Electrical Safety--Article Index and Intro

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  1. Hazards of Electricity
  2. Basic Physics of Electrical Hazards
  3. Electrical Safety Equipment--part 1; part 2
  4. Safety Procedures and Methods -- part 1; part 2; part 3; part 4
  5. Grounding and Bonding of Electrical Systems and Equipment
  6. Electrical Maintenance and Its Relationship to Safety
  7. Regulatory and Legal Safety Requirements and Standards
  8. Accident Prevention, Accident Investigation, Rescue, and First Aid
  9. Medical Aspects of Electrical Trauma
  10. Low-Voltage Safety
  11. Medium- and High-Voltage Safety
  12. Human Factors in Electrical Safety
  13. Safety Management and Organizational Structure
  14. Safety Training Methods and Systems


Intro to Electrical Safety

Electrical power makes modern life easier. It provides energy for appliances and factory processes that simplify life and industry. Electricity can be manipulated to carry signals that are easy to interpret, and it can be easily converted to other forms of energy.

However, the hazards associated with electricity can also cause injuries.

In most instances, electricity must be converted to another form before it can be used.

For example, electrical energy must be converted to thermal energy before it can be used to cook food, heat water, or warm a room. When electrical energy is converted to a more useful form, the conversion process must be a controlled event. When controlled, the con version process is desirable, the result is good, and the process is safe.

Normally, a user of electricity does not think about the conversion process. It is not necessary for process operators to think about converting electrical energy into mechanical energy for the rotation of a motor when they push a start button. Electrical workers and electrical manufacturers have provided the necessary electrical equipment to convert the electrical energy safely to make the motor run.

Consensus electrical standards provide adequate guidance for manufacturers, engineers, employees, and employers. When workers are trained to understand and follow the guidance provided by consensus standards, operators can push a start button without concern for their safety. However, when they do not understand the guidance, workers sometimes create hazard exposures.

Electrical hazards exist in many different forms. Direct contact with an energized conductor exposes workers to current flow through their body. Current flowing through body tissue produces heat and damages or destroys the tissue, sometimes resulting in death. An arcing fault is electrical energy that is being converted to another form of energy, such as heat or pressure, by an uncontrolled process. An arcing fault might expose a worker to injury from the thermal hazard or from the effects of the accompanying pressure wave.

To avoid injury from an electrical hazard, workers must avoid exposure to the hazard or use adequate protective equipment and safe work practices. The most important safe work practice is to remove all electrical energy and eliminate any chance that the energy might reappear. If the energy cannot reappear, the equipment or circuit is considered to be in an electrically safe work condition. Consensus standards discussed in this guide provide guidance about how to establish an electrically safe work condition.

Each worker must be trained to recognize how exposure to each electrical hazard might exist and how to avoid that exposure. Workers are exposed to electrical hazards in many different ways, including the following:

• Electrical equipment, devices, and components have a normal lifetime. Control devices sometimes wear out and malfunction with age or lack of maintenance. When a failure occurs, a worker is expected to identify the problem, repair the problem, and restore the equipment to normal service.

• Electrical equipment must be maintained. Although the electrical energy sometimes is removed before a worker begins a maintenance task (best practice), those tasks often are executed while the source of electricity is energized.

• Equipment and circuits sometimes are modified to add new devices or circuits. Short term employees might be expected to work in an environment that includes exposure to energized electrical circuits and components. Consultant and service employees are frequently exposed to energized electrical equipment and circuits.

• When a problem exists that causes a process to malfunction, a worker might open a door or remove a cover and expose an energized electrical conductor or component. In many cases, the worker might troubleshoot while the circuit is energized. Components and conductors might be added within a piece of equipment while the equipment or parts of the equipment remain energized.

• After correcting a problem, workers sometimes create further hazardous conditions by leaving an equipment door ajar, leaving latches open, replacing covers with a minimum number of screws, and removing devices that create holes in a door or cover.

When workers understand that these conditions expose themselves or others to possible injury, they are more likely to avoid the hazard exposure. Training must build and reinforce that understanding. This guide provides guidance to help trainers and other workers develop the necessary understanding.

Workers must understand the limits of their knowledge and ability. They should not accept and perform a work/task unless they have been trained and have the experience necessary to avoid all hazards, including electrical hazards. When workers are trained to understand electrical hazards and how to avoid them, then they become a valuable asset to the employer.


Intro to this Guide

This edition of the Electrical Safety Guide comes during an avalanche of changes in the world of electrical safety.

Since the third edition was published, the National Fire Protection Association (NFPA) released the 2009 and 2012 editions of the Standard for Electrical Safety in the Workplace (NFPA 70E). Both documents include numerous changes that both add to and further explain the practical aspects of electrical safety. NFPA 70E has been adopted by a multitude of facilities, companies, and organizations around the world.

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Labor unions such as the International Brotherhood of Electrical Workers have widely promoted the electrical safety portions of their apprenticeship programs. Colleges and universities such as Murray State University have added electrical safety as part of their environmental safety and health (ES&H) degree programs.

Intensive research is ongoing in areas such as the following:

• Electrical shock hazard in systems as low as 30 volts

• Electrical arc hazards in systems of 208 volts and below

• Field testing and measurement of arc energies-a collaboration between NFPA and the Institute of Electrical and Electronics Engineers

• Calculation of incident arc energies in dc systems The many vendors who write and supply the software packages used for performing engineering studies such as arc-flash analysis have frequently updated their software to give the engineering community better and faster tools to perform the necessary calculations.

