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Industrial electrical safety

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Industrial Electrical Safety
John Newquist

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Industrial electrical safety

  1. 1. Industrial Electrical Safety John Newquist Draft 3 14 2015
  2. 2. Dec 2013
  3. 3. Oct 2013
  4. 4. June 2014 • 42-year-old Lynden Endress was washing cattle on his farm. • That's when the power washer he was using short-circuited, electrocuting him.
  5. 5. November 2014 • Dietrich believes the man was electrocuted by his wedding ring after it made contact with a copper wire in the back of the machine. • Albert Washington, his brother- in-law, told officers that he turned the power off to the room. He asked for the power to be put back on to test the machine – and then when a fault was noticed he tried to fix it without turning the electricity off again, at which point he was electrocuted, according to the Daily Mail.
  6. 6. March 2014
  7. 7. Top 10 Most Cited Standards (General Industry Only) 1. Hazard Communication 2. Respiratory Protection 3. Lockout/Tagout 4. Powered Industrial Trucks 5. Electrical, Wiring Methods 6. Machine Guarding 7. Electrical, Systems Design 8. Powered Transmission Apparatus 9. Personal Protective Equipment 10. Abrasive Wheel Machinery
  8. 8. March 2015 • Issues?
  9. 9. Who needs training? • 1910.332(a) • Employees in occupations listed in Table S-4 face such a risk and are required to be trained. Other employees who also may reasonably be expected to face comparable risk of injury due to electric shock or other electrical hazards must also be trained. • At a minimum, be trained in and familiar with the following: • The skills and techniques necessary to distinguish exposed live parts from other parts of electric equipment. • The skills and techniques necessary to determine the nominal voltage of exposed live parts, and • The clearance distances specified in 1910.333(c) and the corresponding voltages to which the qualified person will be exposed.
  10. 10. Table S4 • Typical Occupational Categories of Employees Facing a Higher Than Normal Risk of Electrical Accident • Blue collar supervisors • Electrical and electronic engineers • Electrical and electronic equipment assemblers • Electrical and electronic technicians • Electricians • Industrial machine operators • Material handling equipment operators • Mechanics and repairers • Painters • Riggers and roustabouts • Stationary engineers • Welders
  11. 11. Ohm’s Law • The equations of Ohm’s Law are: • Voltage = Current times Resistance • Current equals Voltage divided by Resistance, • Resistance equals Voltage divided by Current. • 13,800 Volts / 1000 Ohms = 13.8 Amps • 480 Volts / 0.1 Ohms = 4,800 Amps • 480 Volts / 0.01 Ohms = 48,000 Amps
  12. 12. Determine the Current • Voltage is 120 volts. Resistance is 12 ohms. Current, then, is _______ amps. • Voltage is 480, resistance is 1 Ohm = _____ amps • Voltage is 220 resistance is 2200 Ohm = _____ amps
  13. 13. Electrical Current Effect • 1 mA threshold for feeling • 10-20 mA voluntary let-go of circuit impossible • 25 mA onset of muscular contractions 50-200 mA ventricular fibrillation or cardiac arrest • E. A. Lacy, Handbook of Electronic Safety Procedures, Prentice- Hall: Englewood Cliffs, New Jersey (1977)
  14. 14. Electricity and Conductors • To flow, electricity must have a complete path back to earth • Electricity flows through conductors • Water, Metal, the human body can be conductors • Insulators are not conductors
  15. 15. Ventricular Fibrillation • When the heart is in ventricular fibrillation, the musculature of the ventricles undergoes irregular, uncoordinated twitching resulting in no net blood flow. The condition proves fatal if not corrected in a very short space of time.
  16. 16. 120 Volts on the body • If your body resistance is 100,000 ohms, then the current which would flow would be: • I = 120 volts/100,000 ohm or 1.2 mA – able to feel it • Current = Volts/Resistance • But if you are sweaty and barefoot, then your resistance to ground might be as low as 1000 ohms. Then the current would be: • I = 120 V/1000 ohm or 120 mA – ventricular fibrillation
  17. 17. National Electric Code • The National Fire Protection Code, got its first electrical section in 1897 • Concern about many electrical fires and conflicting codes
  18. 18. Knob & Tube • 1881 NY Board of fire underwriters • When it becomes necessary to carry wires through partitions and floors, they must be secured against contact with metal, or other conducting substance, in a manner approved by the Inspector of the Board.
