ELECTRICAL SHOCKS
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 seminar class Active In SP Posts: 5,361 Joined: Feb 2011 26-02-2011, 10:25 AM   Earthing and shocks.pptx (Size: 417.95 KB / Downloads: 103) ELECTRICAL SHOCKS ELECTRIC SHOCK • Occurs when electrical current passes through the body • Causes devastating injuries or even death Why are we prone to shocks? • Because our bodies are good conductors of electricity. • When a part of our body completes an electric circuit, we get an electric shock • You will receive a shock if you touch two wires at different voltages at the same time. Causes of electric shocks  Accidental contact with exposed electrical wiring  Contact with a high voltage source  Contact with a person who is receiving an electric shock  Contact with a live and neutral wires  Due to a lightning strike  Poking metal objects into an electrical outlet  Touching an electrical appliance with wet hands TYPES OF ELECTRIC SHOCKS  MACRO SHOCKS  Most common type of shock  Occurs when current flows across intact skin and through the body  MICRO SHOCKS  Occurs when there is a direct current path to the heart tissue  Usually these shocks are from inside the skin, i.e. a malfunctioning pacemaker, or ungrounded catheter etc. CONSIDERATIONS  A basic electric circuit has three components: voltage, current, and resistance.  The killer component is current.  According to Ohm’s law, V= IR  Resistance of the body varies from one person to another, moisture content between different layers of skin Typical skin resistance : 500 Ω (moist skin) to 300,000 Ω (dry skin)  The low resistance of wet skin allows current to pass into the body more easily and give a greater shock. The severity of an electrical shock depends on –  The amount of electrical current through the body  The duration of the current through the body  The path of the current through the body  The muscle structure of the person Electrical shocks can occur in several forms, and the given description applies to various levels Fibrillation level: This is a function of current over time. For example, you will get fibrillation with 500mA over 0.2 sec or 75mA over 0.5 sec. Let-go threshold: This is the current level at which humans lose muscle control; the electricity causes muscles to contract until current is removed