What Is an Electric Shock?

Offensive "shock" with electric rods, English idiomatic saying: Tase.

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Resistors have the function of preventing or slowing the flow of current. Human body resistance is mainly concentrated on the skin, which is directly related to the condition of the skin. The average dry and healthy skin resistance is 40 times that of thin and moist skin. When the skin is cut, abraded, or current is passed through moist mucous membranes, such as mouth, rectum, vagina, etc., its resistance value is only half of that of wet and intact skin. The resistance of palms or soles with thick cocoons may be 100 times that of thinner skin areas. Electric shock can be caused by lightning, touching household electrical wires, or broken wires in accidents, contacting certain charged bodies, etc., and causing flashes. The severity ranges from mild burns to death, depending on the type and intensity of the electric current, the resistance of the electric shock site, the path of the electric current through the human body, and the duration of the electric shock.

Introduction to Electric Shock

Offensive "shock" with electric rods, English idiomatic saying: Tase.

Translate to an electric shock

Definition in Electric Shock GB

The definition of electric shock in the national standard is as follows:

1. In the national standard GB4776-84, there are electric shocks in 1.4: electric shock

Pathological and physiological effects caused by current passing through the human or animal body.

2. In the building's electrical installations, electric shock protection GB 14821.1-93 is also defined as 3-1.

Electric shock (shock): The pathophysiological effect caused by the current passing through the human body or livestock.

3. 4.6 is also defined in GBT17045-1997, the general part of electric shock protection devices and equipment.

Electric shock: Current flows through the human or animal body, causing it to produce a pathophysiological effect. (IEV 826-03-04)

The heat generated by the current through the body tissue can severely burn and damage the body tissue. Electric shock can short-circuit the body's own conductive system, causing the heartbeat to stop.

Perceived current: Under a certain probability, the minimum current (effective value, the same below) that causes people to feel anything through the human body is called the perceived current under this probability. When the probability is 50%, the average perceived current of adult men is about 1.1 mA, and that of adult women is about 0.7 mA.

Get rid of current: Under a certain probability, the maximum current that a person can get rid of a charged body after an electric shock is called the get rid of current under this probability. Adult males are approximately 16 mA and adult females are approximately 10.5 mA. For safety reasons, the current that can be rid of 99.5% of people should be taken as the basis, which is called the minimum shed current, which is about 9mA for adult males and about 6mA for adult females.

Ventricular fibrillation current: The smallest current that causes fibrillation in the ventricle through the body is called ventricular fibrillation current. Ventricular fibrillation current is the smallest lethal current acting for a short time. Ventricular fibrillation current is closely related to the duration of the current. When the current duration exceeds the cardiac cycle, the ventricular fibrillation current is only about 50 mA; when the current duration is shorter than the cardiac cycle, the ventricular fibrillation current is hundreds of milliamps. When the current duration is less than 0.1S, only the electric shock occurs in the vulnerable period of the heart, and a current of more than 500mA or even several amps can cause ventricular fibrillation.

. Electric shock . Cause

Electric shock can be caused by lightning, touching household electrical wires, or broken wires in accidents, contacting certain charged bodies, etc., and causing flashes. The severity ranges from mild burns to death, depending on the type and intensity of the electric current, the resistance of the electric shock site, the path of the electric current through the human body, and the duration of the electric shock.

Generally, direct current (DC) is less dangerous than alternating current (AC). The effect of alternating current on the body depends largely on the frequency of the current, which is measured in how many cycles (hertz) per second. Low-frequency currents of 50 to 60 Hz are commonly used in the United States. They are more dangerous than high-frequency currents, and are 3 to 5 times more dangerous than direct current with the same voltage and the same current strength (amperes). Direct current often causes strong muscle contractions, which often force the victim out of power. 60 Hz alternating current causes muscle rigidity in the electric shock site, which often prevents the victim from disconnecting from the power source. As a result, the electric shock time is prolonged and serious burns are caused. Whether it is AC or DC, the higher the voltage and current intensity, the greater the damage.

