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A Systems Safety Approach
To Occupational Electrical Safety
H. Landis Floyd II, PE, CSP, CMRP, CESCP, Fellow IEEE
Global Electrical Safety Competency Leader
DuPont
Adjunct Professor, Advanced Safety Engineering and Management
University of Alabama at Birmingham
H.L.Floyd@ieee.org
Abstract For the past decade, the discussion of occupational electrical safety in the U.S. has largely focused on compliance with
NFPA70E, Standard for Electrical Safety in the Workplace. Without taking away from the importance of the requirements in the
standard, this paper describes a more comprehensive solution, based on proven concepts known as systems safety. The paper provides
an overview of systems safety and includes a 20+ year case history of a global Fortune 500 companys effort to change the electrical
safety culture in its operations to demonstrate results of applying systems safety techniques to electrical safety.
Index Terms electrical safety, systems safety, electrical safety management, injury prevention, fatality prevention
I. INTRODUCTION
Over the past 10 years, occupational electrical safety in the U.S. has received heightened attention, primarily due to publicity
of NFPA70E, Standard for Electrical Safety in the Workplace, and to better understanding that arc flash is a unique electrical
hazard, requiring different controls than electric shock. Contact with electrical energy is a leading cause of occupational fatality
in the U.S., ranking as 7th leading cause for general industry, 3rd leading cause in the construction industry and 4th for the mining
industry[1] [2] [3]. Electrical injuries are also disproportionality costly as compared to other causes of lost time injuries. A
study of electric utility companies by Wyzga and Lindroos found that electrical injuries comprised <2% of total injuries of any
given year, yet accounted for 28-52% of total medical cost for the companys workers injuries [4]. In 2010, a major underwriter of
workers compensation insurance found electrical injuries were the second most expensive workers compensation claim [5]. This
means that the risk of financial loss from electrical injuries is much greater than the low frequency of electrical injuries would tend
to indicate.
This paper focuses on a subtle, but critical notation made in the 2009 edition of NFPA 70E, Standard for Electrical Safety in the
Workplace. This revision included the addition of Fine Print Note 2 in article 110.7, as shown in Fig. 1.
110.7 Electrical Safety Program
FPN 1: Safetyrelated work practices are just one component of an overall electrical safety program
FPN No. 2: ANSI/AIHA Z10-2005, American National Standard for Occupational Safety and Health
Management Systems, provides a framework for establishing a comprehensive electrical safety program
as a component of an employers occupational safety and health program.
Fig. 1 Excerpt from NFPA70E-2009 showing addition of Fine Print Note 2
The original Fine Print Note, shown as FPN 1 in Fig. 1 emphasized that NFPA70E focuses on safe work practices and that safe
work practices are just one component of an effective program. The Fine Print Note added to article 110.7 introduced the
importance of integrating the safe work practices in the standard into an overarching safety management system. Safety
management systems utilize concepts such as continuous improvement, comprehensive hazard control measures and engineering
design solutions that are not addressed in NFPA70E. This paper discusses the origin of safety management systems, or systems
safety engineering, and why this subtle notation is so critical to preventing occupational electrical injuries and fatalities.
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II. SYSTEMS SAFETY ENGINEERING
Systems safety engineering has its roots in the 1940s, with the rapidly expanding military and commercial aviation industries
[6]. Designers, manufacturers and pilots were pushing the envelope in technology. As airplanes became more sophisticated, the
cost of mishaps escalated. The aviation industry recognized that the practice of analyzing mishaps after the fact was becoming
unacceptable in terms of human safety and financial loss. In his paper, Using Systems Safety Techniques to Perform Hazard
Analysis, Kolak noted, The costs associated with damaging expensive fighter jets and the development of nuclear energy
(where a single system failure was unacceptable) contributed to the concept that hazards must be anticipated and controlled
before even a single loss occurs [7]. The extraordinary improvement in commercial aviation safety shown in Fig. 2 is largely
attributed to the development and application of systems safety engineering [6].
Fig 2 Annual fatal accident rate per million departures for commercial aviation, 1960 2012.
