Electrical Safety

1. Electrical Safety Steve Geiger, MS, CSP Safety and Occupational Health Manager Code 20_ Shore Safety Programs Naval Safety Center steven.geiger@navy.mil

2. OBJECTIVES • Electrical injuries • Recognizing electrical hazards • Preventing electrical hazards in the workplace • Electrical safety requirements and practices • Electrical accidents 2

3. Shocking! A National Institute for Occupational Safety and Health study showed that during the period from 1992 through 2001, there were 44,363 electrical-related injuries involving days away from work. The number of nonfatal electrical shock injuries was 27,262, while 17,101 injuries were caused by electric arc flash burns.

4. Electrical Injuries & Fatalities • An average of one worker is electrocuted on the job every day • An average of one person is electrocuted in the home every 36 hours • There are four main types of electrical injuries: • Electrocution (death due to electrical shock) • Electrical shock (CNS effects) • Burns • Falls 4

5. Electrical Terminology • Current (amps)– the movement of electrical charge • Resistance (ohms) – opposition to current flow • Voltage (volts) – a measure of electrical force • Conductors – substances, such as metals, that have little resistance to electricity • Insulators – substances, such as wood, rubber, glass, and bakelite, that have high resistance to electricity • Grounding – a conductive connection to the earth which acts as a protective measure 5

6. Electrical Shock • Received when current passes through the body • Severity of the shock depends on: • Path of current through the body • Amount of current flowing through the body • Length of time the body is in the circuit 6

7. 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 Defibrillator in use * mA = milliampere = 1/1,000 of an ampere 7

8. Not a Tickle! • As little as 100 milliamps of 60 Hz alternating current can be fatal (well below that in an average household). Above 12 milliamps, the average individual cannot release their grip on a hand held current source. High voltage energy sources found in industrial setting are extremely hazardous. • Most household electricity is 120 and 240 volt and 15-20 amps. • Industrial setting have regular 120, 240 and high voltage equipment, defined by NEC as anything over 600 volts. • Tasers and stun guns use 20,000 to 150,000 volts of electricity. But only 2-3 milliamps of current – a non-fatal way to incapacitate.

9. Electrical Injuries • The hazards of electricity at the power system supply level includes electrical blast or flash, electrocution, short circuits, overloads, ground faults, and electrical fires. • A person’s main resistance to current flow is skin surface. • Dry skin has a fairly high resistance to the passage of electricity. • Moisture dramatically lowers the skin’s resistance. • Once electricity breaches the skin barrier the body offers little resistance to current flow. 9

10. Electrical Injuries - (cont’d) • These injuries can happen in various ways: • Direct contact with the electrical energy. • When the electricity arcs (jumps) through a gas (such as air) to a person who is grounded (that would provide an alternative route to the ground for the electricity). 10

11. Electrical Injuries - (cont’d) Thermal burns including: flash burns from heat generated by an electric arc, flame burns from materials that catch on fire from heating or ignition by electrical currents. High voltage contact burns can burn internal tissues while leaving only very small injuries on the outside of the skin. 11

12. Electrical Injuries - (cont’d) Muscle contractions from the electricity, a startle reaction, or sudden movement can cause a person to fall from a ladder, scaffold or aerial bucket. The fall can cause serious injuries. 12

13. Low Voltage Does Not Mean Low Hazard • A small amount of electrical current can cause injury, even death • The current from a 7.5-watt, 120-volt lamp, passing across the chest, is enough to cause fatal electrocution • Deaths from 120 volts represent about 12 percent of all electrocutions! 13

14. Electrical Burns • Most common shock-related, nonfatal injury • Occurs when you touch electrical wiring or equipment that is improperly used or maintained • Typically occurs on the hands • Very serious injury that needs immediate attention

15. Severe third degree burns from an electrical arc flash. High Voltage Electrical Shock – his arm literally exploded!

16. Electrical Hazards Do not remove or open receptacle covers, switch plates, or covers of electrical equipment unless qualified and authorized. 16

17. Hazards Assume all exposed wiring is energized until proven otherwise. STOP, protect the area and contact a supervisor if you encounter this situation Potentially energized exposed wires