Current intensity is measured in amps, and milliamps (mA) are 1/1000 amps. The human hand can sense 5 to 10 mA of direct current; it can also sense 1 to 10 mA of 60 Hz alternating current (sensation threshold). The maximum current that can cause the arm muscles to contract, but still allow the release of the hand from the power source, is called "release" current. The release current of direct current is about 75mA, and the release current of AC: 2-5mA for children, 5-7mA for women, and 7-9mA for men, depending on the size of the arm muscles.

An alternating current of 60 to 100 mA, 110 to 220 volts, and 60 Hz passes through the chest instantly, which may cause life-threatening heart rhythm disorders. The direct current that causes the same result is about 300 to 500 mA. If the current flows directly through the heart, such as a pacemaker, very low currents (less than 1 mA) can also cause cardiac rhythm disturbances.

Shock current flow function

Resistors have the function of preventing or slowing the flow of current. Human body resistance is mainly concentrated on the skin, which is directly related to the condition of the skin. The average dry and healthy skin resistance is 40 times that of thin and moist skin. When the skin is cut, abraded, or current is passed through moist mucous membranes, such as mouth, rectum, vagina, etc., its resistance value is only half of that of wet and intact skin. The resistance of palms or soles with thick cocoons may be 100 times that of thinner skin areas. When the current passes through the skin, it encounters the skin's resistance, and most of the energy is released on the skin surface. If the skin resistance is high, a large area of burning can occur at the entrance and exit of the current, and the tissue between the two is carbonized. Depending on the size of the resistor, internal tissues may also burn.

Electric current damage

The path of current through the body is key to the extent of the damage. The most common part of the current into the body is the hand, followed by the head. Most parts of the body where the current flows are the feet. Because current flows through the heart from arm to arm or from arm to foot, it is much more dangerous than from foot to ground. Current passing through the head can cause seizures, cerebral hemorrhage, apnea, and psychological changes (such as short-term memory impairments, personality changes, nervousness, and sleep disorders), and heart rate disorders. Eye damage can cause cataracts.

Electric shock duration

The duration of electric shock is also an important factor. The longer the electric shock, the more severe the tissue damage. People who are tightly adhered to the power supply may be severely burned, but people who are struck by lightning rarely have severe external or internal burns, because the lightning strikes instantly and the current flashes in the body without causing internal tissues. Serious injury. However, lightning strikes can cause short circuits in the heart and lungs, paralyze the heart and lungs, and can damage nerves and the brain.

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Electric shock symptoms

Symptoms depend on the result of a complex interaction of various factors. Electric shocks can cause a sudden shock and cause a fall or cause strong muscle contractions. Both conditions can cause joint dislocations, fractures, and blunt contusions. Patients may also lose consciousness, respiratory paralysis, and cardiac arrest. Electric skin burns are obvious and can also affect deep tissues.

The high voltage current can cause tissue necrosis between the current inlet and outlet and cause large area muscle burns. Large amounts of fluids and electrolytes are lost and dangerously low blood pressure can occur when severe burns are combined. Damaged muscle fibers release myosin, which can cause kidney damage and renal failure.

A person with a wet body is exposed to electrical current, such as a hair dryer falling into a bathtub or stepping into a charged pool while taking a bath. At this time, the skin resistance is low. Although it is not burned, it can cause a pause in heartbeat. If it does not recover quickly, it may die.

Lightning strikes rarely cause burns at the entrance and exit, and rarely cause muscle damage and myosinuria. Loss of consciousness may occur initially, followed by coma and transient mental disorders, which usually disappear within hours or days. The main causes of death from lightning strikes are heartbeat and respiratory arrest.

Children who are just learning to walk may have burned lips due to sucking on the telephone line. Such burns can not only cause facial deformities, but can also cause dental, chin, and facial development disorders. Children with this type of burn should be treated by an orthopedist, oral surgeon or burn doctor. 7 to 10 days after the lip burn may cause the labial artery bleeding due to crust shedding and danger.

