Electrical Safety-Related Work Practices

1. Electrical Safety-Related Work Practices In and around the mines AND The home

2. Jon Montgomery, EFSmontgomery.jon@dol.gov • Albany, NY • 518-489-0780

3. WHAT IS ELECTRICITY??

4. ? • Electricity is a form of energy • High Voltage (>650 volts) • Low Voltage (650 volts or less) • Alternating Current • Direct Current • Static Electricity

9. ELECTRICAL ACCIDENTS • Electrocutions rank fourth in work related fatalities with about half of these at 600 volts or less. • There are an average of over 3,600 disabling electrical related injuries annually. • There are an average of 4,000 non-disabling electrical injuries annually.

10. Let’s talk about personal protection and the home 40,000 residential fires annually which are caused by problems with electrical wiring systems, claiming more than 350 lives Additionally, electric cords and plugs were involved in about 7,100 fires resulting in 120 deaths or about 32% of all deaths associated with residential electrical system fires, occurring each year. Lamps and light fixtures were involved in about 8,900 fires and 60 deaths About 3,600 people are treated for injuries associated with extension cords. Switches and outlets are involved in 4,700 fires and deaths

11. Reported Mining Electrical Accidents (INCLUDES FATALITIES)1990 thru 2000 • Coal-Underground 752 • Coal-Surface 137 • Metal/non-metal-Underground 99 • Metal/non-metal-Surface 655 • Prep Plants 244 • Other 34 Total 1921

12. Fatal Electrical Accidents1990 thru 2000 But more important is the cost in lives…… • Coal-Underground 27 • Coal-Surface 4 • Metal/non-metal-Underground 7 • Metal/non-metal-Surface 29 • Prep Plants 9 • Other 2 • Total 78

13. Causes of Electrical Injuries • Touching live parts. Short circuit Accidental ground Overload

15. Electrical Hazards • Exposed conductors • Frayed and worn insulation • Exposed bus bars and connections • Overloaded circuits • Modified circuits • Removed grounding plug • Jury-rigged connections

16. Effects on the Body • Burns • Flash burns (from electrical arcs) • Electrical burns (entry & exit wounds) • Electrical Shock • Damage to internal organs and body systems

17. Effects on the Body • Approximately 50 volts is needed to overcome skin resistance Resistance is higher on dry skin Resistance is lower on wet skin

18. ENTRY WOUND

19. EXIT WOUND

21. A person receives an electrical shock whenever any part of his/her body becomes part of the electrical circuit through which a sufficient current flows to cause discomfort or worse. Current flow slightly above this threshold is sufficient to cause discomfort: May cause involuntary contraction of the muscles. Stop the heart. Stop breathing. Cause burns. Electrical Shock

22. Electrical Shock • The amount of current that flows through the victim’s body will depend on: • The voltage of the circuit with which he/she is in contact. • The insulating qualities of the place in which he/she is located at the instant. • The resistance of skin or clothing or both. • The area of contact with the live conductor. • The pressure of contact with the live conductor. • The area of contact with the live conductor

23. four major components of an electrical system • sources • conductors • loads • switches

24. SOURCES • provide electricity • batteries • transformers • generators • water system equivalent - water tank

25. CONDUCTORS • carry electricity • wires • cables • bus bars • water equivalent - pipes

26. LOADS • use electricity • motors • pumps • fans • hand tools • lights • heaters • water equivalent -water wheel

27. SWITCHES • control electricity • floats • push buttons • disconnects • duplex outlets / plugs • water equivalent - valves

28. Water system comparison • Voltage = pressure • Current = flow • Resistance = system resistance to flow

29. Ohms Law amps voltage resistance • Since voltage is constant, • current flow depends on resistance

30. 30 CFR 56/57. 12028 • 56/57.12028 Testing grounding systems. • Continuity and resistance of grounding systems shall be tested immediately after installation, repair, and modification; and annually thereafter. A record of the resistance measured during the most recent tests shall be made available on a request by the Secretary or his duly authorized representative.

