Today we have a very interesting and informative article about the effect of electric current on the human body.

I think that each of you at least once thought about the danger of electric current and its consequences. And someone can (God forbid, of course) experienced it on himself.

Introduction

The environment in which we live, as well as everything that surrounds us, contains a potential danger to us. One such threat is electric shock. In addition to the natural environment (), there is also a domestic and industrial one, which are constantly developing and progressing (improvement of technology and the use of new developments), which means that they carry an even greater threat.

Despite the fact that the check of devices is carried out very high quality, no one is immune from errors and unforeseen situations.

Unfortunately, most often electric shock, both at work and at home, happens because precautions and elementary precautions are not followed.

The causes of malfunction and breakdown of appliances (when using an electric kettle, microwave oven, and other household appliances;, or with, or with, and much more) used in everyday life, and electrical units and used directly in production are also not excluded.

As statistics show, the percentage of injuries received from electric shock is much lower compared to injuries received in other ways.

But with electric shock, the percentage of severe injuries and death is much higher.

What is electric current?

The effect of electric current on a person, as well as its consequences, can be better understood after we consider in more detail what a current is.

Electric current is the ordered movement of electrons in a conductor or semiconductor.

In a section of the circuit, the current strength is directly proportional to the voltage at the ends of the section (potential difference) and inversely proportional to the resistance of this section of the circuit -.

In the case when a person touches a conductor that is energized, he thereby includes himself in the circuit. A current will pass through the human body if it is not isolated from the ground, or if it touches the conductor simultaneously with another object that has the opposite potential.

This formula is applicable to two-phase, or it is also called two-pole contact with live parts under voltage. It looks like this:

When a person touches two phases of an electrical installation, a circuit appears through the human body, through which an electric current passes. The magnitude of the electric current in this case depends ONLY on the voltage of the electrical installation and the internal resistance of a person.

For example, the phase voltage of an electrical installation is 220 (V), the line voltage is 380 (V), respectively. Under normal conditions, the average human resistance is approximately 1000 (Ohm).

In this case, the current that will pass through a person when he simultaneously touches two phases (A and B) will be equal to 380 (mA). And this is deadly!

A little differently, the calculation of the current passing through the human body will occur if it touches one phase in a network with an isolated neutral.

In this case, the current circuit will close through the human body, then to the ground and through the phase capacitances.

What threatens the action of electric current?

Electric current produces the following effects on the human body passing through it:

1. Thermal

With such an impact, overheating occurs, as well as a functional disorder of the organs located in the path of the current.

2. Electrolytic

With the electrolytic action of the current in the liquid, which is in the tissues of the body, electrolysis occurs, including in the blood, due to which its physico-chemical composition is disturbed.

3. Mechanical

During mechanical action, tissue rupture and stratification occurs, impact action from the evaporation of fluid from the tissues of the human body. This is followed by a strong contraction of the muscles, up to their complete rupture.

4. Biological

The biological effect of the current carries irritation and overexcitation of the nervous system.

5. Luminous

This action causes damage to the eyes.

Consequences under the action of electric current

The depth and nature of the impact depends on:

• kind of current (alternating or direct) and its strength
• the time of its exposure and the path it takes through the person
• psychological and physiological state of the person.

So, for example, under normal conditions and the presence of dry, intact skin, the resistance of a person can reach several hundred (kOhm), but if the conditions are unfavorable, then the value can drop to one kiloohm.

Below, I will give you an example of a table of how an electric current of various sizes acts on the human body.

A current with a strength of about 1 (mA) will already be quite noticeable. At higher readings, painful and unpleasant muscle contractions in humans will be experienced.

With a current of 12-15 (mA), a person can no longer control his muscular system and is not able to independently break away from the damaging current source.

If the current is higher than 75 (mA), then its effect will lead to paralysis of the respiratory muscles and, consequently, to respiratory arrest.

If the current continues to increase, then the heart will fibrillate and stop.

