Electrical Safety Training

1. Electrical Safety Training

2. Electrical Hazards • Every year, between 300 and 500 people in the U.S. are killed by electrocutions at work. • Many of those killed are people who work with electricity indirectly, including office workers and operators.

3. This course will cover • How electricity acts • How shocks occur • The severity of shocks • The effects of an electric current in the body • Burns and other injuries from electricity • How to correct electrical hazards • Safe work practices

4. How Electricity Works • Many of us take electricity and how it works for granted. We simply flip a switch and it is there. • However, in order to know how to deal with the hazards of electricity, we must know something about how it works.

5. Rules of Electricity • Electricity travels in a completed circuit • Electricity will flow through a variety of materials, shapes and forms • Electricity always travels in the path of least resistance • Electricity always tries to travel to ground

6. Conductors & Insulators • Some substances, such as metals, offer very little resistance to the flow of electric current. They are called conductors. • Other substances, like porcelain, glass and dry wood offer such a high resistance that they can be used to prevent the flow of electric current. They are called insulators.

7. Conductors & Insulators • Water is a good conductor when it contains impurities, such as salt and acid (both are present in perspiration). • When water is present or the skin is wet with sweat, you should exercise even more caution than usual when using electrical devices.

8. SHOCK • Electricity travels in closed circuits, and its normal route is through a conductor. Shock occurs when the body becomes a part of the electrical circuit (the person forms a completed circuit when touching the ground). • A person usually offers a lesser resistance for the electricity. • The current must enter the body at one point and leave at another.

9. SHOCK • Shock occurs in one of three ways – when a person comes in contact with: • Both wires of the circuit • One wire of an energized circuit and the ground • A metallic part that has become ‘hot’ by being in contact with an energized wire, while the person is also in contact with the ground

10. Severity of SHOCK • The severity of the shock received when a person becomes part of an electrical circuit depends on three primary factors: • The amount of current measured in Amps • The path through the body • The length of time the body is in the circuit

11. Effects on the Human Body • 1 mA: Can be felt by the body • 2-10 mA: Minor shock, might result in a fall • 10-25 mA: Loss of muscle control, may not be able to let go of the current • 25-75 mA: Painful, may lead to collapse or death • 75-300 mA: Last for ¼ second, almost always immediately fatal

12. Voltages and Amperes • Voltage = Amps X Ohms(resistance) • Converting voltage to amps • Typical Industrial Voltages • 110/120 Volts = 60milliAmps (mA) • 220/240 Volts = 120 mA • 440/480 Volts = 240 mA

13. Shock-Related Injuries • The most common shock-related injury is a burn. • There are three types of burns: • Electrical burns • Arc burns • Thermal burns

14. Shock-Related Injuries • Electric shock can also cause injuries of an indirect or secondary nature in which involuntary muscle reaction from the electric shock can cause bruises, bone factures, and even death resulting from collisions or falls. • In some cases, injuries caused by electric shock can be a contributory cause of delayed fatalities.

15. Types of Burns • Electrical burns are the result of electric current flowing through tissues or bone. Tissue damage is caused by the heat generated by the current flow through the body. • Electrical burns are one of the most serious injuries you can receive and should be given immediate attention. • Arc and flash burns are the result of high temperatures near the body and are produced by an electric arc or explosion. They should also be attended to promptly.

16. Arcs • In addition to shock and burn hazards, electricity poses other dangers. • For example, when a short circuit occurs, hazards are created from the resulting arcs. If high current is involved, the arcs can cause injury or start a fire. • Extremely high arcs can damage equipment, causing fragmented metal to fly in all directions. • Even low-energy arcs can cause violent explosions in atmospheres that contain flammable gases, vapors, or combustible dusts.

