Transcript Electrical Safety - GTU E

GROUP MEMBERS:
DHRUVI BARIA (ID_009)(ENROLLMENT_006)
JUI GAJJAR (ID_008)(ENROLLMENT_022)
AAKASH PARMAR (ID_017)(ENROLLMENT_061)
VATSAL VAIDYA (ID_004)(ENROLLMENT_122)
GUIDED BY :
MISS KRISHNA CHAUHAN
Electrical Engg Dept.
S.V.I.T Vasad
•This is to certify that
DHRUVI BARIA (ID_009)(ENROLLMENT_006)
JUI GAJJAR (ID_008)(ENROLLMENT_022)
AAKASH PARMAR (ID_017)(ENROLLMENT_061)
VATSAL VAIDYA (ID_004)(ENROLLMENT_122)
Of class Electrical Eng.-1 has completed their active learning
assignment for the term ending in December 2013.
DATE:21/11/2013
•Sign of teacher
Head of the department
Electrical Injuries
Classification of Exposure
Electrical Hazards
Electrical Hazard Control
 High Voltage
 >600 volts: typically associated with “outdoor”
electrical transmission.
Accounts for 60% of electrocutions.
Note: some people classify >480 volts as high
voltage.
 Low Voltage:
 <600 volts: typically associated with “indoor”
electrical service.
Accounts for 32% of electrocutions (OSHA).
Low voltage does not imply safe voltage.
Shock
:Conductors vs.
Resistors
:Grounding
:The Ground Fault
Accident
:GFCIs
 Burns
 Falls
 Fire
An electrical shock can occur upon contact of a
human’s body with any source of voltage high
enough to cause sufficient current through the
muscles or hair.
The minimum current a human can feel is
thought to be about 1 milli ampere(1mA).
Electricity wants to find the path
of least resistance to the ground.
Human tissues and body fluids
are relatively good conductors
because of high water content.
So if a person touches an
energized bare wire or faulty
equipment while grounded,
electricity will instantly pass through
the body to the ground, causing a
harmful, potentially fatal, shock.
Electrical
Current
0.001A
Voltage at
10000ohms
10V
0.005A
50V
0.010.02
100-200V
0.05A
500V
Voltage at Maximum
Physiological effect
1000ohms power(watt)
1V
0.01W
Threshold of feeling an electric
shock,pain.
5V
0.25W
Maximum current which would be
harmless
10-20V
1-4W
Sustained muscular contraction “can
not let go”current
50V
25W
0.1-0.3A 1000-3000V 100-300V 100-900W
6A
60000V
6000V
400000W
Ventricular interference respiratory
difficulty.
Ventricular fibrillation can be fatal
Sustained ventricular contraction
followed by normal heart rhythm.
These are the operation parameters
for a defibrillator. Temporary
respiratory paralysis and possibly
burns.
Grounding is a method of protecting employees
from electric shock.
By grounding an electrical system, a lowresistance path to earth through a ground
connection is intentionally created.
This path offers low resistance and has sufficient
current-carrying capacity to prevent the buildup of hazardous voltages.
A three pronged cord offers a grounding
connection.
White wire (neutral or common
wire), returns the power.
Black wire (hot wire), is connected
to the switch and fuse and carries
the power.
Green (or ground wire).
Three wires for each cord and
terminal.
A two prong plug has a hot prong
and a return prong, no ground
prong.
In any case, never remove the
third (grounding) prong from any
three-prong piece of equipment.
A ground fault accident occurs when a
person touches or grasps an electrically
energized object while the feet or other body
parts are in contact with the ground or a
grounded surface.
In some cases a ground fault accident
occurs when the opposite hand touches
the ground or a grounded object.
A lady working in kitchen
use toaster if a part of coil or
other live wire contact with
metal body of toaster whole
body become a conductor.
Whenever she touch it The
current went through her
body as a result, causing
cardiac arrest and death.
GFCI’s are to be used when using electrical
equipment in a wet environment.
GFCI’s are designed to detect any leakage
of current in an electrical circuit.
GFCI’s turn off or “trip” the circuit
whenever the leakage is greater than
5/1000 of an ampere.
For comparison two 60 Watt light bulbs
draw a total of 1 ampere of current.
Three types of GFCI’s
A GFCI receptacle used in
place of standard receptacle.
A portable GFCI plugs into a
standard receptacle.
A GFCI circuit breaker
combines leakage current
detection with the function of
a circuit breaker.
Whenever working in a wet
area, or outdoors, employees
should use one of these types
of GFCI’s.
Most common nonfatal electrical injury.
Types:
 Internal: “deep tissue”.
 Skin: “entry” and “exit” points.
 Arc: “flash” burns from heat and radiant
energy.
Common sites of visible skin burns are the hands
and feet.
Circuits may produce electrical burns
with relatively massive amounts of
tissue destruction by heating the tissues.
This is due to the physical property of
friction from the passage of electrons
and by destruction of cell membranes
by producing holes in the membranes.
Involuntary muscle
contractions can
“throw” workers and
cause falls.
If working at elevation,
the fall may cause
serious injury or death.