More dangerous than direct current is alternating current.

It is also of no small importance what parts of the body a person touches the current-carrying part. The most dangerous are those paths during which the spinal cord and brain (head-legs and head-arms), lungs and heart (legs-arms) are affected.

The main damaging factors

1. Electric shock

It excites the muscles of the body, leads to convulsions, and then to respiratory and cardiac arrest.

2. Electrical burns

They result from the release of heat after the passage of current through the human body.

There are several types of burns that occur depending on the parameters of the electrical circuit, as well as the state of the person at that moment:

• skin redness
• blistering burns
• tissue charring is possible
• metallization of the skin, accompanied by the penetration of pieces of metal into it, in case of melting of the metal.

Contact voltage is the voltage that acts on a person during his contact with one pole, or with the phase of a current source.

The most dangerous areas of the body are the areas of the temples, back, backs of the hands, shins, back of the head, and also the neck.

Read my article about the group that happened to two electricians when switching in an electrical installation with a voltage of 10 (kV).

P.S. If you have any questions while reading the material, then ask about it in the comments.

The effect of electric current on the human body. Factors affecting the risk of electric shock.

Passing through the body, the electric current produces 3 types of effects: thermal, electrolytic and biological.

thermal the effect is manifested in burns of external and internal parts of the body, heating of blood vessels and blood, etc., which causes serious functional disorders in them.

electrolytic- in the decomposition of blood and other organic fluids, thereby causing significant violations of their physico-chemical compositions and tissue as a whole.

biological the action is expressed in irritation and excitation of the living tissues of the body, which may be accompanied by involuntary convulsive muscle contractions, including the muscles of the heart and lungs. In this case, various disorders can occur in the body, including mechanical damage to tissues, as well as a violation and even complete cessation of the activity of the respiratory and circulatory organs.

There are two main types of damage to the body: electrical trauma and electrical shock.

electrical injury- these are clearly expressed local violations of the integrity of body tissues caused by exposure to electric current or an electric arc. Usually these are superficial injuries, that is, lesions of the skin, and sometimes other soft tissues, as well as ligaments and bones. Electrical burn- the most common electrical injury: burns occur in most victims of electric current 3 kind burns: current, or contact, arising from the passage of current directly through the human body; arc, due to the impact on the human body of an electric arc, but without the passage of current through the human body; mixed, resulting from the action of both of these factors simultaneously, that is, the action of an electric arc and the passage of current through the human body.

electric shock- this is the excitation of living tissues by an electric current passing through the body, accompanied by involuntary convulsive muscle contractions. Depending on the outcome of the negative impact of the current on the body, electric shocks can be conditionally divided into the following four degrees:

1) convulsive muscle contraction without loss of consciousness;

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

3) loss of consciousness and impaired cardiac activity or respiration (or both);

4) clinical death, that is, the absence of breathing and blood circulation.

Prevention of electrical injuries consists in observing the established rules and safety measures during operation, installation and repair

electrical installations. In order to prevent chronic electrical injury that can occur as a result of prolonged exposure to electric fields generated near sufficiently powerful high and ultra-high frequency generators, shielding of generators, special protective suits and systematic medical supervision of those working in these conditions are used.

Risk factors for the body: muscle cramps, people can not unclench their hands; fibrillation (heart muscles chaotically contract. At 50 Hz - cardiac arrest), the effect on the brain. Risk factors: lower atmospheric pressure, closed rooms due to reduced oxygen partial pressure.

Factors affecting the severity of electric shock:

Exposure to electrical current can cause extremely dangerous heart rhythm disturbances, ventricular fibrillation, respiratory arrest, burns, and death. The severity of the injury depends on:

current strength; tissue resistance to the passage of electric current; type of current (alternating, direct); current frequency and duration of exposure.

The electric current in the circuit is always manifested by some of its action. This can be both work in a certain load, and the accompanying action of the current. Thus, by the action of the current, one can judge its presence or absence in a given circuit: if the load is working, there is a current. If a typical current-related phenomenon is observed, there is current in the circuit, etc.