Inset expands the vertical axis for the period 1994 2012. [8]
Systems safety engineering evolved as a way to minimize the consequences and likelihood of mishaps by eliminating causes
attributed to equipment design, equipment reliability, and human error. In 1968, the US Department of Defense published MIL-
STD 882, Standard Practice for System Safety. This standard provides the basis for managing the safety of complex systems
such as military aviation, nuclear weapons, nuclear powered ships and submarines, as well as less complex systems such as
facility operations. The standard has influenced the application of safety system engineering to non-military systems, including
commercial nuclear power generation, commercial aviation and highly hazards petrochemical operations. The following
definitions from MIL-STD 882D, Standard Practice for System Safety provide an introduction to some of the fundamental
concepts of systems safety engineering:
Mishap: an unplanned event or series of events resulting in death, injury, occupational illness, damage to or loss of
equipment or property, or damage to the environment.
System: an integrated composite of people, products and processes that provide the capability to satisfy a stated need or
objective.
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Systems Safety: The application of engineering and management principles, criteria, and techniques to achieve acceptable
mishap risk, within the constraints of operational effectiveness and suitability, time, and costs, throughout all phases of the
system life cycle.
System Safety Engineering: an engineering discipline that employs specialized professional knowledge and skills in
applying scientific and engineering principles, criteria and techniques to identify and eliminate risks, in order to reduce the
associated mishap risk.
Systems safety engineering concepts include hazard identification and analysis, application of a hierarchy of hazard control
measures, and integration of management, engineering, procurement and operations functions in managing safety objectives.
These concepts are the foundation of occupational safety and health management systems standards that emerged in the 1990s,
including OHSAS 18001 Occupational Safety and Health Management Systems Requirements, ANSI Z10 Occupational Health
and Safety Management Systems, and CSA Z1000 Occupational Safety and Health Management. These standards all incorporate
the Deming Quality Improvement model illustrated in Fig. 3 to help assure sustainable continuous improvement in safety
performance.
The Deming
Plan Do Check Act
Quality Improvement Model
PLAN: Design or revise business process components to improve results
DO: Implement the plan and measure its performance
CHECK: Assess the measurements and report the results to decision makers
ACT: Decide on changes needed to improve the process
Fig 3. Elements of the Deming Quality Improvement Model
III. LIMITATIONS OF NFPA 70E
Widely considered one of the most prominent standards regarding workplace electrical safety in the US, NFPA 70E Standard for
Electrical Safety in the Workplace, currently focuses on control measures Warnings, Administrative Controls and Personal
Protective Equipment shown in Fig. 4 and 5. NFPA70E does not address Elimination, Substitution and Engineering Controls,
which, as noted in the left arrow in Fig. 4, are the more effective hazard control measures. Prior to the 2009 edition, the standard
acknowledged this limitation with a Fine Print Note in Section 110.7 Electrical Safety Program, which stated that, Safety-related
work practices are just one component of an overall electrical safety program. The 2009 edition includes a reference to ANSI
Z10, and states ANSI/AIHA Z10-2005, American National Standard for Occupational Health and Safety Management Systems,
provides a framework for establishing a comprehensive electrical safety program as a component of an employers occupational
safety and health program. CSA Z462 Workplace Electrical Safety includes similar notes and refers to CSA Z1000 Occupational
Health and Safety Management. Fig. 5 illustrates the contribution of the safe work practice in NFPA70E and CSA Z462 within
context of comprehensive hazard controls outlined in ANSI Z10 and CSA Z1000.
NFPA 70E-2009 also added an annex that began to address applying system and equipment design solutions (i.e. Elimination,
Substitution and Engineering Controls) to eliminate or reduce the exposure frequency or severity of electrical hazards in the
workplace. NFPA 70E Annex O Safety-Related Design Requirements describes how the hazard risk assessments methods in the
standard, commonly used for the selection of personal protective equipment, can also be used to compare design options and
choices to facilitate design decisions that serve to eliminate risk, reduce frequency of exposure, reduce magnitude or severity of
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exposure, enable the ability to achieve an electrically safe work condition, and otherwise serve to enhance the effectiveness of the
safety-related work practices contained in this standard.
Fig 4. Hierarchy of hazard controls from ANSI Z10, Occupational Health and Safety Management Systems
Although the more effective hazard control measures are not directly addressed in NFPA 70E, the importance of mitigating
electrical hazards through engineering solutions that eliminate, prevent, or reduce risk has been addressed by numerous papers
presented at IEEE conferences [9] [10] [11] [12] [13]. It is important to note that there is nothing in the body of NFPA 70E that
suggests application of the engineering solutions described in detail in these papers.
