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Electrical Safety.pptx
- 1. ELECTRICAL SAFETY BASIC AWARENESS Per OSHA 29 CFR 1910 SUBPART S 1 PPT-008-02 Bureau of Workers’ Compensation PA Training for Health & Safety (PATHS)
- 2. Electrical Injuries AN AVERAGE OF ONE WORKER IS ELECTROCUTED ON THE JOB EVERY DAY! There are four main types of electrical injuries: • Electrocution (death due to electrical shock) • Electrical Shock • Burns • Falls 2 PPT-008-02
- 3. US fire statistics on electrical fire causes (2002-2005) Statistics U.S. Fire Administration Factor contributing to ignition in reported structure fires Fires % unclassified electrical failure or malfunction 36,300 7 unspecified short circuit arc 21,400 4 short circuit arc from defective or worn insulation 11,400 2 arc or spark from operating equipment 4,000 1 arc from faulty contact or broken conductor 3,600 1 short circuit arc from mechanical damage 3,400 1 water caused short circuit arc 1,600 <1 3 PPT-008-02
- 4. How is an Electrical Shock Received? When two wires have different potential voltages current will flow if they are connected. • In most household wiring the black wires are at 110 volts relative to ground • The white wires are at zero volts because they are connected to ground Contact with an energized (live) black wire while touching the white grounded wire = ELECTRICAL SHOCK! 4 PPT-008-02
- 5. Electrical Burns • Are the most common shock related nonfatal injury • Occur 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 5 PPT-008-02
- 6. Falls • Electrical shock can also cause indirect or secondary injuries. • Employees working in an elevated location who experience a shock can fall resulting in serious injury or even death. 6 PPT-008-02
- 7. Inadequate Wiring Hazards A hazard exists when a conductor is too small to safely carry the current. Example: using a portable tool with an extension cord that has a wire too small for the tool • Tool draws more current than cord can handle = overheating, possible fire without tripping the circuit breaker • Circuit breaker could be the right size for the circuit but not for the smaller wire extension cord 7 PPT-008-02
- 8. Hazards of Overloading • Too many devices plugged into circuit = wires heat to very high temperature = possible fire. • Wire insulation melts = arcing may occur = fire in area where overload exists (even inside a wall). 8 PPT-008-02
- 9. Electrical Protective Devices • Shut off electricity flow in the event of an overload or ground-fault in the circuit. • Include fuses, circuit breakers, and ground- fault circuit interrupters (GFCI). • Fuses and circuit breakers are “over current” devices (too much current = fuses melt and circuit breakers “trip” open). 9 PPT-008-02
- 10. Ground Fault Circuit Interrupter • Protects you from dangerous electrical shock. • Detects a difference in current between the black and white circuit wires (could happen when electrical equipment is not working properly causing a current “leakage” known as ground fault). • Ground fault detected = GFCI can shut off electricity flow in as little as 1/40 of a second protecting you from a dangerous shock. 10 PPT-008-02
- 11. Examples: OSHA Electrical Requirements GROUNDING PATH The path to ground from circuits, equipment, and enclosures must be permanent and continuous. The violation shown here is an extension cord with the third/grounding prong missing. 11 PPT-008-02
- 12. Examples: OSHA Electrical Requirements • Hand-held electrical tools pose a potential danger because they make continuous contact with the hand. • To protect you from shock, burns, and electrocution, tools must: o Have a 3 wire cord with ground and be plugged into a grounded receptacle or o Be double insulated or o Be powered by a low-voltage isolation transformer 12 PPT-008-02
- 13. Guarding Live Parts Must guard “live” parts of electric equipment operating at > 50 volts against accidental contact by: • Approved cabinets/enclosures or • Location or permanent partitions (thereby only accessible to qualified persons) • Elevation of 8 feet or more above the floor or working surface • Mark entrances to guarded locations with conspicuous warning signs 13 PPT-008-02
- 14. Guarding Live Parts • Where electrical equipment is in locations that it can suffer physical damage it must be guarded. • The violation shown here is physical damage to conduit. 14 PPT-008-02
- 15. Cabinets, Boxes, Fittings • Junction boxes, pull boxes, and fittings must have approved covers. • Unused openings in cabinets, boxes and fittings must be closed (no missing “knockouts”). • Photo shows violations of these two requirements. 15 PPT-008-02
