What are the dangers of being electrocuted

We must ensure safety when using electricity in our daily lives, especially families with children must protect the plugs and not let children touch them with their hands. What are the dangers of being electrocuted? Different intensities of electric current will have different effects on the human body, and people's reactions will also be different. When strong current passes through the human body, it will cause the heart and breathing to stop in a short time, thus endangering life, so you must use electricity safely.

Electric injuries are mainly caused by electric current.

When electric current flows through the human body, it produces varying degrees of tingling and numbness, accompanied by involuntary skin contraction. When the muscles contract, the strong contraction of the pectoral muscles, diaphragm and glottis muscles will hinder breathing and cause death of the person who is electrocuted. Passing an electric current through the respiratory control center of the central nervous system can stop breathing. The electric current passing through the heart causes heart dysfunction, namely ventricular fibrillation, which can cause the person who is electrocuted to die quickly due to lack of oxygen to the brain.

The following is an explanation from various aspects -

1. The impact of current intensity on the human body

The so-called current intensity refers to the amount of electricity passing through the cross-section of a conductor per unit time. It is measured in amperes and is represented by the symbol A. The amount of electricity that passes through 1 coulomb (expressed by the symbol C) per second is called 1A, and 1A is equal to 1000mA.

The greater the current passing through the human body, the more obvious the body's physiological reaction, the stronger the feeling, the shorter the time required to cause ventricular fibrillation, and the greater the fatal danger.

According to the different sensations and reactions caused by the current passing through the human body, the current can be divided into:

(1) Sense electric current. The minimum current that causes human sensation is called perception current. Experimental data show that the perceived current is different for different people. The average perceived current for adult males is about 1.1mA; for adult females it is about 0.7mA.

(2) Get rid of the electric current. The maximum current that a person can independently get rid of the power source after being electrocuted is called the escape current. Experimental data show that the escape current is different for different people: the average escape current for adult males is about 16 mA; the average escape current for adult females is about 10.5 mA. The minimum escape current for an adult male is about 9 mA; the minimum escape current for an adult female is about 6 mA. The minimum escape current is considered based on a 99.5% probability.

(3) Lethal electric current. The minimum current that endangers life in a shorter period of time is called lethal current. When the current does not exceed a few hundred milliamperes, the main cause of death from electric shock is ventricular fibrillation or asphyxiation caused by current. Therefore, it can be considered that the current that causes ventricular fibrillation is the lethal current.

2. The effect of the duration of electric current passing through the human body on the human body

As the electric current passes through the human body for a longer time, the body's resistance gradually decreases due to fever and sweating, as well as the electrolytic effect of the electric current on the human body. Under the condition of a certain power supply voltage, the current will increase, causing more damage to human tissue and more serious consequences. On the other hand, there is a gap of about 0.1s between each contraction and expansion of the human heart. During this 0.1s process, the heart is most sensitive to electric current. If electric current passes through the heart at this moment, even if the current is very small (only a few tens of milliamperes), it will cause heart fibrillation. Therefore, the longer the power is on, the greater the possibility of overlap during this period, and the greater the danger.

3. The impact of voltage on the human body

When the resistance of the human body is constant, the higher the voltage applied to the human body, the greater the current passing through the human body. In fact, the intensity of the current passing through the human body is not proportional to the voltage acting on the human body. This is because as the voltage of the human body increases, the resistance of the human body drops sharply, causing the current to increase rapidly, which makes the harm to the human body more serious.

When 220~1000V industrial frequency voltage (50Hz) acts on the human body, the electric current passing through the human body can affect the heart and respiratory center at the same time, causing paralysis of the respiratory center and stopping breathing and heart beating. Higher voltages may also cause myocardial fiber transparency, or even myocardial fiber rupture and coagulability.

4. The impact of power frequency on the human body

The commonly used 50-60Hz industrial frequency alternating current is most harmful to the human body. The farther the frequency deviates from the industrial frequency, the less harm the alternating current will cause to the human body. In the case of direct current and high frequency, the human body can withstand a larger current value, but high voltage and high frequency current is still very dangerous to the human body.

5. Influence of human body resistance

When a person is electrocuted, the current flowing through the body (when the contact voltage is constant) is determined by the resistance value of the body. The smaller the human body's resistance, the greater the current flowing through the body, and the more dangerous it is.

Human body resistance mainly includes internal resistance and skin resistance. Internal resistance is fixed and has nothing to do with contact voltage and external conditions. It is about 500Ω. Skin resistance generally refers to the surface resistance of the hands and feet, which varies with the wetness of the skin surface and the contact voltage.

The skin resistance of different types of people varies greatly, which makes the body resistance vary greatly. It is generally believed that the human body resistance is between 1000 and 2000Ω.

There are many factors that affect the resistance of the human body. In addition to the influence of skin thickness, moist, sweaty, damaged or conductive dusty skin will reduce the resistance of the human body. Increasing the contact area and contact pressure will also reduce the resistance of the human body.

① For skin in dry places, the current path is from one hand to both feet.

② For skin in humid places, the current path is from one hand to both feet.

③ For skin in places with water vapor or particularly humid conditions, the current path is from the hands to the feet.

④ The situation in a swimming pool or bathtub is basically the body's resistance.