Podcast
Questions and Answers
What are the three factors that determine whether an electrical shock is fatal?
What are the three factors that determine whether an electrical shock is fatal?
A milliampere (mA) is 1/100 of an ampere.
A milliampere (mA) is 1/100 of an ampere.
False
What is the range of current (in mA) that will typically kill a person?
What is the range of current (in mA) that will typically kill a person?
100 mA to 200 mA
At what current range does a painful shock begin?
At what current range does a painful shock begin?
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What instrument is used for accurately checking resistance?
What instrument is used for accurately checking resistance?
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An ohmmeter indicates an open circuit by showing a resistance of zero.
An ohmmeter indicates an open circuit by showing a resistance of zero.
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Voltage drop is caused by an electrical load, a loose connection, or an __________ conductor.
Voltage drop is caused by an electrical load, a loose connection, or an __________ conductor.
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What is often the symbol for unlimited resistance?
What is often the symbol for unlimited resistance?
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What percentage range do most loads operate properly within?
What percentage range do most loads operate properly within?
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A drawbridge analogy is used to explain the concept of an __________ circuit.
A drawbridge analogy is used to explain the concept of an __________ circuit.
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Study Notes
Factors Determining Fatal Electrical Shock
- Electrical shock fatality is influenced by current (amperage), duration of exposure, and path through the heart.
- A milliampere (mA) equals 1/1000 of an ampere.
- Current between 100 mA to 200 mA is lethal, comparable to 1/10 of the current needed for a 100 W bulb.
Safe and Unsafe Current Values
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Safe Levels:
- 1 mA: No sensation felt.
- 1 mA to 8 mA: Shock sensation without pain or muscle control loss.
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Unsafe Levels:
- 8 mA to 15 mA: Painful shock, muscle control intact.
- 15 mA to 20 mA: Painful shock with hand muscle contraction, inability to release.
- 20 mA to 75 mA: Painful shock with severe muscle contractions and breathing difficulty.
- 100 mA to 200 mA: Painful shock leading to ventricular fibrillation, a rapid and fatal heart condition.
- Over 200 mA: Severe burns and muscle contractions that may stop the heart, requiring immediate artificial respiration.
Ohmmeter and Continuity Testing
- Ohmmeter measures electrical resistance, available in analog and digital forms.
- Used to check for continuity, ensuring complete circuit pathways for electrons.
- Low resistance readings confirm intact circuits; high resistance indicates problems.
- Analog ohmmeters show open circuits with a needle peged out, while digital read "OL" for overload.
Open Circuit Characteristics
- An open circuit halts electron flow due to breaks in the circuit, indicated by high resistance.
- Causes of open circuits include open switches, blown fuses, or broken wires.
Voltage Drop in Electrical Circuits
- Voltage drop signifies loss of electromotive force (voltage) between source wires or across loads.
- Causes include electrical loads, loose connections, or undersized conductors.
- Proper wire type, size, and length minimize voltage drop to prevent overheating and ensure adequate voltage for loads.
- Most electrical loads operate within ±5% of rated voltage; excess drop can be detected using a multimeter.
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Description
This quiz explores the factors influencing fatal electrical shock, including current levels, duration of exposure, and the path through the heart. It also covers safe and unsafe current values, detailing the effects different levels of current can have on the human body. Test your knowledge about electrical safety and the risks involved!
