What is an Arc Flash?

Electrical hazards can be some of the most important things to pay attention to in the workplace. These types of hazards can be extremely dangerous and can easily result in loss or damage of property, major injury, or even death. Luckily, with the proper procedures and the consistent use of safety equipment, you can protect your employees from these risks. One of the main electrical hazards to be aware of is the arc flash.

An arc flash, sometimes referred to as a flashover, can be an incredibly dangerous event. OSHA defines an arc flash as “a phenomenon where a flashover of electric current leaves its intended path and travels through the air from one conductor to another, or to ground.”

Arc flashes can happen within seconds with no prior warning, which is part of what makes them so dangerous. Temperatures in an arc flash explosion can exceed 35,000 degrees Fahrenheit, over three times hotter than the surface of the sun.


What Causes an Arc Flash?

Fortunately, many of the common reasons that an arc flash might occur are preventable and are typically credited to human error. A majority of arc flashes happen when maintenance staff are working on live equipment for repairs or testing and a short circuit or fault is accidentally caused.

Some of the other major reasons why an arc flash may occur include improper work techniques or processes, corroded equipment, improper tools or equipment, or lack of employee safety training, and even small animals or reptiles seeking shelter and warmth. Even something as seemingly simple as dust, accidental contact, condensation, or dropping tools could contribute to an arc flash.


Arc Flash Compliance

As you might expect, OSHA is very serious when it comes to identifying and remedying arc flash risks. OSHA mandates that all employers must identify electrical hazards and inform their employees of the situation at hand, as well as provide training and protective equipment. There are several specific regulations from OSHA and other organizations that you can refer to in order to learn more about arc flash analysis.

OSHA Standards 29-CFR, Part 1910, covers standards for acceptable work practices. Essentially, this standard discusses the required use of protective equipment in the presence of a potential electrical hazard and the responsibility of employers to have their workplace assessed and to provide protective equipment for their workers.

NFPA 70E sets forth how to ensure appropriate procedures are put in place to protect workers that may be handling exposed conductors or circuit parts with the potential to become energized. It also states that, if there is suspicion of a potential arc flash hazard, an Arc Flash Risk Assessment much be done. Finally, NFPA 70E establishes how to label panels properly in regard to the Arc Flash Hazard Warning Label.

You can also look to IEEE 1584, which informs workers how to perform the Arc Flash Hazard Study. NFPA Standard 70 states that the National Electrical Code provides information on ANSI compliance and proper warning labels.


Severity of Arc Flash Injury

Arc flashes almost always result in serious (and sometimes fatal) injury if an employee is around. The severity of the injury, however, depends mainly on the proximity of a person to the hazard, duration, and energy (in the form of heat) of the arc flash.

One of the most common injuries resulting from an arc flash is burns, particularly if the employee is not wearing fire-resistant clothing. Fire could break out and quickly spread throughout the facility as well. Potential injuries can come from flying objects impacted by the high blast pressure. Injury can even occur from the sound blast, as an arc flash can reach noise levels as high as 140 dB, which is as loud as a gun firing.

Protection Measures and Equipment

Employers and workers can take a number of steps to ensure the utmost safety when employees will potentially be exposed to an arc flash hazard. One of the simplest ways to prevent the hazard of an arc flash is to deenergize the equipment before work begins. Other protection methods like insulation, barricades, guarding, and grounding can also help to keep employees safe.

If you’re unable to deenergize the circuit for whatever reason, there is still a range of practices you can employ to prevent injury. It is ultimately up to the employer to develop and enforce any and all safety-related practices to put in place within the workplace, but some of these practices may include a written safety program, insulated tools, or an energized electrical work permit.

No matter what other measures an employer chooses to put in place, the use of personal protective equipment (PPE) is vital. PPE is divided into categories 0-4; the higher the category, the more protective the clothing is. For instance, category 0 is simply untreated cotton, which can only withstand 1.2 cal/cm2 of incident energy. However, category 3 consists of a cotton underwear fire-resistant shirt, fire-resistant pants, and fire-resistant coveralls and can withstand 8 cal/cm2 of incident energy.

Once an arc flash hazard analysis is performed, the information that results can help you make an informed decision about what level of PPE would be most appropriate for your workplace. For instance, Category 4 PPE is incredibly effective but can also be hot and cumbersome to work in, so if there is a way to decrease the workplace risk and allow your employees to wear a lower category of PPE, it is worth considering.


Being aware of the potential causes and risk of arc flashes can help you be more prepared and can prevent serious injury or even death. It all starts with an analysis of your facility. MTAEE is proud to offer electrical safety services to your businesses. Our Arc Flash Analysis is one of our most popular services and is always performed by an experienced field engineer who can help you understand your system and recommend the proper safety precautions to take.


Contact us today to learn more about our services or to schedule an appointment for an analysis!

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