Shock, Arc, and Blast Flashcards
Who work with electricity directly
Engineers and Qualified Electrical workers
who works with electricity indirectly
office workers and sales person
statistic of lineman incidents in 2004
number of incidents# 50
Fatalities # 40
Hospitalized # 16
non-hospitalized # 2
tostatistic of lineman incidents between 1995 to 2003
number of incidents# 552
Fatalities # 383
Hospitalized # 213
non-hospitalized # 26
Are all fatalities and injuries preventable
Yes
What are the hazards associated with electricity
Shock
Arc
Blast
Electricity flow of pressure
is measure in volts
Electricity flow of resistance
is measure in ohms
measure of ohm is dependent on 3 factors
the nature of the substance itself,
the length and cross-sectional area of the substance,
the temperature of the substance.
substance that offers resistance are
porcelain
polymers
plastics
bakelite,
dry wood
note these are insulator
the relationship between resistance current and voltage
Ohms law
What is the ohms law formula
Current = voltage divided by resistance (I = ER)
What is the human body resistance
1)Hand to hand: 1,000 ohms
2)120 volts
3)Formula I = ER
4)120/1,000 = 0.120 amperes or 120 mA
How does electivity travels
it travels in a close circuit.
note it takes any path available to complete a circuit
How does shock occurs
it happens when the body become part of the circuit that electricity travels through.
note it enter one part of the body and leaves in another
There 3 ways that shock normally occurs
the individual must come in contact with both wires of the electrical circuit
one wire of the electric circuit and the ground
a metallic part that has become “hot” by being in contact with an energized wire while the individual is also in contact with the ground
what is the body cover by
Skin is made up of 3 layer
What is the most important layer of the skin
The outer layer which is made up of dead skin is called the horny layer
What is the outer skin made up
Its made from a protein called keratin
what can drop the resistance of the horny layer
when the skin is moist or when it has an abrasion such as a cut
What provide the human body largest resistance from electricity
Keratin
At what volts does the skin get punctured
600 Volts
What are the volts of a Power distribution systems
They usually are 480 volts or higher
what causes the blood to flow
The contraction of the blood muscles
What makes muscles to contract
electrical impulses
At what milliamperes can the rhythmic of the heart stops
75 milliamperes
how do electric impulses travel
through the nerves
What are the 3 things that affects the severity of the shock are
-The amount of current flowing through the body
(measured in amperes)
-The path that current flows through the body
-The length the body is in the circuit
Apart of the main 3 what are other severity that affects the body
-The frequency of the current
-Phase of the heart when the shock happened
-General person health
What is the common related injury
A Burn
What are the 3 types of burn that happens in an electrical accident
-Electrical burns
-Arc Burns
Thermal Contact burns
Metal arcing of metal can reach what temperature
Up to 35,000 Freiheit
note: Four times hotter than the sun
What causes electric arc
It happens due to poor electrical contact or insulation by the passage of substantial amounts of current through the vaporized terminal material such as metal or carbon
How does a blast happen
By the pressure made of the heating of air surrounding the arc and the expansion of the metals as its vaporized
what the hazard associated with blast
It can hurl people, switch gear and cabinet with great distance
What is a benefit of a blast
can hurl nearby personnel alway from the arc
When a hazard cant be remove what do you need to work around it
You need Personal Protective equipment
What you need to do in order to have the proper PPE for the job
Hazard assessment
What is the NFPA 70E
Standards that specified the amount and type of PPE needed for an hazard
In order for rubber material to be valid to use for hazard what it to pass through
ANSI standards in their manufacture and subsequent electrical testing
1 milliampere
Perception level. Just a faint tingle.
5 milliamperes
Slight shock felt; not painful but disturbing. Average individual can let go. However, strong involuntary reactions to shocks in this range can lead to injuries.
6 to 25 milliamperes (women)
9 to 30 milliamperes (men)
Painful shock, muscular control is lost. This is called the freezing current or “let-go” range.
50 to 150 milliamperes
Extreme pain, respiratory arrest, severe muscular contractions.* Individual cannot let go. Death is possible.
1,000 to 4,300 milliamperes
Ventricular fibrillation. (The rhythmic pumping action of the heart ceases.) Muscular contraction and nerve damage occur. Death is most likely.
10,000 milliamperes
Cardiac arrest, severe burns, and probable death.
