Ensuring industrial electrical safety

Sept. 15, 2010
Raise the level of electrical hazard awareness: Every employee should know these elements of electrical safety.

Electricity has long been recognized as a serious workplace hazard, exposing employees to shock, electrocution, burns, fires and explosions. According to the Occupational Safety and Health Administration (OSHA), electrical accidents rank sixth among causes of work-related fatalities in the United States, with more than 300 deaths and 4,000 workplace injuries reported each year. OSHA statistics indicate that between 2003 and 2007, more than 13,000 workers required time off from work caused by injuries from electrical accidents. The fact that most of these accidents could have been avoided easily makes these statistics all the more needless and tragic.

Electricity is a necessary source of energy that we depend on for our daily functions. When it’s installed and maintained properly, it can be controlled easily and effectively. However, when electricity is taken for granted and there is a lack of understanding of the hazards it can produce, non-electrical workers are far more likely to become exposed unknowingly.

Employers should ask this simple question: Are your employees trained to protect themselves from exposure to electrical hazards? If you think your electrical hazards are covered by your qualified electrical workers, think again. Non-electrical workers also can face serious electrical hazards in their daily tasks. A job as simple as picture-hanging can be a source of dangerous electric shock if workers are unaware of wiring behind the walls. Examples of potential exposure to electrical hazards by non-electrical workers include:

  • Saw-cutting and core-boring concrete walls and floors
  • Seismic anchoring into walls and floors
  • Making penetrations into metal/wood framed and drywall covered walls and ceilings
  • Working in suspended ceiling areas where exposed electrical hazards are present (i.e., openings in electrical boxes, missing protective covers, abandoned circuits that are still energized)

While many employers focus on providing comprehensive electrical training and evaluation for their qualified workers, often they overlook the potential exposure risk to non-electrical personnel. Because many employees and contractors aren’t directly involved in the maintenance and repair of electrical systems, they’re often unaware or unmindful of the potential exposure to a variety of electrical hazards.

OSHA standards require that employees who work near any part of an electrical power circuit or are exposed to electrical hazards be protected. OSHA 1910.331 through 1910.335 specify that employers provide training to employees — both electrical workers and non-electrical workers — who can be exposed to electrical hazards and to offer retraining or updating as needed to maintain safety awareness. Employers that implement electrical safety awareness training for non-electrical employees can not only ensure their compliance with OSHA safety standards but, more importantly, reduce the risk of electrical accidents and enhance the level of protection for all their workers.

Orientation, training and awareness

Because many companies provide a general orientation program as part of the new hire process, including electrical hazard awareness training along with general workplace safety instruction is the best way to guarantee that new employees are alerted to potential electrical hazards. A well-designed initial orientation enhances worker safety awareness, can help prevent serious injury or worse, and sends a strong message that the employer is serious about establishing and adhering to safe work practices. Keep that in mind if you have non-electrical workers that don’t have electrical hazards awareness training and will be working in and around hazards.

An effective electrical safety and hazard awareness program provides an overview of potential electrical hazards, strategies for protection and avoidance, and instruction on company policies and procedures that support safe work practices. While the specific elements of an awareness program vary depending on the industry, facility, machinery and equipment, a useful training curriculum could include a variety of elements.

  • General electrical awareness
  • Consequences of electrical hazards
  • The safety model
  • Major hazards and prevention strategies
  • Lockout/tagout (LOTO) awareness
  • Basic personal protective equipment (PPE) awareness
  • Reporting hazards to a supervisor
  • Follow-up training

Because electricity is such a familiar part of everyday life, this powerful energy source often is used with minimal caution and little thought regarding its potential hazards. Workers are especially vulnerable to electrical hazards because they’re often operating in fast-paced situations involving intricate machinery, power tools, crowded work areas, and exposure to variable weather and other environmental factors.

Because the average worker often lacks basic electrical knowledge, a general overview of how electricity works is a good place to start electrical safety awareness training. Just as the fire triangle provides the three elements that produce a fire — oxygen, heat and a fuel source — there are three basic elements that comprise a complete electrical circuit — a source of energy, a load and a complete path. The primary goal of awareness training is to keep workers from becoming part of this electrical circuit.

Topics that can be used in electrical awareness training include:

  • Electrical hazard awareness: (see Safety Model)
    • What is the hazard?
    • What are the risks and dangers?
    • How can it be controlled?
  • Basic electrical terms
    • Voltage and current
    • Insulators and conductors
    • Alternating and direct current
    • How a transformer works
    • Grounding
    • Protected and exposed
    • Energized and deenergized
  • Ground fault circuit interrupters and assured grounding program
  • Working clearances
  • Use of flexible cords and extension cords
  • Overhead power lines and underground utilities
  • Barriers, approach boundaries and signage
  • Required PPE and its proper use
  • Inspection process for each worker’s tools, extension cords and ladders. This process can happen at the same time that the workers are getting their needed tools out and placing them in their work area.

Another important topic to incorporate into the training is a job hazard analysis (JHA), which allows workers to meet at the beginning of their shift to identify the hazards they’ll be facing in their tasks. JHA also identifies the tasks other workers will be doing so that affected workers are aware of the work going on around them. A communication process also should be included so that if changes occur in the work or the process, workers would be notified.

