Arc flash studies are something most industrial facility managers have heard of but fewer have actually completed for their own sites. I’ve talked to maintenance supervisors who’ve been running the same equipment for fifteen years without one. They know their systems well, they haven’t had a major incident, and they figure that means things are fine. What they don’t always appreciate is that an arc flash event doesn’t give you a warning before it happens.
It doesn’t build up gradually in a way that gives you time to respond. It happens in a fraction of a second and the consequences for anyone nearby can be catastrophic. At Roman Electric, we work with industrial facilities on electrical safety assessments regularly and the gap between what facilities assume about their systems and what the analysis actually reveals is often significant.
What an Arc Flash Actually Is
The importance of arc flash studies can be better understood after knowing what an arc flash event is.
A sudden intense discharge of electricity, referred to as an arc flash, occurs when electricity travels through air between conductors or a conductor and ground. A large amount of energy is released in that instant. The arc point can reach temperatures of 35,000 degrees Fahrenheit, which is about four times greater than that of the sun. The explosion generates powerful heat energy, a pressure wave, molten metal, and UV radiation.
A worker can expect sustained severe burns, hearing loss, vision loss, or fatality if they are standing within several feet of an arc flash event. The level of potential injury depends on the incident energy released, which varies depending on the characteristics of the electrical system at the place where the outcome takes place.
This is not a theoretical risk. The Electrical Safety Foundation International estimates that arc flash incidents cause hundreds of fatalities and thousands of serious injuries in the United States every year. Many of those incidents happen at facilities that had no arc flash analysis in place and no proper labeling on their equipment.
What Arc Flash Studies Actuall Involve
Arc flash studies are a type of engineering analysis of an electric power system that indicates the incident energy at specific sites throughout a facility. This incident energy is used to establish safety boundaries and personal protective equipment environments for work near energised equipment.
The study process consists of several connected components.
Data Collection and System Modeling
The first step is gathering accurate data about the electrical system. That means documenting every significant component in the power distribution system including utility service characteristics, transformers, switchgear, panelboards, cables, and protective devices like breakers and fuses.
This data gets entered into power system analysis software that models how the system behaves under fault conditions. The accuracy of the study depends entirely on the accuracy of the input data. A model built on outdated or assumed data produces results that may not reflect what actually happens in the real system.
At Roman Electric, our arc flash study process starts with thorough field verification of system data rather than relying on existing documentation that may not reflect the current state of the system.
Short Circuit Analysis
The short circuit analysis calculates the maximum fault current available at each point in the system. This determines how much energy can potentially be released during a fault event. Higher available fault current generally means higher incident energy and more severe arc flash hazard.
Protective Device Coordination Study
The coordination study examines how protective devices throughout the system respond to fault conditions. When protection is well coordinated, the device closest to the fault operates first and secures the fault. Provided this takes place quickly and efficiently, energy released during an arc flash event will be minimized.
failures occur in upstream devices instead of or in addition to the device closest to the fault due to poor coordination. This lengthens the time of the arcing event and greatly increases the incident energy released.
According to the National Fire Protection Association, NFPA 70E requires employers to assess the arc flash hazard and establish arc flash boundaries and PPE requirements for all work near energized electrical equipment. Proper protective device coordination is central to managing that hazard at acceptable levels.
Incident Energy Analysis
Using the results of the short circuit analysis and the coordination study, the incident energy analysis calculates the actual arc flash hazard at each piece of equipment throughout the facility. The results determine the arc flash boundary distances and the arc flash PPE category or incident energy level that workers need protection for at each location.
These results get translated into arc flash warning labels that are applied to equipment throughout the facility. Those labels tell workers what PPE is required before opening or working near that equipment.
Why the Results Often Surprise Facility Managers
A common result of arc flash studies at facilities where one has never been done is that the hazard levels at certain equipment locations are much more hazardous than anyone thought.
This is a generic illustration of how incident energy levels correspond to hazard severity:
| Incident Energy Level | Hazard Category | Minimum PPE Required |
| Up to 1.2 cal/cm² | Category 1 | Arc-rated clothing 4 cal/cm² minimum |
| 1.2 to 12 cal/cm² | Category 2 | Arc-rated clothing 8 cal/cm² minimum |
| 12 to 40 cal/cm² | Category 3 | Arc-rated clothing 25 cal/cm² minimum |
| 40 cal/cm² and above | Category 4 | Arc-rated clothing 40 cal/cm² minimum |
| Above 40 cal/cm² | Extreme hazard | Detailed engineering review required |
Facilities operating without arc flash labeling often have workers performing routine tasks near equipment where the actual incident energy level requires Category 3 or Category 4 protection. Those workers are doing that work in standard work clothes because nobody has told them otherwise.