In general, electric current is capable of causing various actions: thermal, chemical, magnetic (electromagnetic), light or mechanical, and various kinds of current actions often appear simultaneously. These phenomena and actions of the current will be discussed in this article.

Thermal effect of electric current

When a direct or alternating electric current passes through a conductor, the conductor heats up. Such heating conductors under different conditions and applications can be: metals, electrolytes, plasma, metal melts, semiconductors, semimetals.

In the simplest case, if, say, an electric current is passed through a nichrome wire, then it will heat up. This phenomenon is used in heating devices: in electric kettles, boilers, heaters, electric stoves, etc. In electric arc welding, the temperature of the electric arc generally reaches 7000 ° C, and the metal melts easily - this is also the thermal effect of the current.

The amount of heat released in the circuit section depends on the voltage applied to this section, the value of the current flowing and on the time of its flow ().

By transforming Ohm's law for a section of the circuit, it is possible to use either voltage or current to calculate the amount of heat, but then it is imperative to know the resistance of the circuit, because it is it that limits the current and causes, in fact, heating. Or, knowing the current and voltage in the circuit, you can just as easily find the amount of heat released.

Chemical action of electric current

Electrolytes containing ions, under the action of a direct electric current - this is the chemical effect of the current. Negative ions (anions) are attracted to the positive electrode (anode) during electrolysis, and positive ions (cations) are attracted to the negative electrode (cathode). That is, the substances contained in the electrolyte, in the process of electrolysis, are released on the electrodes of the current source.

For example, a pair of electrodes is immersed in a solution of a certain acid, alkali or salt, and when an electric current is passed through the circuit, a positive charge is created on one electrode, and a negative charge on the other. The ions contained in the solution begin to be deposited on the electrode with the opposite charge.

For example, during the electrolysis of copper sulfate (CuSO4), copper cations Cu2+ with a positive charge move to a negatively charged cathode, where they receive the missing charge, and become neutral copper atoms, settling on the surface of the electrode. The hydroxyl group -OH will give up electrons at the anode, and oxygen will be released as a result. Positively charged H+ hydrogen cations and negatively charged SO42- anions will remain in solution.

The chemical action of electric current is used in industry, for example, to decompose water into its constituent parts (hydrogen and oxygen). Also, electrolysis allows you to get some metals in their pure form. With the help of electrolysis, a thin layer of a certain metal (nickel, chromium) is coated on the surface - this, etc.

In 1832, Michael Faraday found that the mass m of the substance released on the electrode is directly proportional to the electric charge q that has passed through the electrolyte. If a direct current I is passed through the electrolyte for a time t, then Faraday's first law of electrolysis is valid:

Here the coefficient of proportionality k is called the electrochemical equivalent of the substance. It is numerically equal to the mass of the substance released during the passage of a single electric charge through the electrolyte, and depends on the chemical nature of the substance.

In the presence of an electric current in any conductor (solid, liquid or gaseous), a magnetic field is observed around the conductor, that is, a current-carrying conductor acquires magnetic properties.

So, if a magnet is brought to the conductor through which the current flows, for example, in the form of a magnetic compass needle, then the arrow will turn perpendicular to the conductor, and if the conductor is wound on an iron core and a direct current is passed through the conductor, the core will become an electromagnet.

In 1820, Oersted discovered the magnetic effect of current on a magnetic needle, and Ampere established the quantitative laws of the magnetic interaction of conductors with current.

A magnetic field is always generated by current, that is, by moving electric charges, in particular by charged particles (electrons, ions). Oppositely directed currents repel each other, unidirectional currents attract each other.

Such a mechanical interaction occurs due to the interaction of magnetic fields of currents, that is, it is, first of all, a magnetic interaction, and only then a mechanical one. Thus, the magnetic interaction of currents is primary.

