Electrical Safety

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Electrical Safety
Protecting the Safety Health of Hispanic
Workers www.hispanicsworksafe.org
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After completing this unit, you will

• Know about how electricity works
• Understand the potential effects of electricity
  on the human body
• Recognize the primary hazards of electricity
• Be familiar with electrical protective devices
• Be able to identify safe work practices when
  working with electricity

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Magnitude of the Problem
Electricity is the second leading cause of death
in construction
About 5 workers are electrocuted every week
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Magnitude of the Problem

• Every year
• Electrocutions make up 12 of construction
  fatalities
• Over 600 deaths occur due to electrocution
• Over half of those deaths are in construction
• Over 30,000 non-fatal shocks occur

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Working with Electricity
Because of the high rate of electrical accidents,
OSHA has very strict guidelines for working with
electricity
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Electricity

• We are in the electronic age
• Use of electricity has become extremely common
  lights, television, computer, etc
• Electrical and electronic equipment
• Makes things cheaper and more convenient
• Provide new capabilities
• But.

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Leading Causes of Electrical Accidents

• Drilling and cutting through cables
• Using defective tools, cables and equipment
• Failure to maintain clearance distances
• Failure to de-energize circuits and follow
• Lockout/Tagout procedures

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Leading Causes of Electrical Accidents

• Failure to guard live parts from accidental
  worker contact
• Unqualified personnel working with electricity
• Improper installation/use of temporary electrical
  systems and equipment
• By-passing electrical protective devices

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Electricity How it Works

• Electricity travels in a closed circuit
• Electricity flows through conductors
• water, metal, the human body

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Fundamentals of Electricity

• Electrical current is the flow of electrons
  through a conductor.
• A conductor is a material that allows electrons
  to flow through it.
• An insulator resists the flow of electrons.
• Resistance opposes electron flow.

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Primary Hazards of Electricity

• Electrical shocks
• Burns
• Explosions
• Fires

The most common electrical hazard!
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Electrical Shock
Electrical shock occurs when the human body
becomes part of the path through which current
flows
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You will get an electrical shock if

• A part of your body completes an electrical
  circuit by
• Touching a live wire and an electrical ground, or
• Touching a live wire and another wire at a
  different voltage

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Electrical Shock

• The direct result can be electrocution

• The indirect result can be injury resulting from
  a fall or movement into machinery because of a
  shock

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Shock Severity

• Severity of the shock depends on
• Path of current through the body
• Amount of current flowing through the body (amps)
• Duration of the shocking current through the body

LOW VOLTAGE DOES NOT MEAN LOW HAZARD
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It can happen to you!
Luling, La. - A man was electrocuted when his
sweat dripped into the electric drill he was
using to build a swing set in his backyard, the
coroner said. Richard Miller was pronounced
dead Sunday at St. Charles Hospital, said David
Vial, St. Charles Parish coroner. Miller, 54,
had been using an electric drill in 90 degree
heat, Vial said Monday. Apparently the man was
sweating profusely, Vial said. He probably was
pushing against the drill with his chest and his
perspiration went into the drill itself and made
a contact. The Associated Press
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Dangers of Electrical Shocks
More than 3 mA painful shock More than 10
mA involuntary muscle contractions More than 30
mA lung paralysis temporary More than 50
mA heart dysfunction, usually fatal 100 mA to 4
Amps fatal Over 4 Amps heart paralysis severe
burns
75 mA is not much current A small power drill
uses 30 times as much
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What to do if someone is shocked by electricity?

• Disconnect the power
• Call emergency medical services, or 911

Use appropriate first aid and CPR techniques only
if you are trained to do so
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What to do if someone is shocked by electricity?
Dont

• Dont touch the victim unless you are certain
  that the power has been shut off. If you do, you
  must be the next victim!
• Dont touch bare wires, power lines, or power
  company equipment
• Dont try to put out a fire started by
  electricity with water. The water can conduct
  electricity

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More electrical hazards Burns
Burns can result when a person touches electrical
wiring or equipment that is improperly used or
maintained (energized)
Burns are the next most common injury after
electrical shocks
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More electrical hazards Burns
Electricity can cook internal organs or cause
internal bleeding! Internal effects may happen
days later
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More electrical hazards Burns
Burns typically occurs on hands and the feet
Burns are very serious injuries that need
immediate attention injuries might not be
visible and cardiac arrest can occur hours after
the initial burn.
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More electrical hazards EXPLOSIONS
Explosions occur when electricity provides a
source of ignition for an explosive mixture in
the atmosphere
Explosions can be caused from sparks given off
from overheated equipment
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More electrical hazards FIRES

• Electricity is one of the most common causes of
  fires
• Defective or misused electrical equipment is a
  major cause

• Overloading circuits and using unsafe work
  procedures might also contribute to increased
  heat levels which can start fires

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More electrical hazards Falls

• Electric shocks can also cause indirect injuries
  
• Workers in elevated locations who experience a
  shock may fall, resulting in serious injury or
  death

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How can we control electrical hazards?

