Electrical Safety for Construction

1. Electrical Safety for Construction

2. Electrical regulations • Subpart K of 29 CFR 1926 1a

3. Electrical regulations • Part I - Safety requirements for installing/using equipment • approval of electrical components • examination, installation, use of electrical equipment • guarding of electrical equipment • overcurrent protection • grounding of equipment 1b

4. Electrical regulations • Part II - Safety-related work practices • protection of employees • passageways and open spaces • lockout/tagging of circuits 1c

5. Electrical regulations • Part III - Safety-related maintenance and environmental considerations • protection of wiring components • environmental deterioration of equipment 1d

6. Electrical regulations • Part IV - Safety requirements for special equipment • batteries and battery charging • PPE • emergency eyewash stations 1e

7. How electricity works • Current flows from a generating source through conductors, to a load • Complete circuits are needed 2a

8. How electricity works • Normal route is through conductors • Shock occurs when the body becomes a part of the electrical circuit 2b

9. E I R Ohm’s Law I = Current (amperes) E = Voltage (volts) R = Resistance (ohms)

10. Human Resistance Body AreaOHMS Dry Skin 600,000 Wet Skin 1,000 Internal Organs 400-600 Ear to Ear 100

11. Fatalities at 50 Volts 50 Volts 1,000 OHM = .05 amps (50 mA) 50 Volts 100 OHM = .5 amps (500 mA)

12. Electric shock • Occurs when current enters the body at one point and exits at another • Shock occurs when you touch: • both wires of an electric circuit; • one wire of an energized circuit and ground; or • a metallic part that is “hot” 3a

13. Electric shock • Severity of shock depends on the: • amount of current • path of the current • amount of time exposed 3b

14. Electric shock • Effects range from a tingle, to cardiac arrest, severe burns, and probable death • Typical household current of 15 amps can cause death 3c

15. 00.001 amps 00.015 amps 00.020 amps 00.100 01.200 15.000 Barely felt “let go” threshold Muscular paralysis Ventricular fibrillation 100 Watt light bulb Common household fuse Electricity’s Physiological Effect

16. Effects of Current 1-8 mA = shock, not painful 8-15 mA = Pain 15-20 mA = Muscle contraction 20-100 mA = Severe pain & paralysis of breathing muscles 100-1000 mA = Ventricular fibrillation (Usually cause death) > 1,000 mA = Heart stops

17. Grounding • Protects you from electrical shock • Safeguards against fire • Protects electrical equipment from damage 4a

18. Grounding • Two types of grounding include: • Service or system ground • Equipment ground 4b

19. Circuit protective devices • At construction sites, the most common electrical hazard is the ground fault electrical shock • OSHA requires either: • Ground fault circuit interrupters (GFCIs); or • Assured Grounding Conductor Program 5a

20. Circuit protective devices • Circuit protective devices include: • fuses and circuit breakers - protect conductors and equipment • GFCIs - limit or shut off current flow 5b

21. Ground fault circuit interrupters • A fast-acting circuit breaker that senses small imbalances in the circuit caused by current leakage to ground 6a

22. 1 AMP COIL 1 AMP PLUG 1 AMP NEUTRAL HOT LOAD 1000 mA COIL 995 mA PLUG 5 mA HOT NEUTRAL LOAD GROUND

23. 1000 mA COIL 1000 mA PLUG 5 mA NEUTRAL HOT 1 AMP GROUND LOAD 995 mA

24. Polarity

25. Assured Equipment Grounding Conductor program • If GFCIs are not used, employers must have a scheduled and recorded Assured Equipment Grounding Conductor program 7a

26. Assured Equipment Grounding Conductor program • The AEGC program is an inspection program covering: • all cord sets • receptacles that are not part of a permanent wiring structure • equipment connected by cord and plug 7b

27. Assured Equipment Grounding Conductor program • Equipment must be visually inspected for damage/defects before each day’s use 7c

28. Assured Equipment Grounding Conductor program • Tests must be performed: • before the first use of new equipment • after suspected damage to equipment • at three month intervals • continuity test • grounding conductor test 7d

29. Lockout/Tagout • Electrical equipment deactivated for repair must be locked out and tagged at the point where it can be energized • Protects maintenance workers • Warns others that work is being performed 8a

30. Lockout/Tagout • Only the person who locked/tagged the equipment can turn it back on • Before equipment is energized, a qualified person must conduct tests and visual inspections 8b

31. Lockout/Tagout • Each lock/tag must be removed by the person who applied it 8c

32. Lockout/Tagout • If the employee is absent, the lock/tag can be removed by a qualified person if: • the employee who applied the lock has left the premises • it is visually determined that all employees are clear of the circuits/equipment 8d

33. Guarding requirements • Any live parts of electrical equipment operating at 50 volts or more must be guarded to avoid accidental contact 9a

34. Guarding requirements • Entrances to areas with live electrical parts must be marked with warning signs • Signs should forbid entrance except by qualified persons 9b

35. Insulation • Check equipment daily for insulation breakdown • Check for: • exposed wires • broken wires • scuffed insulation on extension cords 10a

36. Insulation • Use non-conducting mats, shields, or barriers when necessary • Use non-conducting coatings on hand tools 10b

37. Personal protective equipment • Employers must provide electrical protective equipment to employees who work near electrical hazards 11a

38. Personal protective equipment • Use appropriate equipment for the hazards, including: • helmets • eye and face protection • gloves and sleeves • aprons • protective footwear 11b