Arc Flash Study:
When and Why Your Facility Needs One
An arc flash study is an engineering assessment that evaluates your facility’s electrical system to calculate incident energy levels. This determines the personal protective equipment (PPE) workers need when exposed to an electrical arc flash hazard (and to an extent, the electrical shock hazard). NFPA 70E requires facilities with equipment operating at 50 volts or higher to conduct this analysis and review it for accuracy (as discussed later).
Arc flash incidents represent one of the most severe electrical hazards in industrial and commercial facilities. With the core of the arc reaching temperatures up to 35,000°F, approximately four times hotter than the surface of the sun, these explosive events can cause catastrophic burns, blindness, hearing loss, and death. Understanding when your facility needs an arc flash study, and why this assessment matters, is essential for protecting your workforce and maintaining regulatory compliance.
What Is an Arc Flash Study?
An arc flash study, also called an arc flash hazard analysis or arc flash risk assessment, is a comprehensive engineering evaluation of a facility’s electrical distribution system. The study identifies potential arc flash hazards at each piece of electrical equipment, where energized tasks are likley to occur, and calculates the thermal energy workers could be exposed to during an arc flash event. For those new to electrical safety concepts, our arc flash basics guide provides foundational information on how these dangerous events occur.
The analysis produces critical safety information including incident energy values measured in calories per square centimeter (cal/cm²), arc flash boundaries that define safe working distances, and PPE requirements based on hazard categories. This data allows facility managers to implement appropriate protective measures and ensure workers have the equipment and training needed to work safely around energized electrical systems.
A complete arc flash study typically includes several interconnected analyses. Engineers first conduct a short circuit study to determine the available fault current at each point in the electrical system. They then perform a protective device coordination study to evaluate how circuit breakers, fuses, and relays work together to clear faults. These foundational studies feed into the arc flash calculations, which use standardized methods from IEEE 1584 to predict incident energy levels and arc flash boundaries potentially recommending system improvements to reduce the incident energy or optimize the protective device coordination.
The Regulatory Framework
Multiple standards and regulations create the framework that makes arc flash studies necessary for most facilities. Understanding how these requirements work together helps facility managers recognize their compliance obligations.
OSHA’s general duty clause under 29 CFR 1910.132 requires employers to assess workplace hazards and provide appropriate protective equipment. While OSHA does not explicitly mandate arc flash studies, the agency uses NFPA 70E as the benchmark for electrical safety compliance and has cited employers who fail to protect workers from arc flash hazards.
NFPA 70E, the Standard for Electrical Safety in the Workplace, provides the most specific guidance on arc flash requirements. Article 130.5 states that an arc flash risk assessment shall be performed to identify arc flash hazards and estimate the likelihood of occurrence of injury or damage and the potential severity of injury or damage. The standard requires that incident energy analysis data be reviewed for accuracy at intervals not exceeding five years or whenever changes occur that could affect the results.
IEEE 1584, the Guide for Performing Arc-Flash Hazard Calculations, provides the mathematical models and calculation methods used to determine incident energy and arc flash boundaries. The 2018 edition of this standard significantly updated the calculation methodology based on over 1,800 laboratory tests, introducing five electrode configurations and more accurate predictions of hazard levels.
The National Electrical Code (NEC), also known as NFPA 70, addresses arc flash labeling requirements. Article 110.16 requires equipment likely to require examination, adjustment, servicing, or maintenance while energized to be field or factory marked with arc flash warning labels.
When Is an Arc Flash Study Required?
Several conditions trigger the need for an arc flash study. Recognizing these triggers helps facilities maintain compliance and ensure worker safety.
New installations require an arc flash study before workers perform any energized work on the electrical system. This establishes baseline hazard information and ensures proper labeling from the start of operations.
System modifications that could affect fault current levels or protective device operation necessitate updates to the arc flash analysis. Changes that trigger updates include adding or replacing transformers, modifying circuit breaker settings, installing new electrical distribution equipment, adding generation sources including solar installations, utility changes, and changing cable sizes or routing.
