The Dangers of Electrical Shock
You’ve worked hard to build your business, now it’s time to protect it. Educate yourself and your employees on the dangers of electrical shock, so you can reduce risks and energize your dreams with confidence.
As a source of energy, electricity is used without much thought about the hazards it can cause. Because electricity is a familiar part of our lives, it often is not treated with enough caution. As a result, an average of one worker is electrocuted on the job every day of every year!
An electrical shock is received when electrical current passes through the body.Whenever two wires are at different voltages, current will pass between them if they are connected. Your body can connect the wires if you touch both of them at the same time, or you provide a ground and thus, current will pass through your body.
The length of time of the shock greatly affects the amount of injury. If the shock is short in duration, it may only be painful. A longer shock (lasting a few seconds) could be fatal if the level of current is high enough to cause the heart to go into ventricular fibrillation or cause respiratory paralysis.
The amount of current passing through the body also affects the severity of an electrical shock. Greater voltages produce greater currents. So, there is greater danger from higher voltages.
The severity of injury from electrical shock depends on the amount of electrical current and the length of time the current passes through the body. For example,
- 1/10 of an ampere (amp) of electricity going through the body for just 2 seconds is enough to cause death.
- Currents above 10 milliamps (mA) can paralyze or “freeze” the muscles of a worker. When this “freezing” happens, the worker is no longer able to release a tool, wire, or other object. For this reason, hand-held tools that give a shock can be very dangerous. If you can’t let go of the tool, current continues through your body for a longer time, which can lead to respiratory paralysis.You stop breathing for a period of time. People have stopped breathing when shocked with currents from voltages as low as 49 volts. Usually, it takes about 30 mA of current to cause respiratory paralysis.
- Currents greater than 75 mA cause ventricular fibrillation (very rapid, ineffective heartbeat). This condition will cause death within a few minutes unless a special device called a defibrillator is used to save the victim. Heart paralysis occurs at 4 amps, which means the heart does not pump at all. Tissue is burned with currents greater than 5 amps.
Sometimes high voltages lead to additional injuries. High voltages can cause violent muscular contractions. You may lose your balance and fall, which can cause injury or even death if you fall into machinery that can crush you. High voltages can also cause severe burns.
At 600 volts, the current through the body may be as great as 4 amps, causing damage to internal organs, such as the heart. High voltages also produce burns. In addition, internal blood vessels may clot. Nerves in the area of the contact point may be damaged. Muscle contractions may cause bone fractures from either the contractions themselves or from falls. A severe shock can cause much more damage to the body than is visible. A person may suffer internal bleeding and destruction of tissues, nerves, and muscles. Sometimes the hidden injuries caused by electrical shock result in a delayed death. Shock is often only the beginning of a chain of events. Even if the electrical current is too small to cause injury, your reaction to the shock may cause you to fall, resulting in bruises, broken bones, or even death.
The path of the electrical current through the body affects the severity of the shock. Currents through the heart or nervous system are most dangerous. If you contact a live wire with your head, your nervous system may be damaged. Contacting a live electrical part with one hand—while you are grounded at the other side of your body—will cause electrical current to pass across your chest, possibly injuring your heart and lungs.