Electrical accidents create personal injuries, which are the subjects of attorneys' lawsuits. Expert witnesses reconstruct these accidents for lawyers and establish their liabilities. Among these accidents are electric shocks, electrocutions, electrical explosions, electrical fires, and flash burns. Lawyers are particularly interested in product liability cases. This lawyer's tutorial explains the basics of electrical accidents as an introduction to dealing with expert witnesses.
Electricity is a major asset but, along with gasoline, drugs, and explosives it can do major harm if not handled carefully. Electricity is invisible and has no sound or smell but it can give you a shock which may startle you, paralyze you, damage your internal organs in many ways, burn your skin, and kill you. The heat from a short circuit arc may give you a flash burn and a blast injury, the radiation from an electrically powered X-ray tube, laser, or radar antenna can cause internal or external burns, a lightning strike may give you a major shock or electrocution, and an electrically operated device may malfunction and injure you. Other than shocks to people electrical accidents can start fires, cause explosions, and damage equipment.
Many forms of electricity have been applied to the body for therapy and the electricity generated within the body is measured for diagnosis. Consider, for examples, the defibrilator, electro-shock therapy, the pacemaker, the electro-cardiograph, the electro-encephelograph, the electro-cauterizer.
Electricity is used for capital punishment and for torture.
Every year approximately 400 people in the U.S. are killed by electric shock. More are injured by being startled by an electric shock, lose their balance, and fall off a ladder. To cause a shock the electricity must enter at one place on your body and exit at another place. It is the current through your body which causes the shock, not the voltage at a single place. A bird on a high voltage wire gets no shock. It is common for one of the shock places to be the earth or a piece of metal connected to the earth. Think of a faucet in your bathroom for an example. Think of bare feet on wet ground for another example.
Electricity through your body spreads out between the two places and can raise bloody hell between. If enough passes through your heart your story ends by ventricular fibrillation followed by asphyxiation because the heart stops pumping blood. Electric current can damage your organs and your nervous system. Among my clients is one whose one bare foot was on the ground, whose other bare foot stepped on a manhole cover, and whose body shakes to this day. Dogs are sometimes electrocuted sniffing around construction sites. Cows give less milk when they get small shocks from milking machines; there is major litigation as a result. People get shocked, and sometimes killed, by touching an electrocuted body in order to rescue it from contact with a fallen high voltage wire. A minor electric shock to a person on a ladder can startle a person who then loses his balance, falls off, and is seriously injured by the fall. I will talk about electric tools later on.
A common mode of shock comes from touching a defective electrical appliance, such as a hair dryer, with one hand and a water faucet with the other. To say nothing about standing in a bathtub of water.
There are several odd effects of electricity on the body. If you get a shock through an arm, if the current exceeds a 'let go' level, your arm will be paralyzed. (It happened to me.) A second effect is that your arm may jerk, as did Signor Galvani s laboratory frog leg for the world's first galvanic response. The jerk may make you fall off a ladder, and often does. A third effect is that the heart is sensitive to electrocution during only approximately 1/7 of its cycle. (I was an example of let go paralysis and heart cycle insensitivity when I forgot to pull the switch on a 440 volt power supply and picked up two wires, hand to hand.)
Many electric shocks result from improper handling of electrical wires and devices. An entire class of shocks comes from the accidental touching of overhead high voltage electric wires. These have been touched by cranes, irrigation pipes being handled, grain augers, trucks, workers on scaffolding or roofs, boat masts, radio and TV antennas, tree branches, and workers with long tools, and by trespassers. Yet such wires can be handled quite safely if handled with proper insulated tools and trained skill.
Electric current through anything heats it. If the anything is a light bulb the heat radiates light; that is how Edison started the electric utility industry. But if the anything is combustible insulation, and the current in an adjacent wire is accidentally too high, the heat can start a fire. Much of the National Electric Code is to prevent such fires. Short circuit current can be enormous for a fraction of a second before a fuse or circuit breaker interrupts it. If it flows through an arc before interruption, radiant heat from the arc can cause a skin burn and clothing fire and the hot gas of the arc can cause an explosion.
In addition to human damage electricity can cause material losses by being too high or too low a voltage, having momentary high voltage pulses, having the wrong alternating current wave-form and by unplanned interruption.
This article written by Lawrence Kamm, P.E.was published in the San Diego Daily Transcript on October 18, 2006 as part of the Forensic Consultants Association Newsletter. Lawrence Kamm, P.E. is a licensed Electrical Engineer who analyzes accidents and defective products. He can be contacted through his web site - www.ljkamm.com/
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