- 16. Use of Flexible Cords • Are more vulnerable than fixed wiring. • Made be of industrial commercial quality. • May not be used as permanent wiring. • Improper use of flexible cords can cause shocks, burns, or fire. • Approved by a recognized testing agency. 16 PPT-008-02
- 17. Flexible Cords • Uncoil an extension cord fully before use. • Be sure the amperage of the cord is appropriate for the job you are doing. • Do not use equipment that delivers mild electrical shocks, gives off unusual heat or smells odd. • If in doubt, have it checked and repaired or replaced. 17 PPT-008-02
- 18. Flexible Cords Extension cords shall not be fastened with staples, hung from nails, or suspended by wire. 18 PPT-008-02
- 19. Permissible Uses of Flexible Cords 19 PPT-008-02 Pendant or Fixture Portable lamps, Stationary equipment Wiring tools or appliances to facilitate interchange Examples
- 20. Prohibited Uses of Flexible Cords 20 PPT-008-02 Substitute for Run through walls, ceilings Concealed behind fixed wiring floors, doors, or windows or attached to building surfaces Examples
- 21. Electrical Extension Cords Homemade “Gang Box” Not allowed in work setting per OSHA: 29 CFR 1910.305 29 CFR 1926.405 21 PPT-008-02
- 29. Top 5 – Electrical Fire Causes 1. Most electrical fires are caused by faulty electrical outlets and old, outdated appliances. Removing the grounding plug from a cord so it can be used in a two-prong electrical outlet can also cause a fire. 29 PPT-008-02
- 30. Top 5 – Electrical Fire Causes 2. Light fixtures, lamps and light bulbs are another common reason for electrical fires. o Installing a bulb with a wattage that is too high for the lamps and light fixtures is a leading cause of electrical fires. o Always check the maximum recommended bulb wattage on any lighting fixture or lamp and never go over the recommended amount. 30 PPT-008-02
- 31. Top 5 – Electrical Fire Causes 3. Misuse of extension cords is another electrical fire cause. o Appliances should be plugged directly into outlet and not plugged into an extension cord for any length of time. o Only use extension cords as a temporary measure. o If you do not have the appropriate type of outlets for your appliances, hire an electrician to install new ones. 31 PPT-008-02
- 32. Top 5 – Electrical Fire Causes 4. Space heaters are a major cause of electrical fires. o Because these types of heaters are portable, many times people put them too close to combustible surfaces such as clothing, chairs, and rugs. o Coil space heaters are especially dangerous. I o f you do use space heaters, use the radiator-type that diffuse heat over the entire surface of the appliance. 32 PPT-008-02
- 33. Top 5 – Electrical Fire Causes 5. Outdated wiring often causes electrical fires. o Breakers should be triggered when circuits get overloaded by too much electricity, o Outdated breaker boxes often have worn connectors that do not work, causing the system to overload and start an electrical fire. 33 PPT-008-02
- 34. Safety • Check the information on your cord. o Extension cords are labeled with valuable information as to the use, size and wattage rating of the cord. o Cords offered in many lengths and are labeled with size or “gauge.” • Determine the gauge needed. All appliances indicate how much wattage is consumed when operated. 34 PPT-008-02
- 35. Safety • Decide whether you will be using the appliance indoors or outdoors. o Extension cords that can be used outdoors will be clearly marked “Suitable for Use with Outdoor Appliances.” • Never use an indoor extension cord outdoors; it could result in an electric shock or fire hazard. 35 PPT-008-02
- 36. Safety • Determine how long you need the cord to be. A cord, based on its gauge, can power an appliance of a certain wattage only at specific distances. o As cord gets longer, the current carrying capacity of the cord gets lower. o Example: 16 gauge extension cord less than 50 feet in length can power a 1625 watt (W) appliance; 16 gauge cord that is longer than 50 feet can only power an appliance up to 1250W. 36 PPT-008-02
- 37. Safety Place the cord correctly. o Do not place underneath carpets or heavy furniture. o Should not be tacked in place to a wall or taped down. o Should not be used while coiled or bent. o Match the length of the cord to the length of your needs. 37 PPT-008-02
- 38. Training Train employees working with electrical equipment in safe working practices including: • De-energizing electrical equipment before inspecting or making repairs • Using electric tools in good repair • Using good judgment when working near energized lines • Using appropriate protective equipment (PPE) 38 PPT-008-02
