What Is An Arc Flash Study?
An Arc Flash study is a risk assessment of a workplace environment that determines Arc Flash hazards. An expert in electrical safety conducts an assessment to ensure that a company understands the risks their workplace poses to their team and how to protect against them. Assessment providers may also offer training to increase your team’s awareness and options for periodic reviews.
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Contents
What is the purpose of the arc flash study?
What is the purpose of an arc flash study? An arc flash analysis identifies electrical safety violations, hazards, and non-compliance in your facility. The assessment determines the incident energy to which a worker may be exposed and how to protect the worker from an arc flash accident and other electrical hazards.
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When should you do an arc flash study?
NFPA 70 (National Electrical Code) requires electrical equipment that may be serviced while energized to be labeled with potential arc flash hazards. Methods for performing and calculating arc flash hazard are defined in NFPA 70E – Standard for Electrical Safety in the Workplace and IEEE 1584 – Guide for Performing Arc-Flash Hazard Calculations. 
Arc flash hazard studies should be performed by experienced and qualified electrical engineers knowledgeable in power system engineering, IEEE 1584, NFPA 70E, short circuit, device coordination and arc flash studies. NFPA 70E states that arc flash hazard calculations need to be reviewed every five years or whenever there is a significant change in the electrical system.
- Bonus Content: What is an Arc Flash? An arc flash is an electrical explosion resulting from a release of energy that travels through the air between one conductor to another, or to ground.
- The results are often violent and potentially dangerous to personnel nearby.
- An arc flash may produce extreme temperatures, intense light, sound waves, and in extreme circumstances, an arc blast.
Personnel who experience an arc flash may suffer from burns, blindness, hearing loss, other bodily injuries and possibly death. An arc flash can be the result of several conditions, but some of the more common causes include:
Accidental contact with equipment Worn or gaps in conductor insulation Damaged equipment or equipment that is underrated for the available short circuit current Dust, corrosion or other impurities on the surface of the conductor
Bonus Content: How is an Arc Flash prevented? While it is impossible to completely prevent an arc flash, there are several ways to mitigate the risk. One way is to de-energize electrical equipment prior to performing work on it. This removes the arc flash risk while the equipment is in service and should always be the first choice of action.
- Another way is to perform an arc flash study on the system to determine the level of risk associated at each piece of equipment and identify the proper PPE needed to protect personnel in the case of an arc flash.
- Protective device coordination in conjunction with an arc flash study can identify additional steps to adjust upstream equipment and modify electrical systems to lower the risk at pieces of equipment.
Questions about Arc Flash Studies? Contact Nate Boland (319) 325-6171 back to Ask An Engineer
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What is arc study?
What is an Arc Flash Study? – An Arc Flash Study is an analysis of an electrical distribution system to determine by calculation the worst-case arc flash hazard that personnel could be exposed to if an arc flash event occurred. Once the Arc Flash hazard has been quantified, control measures can be put in place to mitigate the hazard.
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What is needed for an arc flash study?
The data requirements for an arc flash study can be broken down into three categories: impedance data for a short circuit study, protective device data to define the arc duration and equipment data used to define the enclosure size, bus gap and electrode configuration.
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Why is it called arc flash?
Preventing injuries – Both arc flash and arc blast can cause injuries and be potentially fatal. Taking the proper precautions to prevent an arc fault and stay safe if one does occur is important. Read Arc fault boundary and safety to learn what steps to take in order to stay safe.
Video transcript: This video is not intended to provide safety training. You must comply with your employer’s safety standards and obtain necessary training before making electrical measurements. In addition to shock hazards, one of the most dangerous anyone working with electricity faces is an arc flash.
An arc flash is an explosive release of energy from an electrical arc when the electrical current passes through ionized air. In less than a second, an arc flash is initiated from a phase to ground or a phase to phase fault. It can result from accidental contact with the electrical systems, the buildup of conductive dusts, corrosion, dropped tools, or improper work procedures.
The plasma arc has a virtually unlimited current carrying capacity once it’s established. The energy of an arc flash converts primarily to heat and light. Although there are other hazards created such as the arc blast or pressure wave, the acoustic wave, and toxic gasses. Within a millisecond, temperatures at the epicenter of an arc flash can reach 35 thousand degrees Fahrenheit.
That’s 4 times hotter that the surface of the sun. These extreme temperatures are capable of explosively vaporizing metals such as copper, aluminum, and steel. The presence of these vaporized metals can help sustain the arc causing a single-phase arc to propagate into a three-phase arc.
