20.6 Electric Hazards and the Human Body
3 min read•june 18, 2024
Electric hazards pose serious risks, from thermal dangers like fires to potentially fatal shocks. Understanding the effects of on the body is crucial. Factors like current path, duration, and frequency influence shock severity, with even small currents potentially dangerous.
Safety measures are essential to prevent electric accidents. , , circuit breakers, and GFCIs all play vital roles in protecting against shocks and fires. Knowing these risks and precautions is key to electrical safety.
Electric Hazards
Thermal vs shock hazards
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- Thermal hazards occur when electric current generates heat potentially causing burns or fires from overloaded circuits, short circuits, or faulty wiring (electrical fires, overheated components, melted insulation)
- Shock hazards occur when electric current passes through the human body disrupting normal bodily functions like heart rhythm and breathing with severity depending on current path, duration, and frequency
Effects of current on body
- 1 mA or less typically not perceptible
- 1-5 mA causes slight tingling sensation usually with no lasting harm
- 5-10 mA results in noticeable shock with possible involuntary muscle contractions
- 10-20 mA leads to painful shock, loss of muscle control, inability to let go of energized object
- 20-100 mA causes severe pain, difficulty breathing, potentially fatal (uncoordinated heart contractions) without immediate medical attention
- 100-200 mA likely causes ventricular fibrillation, severe burns, muscle damage with high risk of fatality
- Above 200 mA results in severe burns, internal organ damage, , usually fatal without immediate medical intervention
- can occur at contact points and internally along the current path
Factors influencing shock severity
- Current path depends on points of contact with the body
- Hand-to-hand or hand-to-foot paths more dangerous as current may pass through the heart
- Skin-to-skin contact on the same body part less severe
- Duration of exposure
- Longer exposure to electric current increases risk of injury or death
- Even low currents can be dangerous if exposure is prolonged
- Frequency of the current
- AC (alternating current) generally more dangerous than DC (direct current) at the same
- AC can cause involuntary muscle contractions making it harder to break contact with energized object
- Higher frequencies (above 100 kHz) less likely to cause ventricular fibrillation but can still cause burns
- Other factors
- Voltage: Higher voltages can drive more current through the body
- Skin : Dry, calloused skin offers more resistance than wet or broken skin
- Overall health: People with heart conditions or pacemakers may be more susceptible to injuries
Electrical Safety Measures
- : Provides a safe path for excess current to flow to the earth, reducing shock risk
- Insulation: Prevents direct contact with live electrical parts, reducing the risk of shock and short circuits
- Circuit breakers: Automatically interrupt the flow of electricity in case of overload or
- Ground Fault Circuit Interrupters (GFCIs): Quickly shut off power when they detect current leakage, protecting against severe shocks
- : Guidelines and regulations set by organizations to ensure safe electrical installations and practices
Key Terms to Review (30)
Air resistance: Air resistance is a force that opposes the motion of an object through the air. It depends on the object's speed, surface area, and shape.
Capacitor: A capacitor is an electrical component that stores energy in the form of an electric field, created by a pair of conductors separated by an insulating material. The ability to store charge is measured in farads (F).
Capacitor: A capacitor is a passive electronic component that stores electrical energy in an electric field. It consists of two conductors separated by an insulator, and it is used in various electronic circuits and devices to store and release electrical charge.
Cardiac Arrest: Cardiac arrest is a sudden and unexpected loss of heart function, breathing, and consciousness. It occurs when the heart abruptly stops pumping blood effectively throughout the body, leading to a life-threatening medical emergency that requires immediate intervention.
Circuit Breaker: A circuit breaker is an electrical safety device that automatically interrupts the flow of electric current in a circuit when it detects an abnormal condition, such as an overload, short circuit, or ground fault. It is designed to protect electrical systems and equipment from damage caused by excessive current or electrical faults.
Conductivity: Conductivity is a measure of a material's ability to allow the flow of electric current. It is a fundamental property that determines how easily electrons can move through a substance, and it plays a crucial role in understanding various electrical phenomena and applications.
Current: Current is the flow of electric charge in a circuit, typically measured in amperes (A). It represents how much charge passes through a point in the circuit per unit of time, and it plays a crucial role in determining how electrical energy is distributed and consumed in various applications.
Dielectric Breakdown: Dielectric breakdown is the failure of an insulating material to act as an effective insulator, resulting in the material becoming conductive and allowing the flow of electric current. This phenomenon occurs when the electric field strength within the insulator exceeds the material's inherent ability to resist the flow of charge carriers.
Electric Shock: An electric shock is the physical reaction or injury caused by the passage of an electric current through the body. It occurs when the body becomes part of an electrical circuit, allowing the current to flow through the tissues and muscles, potentially causing a range of effects from mild tingling to severe injury or even death.
