for the installation of electrical installations (PUE) all premises are divided into the following three classes:

I. Premises without increased danger: dry, with normal air temperature, with non-conductive floors.

II. Premises with increased danger: damp with relative air humidity (long-term) more than 75%; hot with air temperature exceeding +30°C for a long time; with floors made of conductive materials; with a large amount of emitted conductive technological dust deposited on the wires and penetrating inside electrical installations; with the placement of electrical installations with metal cases connected to the ground, metal structures of buildings and technological equipment, allowing simultaneous contact with them.

III. Particularly dangerous premises: especially damp with relative air humidity close to 100%, chemically active environment, simultaneous presence of two or more conditions typical for premises with increased danger.

One of the measures to ensure electrical safety in rooms of II and III classes is the use of low voltage current.

As examples of the division of premises according to the degree of danger, the following can be cited: class I includes office premises and laboratories with precision instruments, assembly shops of instrument factories, watch factories, etc.; to class II - storage unheated premises, stairwells with conductive floors, etc.; to class III - all workshops of machine-building plants: galvanic, storage batteries, etc. They also include areas of work on the ground in the open and under a canopy.

59) Providing first aid to the victim from the action of electric current

If you have witnessed that a person has become energized, first of all, you need to free the victim from the action of electric current as soon as possible, especially if the person is holding a bare wire with his hand and is not able to independently break contact with the electrical installation.

The severity of electric shock directly depends on the duration of the current on the body. To do this, it is necessary to turn off the electrical installation with devices specially designed for this (switches, knife switches, removing fuses).

If there is no possibility of a quick shutdown, it is necessary, using improvised means, to create conditions for a quick shutdown of the electrical installation section with the victim. These can be attacks on overhead lines, interrupting a cable or electrical wiring with an ax, removing fuses with a dry rag, etc.

1. When providing first aid in electrical installations up to 1000V, it is allowed to use improvised means that do not conduct electricity (dry board, stick, rope) to separate the victim from current-carrying parts. It is possible to pull the victim by the clothes.

2. In electrical installations above 1000V to provide first aid to the victim, it is necessary to use protective equipment, use dielectric gloves and boots, using insulating rods.

In this case, you must follow the rules of your own safety, the person who provides assistance must ensure that he himself does not come into contact with live parts.

2) assessment of the victim's condition.

After the victim is released from the impact of the traumatic factor, it is necessary to assess his physical condition. When assessing the condition, it is necessary to pay attention to the following main signs:

Consciousness: normal, impaired (inhibited or excited), absent;

Respiration: normal, disturbed (wheezing), absent;

Pulse (determined on the carotid arteries): normal (determined well), disturbed, absent.

3) determination of the nature of the injury that poses the greatest threat to the life of the victim.

That is, if a person is unconscious and other characteristic injuries are also visually visible (a broken arm, bleeding, etc.), then first of all it is necessary to proceed with measures that allow the victim to return to consciousness.

4) carrying out the necessary measures to save the victim.

The absence or presence of consciousness is determined visually.

If the victim is unconscious, it is necessary to control his breathing, if breathing is disturbed due to the retraction of the tongue, it is necessary to push the lower jaw forward. Bring the victim back to consciousness by giving him a sniff of ammonia or splashing his face with cold water.

If the victim is in an unconscious state, his pulse is not determined and there is no breathing, you need to start restoring the vital functions of the body by performing artificial respiration and external heart massage.

Artificial respiration is performed if the victim is not breathing on his own, or when breathing is infrequent and convulsive.

5) maintaining the vital functions of the victim until the arrival of the medical staff.

Even if the victim does not show any signs of life (breathing, pulse), he cannot be considered dead, but it is necessary to continue to provide resuscitation until the arrival of qualified medical personnel.

6) call the medical staff or independently organize the transportation of the victim to a medical institution.