In 1831, Faraday established that a changing magnetic field from one circuit generates a current in another circuit: the generated emf is proportional to the rate of change of the magnetic flux. It is logical that it is the magnetic action of currents that is used to this day in all transformers, and not only in electromagnets (for example, in industrial ones).

In its simplest form, the luminous effect of electric current can be observed in an incandescent lamp, the spiral of which is heated by the current passing through it to white heat and emits light.

For an incandescent lamp, light energy accounts for about 5% of the electricity supplied, the remaining 95% of which is converted into heat.

Fluorescent lamps more efficiently convert current energy into light - up to 20% of electricity is converted into visible light thanks to the phosphor, which receives from an electrical discharge in mercury vapor or in an inert gas such as neon.

The luminous effect of electric current is realized more effectively in light-emitting diodes. When an electric current is passed through the p-n junction in the forward direction, charge carriers - electrons and holes - recombine with the emission of photons (due to the transition of electrons from one energy level to another).

The best light emitters are direct-gap semiconductors (that is, those that allow direct optical band-to-band transitions), such as GaAs, InP, ZnSe, or CdTe. By varying the composition of semiconductors, it is possible to create LEDs for all possible wavelengths from ultraviolet (GaN) to mid-infrared (PbS). The efficiency of an LED as a light source reaches an average of 50%.

As noted above, each conductor through which an electric current flows forms around itself. Magnetic actions are converted into motion, for example, in electric motors, in magnetic lifting devices, in magnetic valves, in relays, etc.

The mechanical action of one current on another describes Ampère's law. This law was first established by André Marie Ampère in 1820 for direct current. From it follows that parallel conductors with electric currents flowing in one direction attract, and in opposite directions they repel.

Ampère's law is also called the law that determines the force with which a magnetic field acts on a small segment of a current-carrying conductor. The force with which the magnetic field acts on a conductor element with current in a magnetic field is directly proportional to the current in the conductor and the vector product of the conductor length element and magnetic induction.

It is based on this principle, where the rotor plays the role of a frame with a current, oriented in the external magnetic field of the stator with a torque M.

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How does electric current affect a person?

electrical injury

An electric current strikes a person suddenly. The passage of current through the human body causes electrical injuries of a different nature: electric shock, burns, electrical marks.

Electric shock is called electric shock, in which shock occurs, that is, a kind of severe reaction of the body to a strong stimulus - an electric current.

The outcome of shock is different. In severe cases, shock is accompanied by circulatory and respiratory disorders. Fibrillation of the heart is possible, that is, instead of a simultaneous rhythmic (about 1 time per second) contraction of the heart muscle, a chaotic twitching of its individual fibers - fibrils occurs. This stops the normal functioning of the heart, blood flow stops, and death can occur.

The defeat of a person by current at a voltage of up to 1000 V is in most cases accompanied by an electric shock.

Burns occur when exposed to a significant current (about 1 BUT and more) or from an electric arc. So, when approaching current-carrying parts with a voltage above 1000 V, an unacceptably small distance between the current-carrying part and the human body causes a spark discharge, and then an electric arc, which causes a severe burn. In case of accidental contact with a live part with a voltage of up to 1000 V, the current passing through the human body heats the tissues up to 60-70°C. This causes the protein to fold. Electrical burns are difficult to heal. They capture a large surface of the body and penetrate deeply.

Electric signs (marks) are skin necrosis in the form of yellow callus with a gray border at the place of current entry and exit. If the lesion has penetrated deeply, then the tissues of the body gradually die off.

The nature of the impact of alternating electric current, depending on its magnitude, is given in table. one

From Table. 1 it follows that a current of more than 15 mA is dangerous for a person, at which a person cannot free himself. A current of 50 mA causes severe injury. A current of 100 mA, acting for more than 1-2 seconds, is deadly.

Factors affecting the outcome of the lesion

The magnitude of the electric current passing through the human body, and consequently, the outcome of the lesion depends on many circumstances.

