Environmental Safety Flashcards
Define voltage.
The pressure pushing electrons
*compares to contractility of the heart in the circulatory system
What is the normal frequency used for alternating current (AC) around the world?
60 Hz
Define circuit.
Path that current flows through.
*Similar to the blood vessels of the circulatory system
Define ohm.
The measure of resistance (skin)
*similar to SVR in the circulatory system
Define hertz.
Number of cycles per second
*similar to heart rate
Define Amps.
The amount of current flow per second
*similar to cardiac index
Define current.
The flow of electrical charges (electrons)
*compares to blood flow in the circulatory system
Describe frequency.
- measured in Hertz (Hz)
- the higher the frequency, the less dangerous
- frequencies between 0-1 Hz can interfere with depolarization and repolarization in the myocardium causing arrhythmias
- frequency at which minimum current induces fibrillation is 50-60 Hz which is the normal AC frequency used worldwide
Describe alternating current (AC).
- variation in electron density within the conductor is time dependent
- intermittent current
Ex: 60 Hz means the current goes from high electron density to low electron density back to high in approx 1/60 sec or 60 times per second
Define conductor.
Material that current moves through easily
- good conductors are copper and bronze
- water is a great conductor
Define insulator.
Substance/material that current moves through poorly
ex: glass and air are poor conductors
* skin is a poor conductor
Describe skin as a conductor.
- skin is very resistant to current flow and a poor conductor
- as current flows through skin, resistance decreases
- dry, healthy, intact skin is 1 million ohms
- perspiring, intact skin is 12,000 ohms
- conducting jelly decreases skin ohms to 1,000
- catheter/pacing wires bypass the skin and go into the body fluid decreasing ohms to <100
How does electricity work?
A specific amount of alternating current (amp) is pushed through a circuit by voltage (120v) at a specified frequency (60 Hz)
Describe current flow.
- Current can flow through an unbroken closed circuit
- travels the path of least resistance
Describe electrical resistance.
- impedance of flow
- can lead to storage of charges (capacitor)
- long power cords cause higher resistance *leading to pressure build up and current leaks
Describe leakage current.
Current can escape the designated circuit and travel an alternative path
- high resistance can lead to leakage current due to excess pressure in the circuit and the currents desire to escape to a path of lower resistance and pressure
Define current density.
The amount of current and area it flows over.
*similar to HCT or viscosity
What are the three wires of a circuit?
- hot wire: supplies the current
- neutral wire: provides a return path
- ground wire: provides a low resistance path for leakage current to flow away from electrical equipment
What is the function of a circuit breaker?
To interrupt the circuit when current flow is too high
-protects from overheating and fire
Describe microshock.
- current is applied directly to heart
- small amounts of voltage or current applied directly to myocardium bypassing skin via IV cath, pacer wires, etc
- current as little as 100 micro amps can cause fatal arrhythmias
Describe macroshock.
- current is applied directly to the body surface
- requires a large amount of current to overcome skin’s resistance
- can cause muscle contraction, pain, burns, open wounds, pacer disruption, arrhythmias
What effects can 100-2500 milliamps at 60 Hz have?
V-fib
What effects can over 6,000 milliamps at 60Hz have?
- sustained myocardial contraction
- respiratory paralysis
- burns if the current density is high
What effect can 50-100 milliamps at 60 Hz have?
- pain
- mechanical injury
