Electrical Safety

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Electrical Safety
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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

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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?

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Electrical Safety Outline

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

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Electrical Circuits

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

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Rules of Electricity

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

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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

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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

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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

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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)

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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.

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Additional Resistance

• Gloves
• Shoes
• Mats

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Hazard Control

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

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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

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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

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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

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Electrical Cord Inspection

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

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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

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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

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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

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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

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Flammable/Ignitable Materials

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

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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

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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

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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.

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Question 1

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

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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.
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Question 2

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

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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.
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Question 3

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

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Question 3

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

The skin offers the most electrical resistance.
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Question 4

• Flammable materials can easily be ignited by
  ___________ electricity.

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Question 4

• Flammable materials can easily be ignited by
  ___________ electricity.

Static electricity can easily ignite a flammable
material.
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Question 5

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

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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.
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Question 6

• When should power tools and extension cords be
  inspected?

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Question 6

• When should power tools and extension cords be
  inspected?

Inspect power tools and extension cords before
each use.
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Question 7

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

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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
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Question 8

• When a circuit breaker trips, you should
  immediately reset it. (True or False)

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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.

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Question 9

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

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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.
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Question 10

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

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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.
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Power Line Safety

• http//www2.worksafebc.com/Publications/Multimedia
  /Videos.asp?ReportID34818

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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.

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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.

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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.

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• Questions?