Keep young electrical engineers grounded

James Cawley and Gerald Homce of the National Institute for Occupational Safety and Health (NIOSH) published key findings in a comprehensive analyses of workplace electrical injuries.

02/01/2008


James Cawley and Gerald Homce of the National Institute for Occupational Safety and Health (NIOSH) published key findings in a comprehensive analyses of workplace electrical injuries. Their report, “Trends in Electrical Injury 1992-2002,” published by the Institute of Electrical and Electronics Engineers in 2006, claims:

 

  • Electrical hazards were the sixth leading cause of workplace fatalities

  • 3,378 workers died from on-the-job electrical injuries

  • The construction industry accounted for 47% of all electrical deaths, and had a electrical fatality frequency rate six times that of the overall workforce

  • 46,598 workers were nonfatally injured by electricity

  • 99% of the electrical fatalities were due to electric shock, but 18,360 of non-fatal electrical injuries involved hospitalization due to electrical burns.

These facts underscore the seriousness of electrical safety in the workplace. There is immeasurable pain, suffering, and trauma to the injured, their families, friends, and co-workers. There are significant financial losses, including medical costs, loss of productive workers, and disruption of operations due to damage of critical electrical systems.

 

Two case histories illustrate the potential impact the electrical design engineer has in helping reduce these injuries and fatalities.

 

The case of the exploding motor starter. The electrician's life will never be the same. The motor control center was less than 10 years old, and installed in a clean, dry, air conditioned room. The task was simple. The overload units in one motor starter needed to be replaced. The electrician turned off the motor starter switch, and locked it in the off position. After successfully replacing one unit, an arc flash occurred as he began to replace the second unit. The electrician received second and third degree burns over 40% of his body. He spent eight weeks in a burn center, and required ongoing reconstructive and rehabilitation treatment. An investigation determined that one pole of the disconnect switch had failed to open, and the electrician's screwdriver had shorted the energized phase to ground. The electrician had failed to test for absence of voltage. The facility owner had not implemented an arc flash hazard assessment and mitigation program that would have included flame resistant clothing to reduce the extent and severity of the burn injuries.

 

The case of the rolling scaffold. This was a fatal mistake for two construction workers. They had been using a rolling scaffold to insulate an overhead pipeline. They had completed the job and needed to move the scaffold back to the construction storage yard. Rather than dismantle the rolling scaffold, they decided to roll it several hundred yards. This seemed like an acceptable solution, because they would need to use the fully assembled rolling scaffold again the next day. Unfortunately, there was an overhead electric power line adjacent to the constriction storage yard. When the workers approached the storage yard, the scaffold contacted the overhead line and both workers were electrocuted. The investigation determined that the construction workers deviated from the job plan when they decided to roll the assembled scaffold rather than disassemble it. In addition, they had failed to notice the close proximity of the scaffold to the overhead line.

 

Lessons learned

In both cases, the work was routine, the people involved were experienced in their craft, and equipment or facilities designs were not identified as contributing causes to these tragic events. Deficiencies in design were not identified as contributing causes. But could the facilities design engineers helped prevent these events?

 

This presents a number of questions regarding the role, professional responsibility, and legal liability of the design process. In the case of the exploding motor starter, what if the design engineer recognized that a high-impedance grounded neutral system for a 480 V industrial power distribution system (in accordance with NFPA NEC 2005, article 250.36) would have limited ground fault current to a low value—and therefore provide the client with a safer and more reliable power system?

 

If the system had been high-impedance grounded rather than solidly grounded, the screwdriver contact may have resulted in little more than a ground-indicating alarm instead of the life-changing and permanently disabling injuries from a high-energy arc flash. Although this choice would not reduce the shock hazard exposure that was also present in this incident, it may have provided a safer and more reliable power system from an arc flash hazard perspective.

 

In this case, what if an overhead line contact hazard analysis had been conducted during the facilities design, and the site planning had located the construction storage yard in an area not in close proximity to overhead lines?

 

Setting a trend

Let's look at some trends that continue to impact the electrical engineering design profession.

 

Electrification. This is the greatest engineering achievement of the 20th century.

 

Beginning in the late 19th century and continuing today, electrification, or the displacement of other technologies with electrical technology, has transformed all aspects of our modern society. Energy generation and distribution, heating, lighting, transportation, food production and storage, and medical diagnostics are just a few examples where electrical technology has displaced previously used technologies to enable extraordinary advancements and conveniences. In celebrating the beginning of the 21st century, the National Academy of Engineering identified electrification as the most significant engineering achievement of the 20th century. This trend continues to expand the depth and breadth of electrical technology applications for the electrical design engineer.

 

Arc flash. The recognition of arc flash as a distinct electrical hazard, and the emergence of NFPA 70E into the media mainstream, has made this a hot topic. Although the arc flash hazard has been present in electric power systems since the first systems were installed in the late 1800s, it was not until the last two decades of the 20th century that arc flash was recognized as uniquely different from electric shock. With expanding knowledge of the arc flash phenomena came understanding that equipment and system designs, safe work practices, and personal protective equipment that served to protect workers from electric shock did not necessarily protect them from arc flash hazards.