- 39. Summary • Extension cords must be "of proper size and temperature rating to withstand the electrical load and approved by a recognized testing agency.” • Locally purchased extension cords may not meet this standard. • Always check applicable regulations/standards before buying or using extension cords at work. 39 PPT-008-02
- 40. Summary Hazards • Inadequate wiring • Exposed electrical parts • Wires with bad insulation • Ungrounded electrical tools/systems • Overloaded circuits • Damaged power tools/equipment • Overhead power lines All hazards are made worse in wet conditions! 40 PPT-008-02
- 41. Summary PROTECTIVE MEASURES ▪ Proper grounding ▪ Using GFCI’s ▪ Using fuses and circuit breakers ▪ Proper use of flexible cords ▪ Training 41 PPT-008-02
- 42. Contact Information Health & Safety Training Specialists 1171 South Cameron Street, Room 324 Harrisburg, PA 17104-2501 (717) 772-1635 RA-LI-BWC-PATHS@pa.gov 42 PPT-008-02 Like us on Facebook! - https://www.facebook.com/BWCPATHS
Hinweis der Redaktion
- This program addresses electrical safety issues which may be found in OSHA 29 CFR 1910, Subpart S. The intent of this program is to familiarize people with potential electrical hazards at the work site and at home. We suggest you consult an electrician to answer specific questions which may arise.
- Electrical injuries: AN AVERAGE OF ONE WORKER IS ELECTROCUTED ON THE JOB EVERY DAY! There are four main types of electrical injuries: ► Electrocution (death due to electrical shock) ► Electrical Shock ► Burns ► Falls
- The US Fire Administration compiles statistics for various fire incidents. These are for electrical incidents (2002-2005)
- How is an electrical shock received? When two wires have different potential voltages, current will flow if they are connected. ►In most household wiring the black wires are at 110 volts relative to ground ►The white wires are at zero volts because they are connected to ground Contact with an energized (live) black wire while touching the white grounded wire =ELECTRICAL SHOCK! You’re completing the circuit and the voltage wants to go to ground.
- Electrical Burns Are the most common shock related nonfatal injury Occur 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
- Falls. When a person is working at an elevated height and receives a shock, there is the likelihood they may fall from their support. Electrical shock can also cause indirect or secondary injuries. Employees working in an elevated location who experience a shock can fall resulting in serious injury or even death.
- Inadequate Wiring Hazards contribute to overheat conditions. A hazard exists when a conductor is too small to safely carry the current. Example: using a portable tool with an extension cord that has a wire too small for the tool • Tool draws more current than the cord can handle causing overheating and a possible fire without tripping the circuit breaker. • Circuit breaker could be the right size for the circuit but not for the smaller wire extension cord.
- A circuit may be overloaded, e.g. drawing more power than the wires can handle. Too many devices plugged into circuit = wires heat to very high temperature = possible fire. Wire insulation melts = arcing may occur = causing a fire in the area where overload exists (even inside a wall).
- Electrical protective devices are meant to function in the circuit before they can contribute a shock hazard. These devices shut off the electricity flow in the event of an overload or ground-fault in the circuit. Include fuses, circuit breakers, and ground-fault circuit interrupters (GFCI). Fuses and circuit breakers are “over current” devices (too much current = fuses melt and circuit breakers “trip” open).
- The Ground Fault Circuit Interrupter (GFCI) Protects you from dangerous electrical shock. Detects a difference in current between the black and white circuit wires (could happen when electrical equipment is not working properly causing a current “leakage” known as ground fault). Ground fault detected = GFCI can shut off electricity flow in as little as 1/40 of a second protecting you from a dangerous shock.
- Examples: OSHA Electrical Requirements GROUNDING PATH The path to ground from circuits, equipment, and enclosures must be permanent and continuous. The violation shown here is an extension cord with the third/grounding prong missing. At home, check your ground wire outside the house. The wire should run in as straight a line as possible to the buried grounding stake. Some have been found to loop up to the grounding stake. News Flash-lighting does NOT make turns when going to ground! Get professional help to correct the situation.