The arc blast that closely follows is a dynamic pressure wave created the instantaneous expansion of gas, air and the arc plasma ball. The pressure wave can cause panels to rupture, create flying debris, acoustic injuries, and physical trauma. An arc flash lasts until the overcurrent protectant devices open the circuit.
A fast-acting fuse may open the circuit in several milliseconds, or a circuit breaker may operate within six cycles or less but, by that time, the damage has already been done. You might think that these are isolated or infrequent events, but that’s not the case.
- Industry sources estimate that in the U.S., 5 to 10 arc flash accidents occur each day. The U.S.
- Bureau of Labor reported that in one recent year, 1 thousand electrical workers suffered shocks and burns, some fatal.
- Even though there are far more fatalities from shock than from arc flash, the injuries received from an arc flash can be devastating.
While you can’t totally eliminate the dangers of working with electricity, with careful planning and applying what you’ve learned here today, you can reduce them. On behalf of everyone at Fluke Corporation, thank you for watching.
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Who can perform an arc flash analysis?
Who can perform an Arc Flash Analysis? – An arc flash analysis should only be performed by experienced and qualified electrical engineers familiar with power quality, short circuit studies, NFPA 70E, and IEEE 1584. The person performing the analysis can be an in-house electrical engineer, from an external electrical engineering firm, or ideally, from a specialist arc flash analysis company.
IEEE 1584 – IEEE Guide for Performing Arc-Flash Hazard Calculations 1 IEEE Guide for the Specification of Scope and Deliverable Requirements for an Arc-Flash Hazard Calculation Study in Accordance with IEEE Std 1584™ Practical experience
What is the 2 seconds rule for arc flash?
If the time is longer than two seconds, consider how long a person is likely to remain in the location of the arc flash. It is likely that a person exposed to an arc flash will move away quickly if it is physically possible and two seconds is a reasonable maximum time for calculations.
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At what voltage is arc flash a risk?
Understanding the Arc Flash Warning Labels Each piece of equipment operating at 50 volts or more and not put into a deenergized state must be evaluated for arc flash and shock protection.
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What is the first step to an arc flash analysis?
STEP 1: Acquire existing as-built documentation – The usual starting point for an Arc Flash Analysis is to gather all of the existing electrical drawings that an Owner may have. These would typically include:
Drawings (such as floor plans) Riser one-line diagrams
If the documentation does not exist, electrical one-lines have to be developed in the field requiring a detailed field survey. The electrical one-line diagram is the facility electrical distribution road map and is a key part of an Arc Flash Analysis. 
A sample electrical one-line diagram
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How long does an arc flash study take?
An arc flash study is one of the most important requirements to recognize, measure and mitigate risk to electrical workers. In the event of an electrical incident such as arc flash burns or electrical shock, serious injury and even fatalities can occur.
The potential costs for an employer who fails to take preventive risk mitigation steps are estimated to be millions of dollars. Importantly, an arc flash study must be completed before a worker is exposed to an electrical hazard. An arc flash risk assessment should be reviewed every five years, or any time modifications are made to the facility that can effect the outcome of the study.
Major or sometimes minor variations such as fuse type or breaker setting adjustments can have a huge impact on personal safety. As part of a company’s safety protocols, an arc risk assessment provides insight into the steps an employer needs to take to protect workers.
- With the results of these risk assessment analyses, employers can mitigate ore reduce hazards to a manageable level.
- Providing labels to raise awareness, inform employees, and aid in selecting the proper PPE for the task.
- The studies usually take 4 to 6 weeks to complete, depending on the size of the facility.
ESS protocol for arc flash risk assessment includes the following:
Data Collection: Collect necessary data about the facility’s power distribution system, including transformers KVA and impedance, nameplate specifications, fuses, breakers, along with lengths and sizes of all cables. Engineering Analysis of the Data: Perform a short circuit analysis to determine the available fault current at each location. Protective Device Coordination: Determines which upstream overcurrent device will operate first based on fault currents and plotting the time current curves for the fuses or breakers found in the system. Arc Flash Calculations: Determine incident energy levels and flash protection boundaries and complete calculations of all relevant equipment based on IEEE. Arc Flash Study and Analysis Report: Once the calculations are completed a comprehensive report will be built based on the findings in your facility. Label Installation: Creation and installation of warning labels pinpointing incident energy and working distance, arc flash boundary, and nominal system voltage. Include Limited, Restricted approach boundaries, date, and recommended personal protection equipment (PPE) as well.
