The main causes of electric shock in everyday life and at work

Due to the widespread use of electricity, both in production processes and for solving everyday problems, a significant threat of electric shock is created. To prevent such situations, there are a number of rules to protect personnel and ordinary people from the disastrous consequences of illiterate handling of electricity. To do this, it is important to understand the causes of electric shock and the measures necessary in certain situations to prevent electric shock.

Electric shock concept

An electric shock should be understood as a situation where an electric charge from a current source is used by the human body as one of the flow paths or the only path. In this case, the directed movement of particles creates a spontaneous contraction of the muscles that fall under its influence along the flow path; the current destroys tissue and causes other damage.

Electrical shock can occur both during normal operation of electrical installations and in emergency situations (damage to wire insulation, breakdown of dielectrics, destruction of insulators, when an electric arc burns, etc.). In addition to interaction with current in everyday life, there is the possibility of being struck by lightning. But whatever the flow of current, it can cause a number of adverse consequences for the human body.

Types of electrical injuries

Electric shock can be local or general. And according to the place of their receipt, household electric shock is identified, in production conditions, as well as in nature.

Electricity can affect the body simultaneously, as well as over a certain period of time. Instantaneous damage occurs due to current that exceeds permissible values for a short time. This type of lesion requires hospitalization and the person’s stay at least in the intensive care unit or surgery. This is due to possible cardiac arrest. Chronic exposure to electric current occurs due to prolonged exposure of the body to electricity from high-power generators. With this exposure, increased fatigue develops and sleep and memory are disturbed, headaches develop, limbs begin to tremble, blood pressure rises, and pupils dilate.

It is also customary to distinguish other types of electrical injuries:

Local electrical injury (when the eyes are affected, this is called electroophthalmia, also when metal gets under the skin and melts under the influence of an electric arc).
General electrical injury (with this type of injury, muscle groups are affected, and the injury itself is manifested by convulsions, possible cardiac and respiratory arrest).

If we take all those affected by electricity, then:

20% have local lesions;
25% of those affected have general manifestations accompanied by electric shock;
in 55% the lesion is of a mixed nature.

How does electricity affect the human body?

If we do not consider the planned effects of electric current during medical or cosmetic procedures with devices whose action is aimed at passing electric current through the tissues of the body, then in all cases of electrical injury the body receives three main effects of current:

Thermal – cause burns at points of exposure to electric current. Unlike a regular burn, an electrical burn is further complicated by tissue damage from small particles of hot metal. Which, after an impact, remain in the skin, and accordingly, the healing of such wounds takes longer and requires additional effort. Depending on the conditions under which the electrical shock occurs, mild, moderate or severe burns may occur.
Dynamic – causes contraction and subsequent damage to muscles and ligaments. Since all muscles in the body are controlled by electrical impulses, when current flows, their spontaneous contraction occurs. Because of this, mechanical damage to tissues – ruptures – can occur. As well as convulsive compression of the limbs, in which a person cannot independently unclench his fingers and free himself from the action of the current. The same effect occurs in the heart, which can cause fatal shock.
Electrolytic - when current flows, blood vessels have the lowest resistance, which are conductors in the body. When an electric current passes through the vessels, the blood acts as a conductor, which, with prolonged exposure, decomposes into plasma and blood cells.

Depending on the situation, the damage may also result in electric shock. The victim’s condition is characterized by a lack of adequate reaction to ongoing events and dilated pupils. In this state, it is difficult to judge the damage done to the body, due to the fact that the person cannot report his own well-being. Therefore, his condition is determined by indirect factors (pulse, breathing, etc.).

Physiological effects

Current is the movement of electrons or ions in a conductor. The amount of it flowing through the human body determines the response to electrical shock. Most effects on the body involve heating tissue and stimulating nerves and muscles.

