Electrical injury is a physiological reaction caused by an electric current passing through the body (human). Electrical shock occurs when the contact of the body (human) with any source of electricity that causes sufficient current to pass through the meat, viscera or hair of the victim. Physical contact with cables or energized devices is the most common cause of electrical shock. In the case of high-voltage exposure, such as on power transmission towers, physical contact with cables or energized objects may not necessarily cause electric shock, since the voltage may be sufficient to "skip" the air gap between the electrical device and the victim.
Injuries related to electric shock depend on the amount of current. Very small currents may not be visible or produce a mild tingling sensation. Shocks caused by a normally harmless low current can shock a person and cause injury because of a sudden jerking of a power source, which results in someone striking a stationary object, dropping a detained or falling object. Stronger currents can cause some degree of discomfort or pain, while more intense currents can cause unwanted muscle contractions, preventing victims from freeing up electricity. Larger currents usually cause tissue damage and may trigger cardiac fibrillation or cardiac arrest, which can eventually be fatal. If the death of the result of electric shock the cause of death is commonly referred to as electric shock.
Video Electrical injury
Signs and symptoms
Burns
Heating due to resistance can cause extensive and deep burns. A voltage level of 500 to 1000 volt tends to cause internal burns because of the enormous energy (which is proportional to the duration multiplied by the square of the voltage divided by the resistance) available from the source. The current damage is through network heating. For most cases of high-energy electrical trauma, Joule heating in deeper tissues along the extremities will reach damaging temperatures in a few seconds.
Ventricular fibrillation
Domestic power supply voltage (110 or 230 V), 50 or 60 Hz alternating current (AC) through the chest for a fraction of a second can induce ventricular fibrillation at currents as low as 30 mA . With direct current (DC), 300 to 500 mA is required. If the current has a direct path to the heart (for example, via a cardiac catheter or other electrode type), a much lower current of less than 1 mA (AC or DC) may cause fibrillation. If not treated promptly with defibrillation, fibrillation is usually fatal because all heart muscle fibers move independently rather than in the coordinated pulse needed to pump blood and maintain circulation. Above 200 mA, muscle contraction is so strong that the heart muscles can not move at all, but this condition prevents fibrillation.
Neurological effects
Currently it can cause disruption to the control of nerves, especially above the heart and lungs. Repeated or severe electrical shock that does not cause death has been shown to cause neuropathy. Recent research has found that functional differences in neural activation during spatial working memory and implicit learning of oculomotor tasks have been identified in the victims of electric shock.
When the current path through the head, it appears that, with sufficient current applied, loss of consciousness almost always happens quickly. (This is borne out by some self-limited experiments by early designers of electric chairs and by research from the field of farms, where electric shock has been studied extensively).
Arc-flash danger
OSHA found that up to 80 percent of its electrical injuries involve thermal burns due to arcing. Flash arcs in electrical faults produce the same type of light radiation from which the electric welders protect themselves using face shields with dark glass, heavy leather gloves, and full clothing coverage. The heat produced can cause severe burns, especially in unprotected flesh. The explosive arc produced by evaporated metal components can break bones and damage internal organs. The degree of hazard that exists in a particular location can be determined with a detailed analysis of the electrical system, and the appropriate protection that is used if the electrical work has to be done with the power on.
Maps Electrical injury
Pathophysiology
The minimum current that humans can feel depends on the type of current (AC or DC) and the frequency for AC. One can sense at least 1 mA (rms) AC at 60 Hz, while at least 5 mA for DC. Approximately 10 milliamperes, AC current that passes through a 68 kilogram (150 pound) human arm can cause strong muscle contraction; the victim can not control the muscles voluntarily and can not release the electrical object. This is known as "leave the threshold" and is a criterion for shock hazards in electrical regulations.
The current may be, if sufficiently high and transmitted at sufficient stress, causing tissue damage or fibrillation which may cause cardiac arrest; more than 30 mA of AC (rms, 60Ã, Hz) or 300 - 500 mA of DC at high voltage can cause fibrillation. The continuous electric shock from AC at 120 V, 60 Hz is a very dangerous source of ventricular fibrillation because it usually exceeds the let-go threshold, while not providing enough initial energy to push people away from the source. However, the potential seriousness of the shock depends on the path through the body taken by the current. If the voltage is less than 200 V, then the human skin, more precisely the stratum corneum, is a major contributor to body impedance in the case of macroshock - the passage of the current between the two points of contact on the skin. But the characteristics of the skin is not linear. If the voltage is above 450-600 V, then the skin dielectric damage occurs. The protection offered by the skin is lowered by sweat, and this is accelerated if electricity causes muscles to contract above the let-go threshold for a sustained period of time.