The most dangerous is alternating current with a frequency of 50-500 Hz. Most people retain the ability to independently free themselves from currents of this frequency at very low values ​​(9-10 mA). Direct current is also dangerous, but it is possible to get rid of it on your own at somewhat large values ​​(20-25 mA).

The magnitude of the current depends on the voltage of the electrical installation and on the resistances of all elements of the circuit through which the current flows, including the resistance of the human body. Body resistance is made up of active and capacitive resistances of the skin and internal organs . Dry, undamaged skin has a resistance of about 100,000 ohms, wet - about 1000 ohms, and the resistance of internal tissues (with the stratum corneum removed) is about 500-1000 ohms. The skin of the face and armpits has the least resistance.

The resistance of the human body is a non-linear quantity. It sharply, disproportionately decreases with an increase in the voltage applied to the body, an increase in the time of current exposure, with an unsatisfactory physical and mental state, with large and tight contact with the current-carrying part, etc. From fig. 1 it follows that with an increase in the voltage applied to the body from 0 to 140 V, the resistance of the body decreases nonlinearly from tens of thousands to 800 ohms (curve 1). Accordingly, the current passing through the body increases (curve 2).

The resistance of the human body (Ohm) is approximately determined by the formula

Z people \u003d U pr / I people

where U pr- voltage drop across the resistance of the human body - V.

In calculations for electrical safety, it (also approximately) is taken equal to:

Z people = 1000 Ohm

The most dangerous current path through the heart, brain, lungs. Characteristic paths: palm - feet, palm - palm, foot - foot. However, a fatal injury is also possible when the current passes along a path that, it would seem, does not affect vital organs, for example, through the lower leg to the foot. This phenomenon is explained by the fact that the current in the body flows along the path of least resistance (nerves, blood), and not in a straight line - through tissues with high resistance (muscles, fat).

It has been established that the outcome of electric shock depends on the physical and mental state of a person. . If he is hungry, tired, intoxicated or unhealthy, then the likelihood of a severe injury increases. Women, adolescents, men with poor health are able to withstand significantly lower currents (within 6 mA) than healthy men (12-15 mA).

The duration of exposure is one of the main factors affecting the outcome of the lesion. The cycle of the heart is approximately 1 s. There is a phase in the cycle T, equal to 0.1 s, when the heart muscle is relaxed and it is most vulnerable to current: fibrillation may occur. The shorter the current exposure time (less than 0.1 s), the less the likelihood of fibrillation. Prolonged (several seconds) exposure to current leads to a severe outcome: the resistance of the body decreases, and the lesion current increases.

The mechanism of the impact of electric current on a person is complex. On the one hand, in high-voltage installations there were cases when a short-term (hundredths of a second) exposure to a current of several amperes did not lead to death. On the other hand, it has been found that death is possible at a voltage of 12-36 V, when a current of several milliamps is applied. This happens as a result of touching the current-carrying part with the most vulnerable part of the body - the back of the hand, cheek, neck, shin, shoulder.

Given the danger of electrical installations with voltages both up to 1000 and above 1000 V, each worker must firmly remember that you can’t touch live parts, no matter what voltage they are under, you can’t get close to live parts in high-voltage installations, you can’t touch them unnecessarily to the metal structures of switchgear, power transmission line supports, to equipment cases that can become energized when live parts are shorted to them.

Earth faults in electrical installations are usually switched off by the main relay protection in a fraction of a second. Therefore, electrical safety devices (grounding, etc.) can be calculated based on large allowable currents. In this case, a current that does not cause fibrillation in 99.5% of experimental animals, whose body weight and heart weight is close to human, is considered acceptable. Permissible values ​​of current and voltage of contact, obtained in laboratory studies, are given in Table. 2

From Table. 3-2 it follows that currents over 65 mA and voltages over 65 V are allowed for less than 1 s.

