HAZARD ANALYSIS AND SHOCK Flashcards
It is silent, invisible, odorless, and has an “automatic” aspect to it
Electricity
1800s
electricity is harmless
1900s
electricity entails great hazard
The process of collecting and interpreting information on hazards and conditions leading to their presence.
hazard analysis
There Are Three Components of Electrical Power Hazard:
shock, arc, blast
The physical stimulation or trauma that occurs as a result of electric current passing through the body.
shock
The heat and light energy release that is caused by the electrical breakdown and subsequent electrical discharge through an electrical insulator, such as air.
arc
The explosive effect caused by the rapid expansion of air and other vaporized materials that are superheated by the sudden presence of an electric arc.
blast
Is the physical stimulation that occurs when electric current flows through the human body. The distribution of current flow through the body is a function of the resistance of the various paths through which the current flows.
electric shock
The final trauma associated with electric shock is usually determined by the most critical path called the
shock circuit
It is the path that electric current takes through the body. If the shock circuit includes critical organs, severe trauma is more likely than if it does not.
shock circuit
Effects of Electrical Shock
burning, cell wall damage
are caused by electric current are almost always third-degree because the burning occurs from the inside of the body. This means that the growth centers are destroyed. Electric-current burns can be especially severe when they involve vital internal organs.
burning
Research funded by the Electric Power Research Institute (EPRI) has shown that cell death can result from the enlargement of cellular pores due to high-intensity electric fields. This trauma called electroporation allows ions to flow freely through the cell membranes, causing cell death.
cell wall damage
Influencing Factors
- Physical Condition and Physical Response
- Current Duration
- Frequency
- Voltage Magnitude
- Current Magnitude
- Nominal Resistance Values for Various Parts of the Human Body
- Nominal Resistance Values for Various Materials
- Nominal Human Response to Current Magnitudes
- Parts of the Body
A given amount of current flow will usually cause less trauma to a person in good physical condition. Moreover, if the victim of the shock has any specific medical problems such as heart or lung ailments, these parts of the body will be severely affected by relatively low currents. A diseased heart, for example, is more likely to suffer ventricular fibrillation than a healthy heart.
Physical Condition and Physical Response
The amount of energy delivered to the body is directly proportional to the length of time that the current flows; consequently, the degree of trauma is also directly proportional to the duration of the current.
Current Duration
The table below lists the broad relationships between frequency and the harmful effects of current flow through the body. Note that at higher frequencies, the effects of Joule (I2t) heating become less significant. This decrease is related to the increased capacitive current flow at higher frequencies.
Frequency
Historically, little attention was paid to the effect that voltage magnitude has on an electrical trauma. It was assumed that a 200-V source would create the same amount of physical trauma that a 2000-V source would—assuming that the current magnitude is the same. In fact, higher voltages can be more lethal for at least three reasons:
Voltage Magnitude
At voltages ___ ____ the electrical pressure may be sufficient to puncture the ____.
above 400V, epidermis
The degree of electroporation ____ for greater cellular voltage gradients.
is higher
Higher voltages are more likely to create ___ ____.
electrical arcing
The magnitude of the current that flows through the body obeys Ohm’s law
current magnitude
Current flow affects the various bodily organs in different manners. For example, the heart can be caused to fibrillate with as little as 75 mA. The diaphragm and the breathing system can be paralyzed, which possibly may be fatal without outside intervention, with less than 30 mA of current flow. The specific responses of the various body parts to current flow are covered in later sections.
parts of the body