The voltage between two points in the current circuit, which are simultaneously touched by a person, is called the touch voltage. The danger of such a touch, assessed by the value of the current passing through the human body, or by the voltage of the touch, depends on a number of factors: the circuit for closing the current circuit through the human body, the voltage of the network, the circuit of the network itself, the mode of its neutral (i.e. grounded or isolated neutral ), the degree of isolation of current-carrying parts from the ground, as well as the value of the capacitance of current-carrying parts relative to the ground, etc.

The most typical are two cases of closing the current circuit through the human body: when a person touches two wires at the same time and when he touches only one wire. With regard to AC networks, the first circuit is usually called two-phase touch, and the second - single-phase.

Two-phase contact is more dangerous, since the highest voltage in this network is applied to the human body - linear, and therefore more current will flow through the person.

A single-phase contact occurs many times more often than a two-phase one, but it is less dangerous, since the voltage under which a person finds himself does not exceed the phase voltage, i.e. less than linear by 1.73 times.

The main causes of electric shock:

1) Accidental contact with live parts under voltage as a result of: erroneous actions during work; malfunctions of protective equipment with which the victim touched current-carrying parts, etc.

2) The appearance of voltage on the metal structural parts of electrical equipment as a result of: damage to the insulation of current-carrying parts; short circuit of the network phase to the ground; falling wire (under voltage) on the structural parts of electrical equipment, etc.

3) The appearance of voltage on disconnected current-carrying parts as a result of: erroneous switching on of a disconnected installation; short circuits between disconnected and energized live parts; lightning discharge into an electrical installation, etc.

4) Occurrence of step voltage on the plot of land where the person is, as a result of: phase short circuit to the ground; removal of the potential by an extended conductive object (pipeline, railway rails); malfunctions in the protective earthing device, etc.

The step voltage is the voltage between the points of the earth, due to the spreading of the fault current to the ground while simultaneously touching them with the feet of a person.

If a person is in a current spreading zone, for example, if an overhead power line is damaged, or if the insulation of a power cable laid in the ground is broken, or if current drains through the ground electrode and stands on the surface of the earth, which has different potentials in places where the feet are located legs, then voltage arises at the step length U w \u003d φ x ─ φ x + 8, where φ x and φ x + 8, are the potentials of the location of the points of the legs; S = 0.8 m - step length.

The electric current flowing through the human body in this case depends on the value of the earth fault current, the resistance of the floor base and shoes, and also on the location of the feet.

The step voltage can be zero if both legs of a person are on an equipotential line, i.e. electric field lines with the same potential. Stress in the step can be reduced to a minimum by bringing the soles of the feet together. The greatest electrical potential will be at the point of contact of the conductor with the ground. As you move away from this place, the potential of the ground surface decreases, and at a distance of approximately 20 m, it can be taken equal to zero.

The step voltage is always less than the touch voltage. In addition, current flow through the lower leg-leg loop is less dangerous than through the arm-leg path. However, in practice, there are many cases of people being injured when exposed to step voltage. The defeat during step voltage is aggravated by the fact that due to convulsive contractions of the muscles of the legs, a person can fall, after which the current circuit closes on the body through the vital organs. In addition, the growth of a person causes a large difference in potentials applied to his body.

The causes of electrical accidents are many and varied. The main ones are:

1) accidental contact with open live parts under voltage. This can occur, for example, during the production of any work near or directly on live parts: in the event of a malfunction of protective equipment, through which the victim touched live parts; when carrying long metal objects on the shoulder, which can accidentally touch uninsulated electrical wires located at an accessible height in this case;

2) the appearance of voltage on the metal parts of electrical equipment (housings, casings, fences, etc.), which are not energized under normal conditions. Most often, this can occur due to damage to the insulation of cables, wires or windings of electrical machines and apparatus, which, as a rule, leads to a short circuit to the case;

3) the appearance of voltage on the disconnected current-carrying parts as a result of the erroneous switching on of the disconnected installation; short circuits between disconnected and energized live parts; lightning discharge into the electrical installation and other reasons

4) an electric arc that can form in electrical installations with a voltage of more than 1000 V between a live part and a person, provided that the person is in close proximity to the live parts;

5) the occurrence of a step voltage on the earth's surface when the wire is shorted to the ground or when current drains from the ground electrode into the ground (in the event of a breakdown to the body of grounded electrical equipment);

6) other reasons, which include such as: uncoordinated and erroneous actions of personnel, leaving electrical installations energized without supervision, admission to repair work on disconnected equipment without first checking for a lack of voltage and a malfunction of the grounding device, etc.

