Electrical Safety 1 1 Terminal Learning Objective Upon
Electrical Safety 1 1 Terminal Learning Objective Upon completion of this module, participants will understand the hazards of electricity and the need for proper planning and control methods to eliminate or reduce those hazards. 2 2
Enabling Learning Objectives In this module, we will: Discuss the hazards of electricity Describe ways to control those hazards Identify several safety-related work practices Explain how hazards can be prevented with thorough planning and training 3 3 Electricity - The Dangers About 5 workers are
electrocuted every week Causes 12% of young worker workplace deaths Takes very little electricity to cause harm Significant risk of causing fires 4 4 Electricity How it Works Electricity is the flow of energy from one place to another Requires a source of power:
usually a generating station A flow of electrons (current) travels through a conductor Travels in a closed circuit 5 5 Electrical Terms Current electrical movement (measured in amps) Circuit complete path of the current. Includes electricity source, a conductor, and the output device or load (such as a lamp, tool, or heater) Resistance restriction to electrical flow Conductors substances, like metals, with little resistance to electricity that
allow electricity to flow Grounding a conductive connection to the earth which acts as a protective measure Insulators substances with high resistance to electricity like glass, porcelain, plastic, and dry wood that prevent electricity from getting to unwanted areas 6 6 Electrical Injuries There are four main types of electrical injuries: Direct Electrocution or death due to electrical shock
Electrical shock Burns Indirect Falls 7 7 Electrical Shock There are four main types of electrical injuries: An electrical shock is received when electrical current passes through the body. You will get an electrical shock if a part of your body completes
an electrical circuit by Touching a live wire and an electrical ground, or Touching a live wire and another wire at a different voltage. 8 8 Shock Severity Severity of the shock depends on: Path of current through the body Amount of current flowing through the body (amps) Duration of the shocking current through the body
** LOW VOLTAGE DOES NOT MEAN LOW HAZARD 9 9 Dangers of Electrical Shock Severity of the shock depends on: Currents above 10 mA* can paralyze or freeze muscles. Currents more than 75 mA can cause a rapid, ineffective heartbeat death will occur in a few minutes unless a defibrillator is used. 75 mA is not much current a small power
drill uses 30 times as much. *1/10 of an ampere (amp) Defibrillator in use 10 10 Burns Most common shock-related injury Occurs when you touch electrical wiring or equipment that is improperly used or maintained Typically occurs on hands Very serious injury that needs
immediate attention 11 11 Falls Electric shock can also cause indirect injuries Workers in elevated locations who experience a shock may fall, resulting in serious injury or death 12
12 Electrical Hazards and How to Control Them Electrical accidents are caused by a combination of three factors: Unsafe equipment and/or installation, Workplaces made unsafe by the environment, and Unsafe work practices. 13 13
Hazard Exposed Electrical Parts Cover removed from wiring or breaker box 14 14 Control Isolate Electrical Parts Use guards or barriers Replace covers Guard live parts of electric equipment operating at 50 volts
or more against accidental contact 15 15 Control Isolate Electrical Parts, Cabinets, Boxes & Fittings Conductors going into them should be protected, and unused openings should be closed. 16
16 Control Close Openings Junction boxes, pull boxes and fittings should have approved covers Unused openings in cabinets, boxes and fittings should be closed (no missing knockouts) Photo shows violations of these two requirements 17
17 Hazard Overhead Power Lines Usually not insulated Examples of equipment that can contact power lines: Crane Ladder Scaffold Backhoe Scissors lift Raised dump truck bed Aluminum paint roller 18
18 Control - Overhead Power Lines Stay at least 10 feet away Post warning signs Assume that lines are energized Use wood or fiberglass ladders, not metal
Power line workers need special training & PPE 19 19 Hazard - Inadequate Wiring Hazard - wire too small for the current Example - portable tool with an extension cord that has a wire too small for the tool The tool will draw more current than the cord can handle, causing overheating and a possible fire without tripping the circuit breaker
The circuit breaker could be the right size for the circuit but not for the smaller-wire extension cord Wire Gauge WIRE Wire gauge measures wires ranging in size from number 36 to 0 American wire gauge (AWG) 20 20
Control Use the Correct Wire Wire used depends on operation, building materials, electrical load, and environmental factors Use fixed cords rather than flexible cords Use the correct extension cord Must be 3-wire type and designed for hard or extra-hard use 21 21 Hazard Defective Cords & Wires Plastic or rubber
covering is missing Damaged extension cords & tools 22 22 Hazard Damaged Cords Cords can be damaged by:
Aging Door or window edges Staples or fastenings Abrasion from adjacent materials Activity in the area Improper use can cause shocks, burns or fire 23 23 Control Cords & Wires
Insulate live wires Check before use Use only cords that are 3-wire type Use only cords marked for hard or extra-hard usage Use only cords, connection devices, and fittings equipped with strain relief Remove cords by pulling on the plugs, not the cords Cords not marked for hard or extra-hard use, or which have been modified, should be taken out of service immediately