The five-year review cycle requires facilities to examine their arc flash study data for accuracy even when no changes have occurred. This review must be documented, and records must be maintained by the equipment owner. The review may reveal that recalculation is necessary, particularly if the original study used older calculation methods that have since been updated.
Changes to utility supply can impact arc flash hazard levels throughout a facility. When the utility modifies transformers, conductors, or protective devices on their distribution system, fault current levels at your facility may change. Facilities should communicate with their utility provider and request updated fault current data as part of regular arc flash reviews.
Regulatory updates may also prompt recalculation. The IEEE 1584-2018 standard introduced new electrode configurations that can nearly double calculated incident energies for certain equipment types compared to earlier methods. Facilities using studies based on the 2002 standard may benefit from recalculation using current methodologies, particularly for higher-amperage equipment (racking type breakers) and equipment in shallow enclosures.
What Does an Arc Flash Study Include?
A comprehensive arc flash study follows a structured process that begins with data collection and ends with actionable deliverables. Understanding this process helps facility managers prepare for the study and evaluate contractor proposals.
Data collection requires gathering detailed information about the electrical distribution system. Engineers need one-line diagrams showing equipment connections, transformer nameplate data including kVA ratings and impedance, utility fault current information, conductor sizes and lengths, protective device specifications and settings, and equipment enclosure dimensions. Accurate data is essential for reliable results—errors or omissions at this stage propagate through all subsequent calculations.
System modeling uses power system analysis software to create a digital representation of the electrical system. Engineers input the collected data to build a model that can simulate fault conditions at each point in the distribution network.
Short circuit analysis calculates the available fault current at each bus and evaluates whether protective devices are rated to interrupt the maximum fault current they might encounter. Equipment with inadequate interrupting ratings poses significant safety risks and may require replacement or system modifications.
Protective device coordination study examines how overcurrent protective devices work together during fault conditions. Proper coordination ensures the device nearest the fault operates first, limiting the affected area and reducing arc flash incident energy. Engineers plot time-current curves to identify miscoordination issues and may recommend setting adjustments to improve performance.
Arc flash calculations apply IEEE 1584 methodology to determine incident energy and arc flash boundaries at each location. The calculations consider equipment voltage, available fault current, protective device clearing time, electrode configuration, and enclosure dimensions. Results identify the worst-case thermal exposure workers face at each piece of equipment.
Deliverables from a complete arc flash study typically include updated one-line diagrams, a detailed analysis report with incident energy values and PPE requirements for each location, arc flash hazard labels for all equipment, and recommendations for reducing hazard levels. Some studies also include short circuit and coordination study reports as separate deliverables.
Understanding Arc Flash Labels
Arc flash labels communicate critical safety information to workers and represent a visible outcome of the arc flash study process. NFPA 70E Article 130.5(H) specifies the minimum information required on these labels. For a detailed breakdown of label requirements, see our guide on arc flash labels compliance and how to read them.
Every arc flash label must include the nominal system voltage and the arc flash boundary. The label must also include at least one of the following: the available incident energy with corresponding working distance, the minimum arc rating of required clothing, or the site-specific PPE level required.
Labels often include additional information beyond the minimum requirements. Shock hazard boundaries, glove class requirements, and the date of the analysis help workers understand the full scope of electrical hazards and ensure they select appropriate protection. The date information also helps facilities track when labels may need updating based on the five-year review cycle.
Label durability matters for compliance. NEC 110.21(B) requires field-applied hazard markings to be durable for their given environment. Labels exposed to moisture, chemicals, sunlight, or abrasion must maintain legibility throughout their service life. Handwritten markings are not permitted except where information is subject to change.
The Cost of Arc Flash Studies
Arc flash study costs vary significantly based on facility size, equipment density, system complexity, and the scope of deliverables required. Understanding the factors that influence pricing helps facilities budget appropriately and evaluate proposals.