All cases of electric shock to a person as a result of an electric shock are possible only when the electrical circuit is closed through the human body, that is, when a person touches at least two points of the circuit, between which there is some voltage.

The voltage between two points in the current circuit, which are simultaneously touched by a person, is called the touch voltage.

A touch voltage of 20 V is considered safe in dry rooms, because the current passing through the human body will be below the threshold non-letting one, and the person who received an electric shock will immediately tear his hands off the metal parts of the equipment.

In damp rooms, a voltage of 12 V is considered safe.

The step voltage is the voltage between the points of the earth, due to the spreading of the fault current to the ground while simultaneously touching the person's legs. The greatest electrical potential will be at the point of contact of the conductor with the ground. As we move away from this place, the potential of the ground surface decreases and at a distance of approximately 20 m, it can be taken equal to zero. Damage with step voltage is aggravated by the fact that due to convulsive contractions of the muscles of the legs, a person can fall, after which the current circuit closes on the body through the vital organs.

1. Accidental contact with live parts under voltage as a result of: * erroneous actions during work; * malfunctions of protective equipment with which the victim touched current-carrying parts, etc. 2. The appearance of voltage on the metal structural parts of electrical equipment as a result of: * damage to the insulation of current-carrying parts, short circuit of the network phase to the ground; * falling wire under voltage on the structural parts of electrical equipment, etc. 3. The appearance of voltage on disconnected current-carrying parts as a result of: * erroneous switching on of a disconnected installation; * short circuits between disconnected and energized current-carrying parts; * lightning discharge into electrical installation, etc. 4. The occurrence of step voltage on the plot of land where the person is located, as a result of: * phase short circuit to the ground; * removal of potential by an extended conductive object (pipeline, railway rails); *faults in the protective earthing device, etc. Step Voltage- the voltage between two points of the current circuit, located one from the other at a step distance, at which a person is simultaneously standing. The highest step voltage is near the fault, and the lowest is at a distance of more than 20 m.

146. The concept of step voltage and touch voltage

In any electrical networks, a person in the current spreading zone may be under step voltage and touch voltage. Step voltage(step voltage) is the voltage between two points of the current circuit, located one from the other at a step distance (0.8 m) and on which a person is simultaneously standing. The danger of step voltage increases if the person who has been exposed to it falls: the step voltage increases, since the current no longer passes through the legs, but through the entire body of a person. The touch voltage is the voltage between two points of the current circuit, which are simultaneously touched by a person. The danger of such a touch is estimated by the value of the current passing through the human body, or by the voltage of the touch, and depends on a number of factors: the circuit for closing the current circuit through the human body, the network voltage, the circuit of the network itself, the mode of its neutral.

Passing through the body, the electric current causes thermal, electrolytic and biological effects.

thermal action It is expressed in burns of certain parts of the body, heating of blood vessels and nerve fibers.

Electrolytic action expressed in the decomposition of blood and other organic fluids, causing significant violations of their physico-chemical compositions.

Biological action manifests itself in irritation and excitation of living tissue of the body, which may be accompanied by involuntary convulsive contraction of muscles, including the muscles of the heart and lungs. As a result, various disorders in the body may occur, including a violation and even a complete cessation of the activity of the respiratory and circulatory organs.

The irritating effect of current on tissues can be direct, when the current passes directly through these tissues, and reflex, that is, through the central nervous system, when the current path lies outside these organs.

