Arc Flash Studies: Why They Matter and When You Need One

An arc flash is a sudden release of energy caused by an unintended electrical fault, resulting in intense heat, light, and a concussive pressure wave that can propel shrapnel. This phenomenon poses significant risks to personnel working on or near electrical equipment. The energy released during an arc flash is measured in calories per square centimeter (cal/cm²), known as incident energy. 

What Is an Arc Flash? 

An arc flash study, also referred to as an arc flash hazard analysis or risk assessment, is a comprehensive evaluation of an electrical system to identify potential arc flash hazards. This study estimates the severity of injury and helps determine the necessary protective measures, including controls and personal protective equipment (PPE), as outlined in NFPA 70E: Standard for Electrical Safety in the Workplace. Essentially, an arc flash study provides critical information regarding the incident energy available at electrical components, aiding in establishing safe approach distances and appropriate PPE for maintenance tasks.

Why Do Nou Need an Arc Flash Study? 

Conducting an arc flash study is essential for several reasons: 

1. Risk Assessment: It helps in understanding the amount of energy that could be released by energized equipment, enabling the identification of potential hazards.  

2. Hazard Mitigation: The study informs designers and safety professionals on how to eliminate or reduce hazards through engineering controls, administrative controls, and the use of appropriate PPE.  

3. Regulatory Compliance: Compliance with standards such as OSHA regulations, NFPA 70E, the National Electrical Code (NFPA 70), and IEEE guidelines necessitates performing an arc flash study to ensure a safe working environment around electrical installations.  

   
   

When Should You Perform an Arc Flash Study? 

An arc flash study should be conducted under the following circumstances:  

• New Installations: Before energizing new electrical equipment, to assess potential hazards and implement necessary safety measures.  

• System Modifications: After any significant changes to the electrical system, such as equipment upgrades, replacements, or alterations in system configuration, as these can affect the incident energy levels and arc flash boundaries. 

• Periodic Reviews: Regularly, as part of an ongoing electrical safety program, to account for any changes in standards, equipment conditions, or operational procedures. NFPA 70E requires reviewing the arc flash analysis at intervals not exceeding five (5) years.  

  
  

Requirements For an Arc Flash Study 

To accurately perform an arc flash study, detailed information about the electrical installation is necessary, including: 

• Utility Data: Operating voltage, available fault current, and details of utility equipment at the service point.  

• Electrical Equipment Details: Manufacturer information, equipment types and sizes, protective device settings, short-circuit interrupting ratings, and specifications of cables or conductors.  

• System Configuration: Information on paralleled sources, such as multiple services, generators, or emergency power systems, and the layout of the electrical distribution system. 

• Connected Motors: Horsepower ratings and other relevant data of motors connected to the system.  

Field verification of conductor lengths and equipment conditions is also crucial to ensure the study reflects the actual as-built conditions.

Who Can Perform an Arc Flash Study? 

Performing an arc flash study is considered practicing engineering and typically requires a licensed professional engineer (P.E.). Therefore, when an arc flash study is needed, it must be conducted by an engineer licensed in the jurisdiction where the project is located. 

In conclusion, arc flash studies are vital components of electrical safety programs, ensuring that personnel are protected from potential hazards associated with electrical systems. By identifying risks, informing hazard mitigation strategies, and ensuring compliance with safety standards, these studies play a crucial role in maintaining a safe work environment. 

Caitlyn explains the key takeaways from this blog and answers common questions about arc flash studies.