Studies for smaller commercial facilities with relatively simple electrical systems may cost between $5,000 and $15,000. Medium-sized industrial facilities with multiple distribution panels and more complex protection schemes typically see costs ranging from $12,000 to $50,000. Large industrial complexes or facilities with extensive electrical infrastructure may require investments of $50,000 to $100,000 or more for comprehensive studies. The first study is usually pricier as a software model is built from scratch and all new labels installed. Renewals are substantially lower since the baseline model and labels have already been established and installed.
Several factors drive cost variation. The number of electrical devices requiring analysis directly impacts engineering time. Equipment age and documentation quality affect data collection effort—facilities with accurate, current one-line diagrams save significant time compared to those requiring extensive field verification. Add-on services like detailed equipment evaluations, coordination studies, or infrared thermography increase the overall investment.
Facilities can reduce costs by preparing ahead of the study. Gathering existing documentation, ensuring equipment is accessible for data collection, and having knowledgeable personnel available to assist engineers all help minimize field time. Some facilities perform portions of the data collection in-house, though this requires staff with appropriate training to ensure accuracy.
When evaluating the cost of an arc flash study, consider the potential consequences of arc flash incidents. Medical costs for severe burn injuries can reach $1.5 million or more per incident. Lost productivity, equipment damage, regulatory fines, and potential litigation add to the financial impact. The investment in a proper arc flash study represents a small fraction of these potential costs while providing the information needed to prevent incidents entirely.
Arc Flash Hazards by the Numbers
The statistics surrounding arc flash incidents underscore the importance of proper hazard assessment and worker protection.
Research compiled for the Fire Protection Research Foundation estimates that 5 to 10 arc flash incidents occur every day in the United States. Other industry reports suggest the annual total may reach 30,000 incidents, resulting in approximately 7,000 burn injuries, 2,000 hospitalizations, and 400 fatalities per year. The variation in reported figures reflects challenges with consistent incident categorization and reporting—many arc flash injuries are documented as burn cases rather than electrical incidents.
The thermal hazards during an arc flash event are extreme. Temperatures can reach 35,000°F, vaporizing metal conductors and igniting clothing. Molten metal droplets can travel at speeds exceeding 700 miles per hour. Pressure waves from the explosive expansion of air can throw workers across rooms and cause hearing damage at sound levels reaching 140 decibels.
A study of arc flash incidents found that two-thirds of injured workers had failed to conduct an arc flash analysis to determine appropriate PPE before beginning work. Even when hazard analysis was performed, approximately half of workers suffered burn injuries from not wearing gloves or face shields with hard hats. These findings emphasize that having an arc flash study is only effective when the information drives actual safety practices.
Reducing Arc Flash Hazard Levels – Safety Through Design
An arc flash study does more than document existing hazards—it identifies opportunities to reduce incident energy levels and improve worker safety. Several strategies can significantly lower arc flash risks. Engineers specializing in this field would benefit from reading IEEE 1814™ IEEE Guide for Electrical System Design Techniques to Enhance Electrical Safety.
Protective device settings optimization often provides the most direct path to hazard reduction. Since incident energy increases with fault clearing time, adjusting relay or breaker settings to clear faults faster reduces worker exposure. The challenge lies in maintaining proper coordination between devices while achieving faster clearing times. Engineers performing arc flash studies typically evaluate setting adjustments as part of their recommendations.
Arc reduction maintenance (ARMS) or maintenance mode (MM) switches allow workers to temporarily reduce arc flash hazard levels during maintenance activities. These switches change protective device settings to clear faults faster while maintenance is being performed, then return to normal settings for standard operation. This approach provides enhanced protection when workers are most at risk without compromising system selectivity during normal conditions. Safety training must address the need to return these switches to normal after use.
Arc-resistant equipment contains the energy from an arc flash event and directs it away from workers. Modern switchgear and motor control centers can be specified with arc-resistant construction that significantly reduces or eliminates worker exposure during arc flash events, even when standing at the equipment front.
