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Electrical_Safety,_Construction_revised.ppt
- 1. Electrical Safety Electrical Safety forConstruction for Construction
- 2. Electrical regulations Electrical regulations Subpart K of 29 CFR 1926 Subpart K of 29 CFR 1926 1a
- 3. Electrical regulations Electrical regulations Part I - Safety requirements for Part I - Safety requirements for installing/using equipment installing/using equipment • approval of electrical components approval of electrical components • examination, installation, use of examination, installation, use of electrical equipment electrical equipment • guarding of electrical equipment guarding of electrical equipment • overcurrent protection overcurrent protection • grounding of equipment grounding of equipment 1b
- 4. Electrical regulations Electrical regulations Part II - Safety-related work Part II - Safety-related work practices practices • protection of employees protection of employees • passageways and open spaces passageways and open spaces • lockout/tagging of circuits lockout/tagging of circuits 1c
- 5. Electrical regulations Electrical regulations Part III - Safety-related Part III - Safety-related maintenance and environmental maintenance and environmental considerations considerations • protection of wiring components protection of wiring components • environmental deterioration of environmental deterioration of equipment equipment 1d
- 6. Electrical regulations Electrical regulations Part IV - Safety requirements for Part IV - Safety requirements for special equipment special equipment • batteries and battery charging batteries and battery charging • PPE PPE • emergency eyewash stations emergency eyewash stations 1e
- 7. How electricity works Howelectricity works Current flows from a generating Current flows from a generating source through conductors, to a source through conductors, to a load load Complete Complete circuits are circuits are needed needed 2a
- 8. How electricity works Howelectricity works Normal route is through Normal route is through conductors conductors Shock occurs Shock occurs when the body when the body becomes a becomes a part of the part of the electrical electrical circuit circuit 2b
- 9. I = Current(amperes) I = Current (amperes) E = Voltage (volts) E = Voltage (volts) R = Resistance (ohms) R = Resistance (ohms) E I R Ohm’s Law Ohm’s Law
- 10. Body Area Body AreaOHMS OHMS Dry Skin Dry Skin 600,000 600,000 Wet Skin Wet Skin 1,000 1,000 Internal Organs Internal Organs 400-600 400-600 Ear to Ear Ear to Ear 100 100 Human Resistance Human Resistance
- 11. 50 Volts 50 Volts 1,000OHM 1,000 OHM = .05 amps (50 mA) = .05 amps (50 mA) 50 Volts 50 Volts 100 OHM 100 OHM = .5 amps (500 mA) = .5 amps (500 mA) Fatalities at 50 Volts Fatalities at 50 Volts
- 12. Electric shock Electric shock Occurs when current enters the Occurs when current enters the body at one point and exits at body at one point and exits at another another Shock occurs when you touch: Shock occurs when you touch: • both wires of an electric circuit; both wires of an electric circuit; • one wire of an energized circuit and one wire of an energized circuit and ground; or ground; or • a metallic part that is “hot” a metallic part that is “hot” 3a
- 13. Electric shock Electric shock Severity of shock depends on Severity of shock depends on the: the: • amount of current amount of current • path of the current path of the current • amount of time amount of time exposed exposed 3b
- 14. Electric shock Electric shock Effects range from a tingle, to Effects range from a tingle, to cardiac arrest, severe cardiac arrest, severe burns, and probable burns, and probable death death Typical household Typical household current of 15 amps current of 15 amps can cause death can cause death 3c
- 15. Electricity’s Electricity’s Physiological Effect Physiological Effect 00.001 amps 00.001 amps 00.015 amps 00.015 amps 00.020 amps 00.020 amps 00.100 00.100 01.200 01.200 15.000 15.000 Barely felt Barely felt “ “let go” threshold let go” threshold Muscular paralysis Muscular paralysis Ventricular Ventricular fibrillation fibrillation 100 Watt light bulb 100 Watt light bulb Common household Common household fuse fuse
- 16. 1-8 mA =shock, not painful 1-8 mA = shock, not painful 8-15 mA = Pain 8-15 mA = Pain 15-20 mA = Muscle contraction 15-20 mA = Muscle contraction 20-100 mA = Severe pain & paralysis 20-100 mA = Severe pain & paralysis of breathing muscles of breathing muscles 100-1000 mA = Ventricular fibrillation 100-1000 mA = Ventricular fibrillation (Usually cause death) (Usually cause death) > 1,000 mA = Heart stops > 1,000 mA = Heart stops Effects of Current Effects of Current
- 17. Grounding Grounding Protects youfrom electrical Protects you from electrical shock shock Safeguards Safeguards against fire against fire Protects electrical equipment Protects electrical equipment from damage from damage 4a
- 18. Grounding Grounding Two typesof grounding include: Two types of grounding include: • Service or system Service or system ground ground • Equipment ground Equipment ground 4b
- 19. Circuit protective Circuit protective devices devices At construction sites, the most At construction sites, the most common electrical hazard is the common electrical hazard is the ground fault electrical shock ground fault electrical shock OSHA requires either: OSHA requires either: • Ground fault circuit interrupters Ground fault circuit interrupters (GFCIs); or (GFCIs); or • Assured Grounding Conductor Assured Grounding Conductor Program Program 5a
- 20. Circuit protective Circuit protective devices devices Circuit protective devices Circuit protective devices include: include: • fuses and circuit breakers - fuses and circuit breakers - protect conductors and equipment protect conductors and equipment • GFCIs - limit or shut off current GFCIs - limit or shut off current flow flow 5b
- 21. Ground fault circuit Groundfault circuit interrupters interrupters A fast-acting circuit breaker A fast-acting circuit breaker that senses small imbalances in that senses small imbalances in the circuit caused by current the circuit caused by current leakage to ground leakage to ground 6a
- 22. PLUG COIL LOAD HOT NEUTRAL 1 AMP 1AMP 1 AMP PLUG COIL LOAD HOT NEUTRAL 1000 mA 995 mA 5 mA GROUND
- 23. 1000 mA PLUG COIL LOAD HOT NEUTRAL 1000mA 1 AMP 5 mA GROUND 995 mA
- 24.
