| ELECTROCUTION | ||||||||||||
| Low voltage: <600V High voltage: >600-750 V Humans more sensitive to alternating currents esp 39 - 150 cps |
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Amperagae is most important factor A = V/R |
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| Household 110-120 V High voltage lines 7500-8000 V High tension lines 100,000 V or higher Direct contact not needed! 1,000 V line can arc through air few mm; 5,000 V - 1 cm; 20,000 V - 6 cm, 40,000 V - 13 cm and 100,000 V - 35 cm |
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| Resistance: Dry skin 100,000 ohms Moist skin 1,000 ohms Moist thin skin 100 ohms |
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| Mechanism of death: low voltage - v fib high voltage - electrothermal injury or respiratory arrest from paralysis (due to central damage to respiratory center by hyperthermic effects of current) |
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| Examples: 120V current, 1000 ohms resistance, 120 mA reach body; 5 sec to v. fib; if skin moist & thin, 100 ohms, 1200 mA (1.2A) reach body and 0.1 sec to v. fib | ||||||||||||
| Muscle contractions may cause fractures: scapula, humerus, femoral neck, T12 and L1. May arch back and neck backwards. | ||||||||||||
| Autopsy Findings: Burns present in all cases of high-voltage, but only 50% of low voltage electrocution. Cannot differentiate antemortem from postmortem electrical burns. Scanning EM can detect small particles of metal from the conducting surface. |
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| Ground-Fault Current Interrupters: monitors current flow and detects a 5 mA difference (required in kitchens, bathrooms and outside outlets). Circuit breakers detect a 15 mA differece. | ||||||||||||
| Lightning: Most indibiduals hit by lightning do survive. 1,000 A or more. Cutaneous burns not severe, but always present. 81% rupture tympanic membrane. Metal objects magnetized. "Lichtenburg" figures: arborescent or fern-like injury to skin. Present 1 - 24 hrs erythema, then fades. Not burns |
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