Loss of neuromuscular control can lead to traumatic consequences ranging from falls to respiratory or cardiac arrest. An approximate list of damaging effects is as follows :

1 mA - sensitivity threshold, feels like a slight tingling sensation;
10-20 mA - the beginning of a stable muscle contraction (it is impossible to let go of the source);
50-150 mA - extreme pain, respiratory arrest;
100-300 mA - ventricular fibrillation of the heart without lethal outcome with short-term exposure;
about 2A - cardiac arrest and irreversible damage to internal organs.

Entry points and resistance

The human body has resistance to current. Since it consists almost entirely of water, the lowest conductivity is inherent in its shell - the skin. For a calloused, dry hand, this value can be in excess of a hundred thousand ohms, due to the thick outer layer of keratinized dead cells.

Skin resistance depends on age, sweating, individual characteristics and drops sharply as a result of high-voltage breakdown, cut, deep abrasion or when immersed in water.

Electricity flows from one point to another. A person receiving an electric shock has at least two points of contact with a voltage source, one of which may be ground. Current in a body is capable of passing through several paths simultaneously, in this case its passage is described by Ohm's laws for parallel and series connections.

Approximate Human Resistance:

hand-to-hand: 1300 Ohm;
hand-foot: 1000 Ohm;
arms and legs: 650 Ohm;
leg-to-leg: 1300 Ohm.

Damage can occur from an electrical arc caused by current passing through air. If it does not contact a person, the consequences will be burns from its heat at the entry point.

High-energy arcs can be accompanied by explosions that create a shock wave that can throw a person, rupture eardrums and damage internal organs.

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Voltage and frequency

Voltage can be thought of as the force that pushes electrical current through the body. All other things being equal, the thermal heating of tissues from the passage of current is directly proportional to the square of the applied voltage. Bones, tendons and fat have great resistance. Maximum conductivity in nerves and vascular tissues.

Main causes of electric shock

The reasons for the effect of electric current on the human body can be determined by various factors and situations. Because of these differences in situations, rules regulate the use of certain remedies or impose obligations to take certain measures. In this connection, the causes of damage are divided into those that can occur in domestic conditions, and those that can occur at work.

At home

The most common causes of injury at home are any malfunctions or careless handling of the devices being used by the person himself. The strength of the current affecting a person depends on the resistance of the electrical circuit, which includes the resistance of the skin, shoes, the spread of current in the floor or some other point. The lowest resistance value is obtained when there are wounds on the skin, wet surfaces of the hands, or when a person touches grounded elements.

Causes of electric shock at home

Particular attention should be paid to the following causes of damage:

Violation of insulation inside appliances - for the most part, all home vacuum cleaners, kettles, microwave ovens, washing machines and other assistants are equipped with reliable insulation at the factory. But, due to natural aging or damage, the insulation resistance may become compromised, resulting in electric shock. This problem is characterized by the transfer of potential to the body or metal parts of electrical devices and causes the occurrence of touch voltage.
Damage to the insulating sheath of wires - applies to both wiring and all kinds of power cords and extension cords. There is a possibility of electric shock from places where kinks, impacts or rubbing occurred, especially if water gets on them.
Contact with homemade devices and exposed live parts . Both do not guarantee a person any compliance with standards. Therefore, interaction with questionable devices or exposed wires can result in severe electric shock.
Spontaneous repair attempts - when people without the necessary skills and knowledge try to repair some devices or electrical wiring. At the same time, they expose themselves to the danger of accidentally touching live elements, which is the cause of the injury. For example, when replacing an electric lamp in a lamp, when the voltage is not removed from the socket.
Using switches or sockets with damaged casings . The body of these devices acts as a natural barrier, which, if damaged, opens access to live elements and poses a risk of electric shock.
Attempting to replace lamps when there is voltage in the socket - due to carelessness, a person may touch the internal elements, which will lead to electric shock. It is also possible that a burnt-out lamp breaks down and disintegrates in your hands, and some parts can become conductors of electric current. In this case, a disconnected switch does not guarantee the absence of voltage due to the fact that it may not break the phase.
Operating electrical appliances with water - attempts to dry your hair with a hair dryer and use an electric razor while in the bathroom, adding water to a switched on electric kettle and other options when the device comes into contact with water can cause electric shock.
Temporary wiring with twists - often in everyday life, in order to speed up the supply of voltage and not waste a lot of time on a full installation in the wall, or at least make an open connection to the channel. It is precisely such “snot”, hung in violation of all norms around the house, barn or garage, that can cause electric shock.