Current-limiting devices such as current-limiting fuses and certain circuit breakers can dramatically reduce incident energy by interrupting faults in less than one-half cycle. Where equipment ratings and coordination requirements allow, installing current-limiting protective devices may be the most effective mitigation strategy.
Remote operation and monitoring removes workers from arc flash hazards entirely. Remote racking devices allow circuit breakers to be inserted or removed from a safe distance. Infrared windows permit thermal scanning without opening equipment enclosures. These approaches eliminate exposure rather than merely reducing it.
Choosing an Arc Flash Study Provider
Selecting a qualified provider for your arc flash study ensures accurate results and actionable recommendations. Several factors distinguish experienced, capable firms from less qualified alternatives.
Engineering credentials matter for arc flash work. Look for firms with licensed professional engineers who specialize in power systems analysis. Experience with IEEE 1584 calculations, protective device coordination, and the specific equipment types in your facility indicates relevant expertise.
Software and methodology should align with current standards. The provider should use recognized power systems analysis software and apply IEEE 1584-2018 calculation methods. Ask about their approach to electrode configuration selection and how they handle equipment outside the standard’s voltage or current ranges.
Scope of services varies among providers. Some firms offer only basic arc flash calculations, while others provide comprehensive studies including short circuit analysis, coordination studies, equipment evaluations, and mitigation recommendations. Understanding what’s included helps compare proposals accurately.
Deliverable quality affects the usefulness of the final product. Request sample reports and labels from prospective providers. Clear, well-organized reports with actionable recommendations deliver more value than dense technical documents that require interpretation. Labels should be durable, compliant with current standards, and clearly readable.
Post-study support can add significant value. Some providers offer training services to help workers understand arc flash hazards and use study results effectively. Others provide ongoing relationships that facilitate future updates and modifications. Consider how the provider can support your long-term electrical safety program.
Maintaining Your Arc Flash Program
Completing an arc flash study marks the beginning of an ongoing safety program rather than a one-time compliance exercise. Effective maintenance ensures the study remains accurate and workers stay protected.
Document changes to the electrical system as they occur. Establish procedures requiring engineering review of proposed modifications for potential arc flash impacts. Minor changes may not require full study updates, but they should be evaluated and documented.
Track the review schedule to ensure the five-year accuracy review occurs on time. Many facilities establish annual internal reviews to catch changes that might require updates before the formal five-year deadline.
Maintain label condition through regular inspections. Replace labels that become illegible, damaged, or detached. Verify that labels reflect current study data, particularly after any system modifications.
Integrate training with the arc flash study results. Workers must understand how to read arc flash labels, select appropriate PPE, and follow safe work practices. NFPA 70E training should occur when workers are first assigned to electrical tasks and be refreshed at least every three years or whenever procedures change. Comprehensive electrical safety training programs help ensure workers can apply study results effectively in the field.
Communicate with stakeholders about arc flash requirements. Contractors working on your electrical systems need access to arc flash study data and must follow your facility’s electrical safety procedures. Clear communication prevents incidents caused by outside parties unfamiliar with specific hazards.
Conclusion
An arc flash study provides the foundation for protecting workers from one of the most severe hazards in industrial and commercial facilities. By quantifying incident energy levels and establishing appropriate safety measures, these studies translate regulatory requirements into practical protection.
The investment in a proper arc flash study—and the ongoing program to maintain its accuracy—pays dividends in worker safety, regulatory compliance, and reduced liability exposure. Facilities that approach arc flash assessment as a continuous improvement process rather than a compliance checkbox create safer working environments and demonstrate genuine commitment to their workforce.
If your facility has electrical equipment operating at 50 volts or higher, or if your existing arc flash study is approaching the five-year review threshold, now is the time to evaluate your arc flash program and ensure your workers have the protection they need. Contact our team to discuss your facility’s arc flash study requirements.
