Electrical safety13


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Electrical safety13

  1. 1. Electrical Safety By Autry Technology Center
  2. 2. You shall be able to identify:  The injuries and fatalities while working near electricity.  Basic electrical principles.  Workers at risk.  Basic electrical hazards. Safe work practices associated with electricity.
  3. 3. Crane contacts electrical lines; causes fire; tires begin to burn
  4. 4.  Each year contact with overhead power lines result in fatalities, serious injury and property damage.  Unintentional contact with overhead power lines resulted in the following: Based on accident statistics in one state  19 serious accidents from July 1999 through September 2005.  16 fatalities. Based on national statistics (NSC–2004)  309 fatalities occurred from 1999 to 2001.
  5. 5.  These statistics only represent facts that have been reported to these agencies; the actual number of fatalities and suffering are far greater.
  6. 6. Electricity - The Dangers  About 5 workers are electrocuted every week  Causes 12% of young worker workplace deaths  Takes very little electricity to cause harm  Significant risk of causing fires
  7. 7.  Fact: an electrical arc generates temperatures in excess of 35,000 degrees F.  This is hot enough to vaporize steel.
  8. 8. Electrical Shock Injury; Note entry and exit point  These accidents can be prevented with improved supervisor and worker safety training and better coordination of work with all utilities involved.
  9. 9. Same injury a few days later
  10. 10. Exit point on bottom of foot
  11. 11. At-Risk Workers  Equipment operators of mobile equipment, dump trucks, drill rigs, cranes, etc. and employees who work around this equipment  Emergency service personnel who respond to car crashes involving power poles and overhead lines, downed power lines, respond to fires involving electrical lines near structures  Employees working from ladders  Employees working with electrical equipment
  12. 12. At-Risk Workers  Employees working from roofs where power lines enter building  Employees who work from scaffolds  Employees who work from Man lifts or bucket trucks around power lines  And Any employee who is near overhead power lines for any reason such as tree trimmers, highway workers, forklift operators, etc.
  13. 13. Electrical Shock An electrical shock is received when electrical current passes through the body. 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.
  14. 14. Electrical Harm Estimated Effects of AC Currents (U.S. Standard 60 Hz) 1 milliamp (mA) Barely perceptible 16 mA Maximum current an average man can grasp and “let go” 20 – 30 mA Paralysis of respiratory muscles 100 mA Ventricular fibrillation threshold 2 Amps Cardiac standstill and internal organ damage 15/20/30 Amps Common U.S. household breakers PATH: Harm is related to the path by which current passes through the body.
  15. 15. Dangers of Electrical Shock  Currents greater than 75 mA* can cause ventricular fibrillation (rapid, ineffective heartbeat).  Will cause death in a few minutes unless a defibrillator is used.  75 mA is not much current – a small power drill uses 30 times as much current. Defibrillator in use
  16. 16. Fundamentals of Electrical Hazards  To flow electricity must have a complete path.  Electricity flows through conductors water, metal, the human body  Insulators are non-conductors.  The human body is a conductor.
  17. 17. Electrical Injuries There are four main types of electrical injuries:  Direct:  Electrocution or death due to electrical shock  Electrical shock  Burns  Indirect - Falls
  18. 18. Burns  Most common shock- related injury.  Occurs when you touch electrical wiring or equipment that is improperly used or maintained.  Typically occurs on hands.  Very serious injury that needs immediate attention
  19. 19. Hit live wire changing a light ballast; lost right index finger
  20. 20. High Voltage Electricity Follows the Path of Least Resistance to Ground Fact:  High Voltage Electricity Follows all Paths to Ground
  21. 21. Worker subjected to arc flash
  22. 22. Fire resistant shirt
  23. 23. Electrical Damage to the Body  If you touch a power line, electricity will attempt to travel through your body  When electricity travels through the body, it heats up and burns body tissue internally  Electricity leaves the body violently, causing burns or even blowing an exit hole
  24. 24. The Sad Reality- this victim contacted an overhead power line while working from an aerial bucket
  25. 25. Myths Fact:  Possibly Dead Wrong! Electricity Travels at the speed of light, 186,000 miles per second.  If you touch another person that is in contact  with a high voltage wire you will instantly  become part of the electrical circuit. You Can Safely Shove a Person Away From Contact With an Energized Power
  26. 26. Car and Truck Tires Are Made of Rubber and Are Non-Conductive Fact:  Tires contain Carbon Black. Carbon Black is a conductive material used to make the tires conductive for a better radio signal and to make them last longer.  If an overhead electrical line falls upon your vehicle stay on or inside the vehicle if at all possible.  If you must leave your vehicle do not touch the vehicle and ground at the same time.  Jump clear and Keep both feet together and hop away. Myths
  27. 27. I Can Safely Use a Tree Limb To Move an Overhead Powerline Fact:  Tree limbs are conductive. Fresh tree limbs are very electrically conductive due to the moisture content.  High voltage electricity will conduct through most items that have contamination or moisture. Myths
  28. 28. Overhead Powerlines Laying on the Ground Are Safe To Be Near. Fact:  Just because a power line is laying on the ground does not mean it is not energized.  Always consider downed power lines live!  High voltage electricity can enter the ground from the power line.  This can create different electrical potentials near the wire that could cause electrocution by contact through your footwear. Myths
  29. 29. I Can Look-Up and Estimate the Distance to The Powerline. Fact:  Few people have the ability to judge vertical distance accurately.  Don’t take a chance with your safety and the safety of those working around you.  Call the owner of the powerlines at least 72 hours prior to working within 50 feet of energized overhead power lines. Myths
  30. 30. I’ve Been Shocked by Electricity Before, So I Know What Electricity Will Do. Fact:  Unless you have seen the destructive power of High Voltage Electricity first hand you have no idea what it can do to material, objects and to people compared to household voltages. Myths
  31. 31. A Powerline Falls Across Your Vehicle, You Should Not Try to Drive Away. Fact:  You should try to drive away if at all possible.  If your vehicle will not start stay inside and warn others to stay away until an electrical line worker tell you it is safe to leave the vehicle. Myths
  32. 32. Scaffold Too Close to Power Lines • The possibility of electrocution is a serious consideration when working near power lines. • Check the clearance distances listed in the OSHA standards.
  33. 33. Ladder Too Close to Energized Electrical Equipment If using ladders where the employee or the ladder could contact exposed energized electrical equipment, they must have nonconductive siderails such as wood or fiberglass. This is an unsafe condition
  34. 34. It’s up to you to prevent contacts with electricity.
  35. 35. Don’t Put Your Life on the Line!