In production

The vast majority of work performed in production involves a number of measures aimed at preventing electric shock. But, due to violation of these measures and rules, personnel in contact with electrical installations or simply performing work in the immediate vicinity may be exposed to voltage.

Consider the most common causes of electric shock at work:

Lack of protective equipment or use of unsuitable ones . This is especially true in situations where any devices remain energized while working on them.
Insulation failure and lack of grounding - in power circuits this means damage to insulators, cable insulation and other severe damage to equipment. They cause the presence of potential on the body and supporting structures, which can lead to fatal injury in the event of contact. Initially, grounding is provided as insurance in case of insulation damage, so electric shock is possible only if there is no or faulty grounding.
The burning of an electric arc can occur either as an integral part of the operation of the same switches, welding machines or short circuits, or as an emergency. Arc injury can cause burns and is characterized by the transfer of part of the charge and the subsequent passage of current through a person.
Wires falling to the ground – creates a danger zone, which is 10 m for open areas and 8 m for indoor areas. In this space, currents spread if the protection does not disconnect the line. Due to the spreading of currents, a potential is formed on the ground surface, which decreases in proportion to the distance from the point of impact. In such a zone, the cause of damage is the step voltage generated by the potential difference between the human feet.

Step voltage
Violation of safety sign requirements - most dangerous places at the enterprise are fenced off. Temporary or permanent signs or posters are hung on the fence itself or in places where voltage may be supplied. If a person intentionally or negligently violates the requirements of the signs, an electric shock may occur.
If switching or operation has not occurred or has not been completed completely . Since most high-voltage equipment is controlled remotely, and electrical contact nodes in switches and disconnectors are quite difficult to control, information about the absence of voltage is obtained through indicators or alarms. In the event that, for mechanical reasons, the switch or disconnector does not turn off at least one of the phases, there is a risk of electric shock in some part of the network, so it is imperative to use an indicator.
Incorrect supply of voltage - when performing work with voltage removal, potential may be accidentally supplied to a line or electrical installation either by workers or as a result of an emergency. If personnel leave the protective zone fenced off by groundings, or do not install them at all, then they are at risk of electric shock.
Induced voltage – is the most dangerous factor in de-energized wires and neutral elements (conductor sections fenced with two insulators). In production, direct current injury is considered the most dangerous. Because the frequency of alternating current spontaneously drops to zero and rises again, which is why its effect is inconsistent.

Formation of induced voltage
Violation of the procedure for removing or hanging the grounding - according to the requirements of the rules, when installing the grounding, it is first connected to the ground and then hung on the conductor. Otherwise, if there is potential in the line, the worker will first connect the ground to the line potential, and when he tries to connect it to the ground loop, he himself will become an element in the current flow circuit. Removal of grounding is carried out in the reverse order - first it is removed from the current-carrying elements, and then disconnected from the circuit. There is also a similar threat when removing it.

Impact force

Of decisive importance for the consequences of electric shocks to a person is the time of exposure and the current density (amount per unit area) passing through tissues and organs, as well as the amount of heat generated.

Do not underestimate the likelihood of accidents caused by falls and their associated consequences. Factors influencing the extent of direct damage include :

type of current (AC or DC);
frequency (for pulse or alternating);
the person’s health status and age;
presence of medical implants in the body;
the path of flow through the body (for example, arm-arm or left arm-right leg);
the magnitude of the step voltage.

