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OSHAcademy Course 715 Study Guide

Electrical Safety Basics

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This document does not constitute legal advice. Consult with your own company counsel for advice on compliance with all applicable state and federal regulations. Neither Geigle Safety Group, Inc., nor any of its employees, subcontractors, consultants, committees, or other assignees make any warranty or representation, either express or implied, with respect to the accuracy, completeness, or usefulness of the information contained herein, or assume any liability or responsibility for any use, or the results of such use, of any information or process disclosed in this publication. GEIGLE SAFETY GROUP, INC., DISCLAIMS ALL OTHER WARRANTIES EXPRESS OR IMPLIED INCLUDING, WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Taking actions suggested in this document does not guarantee that an employer, employee, operator or contractor will be in compliance with applicable regulations. Ultimately every company is responsible for determining the applicability of the information in this document to its own operations. Each employer’s safety management system will be different. Mapping safety and environmental management policies, procedures, or operations using this document does not guarantee compliance regulatory requirements.

OSHAcademy Course 715 Study Guide

How Do You Evaluate Your Risk? ........................................................................................................... 44 Case Study .............................................................................................................................................. 44 Conditions that point to electrical hazards ............................................................................................ 45 Case Study .............................................................................................................................................. 46 Module 6 Quiz ........................................................................................................................................ 48 Module 7: Safe Work Environments .......................................................................................................... 50 How Do You Control Hazards? ............................................................................................................... 50 How Do You Create a Safe Work Environment? .................................................................................... 50 Case Study .............................................................................................................................................. 50 Lock Out and Tag Out Circuits and Equipment ...................................................................................... 51 Scenario #1 ............................................................................................................................................. 52 Scenario #2 ............................................................................................................................................. 52 Control Inadequate Wiring Hazards ...................................................................................................... 53 Control Hazards of Fixed Wiring ............................................................................................................ 53 Control Hazards of Flexible Wiring ........................................................................................................ 54 Use the Right Extension Cord ................................................................................................................ 56 Control Hazards of Exposed Live Electrical Parts: Isolate Energized Components ............................... 57 Control Hazards of Exposure to Live Electrical Wires: Use Proper Insulation ....................................... 58 Ground circuits and equipment ............................................................................................................. 59 Use Ground Fault Circuit Interrupters (GFCI's) ...................................................................................... 61 Bond Components to Assure Grounding Path ....................................................................................... 62 Control Overload Current Hazards ........................................................................................................ 63 Module 7 Quiz ........................................................................................................................................ 65

OSHAcademy Course 715 Study Guide

Course Introduction

This course will present many topics. There are four main types of electrical injuries: electrocution (death due to electrical shock), electrical shock, burns, and falls. The dangers of electricity, electrical shock, and the resulting injuries will be discussed. The various electrical hazards will be described. You will learn about the 3-STEP Electrical Safety Model, an important tool for recognizing, evaluating, and controlling hazards. Important definitions and notes are shown in the margins. Practices that will help keep you safe and free of injury are emphasized. To give you an idea of the hazards caused by electricity, case studies about real-life deaths will be described.

Electrical workers must pay special attention to electrical hazards because they work on electrical circuits. Coming in contact with an electrical voltage can cause current to flow through the body, resulting in electrical shock and burns. Serious injury or even death may occur.

As a source of energy, electricity is used without much thought about the hazards it can cause. Because electricity is a familiar part of our lives, it often is not treated with enough caution. As a result, an average of one worker is electrocuted on the job every day of every year!

•Thoroughly inspect all electrical equipment before beginning to work
•Do not use extension cords as a substitute for fixed wiring. In this case, a weatherproof receptacle should have been installed on the platform.

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What is "amperage"? Amperage is the unit used to measure the amount of electrical current.

Amperage is often referred to as "current" by electrical workers and engineers. Let's go back to our water tank. If the diameter of your pipe coming from the water tank is large, a lot of water (amperage) will flow through the pipe. If the pipe's diameter is small, a smaller amount of water will flow through the pipe. If you need a lot of current (many amps) to operate your equipment, you'll need large wires to run the current or they'll burn up! The symbol for amperage is "I".