Fig 5. Hierarchy of hazard controls from ANSI Z10, Occupational Health and Safety Management Systems
and the limitations in the scope of NFPA 70E and CSA Z462
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IV. Demonstrating Results in Electrical Safety
In 1989, a global Fortune 500 company made a highly visible commitment to reduce the likelihood and severity of injuries to
employees and contractors from electrical hazards. Goals for sustainable improvement were established, financial support
provided and dedicated people empowered to reduce the likelihood of electrical incidents, injuries and fatalities, with the intent
to accomplish a step change in electrical safety performance, as was done in the mid-1950s. At that time the company had
taken action to eliminate the practice of working on energized circuits, which was commonplace in the early days of industrial
electrification [14].
In 1990 and 1992, several leaders in the companys electrical safety improvement initiative collaborated on two award-
winning papers presented at the annual IEEE IAS Petroleum and Chemical Industry Conference and subsequently published in
IEEE Transactions on Industry Applications. The first paper, Maintaining Safe Electrical Work Practices in a Competitive
Environment was presented at the 1990 IEEE IAS Petroleum and Chemical Industry Conference in Houston, Texas. This paper
described the companys concern for improving electrical safety performance and the creation of an organizational
infrastructure to enable and support changes to better manage electrical hazards in company facilities and operations [15].
The second paper, Creating a Continuous Improvement Environment for Electrical Safety, was presented at the 1992
conference in San Antonio, Texas [16]. This paper outlined a strategy for establishing a culture for long term continuous
improvement in electrical safety. The elements of that strategy, shown in Fig. 6, describe organizational culture intent on long
term impact on preventing electrical incidents and injuries. The culture and continuous improvement strategy described in these
papers and nurtured for more than 20 years has resulted in significant improvement in reducing severity and frequency of
electrical injuries in the company. Most dramatic is the impact on the frequency of fatalities from electrical energy. As shown
in Fig. 7, prior to 1993, fatalities from electrical energy were occurring on average every 33 months. The chart in the figure
represents a global work force of employees and contractors that ranged from 80,000 to 120,000 during this period. Since 1993
and through the submission of this paper in January 2014, there have been zero fatalities in company facilities [17].
Understand the business consequences of electrical incidents
Engage all employees
Stimulate near miss reporting
Apply quality improvement model Plan Do Check Act
Build networks
Challenge accepted practices
Improve collaboration among management, electrical experts and safety professionals
Use standards as tools
Promote prevention by design
Address life cycle: design, construct, operate, maintain, dismantle
Fig. 6 Elements of the strategy described in the paper, Creating a Continuous Improvement Environment for Electrical Safety [13]
The electrical hazards have not gone away, and if anything the potential for exposure to hazardous electrical energy has
increased due to dependence on electrical technologies for energy, control and communications in industrial applications. What
changed was the shift in the electrical safety culture driven by the continuous improvement environment.
Fig. 7 Trends in employee and contractor electrocution fatalities in example companys facilities worldwide, illustrating impact of a focused application of
system safety engineering concepts in the late 1980s
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IV. AN ILLUSION OF CONTROL
In the context of total lost time occupational injuries, those from exposure to electrical energy are relatively rare. Fig. 8
shows occupational electrical injuries in the U.S. for the year 2010. Of the 1,191,000 non-fatal lost time injuries, 1,890 or
0.16% of the injuries are due to electric shock or arc flash burns. Fig. 9 shows the same data in a pie chart. Electric shock and
burn injuries are shown as the tiny sliver at the 12:00 position on the chart [18]. Electrical injuries are sufficiently rare that the
absence of electrical injuries in an individuals or organizations experience can create an illusion of electrical safety
excellence. The fact that electrical incidents are low in frequency can do two things:
1. Create the false perception that the management of the hazard is under control;
2. Create a challenge for workers to stay vigilant in the face of a low-probability of occurrence.
Cawley notes that the consequences of electrical accidents are disproportionality severe when compared to other hazards in the
workplace. Contact with electrical energy is the 14th leading cause of lost time injuries in the mining industry, but the 4th leading
cause of fatality. In his study of electrical injuries in the mining industry 1990-1999, he noted that 1 fatality per 272 lost time
accidents, but 1 in 27 electrical accidents was fatal [3]. For all occupational injuries, the potential for an electrical injury to be fatal
is even more severe, one in 13 lost time injuries from contact with electrical energy is fatal. As noted above, only 0.16% of the
lost time injuries are due to electric shock or arc flash burns.
