In most European countries the maximum contact voltage is controlled by regulatory bodies that establish standards. In Germany, for example, the "Association for Electrotechnics, Electronics and Informatics" (Verband der Elektrotechnik, Elektronik und Informationstechnik, VDE) has established that it should not exceed 50 volts for alternating current or 120 volts for direct current; in Austria the maximum values are 65 volts (alternating) or 120 volts (continuous).

For children's toys, useful animal cages and in medical and healthcare technology the maximum contact voltage is limited to only 25 volts alternating current or 60 volts direct current. In the case of low voltage, alternating current produces greater damage than direct current, while in the case of high voltage the opposite occurs. The limit between high and low voltage has been established at 1000 volts alternating current or 1500 volts direct current. For practical reasons, however, the limit value of 500 volts is set for daily clinical routine. For this reason, electrical accidents in the context of the "metro" (underground metropolitan railway) are counted among "high voltage accidents", because, with respect to their consequences, they are clearly clinically differentiated from domestic accidents caused by contact with household electrical current.

Here it is assumed, however, that the effect of the current lasts for about 100 ms. For considerably shorter exposure times, close to 1 ms, high voltage levels of 10,000 volts can be withstood without problems, such as in electric fence installations) or in electromagnetic induction ignition coils.

In contrast, an accident due to prolonged effect of high voltage mainly produces thermal damage to the tissues and manifests itself mainly in the form of burns. This case occurs because the current intensities that act there constitute a multiple of those of low voltage accidents and in addition, very high temperature electric arcs are produced that can sometimes bridge the human body. For example, an approach of less than 5 centimeters to a 30 kilovolt high voltage line produces an electric arc and for a hypothetical body resistance of 5 kiloohms, a current of 6 amperes flows through the body for a short period of time. This produces a thermal power of around 180 kilowatts. Due to this high power, an almost instantaneous evaporation of the aqueous tissues occurs in the area where the entry and exit points of the current are located, which results in the corresponding massive burns.

The effect times are in the range of about 10 milliseconds for high voltage accidents and thus several decimal powers below the effect times in low voltage accidents, which can reach the range of seconds. The short effect times in high-voltage accidents result from the fact that in most cases there is no direct contact with the conductor, so there is no risk of convulsively clinging to the electrical conductor. In the lines that carry high voltage, a flow of current in the air is already produced during the approach, through the electric arc that is formed. For this reason, in the case of high voltage, the mere approach and exceeding the safety distances are dangerous.

In some high-voltage accidents, a separation of the current circuit through the body occurs, conditioned by the process, for example when the affected person falls as a result of the electric shock and the flow of current through his or her body is interrupted. In the case of high-voltage power supply networks, starting at around 100 kilovolts, the current flow is so high on approach that a short circuit occurs and the circuit breaker trips. The peculiarity of outdoor power lines is that - within the framework of the usual automatic reconnection - the line is put under tension again within a few seconds.

When the effect time has been short, there is a small chance that the high voltage accident victim will survive. Even in cases of lightning strikes on the body, there have been individual cases of survival, however, with severe burns.

For the overall resistance of the body, the electrical resistance at the point of entry of the current (the skin), the resistance of the body (the resistance opposed to the flow of current by the tissues of the body individually and as a whole) and the resistance of the junction at the point of exit of the flow of current are decisive. The latter is usually largely determined by the nature of the support surface (for example, the characteristics of the ground) and the shoes.

As a general guideline value, a range between 500 ohms and 3 kiloohms can be assumed for the body resistance. This applies to an adult and a current path, for example from the right hand to the left or right foot. In the case of contact over a large area, in the case of thin skin (as in babies) or when traveling shorter distances, this value may be lower. If the body resistance is measured with a multimeter and at low voltage, very high values of around 1 megohm are obtained. In the specialized literature, a body resistance of 1 kΩ to 2.4 kΩ is assumed. In the case of the defibrillator that is applied to preserve life, the voltage reaches up to 750 volts and is applied between 1 and 20 ms. The bonding resistance of the electrodes to the body is purposely kept at low levels. amperes, given an assumed average body resistance of between 300-1000 ohms.[5]​.

Accidents due to electrification cause damage that depends on the duration of the effect. For example, electrostatic discharges (whose voltage can be up to over 15 kV), despite their high intensity of several amperes, generally only cause scares or possible secondary accidents, because the duration of the discharge is slightly less than a microsecond. In the case of the electric fence (with pulses of a few kilovolts) this feature is used to keep the animals away from the fence, but without causing them harm. In both cases (the electrostatic discharge and the fence) muscle contractions (cramps "Cramp (disambiguation)") are produced, which however do not lead to a dramatic lack of coordination of movements. However, startle reactions can be the cause of secondary accidents.