Injuries from low voltage are more often fatal than from high voltage. The explosive effect of plasma formation when exposed to sources above 1000 V throws the victim away from the conductors, limiting the time of contact.

In such cases, the damage can be surprisingly minor. In contrast, household current at a frequency of 50 Hz can stimulate muscle contraction and cause involuntary seizure, prolonging the effect of electricity, which significantly worsens the consequences.

A similar effect occurs when a person is struck by lightning. This natural phenomenon can be described in the following figures :

the potential of the electric field between the clouds and the surface of the earth reaches a billion volts;
the discharge lasts about 0.02 seconds;
The discharge current can be up to 100,000 A;
the temperature in the plasma channel can be 10,000 °C.

However, most victims survive exposure to lightning due to its indirect effects, which can be compared to the effects of a blast wave. A direct hit is also rarely fatal due to the short duration of the electric current.

High voltage contacts can sometimes look paradoxical. For example, a bird can sit comfortably on high-voltage power lines. At the same time, the latter can destroy electrical insulators such as paint, leather, ordinary shoes and gloves. This is because the bird, unlike humans, does not have the opportunity to be close enough to the ground to complete the circuit to the ground or expose the insulation of its covers to the destructive effects of the arc.

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What to do in case of electric shock?

If you witness someone electrocuted and still under the influence, you need to free them as quickly as possible. Since the outcome of an electrical injury directly depends on the duration of contact, the speed of response should be maximum.

Firstly, it is necessary to de-energize the electrical installation or its parts with which a person interacts. Automatic machines, switches or fuses located in the immediate vicinity are best suited for this. For high-voltage networks, their analogues are switches and disconnectors. If these are not available, other measures can be used to reduce the duration of exposure.

The most important rule during release is that the rescuer himself must follow the safety rules so that he too does not get electrocuted. Otherwise, to prevent death, any means will do.

Release up to 1000 V
For lines up to 1 kV, any dry clothing wrapped around your hand can be suitable, ideally these should be dielectric gloves. They can pull the victim by the loose ends of dry clothing. Use a tool with insulated handles to cut through the wire. You can also break the electrical circuit by placing a sheet of dielectric between the victim and the ground.

Removing the wire with a rod

In devices above 1 kV, approaching the victim is dangerous because the rescuer himself may come under step voltage. But, in this case, you can throw any uninsulated wire between the source and the victim. Try to pull the wire away with an insulating rod, but wear dielectric gloves. The cable, also wearing gloves, can be cut in phases with an ax.

Help with electric shock

First of all, it is necessary to de-energize the scene of the incident, and release the victim from contact with the source without direct touching. For this purpose, dielectrics are used - rubber sheets, ropes, leather belts, dry wooden sticks, poles. If possible, wear rubber gloves on your hands.

If the patient cannot breathe on his own, then immediately begin artificial ventilation of the lungs - “mouth to mouth”. Intermittent breathing support should be continued for the next four hours.

In cases where a person does not have a heartbeat, chest compressions are performed together with artificial ventilation. If the injury is caused by a lightning strike and asystole is observed, a hand blow to the heart is performed, then artificial respiration.

If the lesion occurs from contact with low voltage, then defibrillation is performed. During the examination, special attention is paid to the presence of fractures and bruises of the spine.

Assistance to a victim of electric shock - defibrillation

A person who has received electrochemical burns should be immediately taken to a burn department or traumatology department.

Treatment of wounds in a hospital setting involves removing dead layers of skin. In almost all cases, measures are taken to prevent the spread of infections in the body - antimicrobial treatment.

Patients in a coma require constant monitoring of intracranial pressure. In case of complications or head injuries, special therapy should be used.