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Electric shock prevention

The most important thing is to popularize knowledge about electricity consumption and attach importance to education on safe electricity consumption. Ensuring that all electrical appliances are properly designed, installed, and maintained can help prevent electrical shock at home or in the workplace. All electrical appliances that are likely to come into contact with the body should have reliable grounding and circuit breaker protection devices. A circuit breaker capable of disconnecting a line when the earth leakage current is less than 5 mA is a very effective safety device and has been widely used.

To prevent lightning strikes, take appropriate measures according to the site conditions. For example, during a lightning storm, do not stand on an open field, a baseball field, or a golf course. Look for shelter from the rain. Pool, pond or lake. It is safe to hide in a car.

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Electric shock treatment

Treatment includes removing the wounded from power, restoring heartbeat and breathing, using a cardiopulmonary resuscitation device if necessary, and treating burns and related injuries.

The safest way for the injured person to disconnect from the power source is to immediately cut off the power source, such as pulling down the switch or unplugging the power plug of the electrical equipment. In the case of high-voltage lines, no one can touch the wounded until the current is switched off. High-voltage and low-voltage electricity are difficult to distinguish, especially outdoors, and many rescuers who wanted to save people were injured by electricity during rescue.

As soon as the wounded can be safely contacted, rescuers should immediately find out if he has breathing and pulse. If the wounded can't breathe and can't feel the pulse, he should use CPR immediately. Medical staff should check the injured for fractures, joint dislocations, contusions and spinal injuries. If there is extensive muscle damage, myosin may damage the kidneys, and plenty of fluids should be added to prevent kidney damage.

Lightning strikes may recover with a cardiopulmonary resuscitation device. It is important to be quick and not to abandon resuscitation measures even for the wounded who show signs of death, because such wounded people often recover after stimulating breathing.

An electrocardiogram can be used to monitor the heartbeat of the wounded. If the victim's heart is shocked, he should be monitored for 12 to 24 hours. If the victim is unconscious or has a damaged head, a computed tomography (CT) scan should be performed to check for brain damage.

Electric shock type

Most electric shock fatalities are caused by electric shock. Generally speaking, an electric shock accident basically refers to electric shock.

According to the state of electrical equipment, electric shock can be divided into direct contact electric shock and indirect contact electric shock. The former is an electric shock that occurs when a human body touches a charged body that is charged under normal conditions; the latter is an electric shock that occurs when a human body touches a charged body that is uncharged under normal conditions and accidentally charged under fault conditions. Therefore, the former is also called the electric shock in the normal state, and the latter is also called the electric shock in the fault state.

According to the way the human body touches the charged body and the way the current passes through the human body, the electric shock can be divided into single-phase electric shock, two-phase electric shock, and step voltage electric shock. Single-phase electric shock refers to the electric shock of the human body on the ground or other grounded conductor, and a part of the human body touched a one-phase charged body. Most electric shocks are single-phase electric shocks. The danger of single-phase electric shock is related to the operation mode of the power grid. Under normal circumstances, a single-phase electric shock from a grounded grid is more dangerous than an ungrounded grid. Two-phase electric shock refers to an electric shock accident in which two parts of the human body touch two-phase charged bodies at the same time, and the danger is generally relatively large. When there is a current flowing into the ground from a grounded body, the current generates a voltage drop in the soil around the ground point. When a person is around a grounded body, the voltage appearing between the two feet is the step voltage. The resulting electric shock is called step voltage shock. Higher step voltages may occur at high-voltage fault grounds or near grounding devices where large currents flow.

Electric shock and protection

Electric shock

Electric shock is a pathophysiological effect caused by the current passing through the human body. When the current passing through a part of the human body exceeds 30 mA, if the current is not cut off in a short time, the person will be in a very dangerous situation. The prevention of personal electric shock must meet the requirements of relevant national standards, regulations, installation regulations, formal guidelines and general rules. The relevant IEC standards are: IEC 60364 and IEC 60479 series standards, and IEC 61008, 61009, and IEC 60479-2 standards.

When the electric current passes through the human body, it mainly affects the muscle, blood circulation and breathing functions of the human body, and sometimes causes severe burns. The degree of injury to the human body is related to the magnitude of the electric current, the part of the electric current passing through the human body, and the duration of the electric current.