- Examples of OSHA electrical requirements. Hand-held electrical tools pose a potential danger because they make continuous contact with the hand. To protect you from shock, burns, and electrocution, tools must: Have a 3 wire cord with ground and be plugged into a grounded receptacle or Be double insulated or Be powered by a low-voltage isolation transformer
- The requirement to guard “live” parts of electric equipment operating at > 50 volts against accidental contact can be satisfied by: Approved cabinets/enclosures or Location or permanent partitions (thereby being only accessible to qualified persons) Elevation of 8 feet or more above the floor or working surface to be out of direct or possible accidental contact. Mark entrances to these guarded locations with conspicuous warning signs.
- Live Parts are to be guarded! Where electrical equipment is in locations that it can suffer physical damage it must be guarded. The violation shown here is physical damage to conduit. It can be imagined that the wires running through this have been placed under strain. Also, the possibility exists that insulation has been compressed to the point of heating, burning through, contacting the metal sleeving. This could be a fire or shock hazard.
- Cabinets, Boxes, Fittings (29 CFR 1910.305(b)) Junction boxes, pull boxes, and fittings must have approved covers. Unused openings in cabinets, boxes and fittings must be closed (no missing “knockouts”). Photo shows violations of these two requirements.
- Flexible cords and cables are more vulnerable than fixed wiring. (29 CFR 1910.305(g)) Made be of industrial commercial quality. May not be used as permanent wiring. Improper use of flexible cords can cause shocks, burns, or fire. Approved by a recognized testing agency
- Extension Cords Fully uncoil an extension cord before use. Be sure the amperage of the cord is appropriate for the job you are doing. Do not use equipment that delivers mild electrical shocks, gives off unusual heat or odd odors. If in doubt, have it checked and repaired or replaced.
- Flexible cords (extension cords) Extension cords shall not be: Fastened with staples, (Staples may compress the insulation around the wire. This can lead to heating and deterioration of the insulating wire) Hung from nails, or (This does not provide a secure attachment and the wire may be subject to movement or strain if not properly secured.) Suspended by wire. (This places 2 potential conductors within possible contact one with the other-unsafe.) Strain Relief. Flexible cords shall be connected to devices and fittings so that strain relief is provided which will prevent pull from being directly transmitted to joints or terminal screws. (29 CFR 1926.405(g)(2)(iv).
- Permissible Use: Flexible Cords (29 CFR 1926.405(g)) Pendant or fixture wiring Portable lamps, tools or appliances Stationary equipment to facilitate interchange Each of the above looks at the: Short distances between sources and use, Low power requirements Need to provide power temporarily until permanent tie-in is established.
- Prohibited Use of Flexible Cords These are not a substitute for fixed wiring. (Flex cord may not be up to carry same voltage as fixed arrangement.) They are not run through walls, ceilings, floor, doors or windows. (Too easy to tamper with or come into contact with.) They are not concealed behind or attached to building surfaces. (Subject to humidity and dampness changes.)
- Electrical Extension Cords A Homemade “Gang Box” is Not allowed in a work setting per OSHA: 29 CFR 1910.305 29 CFR 1926.405 Since every type of person, qualified or not, can make one of these, their quality can differ from person to person. When we’re talking about electrical safety, do we really want to use any equipment described as being “homemade?”
- Not only do we have the insulation removed from the orange extension cord but we also have a box with knockouts. The grounding screw is also in contact with the box.
- We do not chain materials to electrical lines; if the material falls it puts a strain on the line or separates the line from its connections. Ladders against the box contribute combustible materials should there be an electrical fire. Also, this limits access which may be required to shut the system down or isolate breakers (OSHA states there should be at least 3 feet of clearance around an electrical box). Also, if there is a fault in the electrical box, could the current flow to the outside of the box contacting conductive materials and be a possible shock or electrocution hazard?
- Another situation where combustible storage obstructs the box. Portable power tool with damaged cord. Also appears to be resting on a conductive surface.
