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Electrical SafetyRelated Work Practices In and around the mines AND The home 1 Jon Montgomery, EFS [email protected] Albany, NY 518-489-0780 2 WHAT IS ELECTRICITY?? 3 ? Electricity is a form of energy High Voltage (>650 volts) Low Voltage (650 volts or less) Alternating Current Direct Current Static Electricity 4 5 6 7 8 ELECTRICAL ACCIDENTS Electrocutions rank fourth in work related fatalities with about half of these at 600 volts or less. There are an average of over 3,600 disabling electrical related injuries annually. There are an average of 4,000 non- disabling electrical injuries annually. 9 Let’s talk about personal protection and the home 40,000 residential fires annually which are caused by problems with electrical wiring systems, claiming more than 350 lives Additionally, electric cords and plugs were involved in about 7,100 fires resulting in 120 deaths or about 32% of all deaths associated with residential electrical system fires, occurring each year. Lamps and light fixtures were involved in about 8,900 fires and 60 deaths About 3,600 people are treated for injuries associated with extension cords. Switches and outlets are involved in 4,700 fires and deaths 10 Reported Mining Electrical Accidents (INCLUDES FATALITIES) 1990 thru 2000 Coal-Underground 752 137 Coal-Surface Metal/non-metal-Underground 99 Metal/non-metal-Surface Prep Plants Other Total 655 244 34 1921 11 Fatal Electrical Accidents 1990 thru 2000 But more important is the cost in lives…… • • • • • • Coal-Underground Coal-Surface Metal/non-metal-Underground Metal/non-metal-Surface Prep Plants Other 27 4 7 29 9 2 Total 78 12 Causes of Electrical Injuries Touching live parts. Short circuit Accidental ground Overload 13 14 Electrical Hazards Exposed conductors Frayed and worn insulation Exposed bus bars and connections Overloaded circuits Modified circuits Removed grounding plug Jury-rigged connections 15 Effects on the Body Burns Flash burns (from electrical arcs) Electrical burns (entry & exit wounds) Electrical Shock Damage to internal organs and body systems 16 Effects on the Body Approximately 50 volts is needed to overcome skin resistance Resistance is higher on dry skin Resistance is lower on wet skin 17 ENTRY WOUND 18 EXIT WOUND 19 20 Electrical Shock A person receives an electrical shock whenever any part of his/her body becomes part of the electrical circuit through which a sufficient current flows to cause discomfort or worse. Current flow slightly above this threshold is sufficient to cause discomfort: May cause involuntary contraction of the muscles. Stop the heart. Stop breathing. Cause burns. 21 Electrical Shock The amount of current that flows through the victim’s body will depend on: The voltage of the circuit with which he/she is in contact. The insulating qualities of the place in which he/she is located at the instant. The resistance of skin or clothing or both. The area of contact with the live conductor. The pressure of contact with the live conductor. The area of contact with the live conductor 22 four major components of an electrical system sources conductors loads switches 23 SOURCES provide electricity batteries transformers generators water system equivalent - water tank 24 CONDUCTORS carry electricity wires cables bus bars water equivalent - pipes 25 LOADS use electricity motors pumps fans hand tools lights heaters water equivalent -water wheel 26 SWITCHES control electricity floats push buttons disconnects duplex outlets / plugs water equivalent - valves 27 Water system comparison •Voltage = pressure •Current = flow •Resistance = system resistance to flow 28 Ohms Law voltage resistance amps • Since voltage is constant, current flow depends on resistance 29 30 CFR 56/57. 12028 56/57.12028 Testing grounding systems. Continuity and resistance of grounding systems shall be tested immediately after installation, repair, and modification; and annually thereafter. A record of the resistance measured during the most recent tests shall be made available on a request by the Secretary or his duly authorized representative. 