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AMAZON multi-meters discounts AMAZON oscilloscope discounts Safety is the job of each individual. One should be concerned not only with their own safety but also with the safety of others around you. This is especially true for persons employed in the electrical field. Some general rules should be followed when working with electric equipment or circuits. TOPICS:
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General Safety RulesNever Work on an Energized Circuit, If the Power Can Be Disconnected When possible, use the following three-step check to make certain that power is turned off: 1. Test the meter on a known live circuit to make sure the meter is operating. 2. Test the circuit that is to become the de-energized circuit with the meter. 3. Test the meter on the known live circuit again to make certain the meter is still operating. Install a warning tag at the point of disconnection so people won’t restore power to the circuit. If possible, use a lock to prevent anyone from turning the power back on. Think Of all the rules concerning safety, this one is probably the most important. No amount of safeguarding or idiot proofing a piece of equipment can protect a person as well as taking time to think before acting. Many technicians have been killed by supposedly "dead" circuits. Don’t depend on circuit breakers, fuses, or someone else to open a circuit. Test it yourself before you touch it. If you are working on high-voltage equipment, use insulated gloves and meter probes to measure the voltage being tested. Think before you touch something that could cost you your life. No Horseplay Jokes and horseplay have a time and place, but not when someone is working on an electric circuit or a piece of moving machinery. Don’t be the cause of someone's being injured or killed, and don’t let someone else be the cause of your being injured or killed. Do Not Work Alone This is especially true when working in a hazardous location or on a live circuit. Have someone with you who can turn off the power or give artificial respiration and/or cardiopulmonary resuscitation (CPR). Several electric shocks can cause breathing difficulties and can cause the heart to go into fibrillation. Work with One Hand When Possible The worst kind of electric shock occurs when the current path is from one hand to the other, which permits the current to pass directly through the heart. A person can survive a severe shock between the hand and foot that would cause death if the current path were from one hand to the other. Learn First Aid Anyone working on electric equipment, especially those working with voltages greater than 50 volts, should make an effort to learn first aid. A knowledge of first aid, especially CPR, may save your own or someone else's life. Avoid Alcohol and Drugs The use of alcohol and drugs has no place on a work site. Alcohol and drugs are not only dangerous to users and those who work around them; they also cost industry millions of dollars a year. Alcohol and drug abusers kill thou sands of people on the highways each year and are just as dangerous on a work site as they are behind the wheel of a vehicle. Many industries have instituted testing policies to screen for alcohol and drugs. A person who tests positive generally receives a warning the first time and is fired the second time. AMAZON multi-meters discounts AMAZON oscilloscope discountsEffects of Electric Current on the BodyMost people have heard that it’s not the voltage that kills but the current. This is true, but don’t be misled into thinking that voltage cannot harm you. Voltage is the force that pushes the current though the circuit. It can be compared to the pressure that pushes water through a pipe. The more pressure available, the greater the volume of water flowing through the pipe. Students often ask how much current will flow through the body at a particular voltage. There is no easy answer to this question. The amount of current that can flow at a particular voltage is determined by the resistance of the current path. Different people have different resistances. A body has less resistance on a hot day when sweating, because salt water is a very good conductor. What one eats and drinks for lunch can have an effect on the body's resistance, as can the length of the current path. Is the current path between two hands or from one hand to one foot? All these factors affect body resistance. --The list below outlines the effects of different amounts of current on the body. This chart is general-some people may have less tolerance to electricity and others may have a greater tolerance. A current of 2 to 3 milliamperes (mA) (0.002 to 0.003 amperes) usually causes a slight tingling sensation, which increases as current increases and be comes very noticeable at about 10 milliamperes (0.010 amperes). The tingling sensation is very painful at about 20 milliamperes. Currents between 20 and 30 milliamperes cause a person to seize the line and be unable to let go of the circuit. Currents between 30 and 40 milliamperes cause muscular paralysis, and those between 40 and 60 milliamperes cause breathing difficulty. When the current increases to about 100 milliamperes, breathing is extremely difficult. Currents from 100 to 200 milliamperes generally cause death because the heart usually goes into fibrillation, a condition in which the heart begins to "quiver" and the pumping action stops. Currents above 200 milliamperes cause the heart to squeeze shut. When the current is removed, the heart usually returns to a normal pumping action. This is the operating principle of a defibrillator. The voltage considered to be the most dangerous to work with is 120 volts, because that generally causes a current flow of between 100 and 200 milliamperes through most people's bodies. Large amounts of current can cause severe electric burns that are often very serious because they occur on the inside of the body. The exterior of the body may not look seriously burned, but the inside may be severely burned. ===
--1. The effects of electric current on the body. == Also see: Electrical safety systems
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Monday, February 25, 2013 15:12