- Right side: Missing insulation on cords. Left side: Permanency attempted by screwing a “bridge” between extension cord and adapter. Again, “Homemade” might get you hurt! Professionally manufactured cords must abide by specific standards. They also go through extensive quality control. Quality Control for “homemade” stuff is usually, “Yep, looks good to me.” This does not assure safety.
- Left: extension cord under carpet permits foot traffic to compress cord and insulation to the point of thinning and distressing the insulation. Potential fire and shock hazard. Right: multiple lines into a power strip permits cords to heat up. Fire hazard.
- Left: Grounding prong in receptacle. Seek professional help to remove and replace receptacle. Right: Damaged insulation and wiring. Destroy and replace.
- Left: cord is tangled; tripping hazard. Right: multiple gang boxes showing the possibility of appliances and tools to far exceed the voltage restrictions on the line.
- Top 5: Number 1 Electrical Fire Cause Most electrical fires are caused by faulty electrical outlets and old, outdated appliances. Removing the grounding plug from a cord so it can be used in a two-prong electrical outlet can also cause a fire.
- Top 5: Number 2 Light fixtures, lamps and light bulbs are another common reason for electrical fires. Installing a bulb with a wattage that is too high for the lamps and light fixtures is a leading cause of electrical fires. Always check the maximum recommended bulb wattage on any lighting fixture or lamp and never go over the recommended amount
- Top 5: Number 3 Misuse of extension cords is another electrical fire cause. Appliances should be plugged directly into outlet and not plugged into an extension cord for any length of time. Only use extension cords as a temporary measure. If you do not have the appropriate type of outlets for your appliances, hire an electrician to install new ones.
- Top 5: Number 4 Space heaters are a major cause of electrical fires. Because these types of heaters are portable, many times people put them too close to combustible surfaces such as clothing, chairs, and rugs. Coil space heaters are especially dangerous. If you do use space heaters, use the radiator-type that diffuse heat over the entire surface of the appliance.
- Top 5: Number 5 Outdated wiring often causes electrical fires. Breakers should be triggered when circuits get overloaded by too much electricity, but outdated breaker boxes often have worn connectors that do not work, causing the system to overload and start an electrical fire. Breaker box is uncovered.
- Safety: Check the information on your cord. Extension cords are labeled with valuable information as to the use, size and wattage rating of the cord. Cords offered in many lengths and are labeled with size or “gauge.” Determine the gauge needed. All appliances indicate how much wattage is consumed when operated.
- Electrical safety also includes: Decide whether you will be using the appliance indoors or outdoors. Extension cords that can be used outdoors will be clearly marked “Suitable for Use with Outdoor Appliances.” Never use an indoor extension cord outdoors; it could result in an electric shock or fire hazard.
- In addition, keep the following safety information in mind: Determine how long you need the cord to be. A cord, based on its gauge, can power an appliance of a certain wattage only at specific distances. As the cord gets longer, the current carrying capacity of the cord gets lower. Example: 16 gauge extension cord less than 50 feet in length can power a 1625 watt (W) appliance; 16 gauge cord that is longer than 50 feet can only power an appliance up to 1250W.
- Place the cord correctly. Do not place underneath carpets or heavy furniture. Should not be tacked in place to a wall or taped down. Should not be used while coiled or bent. Match the length of the cord to the length of your needs.
- Train employees working with electrical equipment in safe working practices including: De-energizing electrical equipment before inspecting or making repairs. Using electric tools in good repair. Using good judgment when working near energized lines. Using appropriate protective equipment (PPE).
- Summary Extension cords must be "of proper size and temperature rating to withstand the electrical load and approved by a recognized testing agency.” (UL: Underwriters Laboratories). Locally purchased extension cords may not meet this standard. Always check applicable regulations/standards before buying or using extension cords at work.
- Summary Hazards - Inadequate wiring - Exposed electrical parts - Wires with bad insulation - Ungrounded electrical tools/systems - Overloaded circuits - Damaged power tools/equipment - Overhead power lines All hazards are made worse in wet conditions!
- Summary PROTECTIVE MEASURES ▪ Proper grounding ▪ Using GFCI’s ▪ Using fuses and circuit breakers ▪ Proper use of flexible cords ▪ Training