If the exposure time exceeds 100 milliseconds, the maximum intensity of ventricular fibrillation (threat of death) decreases drastically and abruptly. This limit is 500 mA for 20 ms of exposure, but for a duration of one second of exposure time, it drops to around 40 mA[6]​ Consequently, the differential switches (safe automatic interruption to avoid shocks) are activated with 30 milliamps after 100 ms. In the case of a higher amperage, the time until the safety triggers is shorter, reaching a minimum of around 20 ms — a value that offers protection, also in the case of contact with a conductor of the electrical network through a person who has contact with ground.

NOTE: There could be forms of electrocution linked more to the magnetic factor of the body in question than to the electrical response as such. There are no scientific arguments in the face of such factors, however. We understand that if we analyze it as an element, a field exists in itself.

Differential circuit breakers protect only in the case of a short circuit to ground, however not in the case of contact with both poles of a voltage source.

In Spain, statistics reveal a high frequency of electrical accidents. These reach an annual figure of 4,850 per year, with 7,300 fires also recorded annually caused by failures in electrical installations. In these accidents, 150 people die from electrocution and burns, while 1,500 are seriously injured per year. A study by the domestic and leisure accident detection program (DADO), dependent on the Ministry of Health and Consumer Affairs, has concluded that, at a national level, accidents due to electricity are a very common cause of hospitalization, ranking 7th among domestic accidents. Likewise, some organizations and associations in the area present wear and tear and lack of maintenance and timely modernization of electrical networks and installations as a possible cause of the accidents.[7]​.

In Germany, 200 people die annually as a result of accidents due to electrification, of which 20% occur due to high voltage and 80% due to low voltage. Approximately 30% of high voltage accidents and 3% of low voltage accidents lead to death.[3]​.

The Institute for Electrical Accident Research (IEU) of the Berufsgenossenschaft Energie Textil Elektro Medienerzeugnisse in the German city of Cologne "Cologne (Germany)") has accumulated statistical data on electrification accidents in Germany for decades. Due to the large amount of data it is possible to make statements about the mortality rate. The table below shows accident data over an unspecified period of time summarizing several decades. The data covers only accidents due to electrification in the area of ​​low voltage from 130 volts to 400 volts with 50 hertz alternating current, where a minimum exposure duration of 300 milliseconds can be assumed.

In experiments with pigs carried out by a group of researchers headed by J. Jacobson, the probability of the appearance of ventricular fibrillation has been studied[8]​ The objective was to investigate comparison factors in order to transfer the measurement data to humans. The conditions of the experiment were as follows:

For the transfer of these current values ​​to human conditions (right arm to left foot) a correction factor of 2.8 was determined. That is, the effective values ​​for the current in the table must be multiplied by 2.8. Conservatively (with a safety margin), this correction factor is taken assuming it to be 1.5.

The most common causes of accidents due to electrocution are:

In many countries there are specific legal regulations aimed at preventing these risks, especially in work contexts. In Spain, the main legal document that establishes rules in this regard is Royal Decree 614 of 2001.[9]​.

The consequences of an accident due to electrification are dependent on the specific sensitivity of each particular tissue.

The electric current preferably follows the path of least resistance. Accordingly, the different resistances offered by the tissues of the human body play a decisive role. Nervous tissues present the least resistance. In ascending sequence, they are followed by arteries, muscles, skin, tendons, adipose tissue and bones.[3]​ Consequently, in the case of direct current and low-frequency currents, the probability of damage to nervous tissue is the greatest, followed by arteries, muscles, etc.

The symptoms are:

In general, here too the chain of first aid interventions must be followed and self-protection must be unconditionally taken into account when providing help. Among others, the following is important here:

In the case of unconscious patients, once the flow of current is cut off, it is first priority to ensure breathing and cardiac and circulatory function. If necessary, cardiopulmonary resuscitation should be initiated immediately. In case of ventricular fibrillation, specialized rescue personnel can perform defibrillation. If available, a special defibrillator for lay use, accessible in some public places, can also be used.

In conscious patients, the burns should be cooled and covered with a clean, lint-free and, if possible, sterilized bandage. Even if the patient feels completely well, he or she should be kept under observation until possible cardiac damage is ruled out. For this it is necessary to perform an electrocardiogram. That is why the emergency rescue services then transport the injured person to the emergency service of a hospital. In the event that changes are detected in the electrocardiogram, it is an accident with high voltage or there are special risk factors, an observation of several hours with electrocardiogram monitoring will be carried out there.

The rest of the measures are guided according to the severity of the burns. Due to the thermal action of the electric current, a loss of fluid occurs in the body. Likewise, the burning of affected tissues (necrosis) can produce the emergence of poisonous substances. There is also a risk of sepsis with the risk of death due to bacterial infection of damaged organs. To minimize damage to the kidneys it is necessary to compensate for fluid loss through an intravenous infusion, for example, with an intravenous sodium chloride solution.