30 Equipment grounding systems high resistance = low current low resistance = high current current flow is what trips fuses/breakers 31 Be sure: all grounds ohms values are as low as possible all wiring connections are clean & tight all conduit connections are clean & tight all plugs have ground prong in place 32 Methods of Contact Step potential Difference in voltages (potential for current flow) between person’s feet Touch potential Difference in voltages between points of contact (usually hands and/or feet) 33 HOW DO WE PROTECT OURSELVES???? LOCK OUTTAG OUT!! LOCKOUT/TAGOUT Types of Devices 35 LOCKOUT/TAGOUT Types of Energy Mechanical Hydraulic Pneumatic Chemical Thermal Other 36 LOCKOUT/TAGOUT Preparation for Shutdown Know the types and amounts of energy that power it. Know the hazards of that energy. Know how the energy can be controlled. 37 VERIFY-VERIFY-VERIFY!!!! (ONLY IF YOU ARE QUALIFIED) 38 HOW ELSE CAN WE PROTECT OURSELVES??? BY USING GFCI’S How does the GFCI work GFCIs constantly monitor electricity flowing in a circuit. If the electricity flowing into the circuit differs by even a slight amount from that returning, the GFCI will quickly shut off the current flowing through that circuit. The advantage of using GFCIs is that they can detect even small variations in the amount of leakage current, even amounts too small to activate a fuse or circuit breaker. GFCIs work quickly, so they can help protect consumers from severe electric shocks and electrocution. 40 Some things a GFCI does not protect you from. A GFCI does not protect a person who comes in contact with two hot wires or any hot wire and the neutral wire. A GFCI does not protect a person from feeling and reacting to shock 41 ALWAYS REMBER! Never work on a Energized Circuit. Unless you are trained to. Always Lock and Tag Never depend on another person to take the power off a circuit that you are going to work on. Its your Life! This should even apply to home. Just remember that Half of what you have is hers. 42 Qualified Employees “One knowledgeable in the construction and operation of the electric power generation, transmission, and distribution equipment involved, along with the associated hazards.” Qualified employees must have training to be considered qualified. 43 Qualified Employees Qualification extends to individual tasks Employees can be qualified in one task, but not in another. Examples: Racking breakers in & out Changing fuses Substation switching 44 Unqualified Employees Unqualified employees and mobile mechanical equipment must maintain a safe distance from energized circuits Overhead power lines Unguarded, exposed, energized conductors 10 feet up to 50,000 volts Additional 4 inches for every 10,000 volts over 50 kV 45 Methods of Protection Insulation Verify insulation is intact Pay particular attention to flexible cords, such as extension cords and tool power cords 46 Methods of Protection Guarding Live parts operating at 50 volts or more must be guarded Locate in a room or vault accessible only by qualified persons Permanent partitions or walls Metal-clad switchgear required if over 600 volts Distance 8 feet (or more) above the floor Warning Signs 47 Methods of Protection Grounding Service ground Neutral conductor is grounded Equipment ground Frame or casing of tool or equipment is wired directly to ground. 48 Methods of Protection Circuit Protection Devices Fuses and Circuit Breakers Designed for equipment protection Open circuit on high current GFCI Ground Fault Circuit Interrupter Designed for personnel protection Opens quickly (1/40 second) on any ground fault 49 Methods of Protection Safe Work Practices De-energize Lockout/Tagout energy sources Use electric tools that are in good repair Do not perform work you are not qualified for Use appropriate protective equipment FR clothing, non-conductive hard hats, rubber mats, line hose, hot sticks, rubber gloves, safety glasses, face shields, etc. 50 Methods of Protection Overhead Lines Only qualified employees can work on or near All others maintain 10-foot rule, or Owner/operator must de-energize and ground lines prior to work 51 Safe Work Practices DO Inspect cords for damage De-energize and L.O.T.O. Keep cords off walkways Wear PPE Perform work only if qualified Use a GFCI DON’T Overload plugs Upsize fuses, or use substitutes Lay cords in water Use defective equipment Assume household current is safe Use conductive ladders 52 IF SOMEONE CONTACTS AN ENERGIZED CONDUCTOR ---WHAT SHOULD ONE DO ?? 53 BLOOD TESTS TO WARN OF FIBRILLATION TO OCCUR TROPONIN CPK ISOENZYME (CREATINE KINASE) 54 PLEASE REMEMBER--- 55 SAFETY FIRST!!!! 56 THANK YOU ALL FOR LISTENING!!! 57