 

Although NFPA 70E, Standard for Electrical Safety in the Workplace, was first published in 1979, it existed in relative obscurity until a fine print note referencing NFPA 70E appeared in the 2002 edition of the NFPA National Electrical Code. This reference, associated with a new requirement in article 110.116 regarding labeling arc flash hazards, provided the tipping point to bring NFPA 70E to the attention of the vast electrical design, construction, and inspection community associated with the application of the National Electrical Code. Today, hardly a week passes without seeing an article on the topics of NFPA 70E or arc flash hazards in the industry magazines.

 

These two trends are having a significant impact on design and consulting firms. More industrial and commercial facilities are addressing arc flash hazard mitigation in their operations and are engaging consultants in performing arc flash hazard analysis of their power systems. Although many arc flash hazard studies have focused on determining the need and performance requirements of personal protective equipment, facility owners and consulting engineers recognize that design decisions for new facilities and renovation of existing power systems impact the severity and frequency of worker exposure to arc flash hazards. This trend asks the design engineer to make wiser choices impacting the electrical safety for the lifecycle of power system designs.

 

Prevention through Design initiative. One of the prevalent beliefs today is that electrical safety from a design engineer's perspective is to ensure compliance with building codes, including the National Electrical Code and ANSI/IEEE C2-2002@, National Electrical Safety Code. This serves to protect occupants and the public from electrical hazards in the facility.

 

However, construction and maintenance workers interact with electricalequipment and systems differently than general occupants or the public, and their safety has historically been more dependent on adherence to worker knowledge and qualifications, and adherence to safe work practices (i.e. NFPA 70E).

 

In July 2007, to recognize that there is great potential to reduce workplace injuries by addressing worker safety differently in systems and facilities design, NIOSH launched “Prevention through Design,” a multiyear initiative to influence regulations, codes, standards, and long-held paradigms to help bring greater emphasis to design decisions that can improve worker safety throughout the facility lifecycle, including construction, commissioning, operation, maintenance, and eventual dismantlement. This initiative aims to alter the roles and responsibilities of design processes and to bring greater prominence to design engineers to specify inherently safer design choices and decisions in the future.

 

A future mentoring model

Things are different for engineers today. Novice engineers are expected to be more computer- and Internet-savvy than veteran engineers, and have a tendency to not read trade publications, join professional societies, and attend technical conferences. Some of these issues are related to social norms for their generation.

 

There also is the pressure for engineering firms to maximize billable hours while pinching budgets for training, travel, and societal dues. One thing that has not changed—most people would like to know their work and professional activities make a positive and lasting impact.

 

As I think about what advice I would give regarding mentoring electrical design engineers today, these four points come to mind:

 

  • Electrical incidents, injuries, and fatalities in the workplace do not have to happen

  • Trends in regulations, standards, and societal expectations are impacting the role electrical design engineers have on electrical safety

  • Design choices can have a significant impact on electrical safety during the full lifecycle of a facility

  • The body of knowledge essential to electrical safety includes electrical technology and safety management.

Engineering firms need to recognize ongoing development of their employees is good for business. Design engineers need to be proactive in ensuring their knowledge and skills are up to date. Every engineer, novices to seasoned veterans, should have a personal professional growth and development plan. For electrical engineers, this includes staying current in relevant electrical safety issues.

 

The venues available for this include self study, computer-based courses, topic-specific seminars and conferences, active involvement in technical professional organizations that may have local organizational units, and both formal and informal mentoring relationships.

 

Looking back more than 35 years in electrical engineering, I can identify what enabled my professional success. Certainly, a high-quality technical education provided the ticket to enter the profession. But it was the knowledge I gained from my personal interaction with other professionals that opened doors or provided the technical edge to advance in both personal rewards and job responsibilities.

 

These interactions came in several venues. At the time, I may not have identified them as mentoring interactions. There were lunchtime discussions with office colleagues, collaboration in professional and technical organizations, impromptu telephone calls, and letters (in early years) and e-mails (in recent years) with an ever-expanding network of people I respected. There also were unplanned encounters with industry experts while waiting at an airport following a technical conference, and formal mentoring relationships.

 

Although these interactions may not all fit some people's definition of mentoring, I now view each of these as part of my personal mentoring process. Although generational norms and business pressures may be perceived as barriers to some of these mentoring avenues, I believe they are all still viable today.

 

For the electrical design engineer, what should be viewed to change is that the mentoring topics need to expand. Electrical safety is no longer just about designing to building codes and standards. The topics also need to encompass how construction and maintenance personnel interact with the electrical systems and equipment, fundamentals of safety management, and lifecycle economics of design decisions made in the conceptual stages of design.

 

Author Information

H. Landis Floyd is principal consultant, electrical safety and technology, with DuPont, Wilmington, Del.



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