In most European countries the maximum contact voltage is controlled by regulatory bodies that establish standards. In Germany, for example, the "Association for Electrotechnics, Electronics and Informatics" (Verband der Elektrotechnik, Elektronik und Informationstechnik, VDE) has established that it should not exceed 50 volts for alternating current or 120 volts for direct current; in Austria the maximum values are 65 volts (alternating) or 120 volts (continuous).

For children's toys, useful animal cages and in medical and healthcare technology the maximum contact voltage is limited to only 25 volts alternating current or 60 volts direct current. In the case of low voltage, alternating current produces greater damage than direct current, while in the case of high voltage the opposite occurs. The limit between high and low voltage has been established at 1000 volts alternating current or 1500 volts direct current. For practical reasons, however, the limit value of 500 volts is set for daily clinical routine. For this reason, electrical accidents in the context of the "metro" (underground metropolitan railway) are counted among "high voltage accidents", because, with respect to their consequences, they are clearly clinically differentiated from domestic accidents caused by contact with household electrical current.

Here it is assumed, however, that the effect of the current lasts for about 100 ms. For considerably shorter exposure times, close to 1 ms, high voltage levels of 10,000 volts can be withstood without problems, such as in electric fence installations) or in electromagnetic induction ignition coils.

In contrast, an accident due to prolonged effect of high voltage mainly produces thermal damage to the tissues and manifests itself mainly in the form of burns. This case occurs because the current intensities that act there constitute a multiple of those of low voltage accidents and in addition, very high temperature electric arcs are produced that can sometimes bridge the human body. For example, an approach of less than 5 centimeters to a 30 kilovolt high voltage line produces an electric arc and for a hypothetical body resistance of 5 kiloohms, a current of 6 amperes flows through the body for a short period of time. This produces a thermal power of around 180 kilowatts. Due to this high power, an almost instantaneous evaporation of the aqueous tissues occurs in the area where the entry and exit points of the current are located, which results in the corresponding massive burns.

The effect times are in the range of about 10 milliseconds for high voltage accidents and thus several decimal powers below the effect times in low voltage accidents, which can reach the range of seconds. The short effect times in high-voltage accidents result from the fact that in most cases there is no direct contact with the conductor, so there is no risk of convulsively clinging to the electrical conductor. In the lines that carry high voltage, a flow of current in the air is already produced during the approach, through the electric arc that is formed. For this reason, in the case of high voltage, the mere approach and exceeding the safety distances are dangerous.

In some high-voltage accidents, a separation of the current circuit through the body occurs, conditioned by the process, for example when the affected person falls as a result of the electric shock and the flow of current through his or her body is interrupted. In the case of high-voltage power supply networks, starting at around 100 kilovolts, the current flow is so high on approach that a short circuit occurs and the circuit breaker trips. The peculiarity of outdoor power lines is that - within the framework of the usual automatic reconnection - the line is put under tension again within a few seconds.

When the effect time has been short, there is a small chance that the high voltage accident victim will survive. Even in cases of lightning strikes on the body, there have been individual cases of survival, however, with severe burns.

For the overall resistance of the body, the electrical resistance at the point of entry of the current (the skin), the resistance of the body (the resistance opposed to the flow of current by the tissues of the body individually and as a whole) and the resistance of the junction at the point of exit of the flow of current are decisive. The latter is usually largely determined by the nature of the support surface (for example, the characteristics of the ground) and the shoes.

As a general guideline value, a range between 500 ohms and 3 kiloohms can be assumed for the body resistance. This applies to an adult and a current path, for example from the right hand to the left or right foot. In the case of contact over a large area, in the case of thin skin (as in babies) or when traveling shorter distances, this value may be lower. If the body resistance is measured with a multimeter and at low voltage, very high values of around 1 megohm are obtained. In the specialized literature, a body resistance of 1 kΩ to 2.4 kΩ is assumed. In the case of the defibrillator that is applied to preserve life, the voltage reaches up to 750 volts and is applied between 1 and 20 ms. The bonding resistance of the electrodes to the body is purposely kept at low levels. amperes, given an assumed average body resistance of between 300-1000 ohms.[5]​.

Accidents due to electrification cause damage that depends on the duration of the effect. For example, electrostatic discharges (whose voltage can be up to over 15 kV), despite their high intensity of several amperes, generally only cause scares or possible secondary accidents, because the duration of the discharge is slightly less than a microsecond. In the case of the electric fence (with pulses of a few kilovolts) this feature is used to keep the animals away from the fence, but without causing them harm. In both cases (the electrostatic discharge and the fence) muscle contractions (cramps "Cramp (disambiguation)") are produced, which however do not lead to a dramatic lack of coordination of movements. However, startle reactions can be the cause of secondary accidents.

