By Lawrence Kamm
Electric Shock and Fire Expert Witness And Consultant
Electric Shock and Fire Expert Witness And Consultant
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 defibrillator, electro-shock therapy, the pacemaker, the electro-cardiograph, the electro-encephalograph, the electro-cauterizer.
Electricity is used for capital punishment and for torture.
I will talk about some of the casualties and how we protect against them, and I will describe some of the lawsuits involving them in which I participated as a consultant or expert witness.
First, Shocks and Electrocutions
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.
The combination of utility and danger has given rise to major engineering and to major law to permit the utility and to protect from the danger. A few examples:
Electrical circuits may be passed through fuses of low melting point metal which melt and open the circuit if the current exceeds their rating. The disadvantage of fuses is that they are one-shot and must be replaced after each action. Older homes used fuses.
Instead of a fuse an electro-mechanical circuit breaker pops open if the current exceeds its rating and may be re-closed either by hand or by remote control. Newer homes use manual reset circuit breakers. Circuit breakers are sized from small fractions of an ampere in electronic circuits to many thousands of amperes at high voltage in public utilities. I had a case in which a large circuit breaker exploded and sprayed burning oil on workers.
A truly wonderful device, now used almost everywhere in homes, is the Ground Fault Circuit Interrupter, the GFCI, invented by professor Dalziel at UC Berkeley. It is a circuit breaker which opens within a tenth of a second if a shock current exceeds six milliamperes, a safe combination. They are incorporated in electrical outlets near water faucets in bathrooms since a common source of shocks is from holding a defective hair dryer and touching the faucet or standing in the bath. Also elsewhere, of course.
The most common safety device is the three prong plug. In addition to the two prongs which connect to the power wires there is a third prong which is wired to the metal body of the connected device, and which touches a contact in the socket which is wired to ground. If a defect in the device connects a power wire to the metal body, the resulting short circuit blows a fuse or circuit breaker but prevents a power connection to the user who may also be touching ground.
There is now a dangerous practice of depending on a wide blade prong to connect the device body to that power side which is typically grounded and dispensing with the third prong ground connection. This is the practice with plastic body electric hand tools which boast of double insulation of the motor winding. I had a corpse which disputed this small economy. Sure, the winding was well insulated but the motor brushes and commutator could not be. I measured a direct connection from power wire to brush to commutator to internal moisture to motor shaft to metal gears to drill chuck. Thence to hand, through the user, to his wet feet to ground where that corpse now lies. The product liability settlement included an secrecy agreement about my analysis. And yes, the printed instructions said that you should not use the drill in a wet environment. I have things to say about printed instructions.
A vital if mundane safety is the lockout/tagout requirement to protect an installation or maintenance technician from encountering live wires. I had a case in which, among other things, an electrician melted the jaws of his wire cutter by cutting a two conductor cable he assumed had been locked out.
In industry large electric motors are connected to power by three wires instead of two. (It is called 3 phase power.) If any two wires are interchanged in error the motor runs the wrong way. I had a lawyer's client with crushed fingers as a result.
Next, how about another few cases which might resemble yours?
An electrical tool was enclosed in a pair of matching plastic case halves. Its power cord used stranded wire for flexibility, as is common practice. But there was inadequate internal insulation so one bare strand peeked out between the halves, shocked the user, and he fell off his ladder.
A dog wash operator with wet feet used a hair dryer on a dog and was shocked. No GFCI of course.
A boat owner improperly connected an extension cord to his boat. His friend also was shocked when he touched and moved the body. No GFCI of course.
A $2.5 million dollar fire was blamed on a neon sign transformer. An electrical expert set up and video recorded a classic example of a neon sign transformer starting a fire, which it absolutely can do under certain circumstances. I know about such transformers and demonstrated that these circumstances did not obtain. The $2.5 million suit was settled for $13,000.
That circuit breaker explosion was due to an inadequately trained electrician who left an improper setting within the breaker, as I explained to the juries in two trials. The burned electrician was awarded $1.1 million, the largest ever award in Southern Ohio.
Power to an AC motor was incorrectly measured by measuring motor current and voltage. AC motor power can only be measured by a wattmeter. (Motor current includes a component which does not deliver power.)
ABOUT THE AUTHOR: Lawrence Kamm
Mr. Lawrence Kamm is an expert witness for industrial accidents, product liability, electric shock, electrocution, fire, explosion, and patent infringement. He is a licensed professional engineer (California E5897), specializing in electrical, mechanical, and electro-mechanical engineering. He is a former registered patent agent. He has 50 years experience including depositions and trials.
Copyright Lawrence Kamm
Disclaimer: While every effort has been made to ensure the accuracy of this publication, it is not intended to provide legal advice as individual situations will differ and should be discussed with an expert and/or lawyer.For specific technical or legal advice on the information provided and related topics, please contact the author.