Electrical Burns: Electrical burns are a type of thermal injury caused by the passage of electric current through the body. They can result in severe tissue damage and are considered a medical emergency due to the potential for life-threatening complications.
Electrical Safety Standards: Electrical safety standards are a set of guidelines and regulations designed to ensure the safe use and handling of electrical systems and devices. These standards aim to minimize the risk of electrical hazards, such as electric shocks, fires, and explosions, to protect individuals, property, and the environment.
Electrocution: Electrocution refers to the injury or death caused by electric shock, where an electric current passes through the body. It is a serious hazard associated with the use of electrical devices and systems, and understanding its causes and prevention is crucial for electrical safety.
Ground Fault Circuit Interrupter (GFCI): A ground fault circuit interrupter (GFCI) is a safety device that monitors the flow of electricity in a circuit and quickly cuts off power if it detects an imbalance, preventing electric shock and reducing the risk of electrical fires.
Grounding: Grounding is the process of connecting an electrical circuit to a reference point, typically the Earth, to ensure safety and stability. It allows excess charge to dissipate safely into the ground.
Grounding: Grounding is the process of establishing a low-resistance connection between an electrical circuit or device and the earth or a conductive body that serves as a ground. This connection ensures the safe dissipation of excess electrical charges, protecting against electric shocks and other electrical hazards.
Insulation: Insulation is a material or method used to reduce the transfer of heat or electricity between objects or environments. It plays a crucial role in maintaining temperature control in various settings, while also protecting individuals from electrical hazards. By slowing down the movement of heat or electrical current, insulation enhances safety and efficiency in both thermal and electrical applications.
Joule Heating: Joule heating, also known as resistive heating, is the process by which the passage of an electric current through a conductor generates heat. This phenomenon occurs due to the electrical resistance of the conductor, which causes the energy of the moving electrons to be converted into thermal energy.
Microshock sensitive: Microshock sensitive describes a condition where an individual is highly susceptible to electric currents as small as microamperes, typically due to the presence of medical devices that provide a direct path to the heart. This sensitivity can lead to severe physiological effects even at extremely low current levels.
Resistance: Resistance is a measure of the opposition to the flow of electric current in a circuit. It is a fundamental concept in electrical engineering and physics, as it determines the behavior of electrical systems and the energy dissipation within them.
Resistivity: Resistivity is a measure of how strongly a material opposes the flow of electric current. It is denoted by the Greek letter $\rho$ (rho) and has units of ohm-meters ($\Omega \cdot m$).
Resistivity: Resistivity is a fundamental property of materials that measures their ability to resist the flow of electric current. It is a measure of how strongly a material opposes the passage of electric charge, and it is a crucial factor in understanding the behavior of electrical circuits and the design of electrical components.
Respiratory Paralysis: Respiratory paralysis is a condition in which the muscles responsible for breathing become paralyzed, leading to the inability to breathe independently. This can result in life-threatening consequences if not promptly addressed.
Shock hazard: A shock hazard occurs when electrical current passes through a person's body, potentially causing injury or death. It is often the result of direct contact with live wires or faulty electrical devices.
Short circuit: A short circuit occurs when there is a direct connection between two points in an electrical circuit that have different potentials, allowing current to flow along an unintended path with little or no resistance. This can lead to excessive current flow and potential damage to the circuit.
Thermal conductivity: Thermal conductivity is a material's ability to conduct heat. It measures the rate at which heat energy passes through a material.
Thermal hazard: A thermal hazard occurs when electrical components or circuits generate excessive heat, posing risks of burns, fires, or damage to equipment. It is a critical safety concern in electrical systems and devices.
Ventricular Fibrillation: Ventricular fibrillation is a life-threatening heart rhythm disorder characterized by rapid, uncoordinated contractions of the ventricles, the lower chambers of the heart. This condition prevents the heart from effectively pumping blood throughout the body, leading to sudden cardiac arrest if not promptly treated.
Voltage: Voltage, also known as potential difference, is the electrical potential energy difference between two points in an electrical circuit. It is the driving force that causes the flow of electric current, and it is measured in units of volts (V).
Voltmeter: A voltmeter is an electronic instrument used to measure the potential difference, or voltage, between two points in an electrical or electronic circuit. It is a crucial tool for understanding and analyzing electrical systems across various contexts, including the study of electrical potential, electric hazards, and the operation of DC circuits.
Voltmeters: Voltmeters are instruments used to measure the electrical potential difference, or voltage, between two points in an electric circuit. They are connected in parallel with the component across which the voltage is to be measured.