Regulatory Requirements Around Arc Flash Studies
The laws and regulations surrounding arc flash hazards management have become more clearly defined over time & the responsibilities of employers are real and enforceable.
NFPA 70E is the main workplace electrical safety standard. Employers must evaluate workplace happenings involving energized electrical installation for the likelihood of arc flash hazards and designate arc flash boundaries accordingly, at which PPE must be used by workers. It must also provide training on the hazards of arc flash to workers qualified to work on in-house electrical installations.
OSHA enforces arc flash safety using its General Industry Electrical Standards and the General Duty Clause when no specific standard applies to a situation. Failure to conduct proper assessments on facilities where arc flashes occur exposes them to significant regulatory scrutiny.
IEEE 1584 is the relevant standard that engineers use to do the incident energy calculations that underlie arc flash studies. The calculation strategy was revised in 2018, and the results were different hazard levels from those predicted by a study done beforehand. Facilities that had an arc flash study done before 2018 should evaluate whether their studies should be updated to the current standard.
How Often Arc Flash Studies Need to Be Updated
An arc flash study reflects the state of the electrical system at a specific point in time. Changes to the system change the validity of the study results.
Any significant modification to the electrical distribution system requires the study to be reviewed and potentially updated. That includes changes to utility service characteristics, transformer replacements, modifications to protective device settings, addition of significant load, and major equipment replacements.
NFPA 70E recommends reviewing arc flash studies whenever changes are made to the electrical system and at a maximum interval of five years even if no changes have been made. Systems do change in ways that aren’t always formally documented and periodic reverification ensures the study still accurately reflects reality.
Roman Electric provides arc flash study update services for facilities whose existing studies are outdated or whose systems have changed since the last study was completed.
The Connection Between Arc Flash Studies and Electrical System Reliability
Arc flash studies aren’t only about worker safety. The protective device coordination work that’s part of a comprehensive arc flash study also improves the reliability of the electrical system.
Poorly coordinated protection causes unnecessary tripping of upstream devices during faults, which takes down larger portions of the facility than the fault itself warrants. Good coordination means faults are isolated quickly and precisely, minimizing production disruption.
Facilities that complete arc flash studies frequently discover coordination problems that have been causing unexplained nuisance tripping for years. Correcting those coordination issues improves both safety and system reliability at the same time.
FAQs
Q: How long does an arc flash study take to complete?
A: It depends on the size and complexity of the electrical system. A straightforward single-facility study might take several weeks from data collection through final report. Larger or more complex systems take longer.
Q: Who is qualified to perform an arc flash study?
A: Arc flash studies should be performed by licensed electrical engineers with specific experience in power system analysis. The calculations involve specialized software and engineering judgment that requires appropriate credentials and experience.
Q: Does an arc flash study identify problems that need to be fixed?
A: Frequently yes. Studies often identify coordination issues, equipment deficiencies, and hazard levels that require engineering changes to bring to acceptable levels. The study report typically includes recommendations for mitigation.
Q: What does arc flash labeling on equipment actually tell workers?
A: Arc flash labels identify the incident energy level or PPE category at that equipment location, the arc flash boundary, the working distance used in the calculation, and the date of the study.
Q: Is an arc flash study required by law?
A: NFPA 70E requires arc flash hazard assessments for work near energized equipment and OSHA enforces electrical safety requirements. Facilities without arc flash hazard assessments are exposed to regulatory liability, especially if an incident occurs.
Conclusion
If you take the safety of electrical workers seriously in an industrial facility, then do an arc flash study. The hazard is real, there are regulations, and an arc flash incident at a facility with no hazard assessment or labelling, or PPE programmes will have severe consequences for workers and significant consequences for business.
A facility that carries out a proper arc flash study understands what its hazards actually are, has its equipment properly labelled, can train its workers on specific PPE requirements for specific tasks, and has a documented safety program demonstrating compliance with applicable standards.
Contact Roman Electric for arc flash studies engineered to satisfy the needs of your facility. If your facility has not had any arc flash studies done in the past or if your study is due for an update, you can come to our electrical engineering service team for assistance. We offer the engineering capability and the field experience needed to deliver a study that accurately reflects your system. The information your workers will receive from your arc flash study will help keep them safe.
