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12 Cards in this Set
- Front
- Back
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Fundamentals of Electrical Hazards |
• To flow, electricity must have a complete path. • Electricity flows through conductors • The human body is a conductor. |
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How does current enter the body? |
Typical points of entry are the hands and feet as they come in contact with electrical current. Moisture beneath a ring or watch will decrease the skin's resistance and allow current flow. |
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How does current travel through the body? |
The body, composed mostly of water, is a conductor of electricity, so current travels easily. Current travels the path of least resistance to complete its circuit. This path could be through upper limbs or between upper and lower limbs. If this includes the heart and respiratory systems, it can result in serious injury. |
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RESISTANCE OF MATERIALS |
•Most metals - >0 to 50 ohms •Dry wood – 100,000 ohms •Wet wood – 1,000 ohms •Rubber – 100,000 giga-ohms |
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RESISTANCE OF THE HUMAN BODY |
• inner resistance - about 500,000 ohms when dry • 300 ohms when wet |
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More than 3 ma |
Painful shock |
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More than 9 ma |
muscle contraction “no-let-go” danger |
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More than 30 ma |
lung paralysis- usually temporary |
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More than 50 ma |
possible ventricular fib. (heart dysfunction, usually fatal) |
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100 ma to 4 amps |
certain ventricular fibrillation, fata |
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Over 4 amps |
heart paralysis; severe burns. Usually caused by >600 volts |
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ELECTRICAL HAZARDS TO WATCH OUT FOR |
• Inadequate wiring• Exposed electrical parts • Overhead powerlines• Defective insulation • Loose electrical connections • Cord with frayed insulations • Plugs that do not match their outlets, e.g. 3-prong male plug to 2-prong female outlet • Non waterproof cords, plugs and outlets used outdoors • Equipment running over capacity • Tools that smell, smoke, spark • Electrical cord in contact with hot appliances or soaked in water • Overload circuits |