Consequences of electrical hazards

It’s essential that electrical safety awareness training provide workers with a clear understanding of the consequences of unprotected exposure to electrical hazards. While the intent isn’t to foster fear that affects productivity, the information on electrical hazard consequences should be clear and detailed to produce a healthy respect for the effect of direct contact with electrical current.

The following is an example of a basic approach to explain how electric current affects the body.

Three primary factors affect the severity of the shock when a person is a part of an electrical circuit:

  • Amount of current flowing through the body (measured in Amperes) and the amount of time the current is flowing
  • Path of the current through the body
  • Length of time the body is in the circuit.

Other factors that might affect the severity of the shock are:

  • Voltage
  • Moisture in the environment
  • The phase of the heart cycle when the shock occurs
  • The general health of the person

Effects can range from a barely perceptible tingle to severe burns and immediate cardiac arrest. There’s a difference of less than 100 mA between a barely perceptible current and one that can kill. Although the exact injuries that result from any given amperage aren’t known, the following table demonstrates this general relationship for a 60-Hz, hand-to-foot shock of one second duration:

Current level Probable effect on human body
1 mA Perception level. Slight tingling sensation. Still dangerous under certain conditions.
5 mA Slight shock felt; not painful but disturbing. Average individual can let go. However, strong involuntary reactions to shocks in this range might lead to injuries.
6-30 mA
Painful shock, muscular control is lost. This is called the freezing current or "let-go" range.
50-150 mA
Extreme pain, respiratory arrest, severe muscular contractions. Individual can’t let go. Death is possible.
1000-4300 mA
Ventricular fibrillation (the rhythmic pumping action of the heart ceases). Muscular contraction and nerve damage occur. Death is most likely.
10,000 mA
Cardiac arrest, severe burns and probable death.

Current level Probable effect on human body 1 mA Perception level. Slight tingling sensation. Still dangerous under certain conditions. 5 mA Slight shock felt; not painful but disturbing. Average individual can let go. However, strong involuntary reactions to shocks in this range might lead to injuries. 6-30 mA Painful shock, muscular control is lost. This is called the freezing current or "let-go" range. 50-150 mA Extreme pain, respiratory arrest, severe muscular contractions. Individual can’t let go. Death is possible. 1000-4300 mA Ventricular fibrillation (the rhythmic pumping action of the heart ceases). Muscular contraction and nerve damage occur. Death is most likely. 10,000 mA Cardiac arrest, severe burns and probable death. 


Under dry conditions, human skin has high ohmic resistance, but wet skin dramatically drops the resistance, and wet conditions are common during low-voltage electrocutions. If an electric shock excites the extensor muscles, the person might be thrown, which can result in a fall that could kill even when electrocution doesn’t.

When muscular contraction caused by stimulation doesn’t allow the victim to get free from the circuit, even voltages as low as 6 mA can be dangerous, because the degree of injury increases with the length of time the body is in the circuit. Low voltage does not imply low hazard.

Examples of shock-related injuries include burns, internal injuries and injuries caused by involuntary muscle contractions. Electrical burns, the most common shock-related injury and often one of the most serious, are the result of heat generated by the flow of electric current through the body. High temperatures near the body produced by an electric arc or explosion cause arc or flash burns. Thermal contact burns occur when skin comes in contact with overheated electric equipment, or when clothing is ignited in an electrical incident.

Electricity flowing through the body can cause serious damage to internal organs, including hemorrhage or internal bleeding, tissue destruction, and nerve or muscle damage. Internal injuries might not be immediately apparent to the victim or observers; however, left untreated, they can result in death. Muscles contract violently when stimulated by excessive electricity. These involuntary contractions can damage muscles, tendons, and ligaments and might even cause broken bones. If the victim is holding an electrocuting object, hand muscles might contract, making it impossible to drop the object to avoid prolonging contact with the current. Injury or death might result when violent muscle contractions cause workers to fall from ladders and scaffolds or strike other objects inadvertently.

The safety model

Introducing the classic safety model as part of an electrical hazard awareness orientation gives employees a framework for safe work practices and encourages them to understand their jobs well enough to avoid the potential pitfalls of working with or around electricity. The safety model directs employees to:

  1. Recognize the hazards in their environment to avoid or control them. Discussion and planning with supervisors and co-workers can increase awareness of less obvious hazards and reduce the risk of injuries for all.
  2. Evaluate the risk of injury from each identified hazard to apply the appropriate method of control. It’s important to emphasize that risk evaluation is an ongoing process because of constant changes in the workplace, such as shift changes and variability in weather.
  3. Control hazards based on the evaluation of risks associated with each job and worksite. Methods of control might range from posting warning signs in a work area or replacing frayed extension cords to bringing in qualified electrical workers to execute more technical safety procedures, such as locking out and tagging electrical panels before maintenance is done.

The safety model is a commonsense approach to electrical safety awareness that can establish a mindset of alertness and vigilance in all workers and encourage consistent, safe work practices.

