Electrical injury
An wut up electrical workers this is ryan lenihan from bourne mass bourne 1991 from wareham electric shocks suck i hate them even tho i only got shocked once in my life but wut eva can occur upon contact of a human or animal body with any source of voltage high enough to cause sufficient current flow through the muscles or nerves. The minimum detectable current in humans is thought to be about 1 mA. The current may cause tissue damage or heart fibrillation if it is sufficiently high. When (and only when) an electric shock is fatal, it is called electrocution.
shock out of pain An electric shock is usually painful and can be lethal. The level of voltage is not a direct guide to the level of injury or danger of death, despite the common misconception that it is. A small shock from static electricity may contain thousands of volts but has very little current behind it due to high internal resistance. Physiological effects and damage are generally determined by current and duration. Even a low voltage causing a current of extended duration can be fatal. Ohm's Law directly correlates voltage and current for a given resistance; thus, for a particular path through the body under a particular set of conditions, a higher voltage will produce a higher current flow.
'Let go' current
With sufficiently high current there can be a muscular spasmya your muscules with twitch like your hands will open and close really fast i learned thatfrom my shop teacher which causes the affected person to grip and be unable to release from the current source. The maximum current that can cause the flexors of the arm to contract but that allows a person to release his hand from the current's source is termed the let-go current. For DC, the let-go current is about 75 mA for a 70-kg man. For alternating current, the let go current is about 15 mA, dependent on muscle mass.
Shock effects
The perception of electric shock can be different depending on the voltage, duration, current, path taken, etc. Current entering the hand has a threshold of perception of about 5 to 10 milliamperes (mA) for DC and about 1 to 10 mA for AC at 60 Hz.
Physiological
Burns
Tissue heating due to resistance can cause extensive and deep burns. High-voltage (> 500 to 1000 V) shocks tend to cause internal burns due to the large energy (which is proportional to the square of the voltage) available from the source. Damage due to current is through tissue heating.
A low-voltage (110 to 220 V), 60-Hz AC current traveling through the chest for a fraction of a second may induce ventricular fibrillation at currents as low as 60mA. With DC, 300 to 500 mA is required. If the current has a direct pathway to the heart (eg, via a cardiac catheter or other electrodes), a much lower current of less than 1 mA, (AC or DC) can cause fibrillation. Fibrillations are usually lethal because all the heart muscle cells move independently. Above 200mA, muscle contractions are so strong that the heart muscles cannot move at all.
Neurological effects
Current can cause interference with nervous control, especially over the heart and lungs.
When the current path is through the head, it appears that, with sufficient current, loss of consciousness almost always occurs swiftly. (This is borne out by some limited self-experimentation by early designers of the electric chair. and by research from the field of animal husbandry, where electric stunning has been extensively studied) [1].
Issues affecting lethality
Other issues affecting lethality are frequency, which is an issue in causing cardiac arrest or muscular spasms, and pathway - if the current passes through the chest or head there is an increased chance of death. From a mains circuit the damage is more likely to be internal, leading to cardiac arrest.
The comparison between the dangers of alternating current and direct current has been a subject of debate ever since the War of Currents in the 1880s. DC tends to cause continuous muscular contractions that make the victim hold on to a live conductor, thereby increasing the risk of deep tissue burns. On the other hand, mains-frequency AC tends to interfere more with the heart's electrical pacemaker, leading to an increased risk of fibrillation. AC at higher frequencies holds a different mixture of hazards, such as RF burns and the possibility of tissue damage with no immediate sensation of pain. Generally, higher frequency AC current tends to run along the skin rather than penetrating and touching vital organs such as the heart. While there will be severe burn damage at higher voltages, it is normally not fatal.
It is believed that human lethality is most common with AC current at 100-250 volts, as lower voltages can fail to overcome body resistance while with higher voltages the victim's muscular contractions are often severe enough to cause them to recoil (although there will be considerable burn damage). However, death has occurred from supplies as low as 32 volts.
Electrical discharge from lightning tends to travel over the surface of the body causing burns and may cause respiratory arrest.
Point of Entry
Macroshock Current flowing across intact skin and through the body. Current traveling from arm to arm or between an arm and a foot is likely to traverse the heart and so is much more dangerous than current traveling between a leg and the ground.