Apparently, the motor had developed a ground fault. Because of the ground fault, the motor was energized and she was electrocuted. A co-worker found the victim slumped over the drum with her face submerged in water. The co-worker tried to move the victim, but was shocked. The assistant manager was dead on arrival at a local hospital.

An investigation showed that the mixing motor was in poor condition. The grounding pin had been removed from the male end of the power cord, resulting in a faulty ground. The circuit was equipped with a ground-fault circuit interrupter (GFCI), but it was not installed properly. A properly wired and functioning GFCI could have sensed the ground fault in the motor and de-energized the circuit.

•The employer should have followed the law. The NEC requires that all pool-associated motors have a permanent grounding system. In this case, this regulation was not followed. Also, electrical equipment is not permitted in areas without proper drainage.

•OSHA requires employers to provide a work environment free of safety and health hazards.

In most household wiring in the U.S., the black wires and the red wires are at 120 volts. The white wires are at 0 volts because they are connected to ground. The connection to ground is often through a conducting ground rod driven into the earth.

If you come in contact with an energized black wire while you are also in contact with the neutral white wire, current will pass through your body. You will receive an electrical shock.

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OSHAcademy Course 715 Study Guide

•Make sure all employees know the importance of de-energizing (shutting off) electrical systems before preforming repairs.

•Equip voltage-regulating equipment with color-coded wiring.

Use this quiz to self-check your understanding of the module content. You can also go online and take this quiz within the module. The online quiz provides the correct answer once submitted.

1. ___________ is a measure of the electrical force that seems to push the current along.

a.Amperage
b.Resistance
c.Voltage
d.Reluctance

4. Whenever two wires are at different _________, current will pass between them if they are connected.

OSHAcademy Course 715 Study Guide

Module 2: The Dangers of Electrical Shock

If you can't let go of the tool, current continues through your body for a longer time, which can lead to respiratory paralysis (the muscles that control breathing cannot move). You stop breathing for a period of time.

People have stopped breathing when shocked with currents from voltages as low as 49 volts. Usually, it takes about 30 mA of current to cause respiratory paralysis.

OSHAcademy Course 715 Study Guide

OSHAcademy	Course 715 Study Guide

Sometimes high voltages lead to additional injuries. High voltages can cause violent muscular contractions. You may lose your balance and fall, which can cause injury or even death if you fall into machinery that can crush you. High voltages can also cause severe burns.

At 600 volts, the current through the body may be as great as 4 amps, causing damage to internal organs such as the heart. High voltages also produce burns. In addition, internal blood vessels may clot.

OSHAcademy Course 715 Study Guide

The length of time of the shock greatly affects the amount of injury. If the shock is short in duration, it may only be painful. A longer shock (lasting a few seconds) could be fatal if the level of current is high enough to cause the heart to go into ventricular fibrillation. This is not much current when you realize that a small power drill uses 30 times as much current as what will kill. At relatively high currents, death is certain if the shock is long enough. However, if the shock is short and the heart has not been damaged, a normal heartbeat may resume if contact with the electrical is eliminated. (This type of recovery is rare.)

Current Amounts

OSHAcademy Course 715 Study Guide

This death could have been prevented!

•The victim should have tested the circuit to make sure it was de-energized.

Module 2 Quiz

Use this quiz to self-check your understanding of the module content. You can also go online and take this quiz within the module. The online quiz provides the correct answer once submitted.

3. An electrical current of _________ can cause extremely painful shock, respiratory arrest, (breathing stops) and severe muscle contractions.

a.1-10 milliamps
b.6-25 milliamps
c.10-40 milliamps
d.50-150 milliamps

5. Which of the following will result in the lowest resistance and greater risk of injury when shocked?

a.Dirty skin
b.Dry skin
c.Wet skin
d.Thin skin