Type of Non-Fatal Injury No. Injuries
Total 1,191,100
Sprains, strains, tears 474,000
Musculoskeletal disorders 346,300
Falls on same level 182,400
Struck by object 138,530
Falls to lower level 73,520
Assault/Violent act by person 40,310
Highway accidents 36,460
Assault/Violent act by animal 7,160
Fires and explosions 3000
Electrical shock and burn 1890 (.16%)
Fig. 8 Comparison of select Non-fatal Occupational Injuries in the
U.S 2010 (U.S. BLS Economic News Release, 2010) [18]
Fig. 9 Same data as Fig.8, but in chart form [18]. Electrical injuries are the tiny sliver at the 12:00 position on the chart.
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V. CONCLUSION
This paper has discussed the role of systems safety engineering, safety management systems standards and the application of
safe work practices as part of a comprehensive solution to reducing the likelihood or severity of electrical injuries. Occupational
electrical injuries are relatively rare, compared to all occupational injuries. The absence of, or infrequency of, electrical injuries
can create an illusion of control or immunity from risk. Electrical injuries are disproportionately severe in terms of disabling
injury, financial loss and likelihood of fatality. Electrical injury and fatality rates are higher in the mining industry than in all
industry segments combined.
The revision to the 2009 edition of NFPA70E discussed in Section I linked the application of electrical safety work practices
to the most powerful injury and fatality prevention methodologies in the history of safety management. Having established this
link, we have the opportunity to explore and apply the concepts of safety systems engineering and safety management systems
to further mitigation of occupational electrical hazards.
The safety management system standards are based on proven principles that are fundamental and essential for robust safety
programs and sustainable safety performance. While strict implementation of requirements in NFPA 70E and CSA Z462 can
enable an organization to realize performance improvement, optimum improvement is likely not achievable without integration
with the proven strategies provided in the safety management systems standards. The case history of one companys experience
in applying systems safety concepts to electrical hazards demonstrates the potential benefit of systems safety engineering
concepts in reducing fatal injuries from electrical contact.
VI. REFERENCES
[1] Cawley, J.C., Brenner, B.C., Occupational Electrical Injuries in the U.S., 2003-2009, IEEE Industry Applications
Magazine, vol. 19, no. 3, May/June 2013, pp 16-20
[2] OSHA Prevention Video, Prevent Electrocutions: Work Safely with Cranes near Power Lines, retrieved January 7, 2014
from the internet at http://www.youtube.com/watch?v=L3xmSQ-30VI
[3] Cawley, J.C., Electrical accidents in the mining industry, 1990-1999; IEEE Transactions on Industry Applications, Volume
39, Issue 6, Nov. Dec. 2003 Page(s):1570 1577
[4] Wyzga, R.E., Lindroos, W., "Health Implications of Global Electrification, Annals of the New York Academy of Sciences,
1999, vol 888, pp1-7.
[5] Work Related Electrical Injuries: Study Sparks New Insights, Liberty Mutual Research Institute for Safety, vol 13, No.
3, Winter 2010
[6] Lewis, C.L., Haug, H.A., The Safety Systems Handbook, self-published, retrieved from the internet at
www.aerohabitat.org/link/2006/14-04-2006%20-%20Lewis%20-
%20Haug,%20System%20safety%20handbook%20(0.3MB).pdf
[7] Kolak, J.J., Using System Safety Techniques to Perform Hazard Analysis, American Society of Safety Engineers Safety
2012 Conference, Denver, CO June 3 - 5, 2012
[8] Statistical Summary of Commercial Jet Airplane Accidents Worldwide Operations 1959 2012, retrieved from the internet at
http://www.boeing.com/news/techissues/pdf/statsum.pdf
[9] Mohla, D.; McClung, L.B.; Rafferty, N.R.; Electrical safety by design; Conference Record of the 1999 IEEE IAS
Petroleum and Chemical Industry Technical Conference, pp 363-369.
