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burned receptacle
The damage resulting from a small arc flash involving a 120VAC duplex receptacle within a single gang box.

Electrical Hazards and the Human Body

The worst-case scenario for any on-site activity is to experience a workplace injury or death. Let’s take a look at the fundamentals of incident prevention.

Harnessed electrical energy has the potential to end human life. Therefore, most electrical construction and maintenance projects have the potential to be high risk. It is necessary for electrical professionals to establish an electrical safety process that successfully manages and eliminates these hazards from becoming life-changing electric shock and arc flash incidences.

Electricity and the human body

In construction and maintenance work, electric shock and arc flash hazards are often present in the workplace. That’s why it’s so important to understand the characteristics of each hazard in order to determine how to properly mitigate the risks in every situation.

Electric shock incidents, commonly referred to as “shocks,” occur when a human body physically becomes a portion of an energized electrical circuit. This happens when current flowing through an electrical circuit flows through a portion of the human body.

Performing live-dead-live tests with an arc flash protective suit during a temporary power cart installation required by a facility’s electrical hazard protection program.

Human skin is the only natural defense a person has against electric shock hazards. The skin protects us against all naturally occurring electrical energy, barring lightning. If the potential of electrical energy is great enough, however, the skin will not provide protection.

The human body can be thought of as an electrolyte soup, held together with bones and covered with skin. If electrical current is allowed to flow beyond skin into the body, the electrical energy will use the human body as a conductor. When this happens, current will travel through the body, completing the perceived circuit and causing great harm in the followings ways:

  • Fourth degree electrical burns — Heat generated from the body’s resistance to electrical current causes burns and damage to muscle, nerve, tissue and bone.
  • Heart issues — Ventricular fibrillation, leading to cardiac arrest.
  • Blunt force injuries — Strong muscle contractions, leading to falls, dislocation and fracture of muscle and bones.

An added complexity to working on electrical systems is that it involves physical exertion and sweating. Engaging in physical activity causes the pores of the skin to open, and sweat is secreted from the pores. Sweat is a salty solution that’s also very conductive. So, when this happens, the perfect condition is created for electricity to defeat our only natural defense: the skin.

Arc flash incidents occur when there is an electrical discharge between two or more points. When there is a fault or short circuit between two electrodes of an electrical distribution system, an arc may be created. If the energy is large enough, the arc has the potential to instantaneously create intense light/heat and pressure, resulting in a violent blast and vaporized material.

Arc flash incidents are associated with creating a short circuit within man-made electrical systems. So, the higher the energy potential within the system, the greater the magnitude of consequences if an arc flash incident were to occur. For example, solid copper is used as a conductor in many distribution systems. When solid copper changes state to gaseous copper, it expands to 67,000 times the original volume of solid copper. This happens instantaneously. So, if a solid piece of copper approximately the size of a small coin was to experience a short circuit, it would instantaneously expand into a burning gaseous metal cloud the size of a refrigerator. If a person is close to the location of a high energy arc, the individual may be engulfed and impacted by the arc flash instance. A few examples of injuries that an arc flash incident may cause are:

  • Third degree burns — Molten and high temperature gaseous material may burn skin, eyes, clothing, lungs, etc.
  • Hearing damage — Air pressure instantaneously spikes, creating a high decibel soundwave capable of temporarily or permanently damaging hearing.
  • Vision damage — Eyes are susceptible to third degree burns. An arc flash incident occurs almost instantaneously, which means you are not able to blink in time to protect your eyes. This may lead to impaired or loss of vision.

Incident prevention

It is important to understand that all electric shock and arc flash incidents are avoidable. In order to prevent them, it is necessary to have a comprehensive mitigation strategy. This strategy should be designed to form a culture of trust with the processes to keep everyone safe in every state of project execution.

People desire a well thought out safety plan. Here are two major challenges to overcome when implementing an effective electrical safety program:

  • The task of keeping everyone safe (including those who do not know about electricity and electrical safety).
  • Electrical construction and maintenance systems are mostly complex.

