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Understanding the Four Types of Arc Flash 

11 April, 2024

A large, printed label sign affixed to concrete warns of an arc flash boundary.

Understanding Arc Flash 

Arc flash incidents are among the most hazardous risks faced by personnel working with or around electrical equipment. These sudden releases of energy can cause severe injuries, burns, and even fatalities if proper precautions are not taken. To ensure workplace safety, it's crucial to understand the distinct types of arc flashes and the unique risks they present. There are four types of arc flash:  

  • Open-air arc  
  • Arc-in-a-box  
  • Ejected arc 
  • Tracking arc  

It is imperative to educate employees about the different types of arc flashes to ensure they understand the potential hazards and take appropriate safety measures. Regular training and safety drills should also be done to make sure employees know proper arc flash safety protocols.  


The 4 Types of Arc Flash 


  • Open-Air Arc Flash:

    The open-air arc flash is perhaps the most widely recognized and extensively studied type of arc flash. In laboratory testing and standard calculations, the open-air arc serves as the primary model for understanding arc flash behavior.  
    This type of arc flash occurs when electrical current arcs through the air between exposed conductors, such as wires or equipment. Factors such as equipment failure, improper maintenance, or human error can trigger open-air arc flashes, making them a common risk in industrial settings. 
  • Arc-in-a-Box:

    Arc-in-a-box is another type of arc flash, primarily utilized in arc testing within the European Union (EU). This method involves enclosing the arc within a controlled environment, allowing researchers to study its behavior and characteristics under specific conditions. While less commonly encountered outside of laboratory settings, arc-in-a-box testing provides valuable insights into arc flash phenomena and helps inform safety standards and protocols. 
  • Ejected Arc:

    An ejected arc occurs when arc plasma forcefully ejects from its source and comes into contact with a worker. This type of arc flash presents a significant danger to personnel, as the high-velocity plasma can cause severe burns and injuries upon impact. While not typically considered in standard calculations and safety standards, ejected arcs are a real-world risk, especially in scenarios involving higher voltages (480V and above). In such situations, an open-air arc can quickly escalate into an ejected arc, highlighting the importance of vigilant safety practices. 
  • Tracking Arc:

    Tracking arcs occur when arc plasma conducts along the surface of a worker's skin or through clothing. This type of arc flash is more common at higher voltages and during electrical contacts, posing serious risks to personnel in its path. While tracking arcs are most prevalent in settings involving very high voltages, they underscore the need for comprehensive safety measures and adherence to protocols, even in seemingly controlled environments. 


Safety Measures 


It's important to note that while the first two types, open-air arc and arc-in-a-box, are considered in safety calculations and standards, real-world scenarios often involve the risk of ejected arcs and tracking arcs, particularly at higher voltages. Laboratory testing provides valuable insights, it's essential to recognize the dynamic nature of arc flash incidents in practical settings. Employers and workers must prioritize safety by implementing robust training programs, adhering to safety protocols, and utilizing appropriate personal protective equipment (PPE) to mitigate the risks associated with arc flash events. Each safety tip provided is to ensure your facility has the best safeguards in place to reduce the risk of an arc flash. 


Electrical Safety Tips 

  • Always assume that electrical equipment is energized unless confirmed otherwise through proper lockout/tagout procedures. 
  • Wear appropriate PPE, including arc-rated clothing, gloves, and face shields. 
  • Use insulated tools and equipment to reduce the risk of accidental contact with energized parts. 
  • Follow established safety protocols and procedures when working on or near electrical equipment. 
  • Conduct regular inspections of electrical enclosures to identify any signs of damage, contamination, or insulation degradation. 
  • Ensure that electrical equipment is properly rated for its intended use and that enclosure doors are securely closed and latched. 
  • Implement proper ventilation and pressure relief mechanisms to minimize the buildup of pressure during an arc flash event. 
  • Implement regular maintenance and testing of electrical systems to identify and address potential issues before they lead to arc flash incidents. 
  • Use circuit protection devices, such as fuses and circuit breakers, rated for specific application and load requirements. 
  • Train personnel on emergency procedures, including evacuation routes and the use of fire suppression equipment.  

Hazard Communication and Prevention 

A thorough understanding of the four types of arc flash—open-air arc, arc-in-a-box, ejected arc, and tracking arc—is essential for promoting workplace safety in environments where electrical hazards are present. By identifying the hazards and implementing proactive safety measures, organizations can minimize the likelihood of arc flash incidents and protect the well-being of their personnel. LO/TO procedures, arc-flash warning labels, and PPE requirement signs are the first step to keeping workers protected. When it comes to electrical safety, knowledge and preparedness are paramount. 

In addition to understanding the types of arc flash, workers must be aware of the factors that contribute to these incidents. Environmental conditions, equipment maintenance, and human mistakes can all increase the risk of arc flash. Regular equipment inspections, proper maintenance protocols, and ongoing safety training are essential pieces of a well-thought-out arc flash prevention program. Creating a culture of safety within the organization is key to preventing arc flash incidents and promoting a safe work environment for everyone. Workers should feel encouraged to report hazards and follow safety protocols. 

DuraLabel’s free Arc Flash Instant Action Guide helps workers create OSHA-compliant labels, a step-by-step guide to lockout tagout, and information on personal protective equipment (PPE) requirements. Download our free guide today. Still not sure how to proceed? Give us a call at 888-897-5580 and one of our safety professionals will guide you through the process. 

Learn more about the various types of signage that can be implemented into your facility with  DuraLabel’s free Facility Signage Handbook.  The handbook can act as your guide to a successful DIY project as it includes full-color sample floor plans, several examples of signage in different facilities and a list of projects that can help kickstart your projects.  

Read Next: 

Arc Flash Labels  

Arc Flash Labeling Instant Action Guide
Learn How to Make Compliant Arc Flash Safety Labels


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