18. Tripping and Abrasion Hazards • Don’t cause tripping hazards or create pinch points for cords • If you must run a cord temporarily across the floor, cover the cord appropriately. Not OK OK 18

19. Damaged or Frayed Cords Visually inspect electrical equipment before each use for damage and/or external defects such as loose, missing or deformed parts, pinched or crushed outer jackets or insulation. This type of external damage may indicate internal damage to the equipment. 19

20. Cabinets, Boxes, and Fittings • Junction boxes, pull boxes and fittings must have approved covers in place • Unused openings in cabinets, boxes and fittings must be closed (no missing knockouts) 20

21. POWER STRIPS !!!!! Never daisy chain multi-outlet strips (plugging into each other) 21

22. Grounding Path • The path to ground from circuits, equipment, and enclosures must be permanent and continuous • Violation shown here is an extension cord with a missing grounding prong • Do not make alterations to polarized blades or ground pin to make plug fit into non-polarized or non-grounded outlet 22

23. Powerline Hazards • Electrical hazards may exist overhead indoors • Crane power rails are an example • Electrical hazards may also exist overhead outdoors • Most lines are bare and high voltage • Contact is not required to initiate an arc or cause shock and burn injuries • Maintain safe approach distances when working near energized overhead lines LADDERS!! 23

24. Damaged Conduit • Electrical equipment and wiring must not be exposed to physical damage • Picture shown here is physical damage to conduit • Stay away from damaged equipment 24

25. Clues that Electrical Hazards May Exist • Tripped circuit breakers or blown fuses • Hot to the touch • Dim and flickering lights • Sizzles and buzzes-unusual sounds • Odor of hot insulation • Mild tingle from contact with case or equipment • GFCI that shuts off a circuit • Worn or frayed insulation around wire or connection • Burn marks or discoloration on receptacle plates or plug prongs 25

26. Safe PracticesConductive Apparel Don’t wear loose conductive apparel, (such as rings, watch bands, bracelets, necklaces, etc.) when plugging in electrical cords Charm contacted plug Burn from arc Charm contacted plug here 26

27. Safe PracticesEquipment Applications Consumer electrical equipment or appliances should be tested and labeled by a recognized testing laboratory. (Look for the UL, CSA, ETL, or CE Label). 27

28. Ground-Fault Circuit Interrupter • Used outdoors or near water. • The GFCI detects a difference in current between the black and white circuit wires. (This could happen when electrical equipment is not working correctly, causing current “leakage” – known as a ground fault.) • Perform the test function on the GFCI to determine if it is functioning properly by pushing the button to verify it shuts off. 28

29. How it works Southwest Safety Training Alliance Inc

30. Electrical Safety Program • Written program unique to your command • Specific to their jobs and potential exposures. • Covers electricians as well as repair personnel, maintenance personnel, and non-electrical workers. • Must also cover contractors at your site. • General electrical safety training for all personnel. • Regular inspections for electrical hazards. • OSH Manager needs to be aware of new installations or purchases which could present electrical hazards.

31. OSHA Regulations • Electrical Safety-Related Work Practices are covered under OSHA regulations, 29 CFR 1910, Subpart S

32. Electrical Safety Requirements • Electrical hazards are best dealt with through DESIGN. • This includes safe installations in accordance with: • NFPA 70E Electrical Safety Requirements, • National Electrical Code (NEC) • Local electrical codes. NEC

33. National Electrical Code • The minimum standard but provides single most comprehensive document dealing with installation and use of electrical equipment. • In most states NEC has been adopted as LAW for all new electrical construction and installations. • First published in 1895, recently updated. Endorsed by ANSI. • Consensus standard developed by the NFPA NEC Committee, issued as ANSI/NFPA 70. • 1,100 pages, very comprehensive – designing, constructing, and installing electrical equipment.

34. Workers at Risk • Workers at risk of electrical injuries include: • Utility, industrial and commercial electrical personnel such as engineers, technicians, electricians, linemen, supervisors. • Other personnel who work on or near energized and de-energized electrical equipment and systems. • Employers determine the specific hazards in any particular equipment or its location before selecting and installing electrical equipment. • The Job Hazard Analysis (JHA) should identify electrical hazards and recommend controls.