A worker fell from the top of a 12-story
building and landed on the concrete below. A
short-circuited electric drill was found dangling
from the building's top floor.
Detectives discovered that the grounding prong
was missing from the drill's plug.
 A nail was lodged in the rubber tread of the
work boot, allowing electricity to flow through the
victim's body to the ground.
 The electrical current caused muscle
contractions strong enough to throw the man
from the building, resulting in death.
In the United States 25% of fires are
caused by electricity.
A build-up of dust, trash and spider
webs increases the potential for fire to
start in the electrical system.
Unprotected light bulbs in work areas
are another potential hazard. They can
be hit, broken and cause a fire.
Electrical wiring can be hit when drilling
holes or driving nails in walls causing a
fire.
Many fires result from defects in, or misuse of the power
delivery system.
Wiring often fails due to faulty installation, overloading,
physical damage, aging and deterioration by chemical
action, heat, moisture and weather.
Such wiring should be replaced and new circuits installed.
Typical home and office electrical systems run like this:
The electrical service enters the house and connects to a
main electrical panel.
From the main electrical panel, wires run in different
directions throughout the house/building to power
lights, outlets, ceiling fans, air conditioners, and various
other direct-wired electrical appliances.
Typical home and office electrical systems run
like this:
The electrical service enters the house and
connects to a main electrical panel.
From the main electrical panel, wires run in
different directions throughout the
house/building to power lights, outlets, ceiling
fans, air conditioners, and various other
direct-wired electrical appliances.
To keep the wire from getting too hot and starting
a fire, circuit wiring attempts to contain the
amount of electrical load on the branch circuit by
limiting the number of potential electrical
appliances that can be running at the same time
on that circuit.
For example, only so many outlets are put on one
branch circuit or larger pieces of electrical
equipment are put on circuits dedicated to that
equipment only.
The homeowner or worker can plug in and run too
many appliances on the same circuit at one time
and overload the circuit.
Each circuit must be protected by a fuse or circuit
breaker that will blow or “trip” when its safe
carrying capacity is surpassed.
If a fuse blows or circuit breaker trips repeatedly
while in normal use (not overloaded), check for
shorts and other faults in the line or devices.
Do not resume use until the trouble is fixed.
It is hazardous to overload
electrical circuits by using
extension cords and multiplug outlets.
Use extension cords only when
necessary and make sure they
are heavy enough for the job.
Avoid creating an “octopus”
by inserting several plugs into
a multi-plug outlet connected
to a single wall outlet. (CDC)
Dimmed lights, reduced output from heaters and poor
television pictures are all symptoms of an overloaded
circuit.
Keep the total load at any one time safely below
maximum capacity.
When using a high wattage device such as a heater, iron
or power tool, turn off all unnecessary lights and devices.
Try to connect into a circuit with little electrical power
demand.
Extension cords should only be used
on a temporary basis in situations
where fixed wiring is not feasible.
DO NOT use extension cords as
permanent wiring. They may
not be able to carry the load.
However, if it is necessary to use an
extension cord, never run it across
walkways or aisles.
 It causes a potential tripping
hazard.
It wears down the insulation.
Wall receptacles should be
designed and installed so
that no current-carrying
parts will be exposed, and
outlet plates should be kept
tight to eliminate the
possibility of shock.
Replace or repair electrical
appliances that over
heated, sparked, shorted
out, smoked or have
damaged cords or cracked
equipment.
If wires are exposed, they may cause
a shock to a worker comes into
contact with them.
Cords should not be hung on nails,
run over or wrapped around objects,
knotted or twisted. This may break
the wire or insulation.
Short circuits are usually caused by
bare wires touching due to
breakdown of insulation.
Electrical tape or any other kind of
tape is not adequate!
Cords in areas of water or other
conductive liquid must be approved
for those locations.
When the outer jacket of a cord is
damaged, the cord may no longer be
water-resistant.
The insulation can absorb moisture,
which may then result in a short
circuit or excessive current leakage to
the ground.
These cords should be replaced
immediately.
Electric cords should be examined on
a routine basis for fraying and
exposed wiring.
Electrical cords should be examined visually
before use on any shift for external defects such
as:
fraying and exposed wiring
loose parts
deformed or missing parts
damage to outer jacket or insulation
evidence of internal damage such as pinched
or crushed outer jacket
If any defects are found the electric cords should
be removed from service immediately.
Pull the plug not the cord. Pulling the cord
could break a wire, causing a short circuit.
Plug your microwave or any other large appliances
into an outlet that is not shared with other
appliances.
Do not tamper with fuses as this is a potential fire
hazard.
Do not overload circuits as this may cause the wires
to heat and ignite insulation or other combustibles.
Keep office equipment properly cleaned and
maintained.
Ensure lamps are free from contact with flammable
material.
Always use lights bulbs with the recommended wattage
for your lamp and ceiling fixtures.
Be aware of the odor of burning plastic or wire.
Always follow the manufacturer recommendations when
using or installing new office equipment.
Wiring installations should always be made by a licensed
electrician or other qualified person.
All electrical appliances should have the label of a testing
laboratory.