24 24 Permissible Use of Flexible Cords DO NOT use flexible wiring where frequent inspection would be difficult or where damage would be likely. Flexible cords should not be... Run through holes in walls, ceilings, or floors; Run through doorways, windows, or similar openings (unless physically protected); Hidden in walls, ceilings, floors, conduit or other raceways
25 25 Grounding Grounding creates a low-resistance path from a tool to the earth to disperse unwanted current. When a short or lightning occurs, energy flows to the ground, protecting you from electrical shock, injury and death. 26
26 Hazard Improper Grounding Tools plugged into improperly grounded circuits may become energized Broken wire or plug on extension cord Some of the most frequently violated OSHA standards 27
27 Control Ground Tools & Equipment Ground power supply systems, electrical circuits, and electrical equipment Frequently inspect electrical systems to insure path to ground is continuous Inspect electrical equipment before use Dont remove ground prongs from tools or extension cords Ground exposed metal parts of equipment 28
28 Control Use GFCI (ground-fault circuit interrupter) Protects you from shock Detects difference in current between the black and white wires If ground fault detected, GFCI shuts off electricity in 1/40th of a second Use GFCIs on all 120-volt, single-phase, 15- and 20-ampere receptacles, or have an assured equipment grounding conductor program
29 29 Control Assured Equipment Grounding Conductor Program Program should cover: All cord sets Receptacles not part of a building or structure Equipment connected by plug and cord Program requirements include: Specific procedures adopted by the employer Competent person to implement the program Visual inspection for damage of equipment connected by cord and plug
30 30 Hazard Overloaded Circuits Hazards may result from: Too many devices plugged into a circuit, causing heated wires and possibly a fire Damaged tools overheating Lack of over-current protection Wire insulation melting, which may cause arcing and a fire in the area where the overload exists, even inside a wall
31 31 Control Electrical Protective Devices Automatically opens circuit if excess current from overload or ground-fault is detected shutting off electricity Includes GFCIs, fuses, and circuit breakers Fuses and circuit breakers are overcurrent devices. When too much current: Fuses melt Circuit breakers trip open
32 32 Power Tool Requirements Have a three-wire cord with ground plugged into a grounded receptacle, or Be double insulated, or Be powered by a low-voltage isolation transformer 33 33
Tool Safety Tips Use gloves and appropriate footwear Keep cords away from heat, oil, & sharp edges
Disconnect when not in use and when changing Store in dry place when not using Dont use in wet/damp conditions Keep working areas well lit Ensure not a tripping hazard Dont carry a tool by the cord Dont yank the cord to disconnect it Accessories such as blades & bits Remove damaged tools from use 34 34 Preventing Electrical Hazards Tools
Inspect tools before use Use the right tool correctly Protect your tools Use double insulated tools 35 35 Temporary Lights
Protect from contact and damage, and dont suspend by cords unless designed to do so. 36 36 Clues that Electrical Hazards Exist Tripped circuit breakers or blown fuses Warm tools, wires, cords, connections, or junction boxes GFCI that shuts off a circuit Worn or frayed insulation
around wire or connection 37 37 Lockout and Tagging of Circuits Apply locks to power source after de-energizing Tag deactivated controls Tag de-energized equipment and circuits at all points where they can be energized Tags should identify equipment or circuits being worked on
38 38 Safety-Related Work Practices To protect workers from electrical shock: Use barriers and guards to prevent passage through areas of exposed energized equipment Pre-plan work, post hazard warnings and use protective measures Keep working spaces and walkways clear of cords 39
39 Safety-Related Work Practices Use special insulated tools when working on fuses with energized terminals Dont use worn or frayed cords and cables Dont fasten extension cords
with staples, hang from nails, or suspend by wire 40 40 Preventing Electrical Hazards Planning
Plan your work with others Plan to avoid falls Plan to lock-out and tag-out equipment Remove jewelry Avoid wet conditions and overhead power lines 41 41 Avoid Wet Conditions If you touch a live wire or other electrical component while standing in even a small puddle of water youll get a shock.
Damaged insulation, equipment, or tools can expose you to live electrical parts. Improperly grounded metal switch plates & ceiling lights are especially hazardous in wet conditions. Wet clothing, high humidity, and perspiration increase your chances of being electrocuted. 42 42 Preventing Electrical Hazards PPE Proper foot protection (not tennis shoes)
Rubber insulating gloves, hoods, sleeves, matting, and blankets Hard hat (insulated nonconductive) 43 43 Preventing Electrical Hazards Proper Wiring and Connectors
Use and test GFCIs Check switches and insulation Use three prong plugs Use extension cords only when necessary & assure in proper condition and right type for job Use correct connectors 44 44 Training
Train employees working with electric equipment in safe work practices, including: De-energize electric equipment before inspecting or repairing Using cords, cables, and electric tools that are in good repair Lockout/Tagout recognition and procedures Use appropriate protective equipment 45 45 Review
In this module, we: Discussed the hazards of electricity Described ways to control those hazards Identified several safety-related work practices Explained how hazards can be prevented with thorough planning and training 46 46 Questions? 47
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