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Introduction to Electrical Safety

Module 1. Introduction to Electrical Safety. Module Objectives. Recognize key statistics relating to electrical injuries. Recognize OSHA regulations and other standards relating to electrical safety. Understand basic electrical terminology. Module Objectives.

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Introduction to Electrical Safety

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  1. Module 1 Introduction to Electrical Safety

  2. Module Objectives • Recognize key statistics relating to electrical injuries. • Recognize OSHA regulations and other standards relating to electrical safety. • Understand basic electrical terminology.

  3. Module Objectives • Identify the four types of injury relating to electrical incidents. • Understand key facts relating to electric shock. • Understand the basic facts of electricity.

  4. Module Objectives • Understand Ohm’s Law and describe how the terms current, voltage and resistance relate to Ohm’s Law. • Recognize the effects of electricity on the human body.

  5. Electrifying Statistics • From 1992-2002, there were 3,378 deaths from on-the-job electrical injuries. • That’s 4.7% of all occupational deaths. • That’s almost one death per day! • Electricity is the 4th leading cause of injury-related occupational death

  6. Electrifying Statistics • Contact with overhead power lines was the leading cause of electrocutions, causing 42% of the deaths. • The second leading cause of electrocutions was failure to properly de-energize equipment.

  7. Electrifying Statistics • The third most common cause was contact with electrical components mistakenly thought to be de-energized. • Contact with buried, underground power lines caused 1% of the fatalities.

  8. Electrifying Statistics Non-fatal injuries were also high, with 46,598 from 1992 through 2002 . • 36% were caused by contact with the electric current of a machine or tool. • 34% were caused by contact with wiring or transformers. • 2% were caused by contact with buried, underground power lines.

  9. OSHA 29 CFR 1910, Subpart I OSHA 29 CFR 1910, Subpart P OSHA 29 CFR 1910, Subpart S OSHA 29 CFR 1910.147 OSHA 29 CFR 1910.333

  10. NFPA 70E • Safety related work practices • Safety related maintenance requirements • Safety requirements for special equipment • Installation safety requirements

  11. NFPA 70E Handbook • A supplement to the NFPA 70E standard • Gives step-by-step instructions for how to implement the standard • Provides the thought process and rationale for the standard

  12. What they all Do OSHA is the SHALL NFPA 70E standard is the HOW NFPA 70E handbook is the STEP-BY-STEP

  13. Qualified Person One who has received training in and has demonstrated skills and knowledge in the construction and operation of electric equipment and installations and the hazards involved.

  14. Important Note This program does not meet the requirements for a qualified person. It is intended to raise your awareness of electrical safety.

  15. Arc Flash

  16. Types of Electrical Injury Electric Shock Electrocution Burns Falls

  17. Rules of Electrical Action • Electric current won’t flow until there is a complete loop. • Electric current always tries to return to its source. • When current flows, work can be accomplished.

  18. How Shock Occurs • The body comes into contact with wires in an energized circuit. • The body comes into contact with one wire of an energized circuit and a path to the ground. • The body comes into contact with a “hot” metallic part that is touching an energized conductor.

  19. Severity of Shock Three factors • The path of the current through the body. • The amount of current flowing through the body. • The length of time the body is in the circuit.

  20. Basic Facts of Electricity ELECTRICITY = ELECTRONS IN MOTION

  21. Basic Facts of Electricity Flow of Electricity Flow of Water CURRENT • Flow of electrons • Measured in amps • I = amps • Flow of liquid • Measured in gallons per minute (gpm)

  22. Basic Facts of Electricity Flow of Electricity Flow of Water FORCE • Measured in voltage • V or E = volts • Measured in pounds per square inch (psi)

  23. Basic Facts of Electricity Flow of Electricity Flow of Water RESISTANCE • Electrical resistance to flow is measured in ohms • R = resistance • Water resistance to flow is measured as friction or baffles

  24. Ohm’s Law A mathematical formula that enables the measurement of electric current moving through a conductive body George Simon Ohm 1789-1854 German Physicist Volts (V) = Amps (I) X Resistance (R) V = IR 1 volt = 1 amp X 1 ohm of resistance

  25. A Visual Way to Remember

  26. Solution 1. Since we know voltage (V) and resistance (R), which version of the formula should we use? I = V/R

  27. Solution 2. Now which numbers do we plug in? I = 120/1,000 3. How many amps? I = .12 amps 4. How many milliamps (mA)? I = 120 milliamps

  28. The Human Body Resistance Model Body Part Resistance • Dry, intact skin • Wet skin • Within the body • Ear to ear • 100,000-600,000 ohms • 1,000 ohms • 400 ohms • 100 ohms

  29. Effects of Electricity Depend On: • Strength of current. • Duration of contact. • Body mass. • Gender of person. • Moisture on the body. • Path of the current.

  30. Photo courtesy of Schneider Electric

  31. Photo courtesy of Schneider Electric

  32. Photo courtesy of Schneider Electric

  33. What the Project Manager Felt 1. The drill had 120 volts. 2. The project manager’s dry skin had a resistance of 100,000 ohms. 3. The flow into the project manager’s hand was 120 volts/100,000 ohms, 0.0012 amps, or 1.2 milliamps.

  34. What the Apprentice Felt 1. The drill had 120 volts. 2. The apprentice’s wet skin had a resistance of 1,000 ohms. 3. The flow into the apprentice’s hand was 120 volts/1,000 ohms, 0.12 amps, or 120 milliamps.

  35. Facts About Lower Amperage • A small circuit in your home carries 12-16 amps of current. • That equals 12,000 to 16,000 milliamps. • As we’ve learned, as little as 120 milliamps can cause death. • Low amperage/voltage circuits are dangerous!

  36. NIOSH Low Voltage Study 600 v 8% 110-120 v 34% 440-480 v 22% 270-277 v 16% 220-240 v 20% That’s over 1 in 3 deaths at 120 v or less!

  37. Action Plan

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