Microshock Direct current path to the heart tissue
Avoiding danger of shock
It is strongly recommended that people should not work on exposed live conductors if at all possible. If this is not possible then insulated gloves and tools should be used. If both hands make contact with surfaces or objects at different voltages, current can flow through the body from one hand to the other. This can lead the current to pass through the heart. Similarly, if the current passes from one hand (especially the left hand) to the feet, significant current will probably pass through the heart.
Also, remember there can be a voltage potential between neutral wires and ground in the event of an improperly wired (disconnected) neutral, or in the event of an uncorrected high current condition.
Current electrical codes in many parts of the world call for installing a residual-current device (RCD or GFCI, ground fault circuit interrupter) on electrical circuits thought to pose a particular hazard to reduce the risk of electrocution. These devices work by detecting an imbalance between the live and neutral wires. In other words, if more current is passing though the live wire than is returning though its neutral wire, it assumes something is wrong and breaks the circuit.
Where live circuits must be frequently worked on (e.g. television repair), an isolation transformer is used. Unlike ordinary transformers which raise or lower voltage, the coil windings of an isolation transformer are at a 1:1 ratio which keeps the voltage unchanged. The purpose is to isolate the neutral wire so that it has no connection to ground. Thus, if a technician accidently touched the hot chassis and ground at the same time nothing would happen.
Neither ground fault circuit interrupters nor isolation transformers can prevent electrocution between the hot and neutral wires. This is the same path used by functional electrical appliances. However, most accidental electrocutions, and especially those not involving electrical work and repair, are via ground -- not the neutral wire.
The plumbing system in a home or other building is connected to ground through its metal pipes. Contrary to popular belief, water is not a good conductor of electricity. However, it does allow more current to flow than the (dry) human body does. Thus, being in the bath or shower will not only ground oneself to return path of the power mains, but lower the body's resistance as well. Under these circumstances, touching any metal switch or appliance that is connected to the power mains could result in electrocution. While such an appliance is not supposed to be hot on its outer metal switch or frame, it may have become so if a hot bare wire or metal part is accidently touching it inside. More use of plastics (which won't conduct electricity), grounding of appliances, and mandatory installation of ground fault circuit interrupters have greatly reduced this type of electrocution over the past few decades.
Shock due to differing ground potentials
In the case of lightning strikes to ground or other causes of large ground currents, large animals may be killed by the potential difference occurring on the ground between their front and rear limbs. Depending on the current, this could theoretically also affect humans if legs are spaced apart.
get a doctor
The recommended first aid for someone who had received a severe electrical shock has three major components
- Call for help
- Make sure the victim is no longer in contact with the electrical current source. Turn off all power if this can be done quickly.
- Check for breathing and heart beat and apply cardiopulmonary resuscitation, if necessary
Deliberate uses
Electric shock as medical treatment
Electric shock can also be used as a medical therapy, under carefully engineered conditions:
- as a (disputed) psychiatric therapy for mental illness, where it's called Electroconvulsive therapy.
- as a treatment for fibrillation or irregular heart rhythms: see defibrillator and cardioversion.
Torture
u will b tortured damn wires Electric shocks have been used as a method of torture, since the received voltage and amperage can be controlled with precision and used to cause pain whilst avoiding obvious evidence on the victim's body. Torture can use electrodes fixed to parts of the victim's anatomy. The genitalia are amongst the most painful, and at the same time humiliating. The nipples of a woman's breasts are also another very frequent target.
Another frequent method of torture is by stunning with an electroshock gun such as a cattle prod or a taser, (provided a sufficiently high voltage and non-lethal amperage is used in the former case)
Capital punishment
Electric shock delivered by an electric chair is sometimes used as a means of capital punishment, although its use has become rare in recent times. Throughout most of the world this practice is now regarded as 'inhumane', (though it is probably truer to say that it is one of the most grisly forms of modern execution to witness), but it remains a legal means of execution in some states of the USA.
Games
Electric shock is sometimes used as a punishment in novelty games such as Lightning Reaction, Shocking Roulette, Shocking Liar, Laser Shock Guns, and Shocking Tanks. In addition to these games, there are some prank toys like a fake pen or a chocolate which give out a mild shock.
See also
External links
- Electrical injury (Merck Manual)
- Electric Shock Hazards (Hyperphysics)
- Question: Why Does Mixing Water and Electricity Cause Electric Shock?
- Electric Shock - a more technical perspective