  19. 19. Electrical Grounding • 1928 NEC "Grounding required in conductive locations such as in basements or in walls containing metal lath, even if the equipment was fed by Knob and Tube wiring, nonmetallic cable lacking a grounding conductor. • Current travels both paths. Grounding involves providing a conductor to carry most of the current into the ground rather than into a body.
  20. 20. GFCI’s –1971 NEC The GFCI operates by sensing the difference between the currents in the Hot and Neutral conductors. Under normal conditions, these should be equal. Will shut off at 5 mA in 1/40th of a second.
  21. 21. Double Insulated • Insulated from shock • Square with square • Watch out for no lab testing
  22. 22. Power Taps • 29 CFR 1910.305(g)(1)(iii) reads as follows: • "Unless specifically permitted in paragraph (g)(1)(i) of this section, flexible cords and cables may not be used: • (A) As a substitute for the fixed wiring of a structure.
  23. 23. Fluorescent Lighting • Most common cause of electrical death among electricians • Changing ballast while live. • Worker not de- energizing circuit nor wearing any PPE.
  24. 24. Working Live • Shall be de-energized before the employee works on or near them, unless the employer can demonstrate that de- energizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations. • Testing live to find fault or short is common reason. Insulated leads alones are not safe. Wear rated gloves.
  25. 25. #1 - Boxes with unused openings • 1910.305(b)(1) Knockout Missing Missing Dead Fronts Note: Circuit breakers are designed to protect property not people.
  26. 26. #2 – Exposed live parts over 50 Volts • 1910.303(g)(2)(i) Exposed wiring Missing electrical housing
  27. 27. #3 – Missing covers • 1910.305(b)(2) Missing cover Receptacle w/o cover
  28. 28. #4 - Hanging pendant boxes • 1910.305(g)(1)(iii) Box has strain relief and no knockouts Knockout can get pushed into box
  29. 29. #5 – Missing Grounding Conductor • 1910.304(f)(4) Missing ground prong Missing ground prong
  30. 30. #6 – Disconnects not labeled • 1910.303(f) Label is tattered No labels on disconnects
  31. 31. #7 – Strain relief • 1910.305(g)(2)(iii) Wire pulled out of shredder Missing on strain relief
  32. 32. #8 – Equipment not used per listing • 1910.303(b)(2) Box used as an extension cord Receptacle box not mounted
  33. 33. Nov 2013 • Citation 2 Item 1 Type of Violation: Willful • 29 CFR 1910.303(b)(2): Listed or labeled electrical equipment was not used or installed in accordance with instructions included in the listing or labeling: • On or about May 24, 2013, and at times prior thereto, Spiral "final" department, employees are allowed to use foreign material to operate control panels. • Employees are using makeshift instruments, including but not limited to clip binders and welding wire bent in the shape of shepherd's hooks to override the "forward" limit switch on the pipe conveyor console panel, so that the pipe can continue horizontally down the conveyor and the incoming pipe can immediately be worked on to reduce workload buildup. • The practice of overriding the limit switch on the console panel exposes employee(s) to hazards associated with being struck by and caught-in between conveyed piping, stopping blocks and other stationary or transported objects.
  34. 34. #9 – 3’ Clear spaces • 1910.303(g)(1)(ii) Panel box blocked Storage in front of panel box
  35. 35. #10 – Electrical Free of Hazards • 1910.303(b)(1) Ground prong stuck in receptacle Open wiring spliced out of box
  36. 36. Receptacles • Receptacles will have hot, neutral, and a grounding conductor
  37. 37. Voltage Detectors • A Voltage detector will sense the magnetic field around an extension cord.
  38. 38. Insulated Gloves Electrical gloves can protect the worker who must test circuits live. Gloves can be bought for work with voltages under 500 volts. These are Class 00 gloves. Gloves must be sized for each employee. Test every six months.
  39. 39. Fuse Pulling Worker died when shocked pulling out barrel fuse with pliers Electrical circuits must be locked out before doing any work on the circuits if possible.
