Sidebar never keep working with a tool that has given

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<Sidebar> Never keep working with a tool that has given you a shock! Mild electric shocks , which do not involve muscle paralysis, present an indirect danger. For example, ü They may cause the person to jerk, drop a tool, fall from a ladder, etc. ü Working on a car battery, a person may accidentally move an arm into the rotating fan! <Sidebar> Mild electric shocks , which do not involve muscle paralysis, present an indirect danger because they may cause the person to jerk, drop a tool, fall from a ladder, etc. The electric resistance of the human skin also depends on the voltage! If the voltage applied to the skin exceeds 240 V, it can puncture the skin, literally burning a hole. Thus high voltages eliminate the main protection of the human body and present a special danger compared to household 120 or 240 V. <Sidebar> High voltages eliminate the main protection of the human body against electric shock because they can puncture the skin. Book Page 104
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EE for 21 st century 1-2 Avoid electrocution 1-2-2 Resistance of the human body © 2015 Alexander Ganago Page 6 of 13 Last printed 2015-07-24 1:06 PM File: 2015 1-2-2 Human R.docx T HE PATHS OF ELECTRIC CURRENT THROUGH THE HUMAN BODY An electric circuit usually includes one or more sources of voltage/current, conducting wires, and various loads – lamps, motors, etc. By touching such a circuit so that a part of the current flows through your body, you change the original circuit and create a shock circuit, which, as the name suggests, may cause an electric shock. <Sidebar> A shock circuit involves the human body and may cause an electric shock. Depending on the circumstances, the shock circuit may include connections: Ø From finger to thumb Ø From hand to hand (Figure 2, left panel) Ø From hand to foot (Figure 2, right panel) Ø From foot to foot, etc. The harm incurred by the electric current in the human body depends on whether this current passes through the heart, lungs, and other vital organs. Therefore, some connections are more dangerous than the others. Evidently, the hand-to-hand and hand-to-foot connections (Figure 2) belong to the most dangerous. By comparison, the finger-to-thumb connection is relatively safe, because it limits the path of currents to one hand and protects the rest of the body: see Figure 3. F ROM FINGER TO THUMB , OR BETWEEN THE FINGERS I just called this connection relatively safe but let me emphasize relatively as the keyword. As a master student, I was an arrogant know-it-all, and thus received a very painful lesson from an electric shock. Without looking at the manual, I decided to repair a 3-kV power supply for a laser setup. The power supply had a safety switch, which disconnected it from power when the lid was removed; I disabled that switch because I wanted to measure voltages inside the power supply. As soon as I touched something inside the power supply, I got an electric shock. The current flowed through my body from finger to thumb of one hand only, because my other hand was busy disabling the safety switch. The electric shock really shook my whole arm, and the next
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  • Fall '07
  • Ganago
  • Electric charge, Alexander Ganago

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