It is important to understand the magnitude of these challenges. Each of these challenges are not trivial problems that are easily identifiable to someone not familiar with the potential hazards. Electrical situations are not as simple as a hole in the floor that someone could fall in. For simple hazards that do not involve electricity, an individual’s basic survival instincts kick in and readily recognize/mitigate the potential dangers. For electrical hazards, the task of establishing a safe construction and maintenance environment requires an individual to correctly apply electrical specific understanding of the situation.

First, education is paramount. Harnessed electrical energy is dangerous — and silent. For individuals without electrical training, electrical energy may be perceived as a magical force or ghost of sorts. The optimal way to ensure safety from harnessed electrical energy is to understand it, anticipate it, and mitigate the risk of the hazards. There is not a middle ground. In order to ensure safety, we must know, and we must act on that knowledge. Applying this knowledge through electrical hazard mitigation strategies must be highly refined in order to provide a safe umbrella for professionals with and without knowledge of electrical systems alike. A safe environment starts with highly educated professionals who can apply their knowledge to effective electrical hazard prevention programs.

Second, because we are applying our knowledge to complex situations, we have to understand how our decisions affect the situation we are in as well as adjacent systems. In the world we live in, there are complex facilities, processes, systems, and equipment. It is extremely important to understand how and why electrical distribution systems work the way they do. This ensures that the system will operate the way that it was engineered to operate and not present additional or elevated hazards. Understanding the application will also give us the ability to plan and implement a mitigation strategy for interacting with the electrical potential of the system and adjacent systems.

When thinking of a task, think safety first. Then, after you have refined your strategy for performing the task, consistently be mindful of safety as the work is being done. This may seem redundant, but has historically been instrumental in catching potential safety issues before they become incidents. Professionals should always be mindful of safety.

A culture of trust

The subject of trust and trust building is not a traditional electrical construction topic, but it is crucial to successfully executing a safety plan nonetheless. The following is a brief list of the three Cs of building trust for construction and maintenance professionals:

  • Caring
  • Competency
  • Commitment

Caring — Care about your team. If you truly care about the welfare of your team members, then your team member’s safety will be at the forefront of your mind. Be intentional with your time and efforts. If the first criteria of your work scope is to do the job safely, then your coworkers will notice that you have placed value on their personal safety. Theodore Roosevelt and later John Maxwell have expressed it best when they communicated the following thought: “Nobody cares how much you know, until they know how much you care.”

Competency — It is hard to trust someone you feel does not have the knowledge or skills necessary to be successful, especially if you feel the individual is not capable of understanding the complexity of the situation you are facing. Industrial work is difficult. The jobs are dangerous and potentially life threatening. If your team does not trust an individual, this is a truly challenging position to be in. When this happens, there will be quite a bit of second guessing, which is completely different from exercising good human performance and questioning attitude. Without competency, complex projects almost become impossible to complete successfully.

Commitment — In order to positively influence the safety culture of an organization, an individual must establish themselves as someone who is consistently focused on safety at all times. Even if individuals feel you have the knowledge, the skill, and the understanding of the situation, they may not trust you if they feel you do not have the integrity to perform your function as designed. If someone feels you may deviate from the intent of the situation for any number of reasons, an individual’s faith in the system may be shaken. It is important to not only have a solid plan, but have a commitment to following that plan.

“Trust but verify” is a quote a previous supervisor of mine would always say. I believe there is insight and truth within this statement. A culture of trust should never negate human performance, specifically peer checking. Actually, a culture of trust demands electrical professionals perform peer checks whenever possible.

Dawes is a registered electrical code official/inspector, licensed master electrician and electrical engineer from the University of Michigan in Ann Arbor. He works in plant support engineering at DTE Energy’s Fermi 2 Nuclear Power Station in Newport, Mich., and represents the Edison Electrical Institute participating on the 2020 NFPA 70 NEC CMP-10. He can be reached at [email protected].

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