35. Electrical Safety Training • Qualified or Unqualified Employee criteria. • Qualified: • Certified to perform specific tasks on designated equipment. • Follow written work practices. • Unqualified: • Touch nothing! • Training to tell them to touch nothing!

36. Training includes: • Electrical shock first aid. • Removal of victim from source. • Conducting CPR. • Use of a defibrillator. Electronic equipment may be sensitive to static electricity, surges, and have capacitors that can be shock hazards. Only authorized, trained personnel should be working on electronic equipment!

37. Test Equipment and PPE • Qualified personnel trained on use of meters and test equipment. • Use of PPE. • Electrical safety shoes • Arc Suits • Face Shields • Rubber gloves & sleeves • Mats and barriers

38. Frequently Cited Electrical Safety Hazards • The most frequently cited during OSHA inspections are: • Overloaded circuits. • Frayed cords or disabled grounding plugs (cut off ground prong or using “cheater” plug). • Missing covers on breaker panels, receptacles, connection boxes, and control panels. • Jury-rigged electrical connections and by-passes.

39. HAZARDOUS ENERGY CONTROL:LOCKOUT/TAGOUT (LOTO)

40. Why is LOTO important? The Lock Out/Tag Out procedure prevents the unexpected start up or release of stored energy that could cause injury to employees by placing a lock and/or warning tag on an energy isolation device.

41. Consequences • Piping system full of sewage. • Workers assigned to replace a leaking valve. • Shut off the one valve. • Began to disassemble bad valve. • Workers opened valve upstream. • Hydrogen sulfide gas released. • Workers asphyxiated. H2S

42. Consequences • Worker assigned to change out bad light switch. • Shuts off breaker at box. • Begins to remove old switch. • Other worker noticed lights were off and goes to breaker box. • Sees breaker off and turns breaker on. • Worker removing light switch is electrocuted. • Second worker said he didn’t know it was supposed to stay off!

43. OSHA Standards • 29 CFR 1910.147 – basic Lockout Tagout • 1910.146 Permit-Required Confined Spaces • 1910.177 Servicing Multi-Piece and Single Piece Rim Wheels • 1910.178 Powered Industrial Trucks • 1910.179 Overhead and Gantry Cranes • 1910.181 Derricks • 1910.213 Woodworking Machinery • 1910.217 Mechanical Power Presses • 1910.218 Forging Machines • 1910.261 Pulp, Paper, and Paperboard Mills • 1910.262 Textiles • 1910.263 Bakery Equipment • 1910.265 Saw mills MIXER

44. 1910.269 Electric Power Generation, Transmission, and Distribution • 1910.272 Grain Handling • 1910.305 Wiring Methods, Components, and Equipment for General Use • 1910.306 Specific Purpose Equipment and Installations • 1910.333 Selection and Use of Work Practices • OSHA standards for construction also contain requirements for protecting workers from electrical hazards • 29 CFR 1926.416 • 29 CFR 1926.417.

45. Hazardous Energy Sources • Electrical • Kinetic - mechanical (i.e. motors, drive belts, moving parts) • Potential – pressure vessels, tanks, pneumatic, hydraulic, springs • Thermal (high or low temps)

46. OSHA’s Control of Hazardous Energy (Lockout/Tagout) Standard29 CFR 1910.147 • Requires a written energy control program that includes defined energy control procedures. • Requires documented employee training. • Requires periodic inspections, at least annually. • Requires certain equipment such as locks, locking devices, and tags.

47. At Risk Workers: • Machinists/machine operators • Craft workers • Laborers • Maintenance workers • Repair personnel MAYTAG

48. Locks and Tags - ProgramEquipment • Must be singularly identified; • Must be the ONLY devices for controlling energy; and • Must NOT be used for any other purposes.

49. Program Equipment Lock out will be accomplished using a lock and key. Chains, or other hardware, may be used in conjunction with the lock to isolate the energy source.

50. Locks • One key will be issued to the authorized employee applying the lock. • Additional keys will only be used to remove locks in the event the abandoned lock procedure must be implemented.