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Module 3

Module 3. Electrical Hazards. Let’s start with a few case histories. “An employee was electrocuted while using a grinder with a frayed cord. The employee was standing in water, wet-grinding stone countertops…”.

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Module 3

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  1. Module 3 Electrical Hazards Southwest Safety Training Alliance Inc

  2. Let’s start with a few case histories “An employee was electrocuted while using a grinder with a frayed cord. The employee was standing in water, wet-grinding stone countertops…” Southwest Safety Training Alliance Inc

  3. “A maintenance employee was electrocuted while attempting to change a light fixture…” (no Lockout/Tagout) “An employee was electrocuted when he made contact with a piece of equipment being hoisted from an excavation. The arm of the backhoe hoisting the equipment contacted an overhead power line…” Southwest Safety Training Alliance Inc

  4. Top Electrical Citations (FY 2005) Electrical, Wiring Design and Protection Elec. Wiring Methods, Components and Equipment, General Use Electrical, General Requirements Electrical, Safety-Related Work Practices, General Requirements Southwest Safety Training Alliance Inc Source: Citation statistics from Federal OSHA data for OSHA fiscal year 2005

  5. Causes of Electrocution Fatalities • Contact with Overhead Power lines • Contact with Live Circuits • Not following Lock/Tagout procedures • Poorly Maintained Extension Cords • Defective Power Tools Southwest Safety Training Alliance Inc

  6. Electrical Injuries There are three direct and two indirect types of electrical injuries: • Direct: • Electrocution or death due to electrical shock • Electrical shock • Burns • Indirect: • Falls • Fire Southwest Safety Training Alliance Inc

  7. 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 Southwest Safety Training Alliance Inc

  8. Overhead Power Lines Hazard • Usually not insulated • Examples of equipment that can contact power lines: • Crane • Ladder • Scaffold • Backhoe • Scissors lift • Raised dump truck bed • Aluminum paint roller Southwest Safety Training Alliance Inc

  9. It’s Your Job to Know! • Know the hazards of electricity • Know the equipment • Use Safe Work Practices • Inspect your PPE before each use • Don’t work on energized circuits without permission Southwest Safety Training Alliance Inc

  10. To protect workers from electrical shock: Use barriers and guards to prevent passage through areas of exposed energized equipment Pre-plan work, post hazard warnings and use protective measures Keep working spaces and walkways clear of cords Safety-Related Work Practices Southwest Safety Training Alliance Inc

  11. “An employee working on a roof made contact with the service entrance riser into the home and was electrocuted…” Southwest Safety Training Alliance Inc

  12. Caution • Special Training is required for work on electrical equipment. Such training is for Authorized Employees and it covers: • Safe Work Practices • Isolation of Electrical Sources • Test Equipment • Tools & PPE • Only Authorized Employees may conduct electrical work Southwest Safety Training Alliance Inc

  13. Control Devices Control circuit devices such as… • push buttons • selector switches • interlocks … may not be used as the sole means for de-energizing circuits or equipment. Southwest Safety Training Alliance Inc

  14. Control – Use GFCI(ground-fault circuit interrupter) • Protects you from shock • Detects difference in current between the black and white wires • If ground fault detected, GFCI shuts off electricity in 1/40th of a second • Use GFCI’s on all 120-volt, single-phase, 15- and 20-ampere receptacles, or have an assured equipment grounding conductor program. Southwest Safety Training Alliance Inc

  15. ELECTRICAL SAFETYEffects of Amount of AC Currentma=1/1000th of an amp • 3 ma- painful shock which cause indirect accidents • 10ma- muscle contraction...”no let go” danger • 30ma- lung paralysis- usually temporary • 50ma- possible ventricular fibrillation (heart dysfunction, usually fatal) • 100 ma- certain ventricular fibrillation, fatal • 4 amps- heart paralysis, severe burns Southwest Safety Training Alliance Inc

  16. How it works Southwest Safety Training Alliance Inc

  17. Are these safe practices? Southwest Safety Training Alliance Inc

  18. Lock & Tag • Lock & Tag all Sources • Place Lock & Tag on each disconnecting means used to de-energize circuits • Attach lock to prevent operating the disconnecting means • Place Tag with each lock Note: Only the person who places the lock may remove it. Southwest Safety Training Alliance Inc