17. Electrical Accidents • Electrical accidents appear to be caused by a combination of three possible factors: • Unsafe equipment and/or installation • Workplaces made unsafe by the environment • Unsafe work practices

18. Preventing Electrical Accidents Insulation • Electricity uses all of the conductor; if the conductor is left exposed, any person touching it would be shocked. That is why conductors have insulation. • An insulator is a material with high resistance to electric current. Insulators such as glass, mica, rubber and plastic are put on conductors to prevent shock, fires, and short circuits. • Before connecting a device to a power source, check the insulation to ensure there are no exposed wires.

19. Preventing Electrical Accidents Guarding • Live parts of electrical equipment operating at 50 volts or more must be guarded against accidental contact. • Installations that are over 600 volts must be controlled by a lock and must be marked with appropriate caution signs.

20. Preventing Electrical Accidents Grounding • Grounding is another method of protecting workers from electric shock. By grounding a tool or device, a low-resistance path to the earth is intentionally created. • When a short occurs in the tool or wiring, the grounding is accomplished through the intentional ground (usually a ground wire), and not through the worker. • The ground does not guarantee that there will be no shock, injuries, or fatalities, but it does reduce the possibilities.

21. Preventing Electrical Accidents Circuit Protection Devices • Circuit protection devices are designed to automatically limit or shut off the flow of electricity in the event of a ground-fault, overload, or short circuit in the wiring system. Fuses and circuit breakers are examples of circuit protection devices. • Fuses are designed to melt when too much current flows through them. • When too much current flows through a circuit breaker, it opens (shuts off). • Fuses and circuit breakers are intended primarily for the protection of conductors and equipment, but they do also protect workers from overheated electrical components.

22. Preventing Electrical Accidents Ground Fault Circuit Interrupter (GFCI) • A GFCI is designed to cut off electrical power within as little as 1/40 of a second. • It works by comparing the amount of current returning from the device along the circuit conductors. It is used in high risk areas such as wet locations and construction sites.

23. Preventing Electrical Accidents Switches • Generally speaking, it is not advisable to break a circuit once it has been established. If the circuit is broken with the appliance on, an arc is usually the result. Switches (circuit breakers) are designed to contain the arc in a safe way. • Shutting down an electric appliance by pulling the plug will result in an arc by breaking the circuit at the plug. The plug is not designed to be a circuit breaker. The result could be damage to the wiring at the outlet or damage to the appliance itself. • Pulling the cord could cause damage to the appliance plug and cord, setting up a short in the cord and causing the appliance to either function improperly or not to function at all. • Always shut down appliances with the switch.

24. Safe Work Practices De-Energize Electrical Equipment • The accidental or unexpected sudden starting of electrical equipment can cause severe injury or death. • Before any inspections or repairs are made, even on low voltage circuits, the current should be turned off and the system locked out.

25. Safe Work Practices Portable Power Tools • Employees should always use tools that work properly. • Tools should be inspected frequently, and those found questionable should be removed from service and tagged. • Never use portable power equipment in wet or damp areas. • Stop using power tools if they become hot or start sparking.

26. Safe Work Practices Extension Cords • Inspect and check for capacity • For temporary work only • Do not use as a rope to pull or lift objects • Should not be fastened with staples or hung over hooks

27. Safe Work Practices GOOD JUDGEMENT • Perhaps the single most successful defense against electrical accidents is the continuous exercising of good judgment or common sense. • When working around energized lines, for example, some basic procedures are to: • Have the line de-energized • Ensure that the line remains de-energized by using lockout/tagout • Use insulated protective equipment • Keep a safe distance from energized lines

28. Safe Work Practices Protective Equipment • Workers whose occupations require them to work constantly and directly with electricity must use the personal protective equipment required for the jobs they perform. • This equipment may consist of • Rubber insulating gloves • Hoods • Sleeves • Matting • Blankets • Line hose • Industrial protective helmets

29. Summary • The control of electrical hazards is an important part of every safety and health program. • Everyone has the right to work in a safe environment. Through cooperative efforts, employers and employees can learn to identify and eliminate or control electrical hazards.