- 25. Assured Equipment Assured Equipment GroundingConductor Grounding Conductor program program If GFCIs are not used, If GFCIs are not used, employers must have a employers must have a scheduled and recorded scheduled and recorded Assured Equipment Grounding Assured Equipment Grounding Conductor program Conductor program 7a
- 26. The AEGCprogram is an The AEGC program is an inspection program covering: inspection program covering: • all cord sets all cord sets • receptacles that are not part of a receptacles that are not part of a permanent wiring structure permanent wiring structure • equipment connected by cord and equipment connected by cord and plug plug 7b Assured Equipment Assured Equipment Grounding Conductor Grounding Conductor program program
- 27. Equipment mustbe visually Equipment must be visually inspected for damage/defects inspected for damage/defects before each day’s use before each day’s use 7c Assured Equipment Assured Equipment Grounding Conductor Grounding Conductor program program
- 28. Tests mustbe performed: Tests must be performed: • before the first use of new before the first use of new equipment equipment • after suspected damage to after suspected damage to equipment equipment • at three month intervals at three month intervals – continuity test continuity test – grounding conductor test grounding conductor test 7d Assured Equipment Assured Equipment Grounding Conductor Grounding Conductor program program
- 29. Lockout/Tagout Lockout/Tagout Electrical equipmentdeactivated Electrical equipment deactivated for repair must be locked out and for repair must be locked out and tagged at the point where it can be tagged at the point where it can be energized energized Protects maintenance workers Protects maintenance workers Warns others that work is being Warns others that work is being performed performed 8a
- 30. Lockout/Tagout Lockout/Tagout Only theperson who Only the person who locked/tagged the equipment locked/tagged the equipment can turn it back on can turn it back on Before equipment is energized, Before equipment is energized, a qualified person must conduct a qualified person must conduct tests and visual inspections tests and visual inspections 8b
- 31. Lockout/Tagout Lockout/Tagout Each lock/tagmust be removed Each lock/tag must be removed by the person who applied it by the person who applied it 8c
- 32. Lockout/Tagout Lockout/Tagout If theemployee is absent, the If the employee is absent, the lock/tag can be removed by a lock/tag can be removed by a qualified person if: qualified person if: • the employee who applied the lock the employee who applied the lock has left the premises has left the premises • it is visually determined that all it is visually determined that all employees are clear of the employees are clear of the circuits/equipment circuits/equipment 8d
- 33. Guarding requirements Guarding requirements Any live parts of electrical Any live parts of electrical equipment operating at 50 volts equipment operating at 50 volts or more must be guarded to or more must be guarded to avoid accidental contact avoid accidental contact 9a
- 34. Guarding requirements Guarding requirements Entrances to areas with live Entrances to areas with live electrical parts must be marked electrical parts must be marked with warning signs with warning signs Signs should Signs should forbid entrance forbid entrance except by except by qualified persons qualified persons 9b
- 35. Insulation Insulation Check equipmentdaily for Check equipment daily for insulation breakdown insulation breakdown Check for: Check for: • exposed wires exposed wires • broken wires broken wires • scuffed insulation on extension scuffed insulation on extension cords cords 10a
- 36. Insulation Insulation Use non-conductingmats, Use non-conducting mats, shields, or barriers when shields, or barriers when necessary necessary Use non- Use non- conducting conducting coatings on coatings on hand tools hand tools 10b
- 37. Personal protective Personal protective equipment equipment Employers must provide Employers must provide electrical protective equipment electrical protective equipment to employees to employees who work near who work near electrical electrical hazards hazards 11a
- 38. Personal protective Personal protective equipment equipment Use appropriate equipment for Use appropriate equipment for the hazards, including: the hazards, including: • helmets helmets • eye and face eye and face protection protection • gloves and gloves and sleeves sleeves • aprons aprons • protective footwear protective footwear 11b