If an electrical circuit is formed by electrodes introduced in the body, through the skin, then the potential for death is much higher if the circuit through the heart is formed. This is known as microshock. A current of only 10 Ã,ÂμA can be sufficient to cause fibrillation in this case with a probability of 0.2%.
Endurance
The voltage required for the electrocution depends on the current through the body and the duration of the current. Ohm's law states that the current drawn depends on the endurance of the body. Human skin resilience varies from person to person and fluctuates between different times of the day. NIOSH states "In dry conditions, the resistance offered by the human body may be as high as 100,000 ohms.The wet or damaged skin can lower the immune system up to 1,000 ohms," adding that "high-voltage electrical energy quickly breaks down human skin, reduces human body resistance up to 500 ohms ".
The International Electrotechnical Commission provides the following values ​​for total body impedance from hand to hand series for dry skin, large contact area, AC 50 Hz current (columns containing impedance distributions in population percentiles, for example 100a, V). 50% of the population has an impedance of 1875? Or less):
Characteristics of voltage current on skin
The current-voltage characteristic of human skin is non-linear and depends on many factors such as the intensity, duration, history, and frequency of electrical stimuli. The activity of sweat glands, temperature, and individual variations also affect the characteristics of skin tides. In addition to non-linearity, skin impedance shows asymmetrical properties and time varies. These properties can be modeled with reasonable accuracy. Resistance measurements performed at low voltages using a standard ohmmeter do not accurately represent the human skin impedance over a significant range of conditions.
For sinusoidal electric stimulation of less than 10 volts, the skin's current-voltage characteristics are quasilinear. Over time, electrical characteristics can become non-linear. The time required varies from seconds to minutes, depending on the stimulus, electrode placement, and individual characteristics.
Between 10 volts and about 30 volts, the skin exhibits non-linear but symmetrical electrical characteristics. Above 20 volts, electrical characteristics are both non-linear and symmetrical. Conductance of the skin can increase by several fold in milliseconds. This should not be confused with the dielectric damage, which occurs in hundreds of volts. For this reason, the current flow can not be calculated accurately simply by applying Ohm's law using a fixed resistance model.
Entry point
- Macroshock: Smooth on whole skin and pierce the body. Current from arm to arm, or between arms and legs, is likely to cross the heart, therefore much more dangerous than the current between the foot and the ground. This type of shock based on this definition must enter the body through the skin.
- Microshock: Very small current source with a path connected directly to the heart tissue. Shock is required to be given from the skin, directly to the heart of the pacemaker, or guide wire, conductive catheter, etc. That is connected to the current source. This is a theoretical danger because modern devices used in this situation include protection against such flows.
Lethality
Electrocution
The term "electrocution," was invented about the timing of the first use of an electric chair in 1890, originally referred to only as electronical exe caution and not for accidental or suicidal electricity. Dead. However, since no English word is available for non-judicial deaths due to electric shock, the word "electrocution" eventually takes over as a description of all the circumstances of the death penalty.
Factors in shutting down electrical shock
The lethality of the electric shock depends on several variables:
- Now. The higher the current, the more likely it is to turn off. Since the current is proportional to the voltage at which resistance is established (ohms law), high voltage is an indirect risk to produce a higher current.
- Duration. The longer the duration, the greater the likelihood of shutting down - the safety switch can limit the current flow time
- Path. If current flows through the heart muscle, it is more likely to be deadly.
- High voltage (over 600 volts). In addition to a larger current flow, high voltage can cause dielectric damage to the skin, thus decreasing the skin resistance and allowing further flow of current.
- Medical implants. Artificial pacemaker or implanted cardioverter-defibrillator (ICD) is sensitive to very small currents.
- Pre-existing medical conditions.
- Age and Gender.
Another problem that affects lethality is frequency, which is a problem in causing a heart attack or muscle spasm. The very high electric current causes the tissue to burn, but it does not penetrate the body far enough to cause a heart attack (see electro surgery). What is also important is the path: if the current passes through the chest or head, there is the possibility of increased death. From the main circuit or power distribution panel, the damage is more likely to be internal, leading to a heart attack. Another factor is the heart tissue has a chronaxie (response time) of about 3 milliseconds, so electricity at higher frequencies of about 333 Hz requires more current to cause fibrillation than is required at lower frequencies.