[10] McClung, B.; Mohla, D.; Electrical design - refined for safety; Conference Record of the 2005 IEEE IAS Industrial and
Commercial Power Systems Technical Conference
[11] Doughty, R.L.; Neal, T.E.; Macalady, T.L.; Saporita, V.; Borgwald, K.; The use of low-voltage current-limiting fuses to
reduce arc-flash energy, IEEE Transactions on Industry Applications, Volume 36, Issue 6, Nov.-Dec. 2000, pp1741
1749
[12] Blair, D.D.; Jensen, D.L.; Doan, D.R.; Kim, T.K.; Networked intelligent motor-control systems; IEEE Industry
Applications Magazine, Volume 7, Issue 6, Nov.-Dec. 2001 Page(s):18 - 25
[13] Tamblingson, J.E., Jr.; Mohla, D.C.; Schouten, D.A.; Wellman, C.M.; Issues of 120 V AC vs. 24 V DC process control
systems; Record of the 2000 IEEE IAS Petroleum and Chemical Industry Conference, pp 123-132.
[14] Lippincott, W.F., Is Hot Electrical Work Necessary?, DuPont Safety Conference, Chicago, IL, 1954
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[15] Doughty, R.L, Epperly, R.A. and Jones, R.A., Maintaining Safe Electrical Work Practices in a Competitive
Environment, IEEE Transactions on Industry Applications, vol. 28, no. 1, Jan/Feb `1992, pp 196-204
[16] Floyd, H.L., Cole, B.C., Doughty, R.L., Jones, R.A., Whelan, C.D., Creating a Continuous Improvement Environment
for Electrical Safety, IEEE Transactions on Industry Applications, vol. 30, no. 3, May/June 1994, pp 543-552
[17] Floyd, H.L. and Cole, B.C., 20 Years Later - Creating a Continuous Improvement Environment for Electrical Safety,
Conference Record of the 2013 IEEE IAS Petroleum and Chemical Industry Technical Conference.
[18] Floyd, A.H.L. and Floyd, H.L., Cultural Drift and the Occlusion of Electrical Safety, Conference Record of 2013 IEEE IAS
Electrical Safety Workshop, March 11 - 15, 2013, Dallas, TX.
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110.7 Electrical Safety Program
FPN 1: Safetyrelated work practices are just one component of an overall electrical safety
program
FPN No. 2: ANSI/AIHA Z10-2005, American National Standard for Occupational Safety
and Health Management Systems, provides a framework for establishing a comprehensive
electrical safety program as a component of an employers occupational safety and health
program.
Fig. 1 Excerpt from NFPA70E-2009 showing addition of Fine Print Note 2
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Fig 2 Annual fatal accident rate per million departures for commercial aviation, 1960 2012.
Inset expands the vertical axis for the period 1994 2012. [8]
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The Deming
Plan Do Check Act
Quality Improvement Model
PLAN: Design or revise business process components to improve results
DO: Implement the plan and measure its performance
CHECK: Assess the measurements and report the results to decision makers
ACT: Decide on changes needed to improve the process
Fig 3. Elements of the Deming Quality Improvement Model
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Fig 4. Hierarchy of hazard controls from ANSI Z10, Occupational Health and Safety Management Systems
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Fig 5. Hierarchy of hazard controls from ANSI Z10, Occupational Health and Safety Management Systems
and the limitations in the scope of NFPA 70E and CSA Z462
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Understand the business consequences of electrical incidents
Engage all employees
Stimulate near miss reporting
Apply quality improvement model Plan Do Check Act
Build networks
Challenge accepted practices
Improve collaboration among management, electrical experts and safety
professionals
Use standards as tools
Promote prevention by design
Address life cycle: design, construct, operate, maintain, dismantle
Fig. 6 Elements of the strategy described in the paper, Creating a Continuous Improvement Environment for Electrical Safety [13]
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Fig. 7 Trends in employee and contractor electrocution fatalities in example companys facilities worldwide, illustrating impact of a focused
application of system safety engineering concepts in the late 1980s
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Type of Non-Fatal Injury No. Injuries
Total 1,191,100
Sprains, strains, tears 474,000
Musculoskeletal disorders 346,300
Falls on same level 182,400
Struck by object 138,530
Falls to lower level 73,520
Assault/Violent act by person 40,310
Highway accidents 36,460
Assault/Violent act by animal 7,160
Fires and explosions 3000
Electrical shock and burn 1890 (.16%)
Fig. 8 Comparison of select Non-fatal Occupational Injuries in the
U.S 2010 (U.S. BLS Economic News Release, 2010) [18]
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Fig. 9 Same data as Fig. 8, but in chart form [18]. Electrical injuries are the tiny sliver at the 12:00 position on the chart.
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