Major hazards and prevention strategies

Effective electrical safety awareness training should address the major hazards that employees encounter and appropriate strategies for avoidance or prevention. While each facility has specific risks, machinery and other factors, OSHA compiled a list of the hazards that cause the most frequent electrical injuries.

Contact with power lines: Overhead and buried power lines are especially hazardous because they carry extremely high voltage. Possible strategies to minimize risk could include calling the local utility to deenergize and ground the power lines or to protect the overhead power lines with insulation, training workers as spotters, using a service to locate the underground power lines, requiring employees to maintain a distance of at least 10 ft from power lines, and providing non-conductive wood or fiberglass ladders when working near power lines.

Lack of ground-fault protection: Regular and repeated use of electrical equipment can cause wear and tear that results in insulation breaks, short circuits and exposed wires. Without protection, a ground fault can send current through a worker's body, causing serious injury and possibly death. Employees who regularly use power tools and other electrical equipment should receive awareness training about ground-fault circuit interrupters and the assured grounding program. They also should be trained to inspect all electrical equipment visually before use and to remove from service any equipment with frayed cords, missing ground prongs or cracked tool casings.

Equipment not used according to manufacturers’ requirements: If electrical equipment is used in ways for which it’s not designed, employers can no longer depend on the manufacturer’s built-in safety features. Common examples of misuse include attaching ungrounded, two-prong adapter plugs to three-prong cords and tools; using modified cords or tools, such as removed ground prongs, face plates or insulation; and using tools with worn insulation or exposed wires. Employees should be strongly advised in electrical safety orientation to use equipment according to the manufacturer's instructions and to refrain from modifying cords or using them incorrectly.

Improper use of extension and flexible cords: The normal wear and tear on extension and flexible cords can loosen or expose wires, producing hazardous conditions. Cords that aren’t three-wire type, not designed for hard-service or have been modified increase the risk of contacting electrical current. Also, improper use of extension cords, such as anchoring them with nails or staples, can pose a serious risk. To avoid these common problems, workers should be trained to inspect cords continually and remove from service or report to their supervisors cords that have been modified or found not to be marked for hard or extra-hard use. Employees also can extend the life of cords by removing them from receptacles by pulling on the plugs, not the cords.

Lack of appropriate barriers and warning/caution signs: Since many employees who aren’t qualified electrical workers face exposure to electrical hazards every day, they should be trained and encouraged to recognize risks and respond appropriately to protect not only themselves but also their coworkers. One of the most obvious safety precautions employers can take is setting up barriers or warning signs to alert employees to potential danger. Unfortunately, they are sometimes overlooked. While non-electrical workers don’t have the technical training to correct many electrical hazard situations, they should be trained not only to heed barriers and warning signs but also to alert management of the need for barriers or signs when they recognize potential danger.


Lockout/tagout (LOTO) refers to a specific process to safeguard employees from the unexpected energization or startup of machinery and equipment, or the release of hazardous energy during service or maintenance activities. An authorized qualified electrical employee turns off and disconnects the machinery or equipment from its energy sources, locks and/or tags the energy-isolating devices to prevent the release of hazardous energy, and takes steps to verify that the energy has been isolated effectively. Affected employees are required to use the lockout/tagout process also. Employees should be trained to recognize a locked and tagged electrical source and to understand how the LOTO process affects their specific work areas.

Employers are required to train qualified electrical employees who deal directly with hazards related to maintaining and repairing electrical systems in the proper use and maintenance of PPE. Because non-electrical employees shouldn’t be working on electrical systems but are nonetheless often exposed to electrical hazards, they should be wearing the same level of personal protective equipment (PPE) as the electrical workers. Offering a brief overview of PPE, with a demonstration of the proper use of basic equipment, such as hard hats, face shields, ear protectors, insulated rubber gloves and insulated leather footwear, might prove beneficial, especially in case of an electrical emergency.

Reporting hazards and follow-up training

One of the most important aspects of electrical safety awareness training is to encourage employees to alert supervisors of any concerns they have regarding potential electrical hazards. Employees often feel intimidated and reluctant to rock the boat, but employers who encourage open communication know that accident prevention isn’t only the right approach, but a practical one as well. A company might sustain far greater costs in injuries, liability and lost time by ignoring employee concerns than they would incur by listening to their frontline workers and taking appropriate protective measures to prevent accidents.

After the initial orientation on electrical safety and hazard awareness, it’s vital to follow up with periodic updates as needed to maintain a safety mindset. Employees need to be notified on a regular basis of changes in or additions to their workplace that could affect their work. Electrical safety awareness information can be incorporated as part of regular staff meetings. Emergency response preparedness also is a vital component of hazard awareness, and basic drills should be conducted so that employees are ready for emergencies, including electrical.

While workplace electrical hazard prevention begins with providing in-depth training to qualified electrical workers, it’s greatly enhanced by offering a safety and hazard awareness orientation and follow-up training to employees who are exposed to electrical hazards. Managers, in partnership with well-trained qualified electrical workers, can take the lead in helping to sustain employee electrical hazard awareness and maintaining high safety standards in the workplace.

Michael Sa is a safety consultant with the OSHA Training Center. Contact him at [email protected] and (866) 936-6742.

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