Precautions to Protect Against Electric Shock

To avoid electric shock and minimize the causes that could cause it, it is enough to follow a number of simple rules:

Do not touch electrical appliances, switches, plugs, sockets with wet hands;
Do not allow faulty devices or devices that do not have chassis grounding to be connected to the network (the absence is allowed only for devices designed for very low voltage);
Do not violate the instructions prescribed by electrical signs that regulate certain actions;
Do not leave the appliances on when leaving home, and do not allow the plug to be pulled out by the cord;
When working in electrical installations, be sure to comply with the requirements of the rules, instructions, and the procedure for technological processes;
Work in electrical installations should only be carried out using the necessary protective equipment.

What are electrical injuries and electrical injuries?

Electrical trauma is a violation of the anatomical relationships and functions of tissues and organs, accompanied by a local and general reaction of the body and caused by the effect of electric current on the human body from faulty electrical equipment or electrical networks.

Electrical injuries are a set of electrical injuries that occur and recur at one time or another in certain groups of the population in similar work, communal, and sports conditions.

What are the dangers of electric shock?

The danger of electric shock lies in the fact that electric current is invisible, odorless, and its effects can only be felt when a person touches faulty electrical equipment or an electrical network, as well as in the case of induced voltage from a high-voltage electrical network.

What factors increase the likelihood of electrical injuries occurring in enterprises?

Maintenance of electrical equipment in unsatisfactory condition, live parts of electrical equipment accessible to unauthorized persons. Lack of preventive maintenance schedules or untimely implementation. Violation by electrical technical personnel of organizational and technical safety measures that must be taken before starting work on electrical installations and during this work. Working on faulty electrical equipment. Use of tools and devices that have not passed timely electrical tests. Insufficient use of electrical protective equipment. Inclement weather.

Insufficient training of workers on electrical safety issues, underestimation by workers of the degree of danger of electric shock. Presence of medical contraindications to work in electrical installations.

What are the characteristics of electric shock?

Electric current has biological, electrolytic and thermal effects on the human body.

Biological is expressed in irritation and excitation of living cells of the body, which leads to involuntary convulsive muscle contractions, disruption of the nervous system, respiratory and circulatory system. In this case, fainting, loss of consciousness, speech disorder, convulsions, and breathing problems (even stopping) may occur. In case of severe electrical injury, death can occur instantly.

Electrolytic effects manifest themselves in the decomposition of blood plasma and other organic liquids, which can lead to a disruption of their physical and chemical composition.

Thermal exposure is accompanied by burns of parts of the body and overheating of individual internal organs, causing various functional disorders in them.

The resulting electric arc causes local damage to human tissues and organs.

What types of electrical injuries can be divided into?

The variety of effects of electric current on the body can be conditionally reduced to two types: local electrical injuries, when local damage to the body occurs, and general electrical injuries (electrical shocks), when the entire body is affected due to disruptions in the normal functioning of vital organs and systems.

Local electrical injuries:

—electrical burns are caused either by heating the area of a person’s body through which an electric current passes, or by exposure to a person caught in the area of an electric arc;

- electrical signs , called current signs or electrical marks, are sharply defined spots of gray or pale yellow color on the surface of the body of a person exposed to current. There are signs in the form of scratches, hemorrhages in the skin, calluses and small dot tattoos or resembles the figure of a lightning bolt. Usually electric signs are painless and their treatment ends well;

—metallization of the skin - penetration into the upper layers of the skin of the smallest particles of metal melted under the influence of an electric arc;

—mechanical damage is a consequence of sharp involuntary convulsive contractions of muscles under the influence of electric current in the form of ruptures of tendons, skin, blood vessels and nervous tissue;

—Electroophthalmia is an inflammation of the outer membranes of the eyes that occurs as a result of exposure to a powerful stream of ultraviolet rays, usually from an electric arc.

General electrical injuries (electrical shock):

- convulsive contraction of the mouse without loss of consciousness;

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

— loss of consciousness and disturbance of cardiac activity or breathing (or both);

— clinical death, i.e. lack of breathing and blood circulation.