The impact of electric current on the human body is unique and versatile. Passing through the human body, the electric current produces thermal, electrolytic, mechanical and biological effects.

As you know, the human body consists of a large amount of salts and liquids, which is a good conductor of electricity, so the effect of electric current on the human body can be lethal.

It's not voltage that kills, it's current.

This is perhaps the most basic problem of the vast majority of ordinary people. Everyone thinks tension is dangerous, but they are only partly right. By itself, the voltage (potential difference between two points of the circuit) does not affect the human body in any way. All processes related to the lesion take place under the influence of an electric current of one size or another.

Higher current - more danger. Partially correct about voltage is that the current strength depends on its value. That's right - no more, no less. Everyone who went to school will easily remember Ohm's law:

Current = voltage / resistance (I=U/R)

If we consider the resistance of the human body as a constant value (this is not entirely true, but more on that later), then the current, and hence the damaging effect of electricity, will directly depend on the voltage. Higher voltage - higher current. This is where the belief comes from that the higher the voltage, the more dangerous it is.

Connection of current with resistance

According to Ohm's law, current also depends on resistance. The lower the resistance, the higher and, therefore, the more dangerous the current. There will be no conditions for the passage of current (circuit resistance is infinite) - there will be no danger at any voltage

Suppose (only theoretically) you stick your finger into the socket while standing on damp ground and get a powerful blow. Since your body has low resistance, the current from the outlet will rush through the human-to-ground circuit.

And now, before you put your finger in the socket, you stood on a dielectric mat or put on dielectric boots. The resistance of a dielectric mat or bot is so high that the current through them and, accordingly, you, will be negligible - microamps. And although you will be under a voltage of 220 V, there will be practically no current flowing through you, which means that you will not receive an electric shock. You won't feel any discomfort at all.

It is for this reason that a bird sitting on a high-voltage wire (it is bare, do not hesitate) calmly cleans its feathers. Moreover, if an overly jumpy person, a kind of Batman, jumps up and grabs the phase wire of a power line, nothing will happen to him either, although he will be energized in kilovolts. Hang and jump. Electricians even have this type of work - energized (do not confuse with work on electrical installations that are energized).

But back to the version with the socket, in which you stood on damp ground. Hit is a fact. But how strong?

Determination of the degree of damage

The resistance of the human body under normal conditions is 500-800 ohms. The resistance of the damp earth can be ignored - it can turn out to be extremely low and not affect the result of the calculations, but in fairness let's add another 200 ohms to the resistance of the body. Quickly calculate with the above formula:

220 / 1000 = 0.22 A or 220 mA

The degree of action of current on the human body Briefly, it can be expressed through the following list:

• 1-5 mA - tingling sensation, slight cramps.
• 10-15 mA - severe muscle pain, convulsive contraction. It is possible to free yourself from the action of the current.
• 20-25 mA - severe pain, muscle paralysis. It is almost impossible to get rid of the action of the current on your own.
• 50-80 mA - respiratory paralysis.
• 90-100 mA - cardiac arrest (fibrillation), death.

Obviously, a current of 220 mA far exceeds the lethal value. Many will say that the resistance of the human body is much more than a kilo-ohm. Right. The resistance of the upper layer of the skin (epidermis) can reach a megaohm or even more, but this layer is so thin that it immediately breaks through with a voltage above 50 V. Therefore, in the case of electrical outlets, you can not count on your epidermis.

The danger depends on the frequency

At voltages up to 400 V, alternating current with a frequency of 50 Hz is much more dangerous than direct current, since, firstly, the resistance of the human body to alternating current is lower than direct current. Secondly, the biological effect of an alternating type electric current is much higher than that of a direct one.

At high voltages, and, as a result, high direct currents, the electrolysis process that occurs in cellular fluids is added to the list of damaging factors. In this case, direct current becomes more dangerous than alternating current. It simply changes the chemical composition of body fluids. As the frequency increases, the picture changes somewhat: the current begins to have a surface character.

