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Electrical Safety

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Title: Electrical Safety


1
Electrical Safety
2
Training
  • Qualified workers
  • Only Qualified workers are allowed to work on or
    near exposed energized equipment.
  • Unqualified workers
  • Unqualified workers are not permitted to work on
    or near exposed energized equipment

3
Concerned About Electricity?
  • How many sets of Christmas lights do you plug
    into one extension cord?
  • Do you still use your hot and sparking electric
    drill?
  • Is your vacuum cleaners cord twisted and frayed?
  • Have you installed outlet covers to protect your
    probing fingers?

4
Electrical Safety Outline
  • Electricity and the human body
  • Electrical hazards and safe work practices
  • Quiz

5
Electrical Circuits
  • A basic completed electrical circuit requires
    three things to function correctly
  • Electrical source
  • Electrical user
  • Wires

6
Rules of Electricity
  • Electricity travels in a completed circuit
  • Electricity always travels in the path of least
    resistance
  • Electricity tries to travel to ground

7
Electricity and People
  • A person usually offers a lessor resistance for
    the electricity
  • The person forms a completed circuit when
    touching the ground
  • Electricity always tries to travel to ground

8
Voltages and Amperes
  • Voltage Amps X Ohms(resistance)
  • Converting voltage to amps
  • Typical Industrial Voltages
  • 110/120 Volts 60milli-amps (mA)
  • 220/240 Volts 120 mA
  • 440/480 Volts 240 mA

9
Effects on the Human Body
  • 1 mA Can be felt by the body
  • 2-10 mA Minor shock, might result in a fall
  • 10-25 mA Loss of muscle control, may not be
    able to let go of the current
  • 25-75 mA Painful, may lead to collapse or death
  • 75-300 mA Last for 1/4 second, almost always
    immediately fatal

10
Bodys Resistance
  • Skin offers most of the bodys electrical
    resistance
  • Increased resistance
  • Thick and callused skin (foot or hand)
  • Dry skin
  • Decreased resistance
  • Thin skin (inner forearm)
  • Wet or sweaty skin
  • Broken or abraded skin (scratches)

11
Resistance Varies
  • Different levels of electrical resistance for
    each person
  • Ranges from 500 ohms to many thousands of ohms
  • The greater the bodys resistance, the less
    chance of harm
  • A similar voltage shock can be minor to one
    person and deadly to another.

12
Additional Resistance
  • Gloves
  • Shoes
  • Mats

13
Hazard Control
  • Electrical systems are inherently safe
  • Injuries typically occur when
  • Procedures are inappropriate
  • Procedures are not followed or ignored
  • Safety systems are circumvented

14
General Electrical Hazards
  • High-voltage overhead power lines
  • Damaged insulation on wires
  • Digging or trenching near buried lines
  • Broken switches or plugs
  • Overloaded circuits
  • Overheated appliances or tools
  • Static electricity
  • Flammable materials

15
Portable Power Tools
  • Inspect portable power tools
  • Never use damaged equipment
  • Tag it out of service
  • Have it repaired or replaced
  • Never use portable power equipment in wet or damp
    areas
  • Stop using power tools if they become hot or
    start sparking

16
Extension Cords
  • Inspect and check for capacity
  • For temporary work only
  • Do not use as a rope to pull or lift objects
  • Should not be fastened with staples or hung over
    hooks

17
Electrical Cord Inspection
  • Deformed or mission pins
  • Damaged outer jacket or insulation
  • Evidence of internal damage
  • If damaged, take out of service until repaired

18
Circuit Protection
  • Energize or de-energize with appropriate
    switches, breakers, etc.
  • Do not energize or de-energize with fuses,
    terminal lugs, or cable splice connections
  • If circuit protection device is trippedinspect

19
Grounding Equipment
  • Most electrical equipment is designed with a
    grounding system
  • Do not use equipment with damaged grounding
    connectors
  • Do not use adapters that interrupt the grounding
    connection

20
Ground Fault Circuit Interrupters
  • GFCIs reduce the likelihood of fatal shocks
  • Detect small amount of earth current and
    automatically switch off the power
  • Used with extension cords and portable tools
  • Fuses and circuit breakers protect equipment, not
    people

21
Static Electricity
  • Created when materials rub together
  • Can cause shocks or even minor skin burns
  • Reduced or prevented by
  • Proper grounding
  • Rubber matting
  • Grounding wires, gloves, or shoes

22
Flammable/Ignitable Materials
  • Flammable gases, vapors, or liquids
  • Combustible dust
  • Can be ignited by static electricity
  • Require specially designed electrical equipment

23
Machine Operators
  • Never tamper with electrical interlocks
  • Do not repair electrical components of your
    machine
  • Properly shut off machinery before working in the
    point of operation
  • Obey warning signs and follow safe procedures

24
Summary
  • Electricity will try to reach ground even if it
    means going through a person
  • Even the small voltage from your home can cause
    serious injury
  • Always inspect power tools and cords and do not
    use them if damaged
  • Do not attempt to repair electrical equipment
    unless trained and qualified

25
Electrical Injuries
  • Call for emergency help immediately
  • Everyone experiences minor electrical shocks from
    time to time. In some cases, however, even small
    amounts of electricity can be life-threatening
    because they can produce unconsciousness, cardiac
    arrest, and cessation of breathing.
  • Electrical shocks also can produce serious, deep
    burns and tissue injury, although often even a
    serious electrical burn appears as only a minor
    mark on the skin.
  • If you find a person whom you think has been
    electrocuted, look first--do not touch. He or she
    may still be in contact with the electrical
    source, and touching him or her may only pass the
    current through you.
  • If possible, turn off the source of electricity.
    If this is not possible, move the source away
    from you and the affected person using a
    non-conducting object made of cardboard, plastic,
    or wood.
  • Once the person is free of the source of
    electricity, check the person's breathing and
    pulse. If either has stopped or seems dangerously
    slow or shallow, initiate resuscitation
    immediately .
  • If the person is faint or pale or shows other
    signs of shock, lay the person down with the head
    slightly lower than the trunk of his or her body
    and the legs elevated.
  • Treat any major burns and wait for emergency
    medical assistance to arrive.