  40. 40. Sign Shock • Worker found unconscious taking out electric receptacle while still energized. Breakers were not locked out. No labels
  41. 41. Air Handler Worker touched an energized horizontal heating coil
  42. 42. Daily Checks • Cord and plug connected equipment should be check daily before use. • 1910.334(a)(2)(i) • Portable cord and plug connected equipment and flexible cord sets (extension cords) shall be visually inspected before use on any shift for external defects
  43. 43. Reverse Polarity • For example, if an internal fault should occur in the wiring as shown in the figure below, the equipment would not stop when the switch is released or would start as soon as a person plugs the supply cord into the improperly wired outlet. This could result in serious injury. On October 30, 2004, Employee #1 was apparently trying to use a portable electric grinder at a work site when he was electrocuted from ungrounded and reverse polarity electrical sources.
  44. 44. Capacitors • Pleasant Prairie WI • OSHA’s investigation found the temp worker had inadvertent contact with electrical equipment while trouble- shooting an electrical failure on a heat- sealing machine. • Company failed to require personal protective equipment for employees working near exposed, energized electrical parts. • The company also did not develop procedures to de-energize circuits and equipment safely or ensure stored energy capacitors were grounded.
  45. 45. Clear Space again • 1926.403(i)(1) • Sufficient access and working space shall be provided and maintained about all electric equipment to permit ready and safe operation and maintenance of such equipment.
  46. 46. Classified Locations • Combustible dust • Exposed wiring.
  47. 47. Quiz • What mA causes muscle contractions? ____ • A GFCI will shut off in ____ of a second. • When the musculature of the ventricles undergoes irregular, uncoordinated twitching resulting in no net blood flow is called _______ _______ • Live parts over ___ volts need to be guarded. • ___ feet of clear space must be maintained in front of electrical panels
  48. 48. ELECTRIC ARC FACTS n TYPICALLY LASTS LESS THAN A SECOND n EXTREMELY HIGH RADIANT ENERGY n EXPLOSIVE IN NATURE • CAN IGNITE AND/OR MELT CONVENTIONAL WORK CLOTHING
  49. 49. Electrical Statistics • As many as 80 percent of all electrical injuries are from an arc-flash contact and ignition of flammable clothing. • 2,000 people are admitted to burn centers • Source: Cooper Bussmann
  50. 50. Arc Flash Incidents • Estimated 5-10 arc flash incidents per day • Numerous fatalities per year • Estimates as to costs of burn injury medical (skin grafts, therapy )and related costs (replacement worker, rehabilitation,) average between 1.0 and 4 million dollars. • And then we have a social cost!!!
  51. 51. Now which of you has seen this label?
  52. 52. New Requirement
  53. 53. If the marking is not there. • The system was turned over without the appropriate hazard warnings. • It is not in compliance with the the 2002 National Electrical Code • If there is an Arc Blast/Flash event what is your exposure???
  54. 54. An arc flash is a short circuit through the air The temperature of an arc can reach approximately 35,000 degrees Fahrenheit or about four times as hot as the surface of the sun.
  55. 55. Causes of Electric Arcs • Dust and impurities • Corrosion • Condensation of vapor and water dripping • Accidental touching • Dropping tools • Over-voltage across narrow gaps • Failure of insulating materials • Improperly designed or utilized equipment • Improper work procedures
  56. 56. Electrical Processes Causing Flashes • Removing or installing circuit breakers or fuses • Voltage testing • Working on control circuits when energized parts exposed • Applying safety grounds • Racking circuit breakers • Racking starters • Removing bolted covers
  57. 57. PPE
  58. 58. PPE will depend on which boundary and task you are in. FR clothing must be work first at Category 1 work.
  59. 59. Power Lines • 10 foot safe clearance. • Avoid storing material under the lines.
  60. 60. Summary • Grounding involves providing a conductor to carry most of the current into the ground rather than into a body.
  61. 61. Summary • Water and other liquids are good - conductors of electricity.
  62. 62. Lastly • A three-pronged plug should never be used in a two pronged outlet
  63. 63. Questions? This is very unsafe!

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