In other words, it passes over the surface of the body without penetrating deep into the body. The higher the frequency, the smaller the "layer" of the human body suffers. For example, at a frequency of 20-40 kHz, heart fibrillation does not occur, since no current flows through it. Instead of this misfortune, another one appears - at a high frequency, a severe lesion (burn) of the upper layers of the body occurs, which, with no less success, leads to death.

Electrical pathways through the body

The effect of current on the human body depends not only on its magnitude, but also on the path of passage. If a person simply climbed into the socket with his fingers, then the current will flow only through the brush. He stands on the damp floor and touched the bare wire - through his arm, torso and legs.

It is quite obvious that in the first case only the hand will suffer, and it will not be difficult to get rid of the action of the electric current, since the muscles of the arm above the hand will retain controllability. The second case is much more serious, especially if the hand is left. Here, the current fetters the muscles, preventing a person from freeing himself from the action of electricity. But worst of all, in this case, the lungs, heart and other vital organs suffer. The same problems await on the way hand-hand, head-hand, head-legs.

The effect of electric current on a person

Passing through the human body, electricity has several types of effects on the body at once. Total there are four of them:

1. Thermal (heating).
2. Electrolytic (dissociation leading to a violation of the chemical properties of liquids).
3. Mechanical (tissue rupture as a result of hydrodynamic impact and convulsive muscle contraction).
4. Biological (violation of biological processes in cells).

Depending on the magnitude, path of passage, frequency and duration of exposure, electric current can cause completely different damage to the body, both in nature and in severity. . The most common of them can be considered:

1. Convulsive muscle contraction.
2. Convulsive muscle contraction, breathing and heartbeat persist.
3. Respiratory arrest, possible cardiac arrhythmias.
4. Clinical death, no breathing or heartbeat.

Safe Voltage

To clarify this issue, you do not need to use any formulas - everything has already been calculated, recorded and endorsed by specially trained people. Depending on the type of current according to PES It is recommended to consider as a safe voltage:

Variable up to 25 V or constant up to 60 V - in rooms without increased danger;

AC up to 6 V or DC up to 14 V - in high-risk rooms (damp, metal floors, conductive dust, etc.).

Definition of step voltage

This question, which is of purely academic interest, requires an answer, if only because almost anyone who leaves the house can get under the stress of a step. So, suppose a wire breaks on a power line and falls to the ground. In this case, no short circuit occurred (the earth is relatively dry and the emergency protection device did not work). But even dry ground has a fairly low resistance and current flows through it. Moreover, it flowed in all directions, both in depth and on the surface.

Due to the resistance of the soil, when moving away from the wire, the voltage gradually drops and disappears at some distance. But in fact, it does not disappear without a trace, but is evenly distributed, "smeared" on the ground. If you stick the voltmeter probes into the ground at a certain distance from each other, the device will show a voltage that will be the higher, the closer the fallen wire and the greater the distance between the probes.

If instead of probes there are legs of a person briskly going to work, then he will fall under voltage, which is called stepping. The closer the dropped wire and the wider the pitch, the higher the voltage.

This type of tension threatens with the same thing as the usual one - with a defeat of one degree or another. Even if the current flowing through the leg-leg loop turns out to be not particularly dangerous, it may well cause convulsive muscle contraction. The victim falls and gets under a higher voltage (the distance of the arm - the leg is greater), which, moreover, begins to flow through the vital organs. Now there can be no talk of safety - a person has come under life-threatening stress.

If you feel that you have fallen under the voltage of a step (the sensation can be compared with those that arise from touching an “electric-fighting” washing machine). Put your feet together, minimizing the distance between them, and look around. If you see an electrical pole (pole) or a transformer substation within a radius of 10-20 m, then, most likely, the ears of the problem grow from there. Start moving in the opposite direction from them in steps of a few centimeters. You remember that the smaller the step, the lower the step voltage. If it is impossible to understand where the tension came from, choose an arbitrary direction.