The comparison between the alternating current dangers on typical transmission transmission frequencies (ie, 50 or 60 Hz), and direct current has been the subject of much debate since the Climate War of the 1880s. Experiments on animals performed so far suggest that alternating current is about twice as dangerous as direct current per current flow unit (or per unit of voltage used).
It is sometimes suggested that the most common human shutting with alternating current at 100-250 volts; However, death has occurred below this range, with inventories as low as 42 volts. Assuming stable current flows (as opposed to shocks from capacitors or from static electricity), shocks over 2,700 volts are often fatal, with those above 11,000 volts which are usually fatal, although exceptional cases have been noted. According to the 17-year-old Guinness Book of World Records, 17-year-old Brian Latasa survived a shock of 230,000 volts in ultra-high voltage tower tower at Griffith Park, Los Angeles on November 9, 1967. A news report about the Event stated that he "snapped in the air , and landed across the line ", and despite being rescued by firefighters, he suffered burns of more than 40% of his body and was completely paralyzed except for his eyelids.
Epidemiology
There were 550 reports of electrical damage in the US in 1993, 2.1 deaths per million inhabitants. At that time, the electrical damage incident decreased. Electric shocks in the workplace cause the majority of these casualties. From 1980-1992, an average of 411 workers were killed each year by electrocution. A recent study conducted by the National Coroners Information System (NCIS) in Australia has revealed three hundred and twenty one (321) deaths due to closed cases (and at least 39 cases of death still under investigation) that have been reported to the Australian coroner where someone died due to power failure between July 2000 and October 2011.
In Sweden, Denmark, Finland and Norway the number of electrical deaths per million inhabitants was 0.6, 0.3, 0.3 and 0.2, respectively, in 2007-2011.
Survivors of electrical trauma can suffer a number of injuries including loss of consciousness, seizures, aphasia, visual impairment, headaches, tinnitus, paresis, and memory disorders. Even without visible burns, electric shock victims can be confronted with long-term muscle pain and discomfort, fatigue, headaches, problems with peripheral nerve conduction and inadequate sensation, balance and coordination, among other symptoms. Electrical injury can cause problems with neurocognitive functioning, affecting the speed of mental processing, attention, concentration, and memory. The high frequency of psychological problems is well established and may be multifactorial. As with any traumatic and life-threatening experience, electrical injury can lead to post-traumatic psychiatric disorders. There are several nonprofit research institutes that coordinate rehabilitation strategies for victims of electrical injury by connecting them with doctors who specialize in the diagnosis and treatment of various trauma arising as a result of electrical injury.
Deliberate use
Medical use
Electrical shock is also used as medical therapy, under carefully controlled conditions:
- Electroconvulsive therapy or ECT is psychiatric therapy for mental illness. The goal of therapy is to induce seizures for therapeutic effects. There is no conscious sensation of electric shock due to anesthesia used before. Convulsive therapy was introduced in 1934 by Hungarian neurologist Ladislas J. Meduna who, erroneously believes that schizophrenia and epilepsy are antagonistic abnormalities, causing first seizures with camphor and then metrazol (cardiazol). The first patient was treated by Lucio Bini and Ugo Cerlettiin. ECT is generally given three times a week for about 8-12 treatments.
- As a surgical tool for cutting or coagulation. "Electrosurgical units" (or ESUs) use high currents (eg 10 amperes) at high frequencies (eg 500 kHz) with various amplitude modulation schemes to achieve desired results - cut or coagulate - or both. This device is safe when used correctly.
- As a treatment for irregular heart fibrillation or rhythm: see defibrillator and cardioversion.
- As a method of pain relief: see Transcutaneous Electrical Nerve Stimulator (more commonly referred to as TENS units).
- As a hostile punishment for the conditioning of individuals with developmental delay with severe behavioral problems. This controversial skin-shock method is only used at the Rotenberg Judge Education Center, a special needs school in Massachusetts.
- As a treatment for Hyperhidrosis with a device called iontophoresis
- As part of the electrodiagnosis diagnostic test including a study of neural conduction and electromyography.
- For genetic engineering and gene delivery using non-viral vector electroporation system
Entertainment
Light electric shocks are also used for entertainment, especially as a practical joke for example in devices such as a surprising pen or surprising gum. But devices like joy buzzers and most other machines in amusement parks today only use vibrations that feel a bit like electric shock to someone who does not expect it.