Electric shock related information

The 1994 edition of IEC 60479-1 specifies four areas of current / time relationship, describing the pathological physiological effects of the human body in each area (see Figure F1). Any contact with a charged metal body may withstand electric shock.

Curve C1 shows that when the current passes from one hand to the other of the human body, if the current exceeds 30 mA, the human body is likely to be killed by electric shock unless the current can be cut off in a relatively short time.

Near the 500ms / 100mA point of the Cl curve, the probability of fibrillation in the heart is about 0.14%. The protection against electric shock in low-voltage electrical installations must meet the requirements of relevant national standards, regulations, installation regulations, formal guidelines and general orders. The relevant IEC standards are: IEC 60364, IEC 60479, IEC 60755, IEC 61008, IEC 61009 and other series standards and IEC 60479-2 standards.

Current I duration (ms)

Time / current effect zones when AC current passes through the human body

Figure 1: Time / current effect partitioning of AC current from one hand to the other through the human body.

AC-1: Unconscious

Zone AC-2: Conscious

AC-3 zone: reversible effect: muscle contraction

Zone AC-4: Irreversible effects may occur

AC-4-1 area: cardiac fibrillation can reach 5%

Area AC-4-2: Fibrillation of the heart can reach 50%

Area AC-4-3: Fibrillation of the heart can exceed 50%

A curve: current sense threshold

B curve: muscle response threshold

Cl curve: 0% chance of ventricular fibrillation threshold

CZ curve: 5% chance ventricular fibrillation threshold

C3 curve: 50% chance of ventricular fibrillation threshold

The necessity of electric shock first aid

The rescue of an electric shocker should be done every second. Patients with respiratory or cardiac arrest are in very critical condition. At this time, they should be rescued and emergency contacted, and the patient should be sent to the nearest hospital for further treatment. The rescue work cannot be interrupted while the patient is being transferred to the hospital.

The necessity of electric shock first aid

Electric shock first aid method

^[1] 1 When dealing with electric shock, pay attention to whether there are other injuries. Such as electric shock bounce off the power or fall from high altitude, often accompanied by craniocerebral trauma, blood pneumothorax, visceral rupture, limbs and pelvic fractures.

2. During on-site rescue, do not move the wounded casually. If it is necessary to move, the rescue interruption time should not exceed 30 seconds. Move the wounded or take them to the hospital. Except for the wounded lying on a stretcher and padding with a flat hard broad plank on the back, the rescue should continue. Those with cardiac arrest and breathing stop should continue artificial respiration and chest heart compression. Treatment cannot be suspended without succession.

3 Do not use ointments or dirty dressings on wounds or wounds that suffer from electrical burns. Instead, use clean dressings or take them to the hospital for treatment.

4 When you encounter lightning and thunder, you should quickly avoid the buildings nearby. When there is nowhere to hide in the wild, remove metal objects such as watches and glasses, find low places to lie down and avoid, and never dodge under a tree. Do not stand on high walls, under trees, near electric poles, or near antennas.

How to treat electric shocked children after electric shock

Once an electric shock occurs, the emergency treatment steps are:

Turn off the power immediately. The first method to cut off the power is to turn off the power switch, pull the brake, and remove the plug; the second is to use a dry wooden stick, bamboo pole, flat load, plastic stick, belt, broom handle, chair back or rope to disconnect the wire.

Quickly move the child to a ventilated place. For those who have stopped breathing and heartbeat, immediately perform artificial respiration and chest heart compression at the scene. Artificial respiration needs to be done for at least 4 hours, or until the child resumes breathing, the condition should be tracheal intubation, pressurized oxygen artificial respiration.

Those who appear unconscious may acupuncture acupuncture points such as middle and middle punch.

Immediately return to the hospital for treatment after breathing and heartbeat, and pay close attention to changes in the patient's illness on the way.

symptomatic treatment. Cerebral edema caused by hypoxia can be dehydrated with mannitol and 50% glucose; fractures and dislocations caused by strong muscle contraction should be reduced and fixed; for burns, exposure therapy is better. ^[2]