All the variety of action of electric current leads to two types of damage: electrical injuries and electric shocks.

electrical injury- these are clearly defined local damage to body tissues caused by exposure to electric current or an electric arc (electric burns, electrical signs, skin plating, mechanical damage).

electric shock- this is the excitation of the living tissues of the body by an electric current passing through it, accompanied by an involuntary convulsive contraction of the muscles.

Distinguish four degrees of electric shocks:

I degree - convulsive muscle contraction without loss of consciousness;

II degree - convulsive muscle contraction with loss of consciousness, but with preserved breathing and heart function;

III degree - loss of consciousness and impaired cardiac activity or respiration (or both);

Grade IV - clinical death, that is, the absence of breathing and blood circulation.

Clinical ("imaginary") death It is a transitional process from life to death that occurs from the moment the activity of the heart and lungs ceases. The duration of clinical death is determined by the time from the moment of cessation of cardiac activity and respiration until the onset of death of cells of the cerebral cortex (4-5 minutes, and in the death of a healthy person from random causes - 7-8 minutes). Biological (true) death- this is an irreversible phenomenon, characterized by the cessation of biological processes in the cells and tissues of the body and the breakdown of protein structures. Biological death occurs after the period of clinical death.

In this way, causes of death from electric shock there may be a cessation of the heart, cessation of breathing and electric shock.

Cardiac arrest or fibrillation, that is, chaotic fast and multi-temporal contractions of the fibers (fibrils) of the heart muscle, in which the heart stops working as a pump, as a result of which blood circulation in the body stops, can occur with the direct or reflex action of an electric current.

Cessation of breathing as the root cause of death from electric current is caused by a direct or reflex effect of current on the chest muscles involved in the breathing process (as a result - asphyxia or suffocation due to lack of oxygen and excess carbon dioxide in the body).

Types of electrical injuries:

- electrical burns –

Skin electroplating

electrical signs

Electric shocks

Electrophthalmia

Mechanical damage

Electrical burn and arise under the thermal action of an electric current. The most dangerous are burns resulting from exposure to an electric arc, since its temperature can exceed 3000 ° C.

Skin electroplating- penetration into the skin under the action of an electric current of the smallest particles of metal. As a result, the skin becomes electrically conductive, i.e., its resistance drops sharply.

electrical signs- spots of gray or pale yellow color, arising from close contact with a current-carrying part (ps of which an electric current flows in working condition). The nature of electrical signs has not yet been sufficiently studied.

Electrophthalmia- damage to the outer shells of the eyes due to exposure to ultraviolet radiation from an electric arc.

Electric shocks - a common lesion of the human body, characterized by convulsive contractions muscles, disorders of the human nervous and cardiovascular systems. Often, electrical shocks are fatal.

Mechanical damage(tissue tears, fractures) occur with convulsive muscle contraction, as well as as a result of falls when exposed to electric current.

The nature of electric shock and its consequences depend on the value and type of current, the path of its passage, the duration of exposure, the individual physiological characteristics of a person and his condition at the time of the defeat.

electric shock- this is a severe neuro-reflex reaction of the body in response to strong electrical stimulation, accompanied by dangerous disorders of blood circulation, respiration, metabolism, etc. This state can last from several minutes to a day.

	At AC 50 Hz	With direct current
	The appearance of sensation, slight trembling of the fingers	Not felt
	Cramps in the hands	Sensation, heating of the skin Increasing heating
	Hands are difficult, but still can be torn off the electrodes; severe pain in the hands and forearms	Heating boost
	Hands become paralyzed, it is impossible to tear them off the electrodes, breathing is difficult	Slight muscle contraction
	Stopping breathing. The onset of cardiac fibrillation	Strong heating; contraction of the muscles of the hands; shortness of breath
	Respiratory and cardiac arrest (with exposure duration of more than 3 s)	Respiratory arrest

43. The impact of electric current on the human body. General and local injuries

Passing through the human body, the electric current has a thermal, electrolytic, mechanical and biological effect on it.