31. Equipment grounding systems • high resistance = low current • low resistance = high current • current flow is what trips fuses/breakers

32. Besure: • all grounds ohms values are as low as possible • all wiring connections are clean & tight • all conduit connections are clean & tight • all plugs have ground prong in place

33. Methods of Contact • Step potential • Difference in voltages (potential for current flow) between person’s feet • Touch potential • Difference in voltages between points of contact (usually hands and/or feet)

34. HOW DO WE PROTECT OURSELVES???? LOCK OUT- TAG OUT!!

35. LOCKOUT/TAGOUTTypes of Devices

36. LOCKOUT/TAGOUTTypes of Energy • Mechanical • Hydraulic • Pneumatic • Chemical • Thermal • Other

37. LOCKOUT/TAGOUTPreparation for Shutdown • Know the types and amounts of energy that power it. • Know the hazards of that energy. • Know how the energy can be controlled.

38. VERIFY-VERIFY-VERIFY!!!! (ONLY IF YOU ARE QUALIFIED)

39. HOW ELSE CAN WE PROTECT OURSELVES??? BY USING GFCI’S

40. How does the GFCI work • GFCIs constantly monitor electricity flowing in a circuit. • If the electricity flowing into the circuit differs by even a slight amount from that returning, the GFCI will quickly shut off the current flowing through that circuit. • The advantage of using GFCIs is that they can detect even small variations in the amount of leakage current, even amounts too small to activate a fuse or circuit breaker. • GFCIs work quickly, so they can help protect consumers from severe electric shocks and electrocution.

41. Some things a GFCI does not protect you from. A GFCI does not protect a person who comes in contact with two hot wires or any hot wire and the neutral wire. A GFCI does not protect a person from feeling and reacting to shock

42. ALWAYS REMBER! Never work on a Energized Circuit. Unless you are trained to. Always Lock and Tag Never depend on another person to take the power off a circuit that you are going to work on. Its your Life! This should even apply to home. Just remember that Half of what you have is hers.

43. Qualified Employees • “One knowledgeable in the construction and operation of the electric power generation, transmission, and distribution equipment involved, along with the associated hazards.” • Qualified employees must have training to be considered qualified.

44. Qualified Employees • Qualification extends to individual tasks • Employees can be qualified in one task, but not in another. • Examples: • Racking breakers in & out • Changing fuses • Substation switching

45. Unqualified Employees • Unqualified employees and mobile mechanical equipment must maintain a safe distance from energized circuits • Overhead power lines • Unguarded, exposed, energized conductors • 10 feet up to 50,000 volts • Additional 4 inches for every 10,000 volts over 50 kV

46. Methods of Protection • Insulation • Verify insulation is intact • Pay particular attention to flexible cords, such as extension cords and tool power cords

47. Methods of Protection • Guarding • Live parts operating at 50 volts or more must be guarded • Locate in a room or vault accessible only by qualified persons • Permanent partitions or walls • Metal-clad switchgear required if over 600 volts • Distance • 8 feet (or more) above the floor • Warning Signs

48. Methods of Protection • Grounding • Service ground • Neutral conductor is grounded • Equipment ground • Frame or casing of tool or equipment is wired directly to ground.

49. Methods of Protection • Circuit Protection Devices • Fuses and Circuit Breakers • Designed for equipment protection • Open circuit on high current • GFCI • Ground Fault Circuit Interrupter • Designed for personnel protection • Opens quickly (1/40 second) on any ground fault

50. Methods of Protection • Safe Work Practices • De-energize • Lockout/Tagout energy sources • Use electric tools that are in good repair • Do not perform work you are not qualified for • Use appropriate protective equipment • FR clothing, non-conductive hard hats, rubber mats, line hose, hot sticks, rubber gloves, safety glasses, face shields, etc.