26
Question 1
  • Where does electricity always want to go, even if
    it means traveling through a person?

27
Question 1
  • Where does electricity always want to go, even if
    it means traveling through a person?

Electricity always wants to travel to ground,
which will complete the circuit.
28
Question 2
  • A shock from an outlet at home may be painful,
    lead to collapse, or even death. (True or False)

29
Question 2
  • A shock from an outlet at home may be painful,
    lead to collapse, or even death. (True or False)

True. A 120-volt outlet at home can give the
average person a shock of 60 mA.
30
Question 3
  • Which part of the human body offers the most
    electrical resistance?

31
Question 3
  • Which part of the human body offers the most
    electrical resistance?

The skin offers the most electrical resistance.
32
Question 4
  • Flammable materials can easily be ignited by
    ___________ electricity.

33
Question 4
  • Flammable materials can easily be ignited by
    ___________ electricity.

Static electricity can easily ignite a flammable
material.
34
Question 5
  • Only ___________________ workers are permitted to
    work on or near exposed electrical components.

35
Question 5
  • Only ___________________ workers are permitted to
    work on or near exposed electrical components.

Only qualified and trained workers can repair or
troubleshoot electrical equipment.
36
Question 6
  • When should power tools and extension cords be
    inspected?

37
Question 6
  • When should power tools and extension cords be
    inspected?

Inspect power tools and extension cords before
each use.
38
Question 7
  • Fuses and circuit breaker are designed to protect
    people from shocks. (True or False)

39
Question 7
  • Fuses and circuit breaker are designed to protect
    people from shocks. (True or False)

False. Fuses and circuit breaker protect
machinery and electrical systems
40
Question 8
  • When a circuit breaker trips, you should
    immediately reset it. (True or False)

41
Question 8
  • When a circuit breaker trips, you should
    immediately reset it. (True or False)
  • False. A tripped breaker could indicate a
    problem, so it should be checked by a qualified
    worker.

42
Question 9
  • Extension cords should never be used as a
    permanent power source. (True or False)

43
Question 9
  • Extension cords should never be used as a
    permanent power source. (True or False)

True. Extension cords are designed as a temporary
power source.
44
Question 10
  • What should be done with a damaged power tool or
    extension cord?

45
Question 10
  • What should be done with a damaged power tool or
    extension cord?

Tag it as out of service and have it replaced
or repaired by a qualified electrician.
46
Power Line Safety
  • http//www2.worksafebc.com/Publications/Multimedia
    /Videos.asp?ReportID34818

47
The hazards of power lines
  • You cannot tell if a downed power line is
    energized just by looking at it.
  • The electricity in a power line always seeks a
    path to the ground. This path might include a
    tree, a vehicle, or a fence. These objects then
    become energized. If you touch the energized line
    or object, the electricity can flow through your
    body. Keep away from any object that is in
    contact with a power line.
  • Once electricity reaches the ground, the ground
    itself becomes energized. This can happen if a
    broken power line falls to the ground or onto a
    vehicle or tree. The electricity then flows
    through the ground over a wide area, spreading
    out like ripples in a pool of water.

48
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49
Safe work practices for first responders
  • Treat downed power lines and anything in contact
    with them as energized.
  • Park away from the power lines. When you arrive
    at the scene, park your vehicle well away from
    any downed lines. Before you exit your vehicle at
    night, shine a flashlight through the window to
    make sure you are not near a downed power line.
  • Stop traffic and keep people away. Pedestrians or
    motorists may not see power lines that are on the
    ground. The surrounding area will be energized.
    Secure the area and keep everyone back at least
    10 metres (33 feet) - more if the voltage is over
    60 kilovolts.
  • Don't become a victim yourself. You cannot help
    anyone if you are injured or electrocuted. Never
    touch anything that is in contact with a downed
    power line, including injured or trapped victims,
    puddles, vehicles, or trees. Do not use a dry
    stick or piece of hose as they will not protect
    you.
  • Call the power company immediately. The power
    company can ensure that automatic switching
    equipment will not restore power to the line. A
    crew with proper training and equipment will
    arrive as soon as possible.
  • Wait for the power company representative to
    confirm that it is safe to approach the scene.
    Only the power company can confirm that the
    system has been de-energized and that power will
    not automatically be restored.

50
Staying safe inside a vehicle that is in contact
with power lines
  • If possible, move the vehicle away to break
    contact with the power line.
  • If the vehicle cannot be moved, stay inside until
    emergency crews can safely approach. If anyone
    approaches the vehicle, open the window and call
    out. Tell them to keep away and to call 9-1-1 for
    help.
  • If there is a fire and you must leave the
    vehicle, jump out with your feet together. Never
    touch the ground and the vehicle at the same
    time. Move away slowly by shuffling and keeping
    both feet close together.

51
  • Questions?
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