In addition, the U.S. Occupational Safety and Health Administration (OSHA) has revised the 29 CFR 1910 regulation, Electric Power Generation, Transmission, and Distribution, to include the requirements for an arc-flash analysis and associated arc-rated clothing and personal protective equipment. The construction equivalent, 29 CFR 1926, Subpart V, Electric Power Transmission and Distribution, has been changed to be consistent with 1910.269. As part of the revisions of 1910.269 and 1926, Subpart V, OSHA also revised 1910.137 and 1926.97, Electrical Protective Equipment, to include class 00, 500-volt ac gloves.

ANSI/IEEE C2, the National Electrical Safety Code, in the 2007 edition required an arc-flash analysis and arc-rated clothing and personal protective equipment. This standard has also been revised for 2012 and expands on and clarifies the existing requirements.

In 2008, the Canadian Standards Association published CSA Z462-08, Workplace Electrical Safety, which is essentially the Canadian version of NFPA 70E.

The third edition of the Electrical Safety Guide (ESH) has continued to be widely accepted and used throughout the electrical industry. In fact, the authors have noted that many copies of the ESH are appearing on booksellers' sales lists from all over the world.

Because of the nationality of the authors, the ESH has always used North American regulatory standards for the purpose of example and identifying regulatory needs. While we continue to use the U.S. and Canadian regulations as our guideline, we have modified some of the text to be more inclusive.

Sections 1, 3, and 4 continue to serve as the central core of the guide by presenting the case for electrical safety ( Section 1), a broad coverage of electrical safety equipment ( Section 3), and detailed coverage of electrical safety procedures ( Section 4). In this fourth edition, we have updated and improved each of these sections. Section 1 has been augmented by inclusion of some information on arc-related hazards such as toxic materials and acoustic injuries. Section 3 has been generally edited and new information added on such topics as arc-fault circuit interrupters. Finally, Section 4 has also been edited and now includes sections on remote operating devices to be used for enhanced safety when operating switchgear.

Section 2 is new to the fourth edition. This new section enhances previous editions of the guide by covering the fundamental physics underlying the various electrical hazards. The material is presented in a much more technical format than Section 1 and uses advanced mathematics and citation of high-level research. The authors' purpose in adding this section is not to move away from the practical information provided in all previous editions. Rather, we are presenting some of the more technical data used as the foundation for all electrical safety research-whether theoretical or practical. In making this information available in a public way, we hope that others will add their voices and efforts to the ongoing work in basic research in electrical safety.

Section 5 provides a detailed and updated overview of the general requirements for grounding and bonding electrical systems and equipment. The fourth edition features many updated, improved diagrams to help clarify the subject of electrical grounding and bonding.

Further, the information in the section has been edited and rewritten to help with a subject that many find very difficult to understand. As with all of the sections in this guide, Section 5 is not intended to replace or be a substitute for the requirements of the current NEC or OSHA regulations. Always use the most current standards and regulations when designing, installing, and maintaining the grounding systems within a facility.

Section 6 has been extensively edited and contains newly written material. In addition to the information first introduced in the third edition, Section 6 has been enhanced with three new sections: the effect of maintenance on the arc-flash hazard, more detailed and technical coverage on the value of a condition-based maintenance program, and the importance of designing safety into the workplace. As always, readers of the fourth edition should refer to other references for more detailed information on electrical maintenance.

One good source of detailed information is the International Electrical Testing Association (NETA), whose website is netaworld.org.

Section 7 updates the third edition coverage of the consensus and mandatory standards and regulations in the workplace. The specific information reprinted from OSHA has been updated to the most recent versions as of the date of this publication. As before, readers should always refer to OSHA publications, available at www.OSHA.gov, for the most recent information.

Section 8 has been generally updated. Also, a new section on the use of automated external defibrillators has been added to provide information on these extremely useful and safe-to-use machines. The sections on pole-top rescue and CPR have also been edited and brought up to date.

Section 9 provides recent injury and fatality statistics and updated medical evaluation and treatment information.

Sections 10 and 11 continue to be a valuable synopsis of low-voltage ( Section 10) and medium- and high-voltage ( Section 11) safety. The reader may refer to these sections for quick coverage of key safety issues in electrical systems. Of course, Sections 3, 4, and 5 provide detailed information. Of particular interest to some might be the addition of arc-fault circuit interrupters in Section 10.

Section 12 includes additional references to standards addressing human factors considerations, as well as new information about electrical industry resources regarding ergonomics and human performance.

In Section 13, in addition to a general edit and some minor error corrections, we have added more detailed information on how to change the so-called electrical safety culture.

Electrical safety, like any human activity, has developed its own share of anecdotes, leg ends, and so-called urban myths. This culture is often based on assumptions that are not valid. Section 13 provides some information on how to change that culture. Section 14 contains new, in-depth information about how adult learners should be trained. We provide a comparison of the four most common ways of training adults- classroom presentations, computer-based training (CBT), Internet (Web-based) training (WBT), and simple video training. The other sections of the section have been edited and clarified in some cases.

Also see: Electrical safety systems

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