If the exposure time exceeds 100 milliseconds, the maximum intensity of ventricular fibrillation (threat of death) decreases drastically and abruptly. This limit is 500 mA for 20 ms of exposure, but for a duration of one second of exposure time, it drops to around 40 mA[6]​ Consequently, the differential switches (safe automatic interruption to avoid shocks) are activated with 30 milliamps after 100 ms. In the case of a higher amperage, the time until the safety triggers is shorter, reaching a minimum of around 20 ms — a value that offers protection, also in the case of contact with a conductor of the electrical network through a person who has contact with ground.

NOTE: There could be forms of electrocution linked more to the magnetic factor of the body in question than to the electrical response as such. There are no scientific arguments in the face of such factors, however. We understand that if we analyze it as an element, a field exists in itself.

Differential circuit breakers protect only in the case of a short circuit to ground, however not in the case of contact with both poles of a voltage source.

In Spain, statistics reveal a high frequency of electrical accidents. These reach an annual figure of 4,850 per year, with 7,300 fires also recorded annually caused by failures in electrical installations. In these accidents, 150 people die from electrocution and burns, while 1,500 are seriously injured per year. A study by the domestic and leisure accident detection program (DADO), dependent on the Ministry of Health and Consumer Affairs, has concluded that, at a national level, accidents due to electricity are a very common cause of hospitalization, ranking 7th among domestic accidents. Likewise, some organizations and associations in the area present wear and tear and lack of maintenance and timely modernization of electrical networks and installations as a possible cause of the accidents.[7]​.

In Germany, 200 people die annually as a result of accidents due to electrification, of which 20% occur due to high voltage and 80% due to low voltage. Approximately 30% of high voltage accidents and 3% of low voltage accidents lead to death.[3]​.

The Institute for Electrical Accident Research (IEU) of the Berufsgenossenschaft Energie Textil Elektro Medienerzeugnisse in the German city of Cologne "Cologne (Germany)") has accumulated statistical data on electrification accidents in Germany for decades. Due to the large amount of data it is possible to make statements about the mortality rate. The table below shows accident data over an unspecified period of time summarizing several decades. The data covers only accidents due to electrification in the area of ​​low voltage from 130 volts to 400 volts with 50 hertz alternating current, where a minimum exposure duration of 300 milliseconds can be assumed.

In experiments with pigs carried out by a group of researchers headed by J. Jacobson, the probability of the appearance of ventricular fibrillation has been studied[8]​ The objective was to investigate comparison factors in order to transfer the measurement data to humans. The conditions of the experiment were as follows:

For the transfer of these current values ​​to human conditions (right arm to left foot) a correction factor of 2.8 was determined. That is, the effective values ​​for the current in the table must be multiplied by 2.8. Conservatively (with a safety margin), this correction factor is taken assuming it to be 1.5.

The most common causes of accidents due to electrocution are:

In many countries there are specific legal regulations aimed at preventing these risks, especially in work contexts. In Spain, the main legal document that establishes rules in this regard is Royal Decree 614 of 2001.[9]​.

The consequences of an accident due to electrification are dependent on the specific sensitivity of each particular tissue.

The electric current preferably follows the path of least resistance. Accordingly, the different resistances offered by the tissues of the human body play a decisive role. Nervous tissues present the least resistance. In ascending sequence, they are followed by arteries, muscles, skin, tendons, adipose tissue and bones.[3]​ Consequently, in the case of direct current and low-frequency currents, the probability of damage to nervous tissue is the greatest, followed by arteries, muscles, etc.

The symptoms are:

In general, here too the chain of first aid interventions must be followed and self-protection must be unconditionally taken into account when providing help. Among others, the following is important here:

In the case of unconscious patients, once the flow of current is cut off, it is first priority to ensure breathing and cardiac and circulatory function. If necessary, cardiopulmonary resuscitation should be initiated immediately. In case of ventricular fibrillation, specialized rescue personnel can perform defibrillation. If available, a special defibrillator for lay use, accessible in some public places, can also be used.

In conscious patients, the burns should be cooled and covered with a clean, lint-free and, if possible, sterilized bandage. Even if the patient feels completely well, he or she should be kept under observation until possible cardiac damage is ruled out. For this it is necessary to perform an electrocardiogram. That is why the emergency rescue services then transport the injured person to the emergency service of a hospital. In the event that changes are detected in the electrocardiogram, it is an accident with high voltage or there are special risk factors, an observation of several hours with electrocardiogram monitoring will be carried out there.

The rest of the measures are guided according to the severity of the burns. Due to the thermal action of the electric current, a loss of fluid occurs in the body. Likewise, the burning of affected tissues (necrosis) can produce the emergence of poisonous substances. There is also a risk of sepsis with the risk of death due to bacterial infection of damaged organs. To minimize damage to the kidneys it is necessary to compensate for fluid loss through an intravenous infusion, for example, with an intravenous sodium chloride solution.