  19. Lockout Devices Southwest Safety Training Alliance Inc

  20. If a Lock cannot be applied… • A tag used without a lock must be supplemented by at least one additional safety measure that provides a level of safety equal to that of a lock. • Examples: • Removal of an isolating circuit element such as a fuse • Blocking of a controlling switch • Opening of an extra disconnecting device. Southwest Safety Training Alliance Inc

  21. Tagout There many different kinds of tags and Lockout devices. Southwest Safety Training Alliance Inc

  22. Release Stored Energy • Stored electric energy must be released before starting work. • Discharge all Capacitors • Short-Circuit & Ground all high capacitance elements Southwest Safety Training Alliance Inc

  23. Is it “Dead”? • Verify System is De-energized • Operate the equipment controls to check that equipment cannot be restarted. • Use test equipment to test the circuits & electrical parts for voltage & current Southwest Safety Training Alliance Inc

  24. Alerting others of hazards • Use barricades to prevent or limit access to work areas with un-insulated energized conductors or circuit parts. • Use safety signs, safety symbols, or accident prevention tags to warn others about electrical hazards which may endanger them. • If signs and barricades do not provide sufficient warning and protection from electrical hazards, an attendant shall be stationed to warn and protect employees. Southwest Safety Training Alliance Inc

  25. Electrical Tools and Cords Southwest Safety Training Alliance Inc

  26. Portable Electric Tools & Cords • Portable equipment must be handled in a manner which will not cause damage. • Flexible electric cords connected to equipment may not be used for raising or lowering the equipment. • Flexible cords may not be fastened with staples or otherwise hung in such a fashion as could damage the outer jacket or insulation. Southwest Safety Training Alliance Inc

  27. Tools & Equipment • Use insulated tools or handling equipment when working near exposed energized conductors or circuit parts. • Use fuse handling equipment to remove or install fuses when the fuse terminals are energized. • Ropes and handlines used near exposed energized parts must be nonconductive. Southwest Safety Training Alliance Inc

  28. Power Tool Requirements • Have a three-wire cord with ground plugged into a grounded receptacle, or • Be double insulated, or • Be powered by a low-voltage isolation transformer Southwest Safety Training Alliance Inc

  29. Preventing Electrical Hazards - Tools • Inspect tools before use • Use the right tool correctly • Protect your tools • Use double insulated tools Double Insulated marking Southwest Safety Training Alliance Inc

  30. Any problems? Southwest Safety Training Alliance Inc

  31. Clues that Electrical Hazards Exist • Tripped circuit breakers or blown fuses • Warm tools, wires, cords, connections, or junction boxes • GFCI that shuts off a circuit • Worn or frayed insulation around wire or connection Southwest Safety Training Alliance Inc

  32. Beware of Old Wiring • Removal of expansion tank (hot water). • Old style knob electrical wiring. • Victim contacted frayed wiring. Southwest Safety Training Alliance Inc

  33. Wire Pulling • Avoid manual wire pulling and use a tugger or a handtool whenever possible• Communication between the puller and feeder to coordinate movements will make the job easier and safer.• Use lighter-weight tools. Southwest Safety Training Alliance Inc

  34. Reducing Body Strains • CHANGE BODY POSITIONS. • Working overhead, at floor level, or in cramped spaces forces the body into awkward postures. • To relieve muscle tension and improve circulation, change body positions, alternate tasks, and stretch throughout the day. Southwest Safety Training Alliance Inc

  35. Summary Electrical equipment must be: • Listed and labeled • Free from hazards • Used in the proper manner If you use electrical tools you must: • Be protected from electrical shock • Use them in a comfortable position • Be provided with necessary safety equipment Southwest Safety Training Alliance Inc

  36. “A tree trimmer was electrocuted when he touched an overhead electrical line while descending a palm tree…” Always remember… It’s your life! “An employee was electrocuted while working on an A/C unit…” Southwest Safety Training Alliance Inc

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