• Electrical Isolation
• Equipment Grounding
• Circuit Interruption
• Safe Work Practices

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Electrical Isolation
We can be safe by keeping electricity away from
us!

• You can
• Insulate the conductors
• Example The insulation on extension cords
• Elevate the conductors
• Example Overhead power lines
• Guard/enclose the conductors
• Example Receptacle covers, boxes, conduit

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Insulating the Conductors
The first way to safeguard workers from
electrically energized wires is through insulation
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1) Insulating the Conductors

• Rubber and plastic is put on wires to prevent
  shock, fires, and short circuits
• It is always necessary to check the insulation on
  equipment and cords before plugging them in

Remember, even the smallest defect will allow
leakage!
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Defective Extension Cords
Plastic or rubber covering is missing
Damaged extension cords tools
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Damaged Cords

• Cords can be damaged by
• Aging
• Door or window edges
• Staples or fastenings
• Abrasion from adjacent materials
• Activity in the area

Improper use of cords can cause shocks, burns or
fire
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Taking care of electric cords wires

• Check before use
• Use only cords that are 3-wire type
• Use only cords marked for hard or extra-hard
  usage
• Cords not marked for hard or extra-hard use, or
  which have been modified, must be taken out of
  service immediately

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Remove cords by pulling on the plugs, not the
cords!
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Extension Cord Use

• Do not pass through holes in walls, floors, or
  ceilings or through windows or doors
• Do not run behind building walls, ceilings, or
  floors
• Do not drive over them
• Do not attach to building surfaces (including
  hanging them from nails, staples or bare wire)
• Do not lay out in a manner that can cause
  tripping
• Do not use as a substitute for the fixed wiring
  of a structure

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Extension Cord Use
Any comments?
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The most unforgivable misuse of an extension cord
is removing the grounding connection!
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Be aware of the environment you will be working
in. If the environment is wet or damp, use
equipment and cords designed for that situation!
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Extension Cord Maintenance

• Clean, inspect, coil and store extension cords.
  Wipe with a dry rag
• Coil cords using a figure 8, regular coil,
  reverse coil, or winding armature
• Store away from oil, dirt, solvents, acids,
  caustics, or moisture. Keep away from sharp tools

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Extension Cord Maintenance
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2) Elevating the Conductors

• The second way to protect workers from
  electrically energized wires is by elevating them
• Wires are often elevated by the power company

Dont forget to check the location of overhead
lines before you begin work and throughout the day
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Remember, never allow yourself, your tools, or
the materials you are working with be within 10
feet (3mt) of energized lines
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Working Near Overhead Lines

• Clearance of worker and any equipment, tool,
  material, or scaffold near uninsulated lines
• Less than 50 kv 10 feet (3mt)
• More than 50 kv 10 feet 0.4 inches (1cm) for
  each 1 kv
• Clearance near insulated lines
• Less than 300 volts 3 feet (91cm)
• 300 - 500 kv 10 feet (3mt.)

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Working Near Overhead Lines
Cranes, Derricks, Hoists

• 50 kv or less min. distance is 10 feet (3mt.)
• Over 50 kv 10 feet 0.4 for each kv over
• In transit no load 4 foot minimum up to 50 kv
• In transit no load 10 foot minimum if gt 50 kv

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Overhead Line Incident

• Two workers were attempting to remove a metal
  pole.
• Pole made contact with 7200 volts.
• One worker died.

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Energized overhead power lines and energized
equipment are EXTREMELY hazardous. Work
safe.Protect Yourself!
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Overhead Power LinesWhat to remember?

• Stay at least 10 feet away (3mt.)
• Post warning signs
• Assume that lines are energized

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Overhead Power LinesWhat to remember?

• Use wood or fiberglass ladders, not metal
• Power line workers need special training
  Personal Protective Equipment (PPE)

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3) Guarding the Conductors

• The third way to protect workers from
  electrically energized wires is by guarding them
• It is always necessary to check that electrical
  boxes and panels are covered and free from
  missing knock-outs.