Law enforcement and personal defense
An electroshock weapon is an incapacitant weapon used to subdue a person by giving electric shocks to disrupt superficial muscle function. One type is a conductive energy device (CED), an electric shock weapon known as the "Taser" brand, which fires a projectile that regulates shock through thin and flexible wires. Although they are illegal for personal use in many jurisdictions, Tasers has been marketed to the general public. Other electric shock weapons such as stun guns, stun batons ("cattle prods"), and electroshock belts provide electric shock with direct contact.
Electrical fencing is a barrier that uses electric shocks to prevent animals or people crossing the line. The shock voltage may have effects ranging from uncomfortable, to painful or even deadly. Most electric fences are used today for agricultural fences and other forms of animal control purposes, although they are often used to improve the security of forbidden areas, and there are places where deadly stresses are used.
Torture
Electrical shock is used as a method of torture, because the received voltage and current can be controlled with precision and are used to cause pain and fear without always appearing to harm the victim's body.
Such torture uses electrodes attached to the victim's body: usually, when the wires are wrapped around the fingers, toes, or tongue; attached to the genitals; or inserted into the vagina to give the circuit back; a voltage source (usually a kind of prod) of controlled pressure is appropriately applied to other sensitive body parts, such as the genitals, breasts, or head. Parrilla is an example of this technique. Other electrical torture methods (such as picana) do not use fixed wires, but they have two electrodes of different polarities, spaced apart by making the circuit through the meat between them when placed on the body, making it easy for the operator to accurately target shocks in places where the victims suffered most and were depressed. When the voltage and current are controlled (most often, high voltage and low current) the victim feels the pain of electric shock but is not physically harmed. Recurrent shocks to the genitals will result in the victim losing control of his bladder and accidental urination, while the wide trajectory of the current through the butt will cause the victim to defecate by accident.
Electoral torture has been used in wars and by repressive regimes since the 1930s: the US Army is known to have used electrical torture during World War II and during Algeria's electrical torture is a favorite method of French military forces; Amnesty International published an official statement that Russian military forces in Chechnya tortured local women by electric shock by sticking wires to their breasts; Japan serial killer, Futoshi Matsunaga uses electric shock to control his victim.
Advocates for the mentally ill and some psychiatrists such as Thomas Szasz have asserted that electroconvulsive therapy (ECT) is torture when used without positive medical benefit to patients who are stubborn or unresponsive. Similar arguments and contradictions apply to the use of a painful shock as a punishment for behavioral modification, a practice that is openly used only at the Judge Rotenberg Institute.
Death penalty
Electric shocks delivered by electric chairs are sometimes used as official tools of capital punishment in the United States, although their use has become rare in recent times. Although some of the original proponents of the electric chair regarded it as a more humane execution method than hanging, firing, poisoning poison, etc., now in general have been replaced by deadly injections in states that practice the death penalty. Modern reporting claims that sometimes it takes a few surprises to shut down, and that the cursed person may actually burn before the process is over.
In addition to parts of the United States, only the Philippines are reported to have used this method, from 1926 to 1976. It was replaced briefly by firing squads, until the death penalty was abolished in the country. Electrocution remains legal in at least 5 states (Virginia, Florida, Alabama, North Carolina and Kentucky) from the United States.
See also
Note
References
- Reilly, J. Patrick (1998). Applied Bioelectricity: From Electrical Stimulation to Electropathology (2nd ed.). Jumper. ISBN 978-0-387-98407-0. LCCNÃ, 97048860. OCLCÃ, 38067651.
- Wright, A.; Newbery, P.G.; Institution of Electrical Engineers (2004). Electric Fuses, 3rd Edition . Power and IEE energy series. Engineering and Technology Institutions. ISBNÃ, 9780863413995 . Retrieved 2014-01-16 .
External links
- National Institute for Occupation Safety & amp; Health: Labor Death by Electrocution, a CDC study
- Electrical physiological effects
- Electric Shock Hazards (Hyperfisis)
- Electric Shock: a more technical perspective
- Ontario Construction Safety Association: Electrocution... articles with case studies
- Protection against electric shocks (wikis): physiological effects and protection rules (PDF version)
- Electrical Safety Board
- Electrical Safety chapter of Lessons in Vol 1 DC series of books books and series.
Source of the article : Wikipedia
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