By individually analyzing these systems and labeling equipment to warn employees of the specific hazards found at that location, you can increase personnel and workplace safety. As required by OSHA and the NFPA 70E, Electrical Safety Specialists (ESS) offers arc flash risk assessment for ensuring worker safety.
- The purpose of our visit is to help save lives and money by safe work practices and minimize the possibility of injuries and lost time accidents.
- Our engineering technicians are experienced and trained on the intricacies of the data collection process for an arc flash study.
- ESS provides the highest quality of service available.
For more information about an arc flash study or electrical safety training provided by ESS, call (816) 925-0443. To request a quote, click here,
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What is an example of an arc flash?
Examples – One of the most common examples of an arc flash occurs when an incandescent light bulb burns out. When the filament breaks, an arc is sustained across the filament, enveloping it in plasma with a bright, blue flash. Most household lightbulbs have a built-in fuse, to prevent a sustained arc-flash from forming and blowing fuses in the circuit panel.
- Most 400 V and above electrical services have sufficient capacity to cause an arc flash hazard.
- Medium-voltage equipment (above 600 V) is higher potential and therefore a higher risk for an arc flash hazard.
- Higher voltages can cause a spark to jump, initiating an arc flash without the need for physical contact, and can sustain an arc across longer gaps.
Most powerlines use voltages exceeding 1000 volts, and can be an arc-flash hazard to birds, squirrels, people, or equipment such as vehicles or ladders. Arc flashes are often witnessed from lines or transformers just before a power outage, creating bright flashes like lightning that can be seen from long distances.
- High-tension powerlines often operate in the range of tens to hundreds of kilovolts.
- Care must usually be taken to ensure that the lines are insulated with a proper “flashover rating” and sufficiently spaced from each other to prevent an arc flash from spontaneously developing.
- If the high-tension lines become too close, either to each other or ground, a corona discharge may form between the conductors.
This is typically a blue or reddish light caused by ionization of the air, accompanied by a hissing or frying sound. The corona discharge can easily lead to an arc flash, by creating a conductive pathway between the lines. This ionization can be enhanced during electrical storms, causing spontaneous arc-flashes and leading to power outages.
As an example of the energy released in an arc flash incident, in a single phase-to-phase fault on a 480 V system with 20,000 amps of fault current, the resulting power is 9.6 MW, If the fault lasts for 10 cycles at 60 Hz, the resulting energy would be 1.6 megajoules, For comparison, TNT releases 2175 J/g or more when detonated (a conventional value of 4,184 J/g is used for TNT equivalent ).
Thus, this fault energy is equivalent to 380 grams (approximately 0.8 pounds) of TNT. The character of an arc flash blast is quite different from a chemical explosion (more heat and light, less mechanical shock), but the resulting devastation is comparable.
- Open air
- Ejected
- Equipment focused (Arc-in-a-box)
- Tracking
What is the most common arc flash?
Human error is the most common cause of arc flash. After a worker has performed the same task over and over without incident, they may bypass a maintenance step or develop a procedural workaround to save time.
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What PPE is required for arc flash?
PPE – safety glasses or safety goggles, hearing protection (ear canal inserts), voltage rated gloves with leather protectors. Clothing – Arc-rated long-sleeve shirt and pants or arc-rated coverall, arc-rated face shield or arc flash suit hood, arc- rated jacket, parka, rainwear, or arc-rated hard hat liner.
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What is the IEC standard for arc flash study?
IEC 61482-2:2009 – IEC 61482-2:2009 is applicable to protective clothing used in work if there is an electric arc hazard. Specifies requirements and test methods applicable to materials and garments for protective clothing for electrical workers against the thermal hazards of an electric arc based on: – relevant general properties of the textiles, tested with selected textile test methods, and – arc thermal resistance properties, such as:
- the arc rating of materials (ATPV or EBT50), when tested with an open electric arc under defined laboratory conditions according to IEC 61482-1-1, or
- the arc protection class of materials and garments (Class 1 or Class 2), when tested with a directed and constrained electric arc under defined laboratory conditions according to IEC 61482-1-2.
What is the first step to an arc flash analysis?
STEP 1: Acquire existing as-built documentation – The usual starting point for an Arc Flash Analysis is to gather all of the existing electrical drawings that an Owner may have. These would typically include:
Drawings (such as floor plans) Riser one-line diagrams
If the documentation does not exist, electrical one-lines have to be developed in the field requiring a detailed field survey. The electrical one-line diagram is the facility electrical distribution road map and is a key part of an Arc Flash Analysis. A sample electrical one-line diagram
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