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Covers, boxes, and enclosures are often put
around conductors to prevent worker contact.
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Remember, electric equipment operating at 50
volts or more must be guarded!
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Grounding

• Grounding creates a low-resistance path from a
  tool to the earth to disperse unwanted or excess
  current
• When a short or lightning occurs, energy flows to
  the ground and keeps you from becoming part of
  the circuit

Grounding is a method of preventing electrical
shock!
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Dont Forget
Grounding helps to safeguard the worker in the
event that a malfunction causes the metal frame
of the tool to become energized
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Examples of Improper Grounding

• Tools plugged into improperly grounded circuits
  may become energized
• Broken wire or plug on extension cord

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Will grounding always work?
Grounding will not work if the electricity can
flow through you more easily than the ground!

• This can happen when
• Your tool doesnt have a ground pin
• Youre working in water
• Youre touching a metal object

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What Must be Grounded?

• All circuits and extension cords.
• All noncurrent carrying metal parts.
• Portable semi-portable tools and equipment
  unless double insulated.
• Exemption for portable generators if less than 5
  kV.
• No grounding by-pass devices!

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Do Not Eliminate the Ground!
These are suicide plugs!
Youll become the next-best path for current!
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And remember

• Ground power supply systems, electrical circuits,
  and electrical equipment
• Frequently inspect electrical systems to insure
  path to ground is continuous
• Inspect electrical equipment before use
• Ground exposed metal parts of equipment

Dont remove ground prongs from tools or
extension cords
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Circuit Interruption

• We can be safer by automatically shutting off the
  flow electricity in the event of leakage,
  overload, or short circuit.
• Fuses, circuit breakers, Ground Fault Circuit
  Interrupters (GFCI) are circuit protection (or
  overcurrent) devices.
• Remember, circuit breakers fuses protect
  equipment, not you, because they take too much
  current too much time to trip.

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Circuit Protective Devices

• Circuit Breakers and Fuses Only protect the
  building, equipment, and tools from heat
  build-up!
• Ground Fault Circuit Interrupter (GFCI) Is the
  only device which will protect the worker from
  shock and electrocution!

Fuses and circuit breakers protect equipment, not
people, and dont protect against shocks and
electrocutions!
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Ground Fault Circuit Interrupter (GFCI)

• Protects you from shock
• Detects difference in current in the circuit
  caused by current leakage to ground and, in a
  fraction of a second, shuts off the electricity

Lets compare
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GFCI Testers
Remember GFCIs must be tested!
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GFCIs
GFCIs need monthly test!
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Safe Work Practices
In summary, anyone working with electric
equipment needs to use safe work practices

• You should
• De-energize (shut down) equipment before
  inspecting or making repairs
• Know how to disconnect power to a piece of
  equipment
• Use circuit protection devices when appropriate

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Safe Work Practices

• Each disconnect switch should be legibly marked
  or labeled
• Switches should be located at the point where the
  circuit originates

De-energized circuits and equipment must be
locked/tagged out
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Safe Work Practices
Have labels that are durable enough to withstand
weather, chemicals, heat, corrosion, or any other
environment to which they may be exposed
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Safe Work Practices
and finally

• No mental ladders for or near electrical work
• No wet hands when plugging or unplugging
• No raising or lowering tools by the cords
• Unless equipment designed for, cannot be used in
  damp and wet locations, or in extremely hot or
  chemically destructive work environments

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And dont forget!
Our families need us!
Everyday, they expect us to return home safe and
healthy.
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Questions?
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Training Evaluation
What did you like about this training?
What suggestions do you have for changes?
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Acknowledgements
This training program was developed by
Hispanics Work Safewww.hispanicsworksafe.org
How to contact us? Maria Julia
Brunette Department of Work Environment
University of Massachusetts LowellOne
University Ave., Lowell, MA 01854Phone
978-934-3248 Fax [phone]Email
Maria_Brunette_at_uml.edu
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Acknowledgements
This training program was funded by grants
from Occupational Safety and Health
Administration (OSHA)
This material was produced under grant number
46A3-HT15 from the Occupational Safety and Health
Administration, U.S. Department of Labor.  It
does not necessarily reflect the views or
policies of the U.S. Department of Labor, nor
does mention of trade names, commercial products,
or organizations imply endorsement by the U.S.
Government.