Arc Flash Studies: A Guide for Industry Leaders (2023)
This is my complete guide to arc flash studies in 2023.
In this guide you’ll learn the answers to these questions:
- What is an arc flash study?
- Why is an arc flash study is important?
- Is an arc flash study required by law?
- When is an arc flash study required?
- How often is an arc flash study is required?
- Who can perform an arc flash study?
- How much does an arc flash study cost?
- And much more…
Let’s get started.
- Chapter 1: Arc Flash Study Basics
- Chapter 2: Legal Requirements and Liability
- Chapter 3: Benefits of an Arc Flash Study
- Chapter 4: Getting an Arc Flash Study Done
- Chapter 5: Keeping Things Up-to-Date
- Chapter 6: What Comes After an Arc Flash Study
CHAPTER 1: Arc Flash Study Basics
Whether you are a maintenance manager, safety professional or electrical supervisor at some point you will need to evaluate the necessity of an arc flash study at your facility (or facilities).
Before we get into the details, I want to make sure you have a good handle of the basics of an arc flash study.
So, in this chapter that’s what we are going to go over.
And we’ll start with a basic definition.
What is an Arc Flash Study?
An arc flash study (also known as an arc flash analysis) is an electrical engineering analysis of a facility’s electrical distribution system that determines how hot an electric arc explosion can get (what’s known as the incident energy) at any point that a worker might interact with that system.
The arc flash study produces all the information required to label each piece of electrical equipment with the specific level of the incident energy (measured in cal/cm2) available at each individual piece of equipment.
Typically, every piece of electrical equipment will have a different incident energy level (unless it’s fed from the exact same location).
Why is an Arc Flash Study Important?
An arc flash study is important because without it your workers (either your employees or contractors) have no practical way of knowing how hazardous the equipment is that they are working on.
Electrical safety (all safety for that matter) comes down to understanding two things.
Hazard and risk.
An arc flash study provides an understanding of the hazard. Specifically, the severity of the hazard can range from the onset of 2nd-degree burns (1.2 cal/cm2) to catastrophic levels of heat (which would be deadly).
Your arc flash training would provide an understanding of the risk.
And for the record…
I say there is no practical way of knowing because there is another method but it is not very useful and I’ve never come across a company in any industry that has implemented it correctly.
What’s the Alternative?
The alternative to doing an arc flash study is using what’s called the Arc Flash PPE Category Method (sometimes referred to as the Arc Flash PPE Category Table Method).
To make a long story short it has two major hurdles to overcome:
- You need to know the maximum available short circuit current; and
- You need to know the maximum fault clearing time.
Most people don’t know these things…
And in order to figure them out, you need to do about 95% of the work required to do an arc flash study.
And if that’s not enough of a reason to stay away from this method, once you are done you get a very conservative estimation of the hazard level (which means wearing more PPE than necessary).
So, stick to doing the arc flash study.
Is arc flash study the same as short circuit study?
The simple answer is no. A short circuit study is merely one of the steps to an arc flash study. A short circuit study is performed to calculate the magnitude of current at each piece of equipment in the event of a fault or short circuit. Arc flash studies will use the short circuit study results (both max and min) in combination with the equipment’s protective device curve to determine the trip time and thus the incident energy or arc flash hazard of the equipment.
CHAPTER 2: Legal Requirements and Liability
Now that you’ve got some of the basics down of what an arc flash is and how deadly it is you need to know what your responsibilities are from a legal standpoint.
This really does boil down to what country you work in.
Since the two most prominent standards on electrical safety and arc flash are NFPA70E and CSAZ462 I’ll focus on the United States and Canada respectively.
So let’s get into this chapter.
Is an Arc Flash Study Required by OSHA?
As of January 1, 2015, an arc flash study is required by OSHA. You can find this requirement listed in the standard 1910.269 Electric power generation, transmission, and distribution.
Here’s what it says:
“1910.269(l)(8)(ii) - For each employee exposed to hazards from electric arcs, the employer shall make a reasonable estimate of the incident heat energy to which the employee would be exposed.”
As I mentioned in chapter 1, the only practical way to make an estimate of the incident heat energy is by performing an arc flash study.
Is an Arc Flash Study Required by OH&S?
There are fourteen jurisdictions in Canada (one federal, ten provincial and three territorial) and each has it’s own occupational health and safety legislation.
Each of these refers to protecting the employee from electrical hazards but do not go into much more detail than that.
However, there is one Bill that everyone can get behind.
Bill C-45 (The Westray bill) is an amendment to the Canadian Criminal Code which states:
"217.1 Every one who undertakes, or has the authority, to direct how another person does work or performs a task is under a legal duty to take reasonable steps to prevent bodily harm to that person, or any other person, arising from that work or task."
So if you (or anyone in your company) are directing electrical work, and there is a possible exposure to an arc flash the first reasonable step would be to figure out the hazard levels associated with that equipment.
Thus, requiring an arc flash study to be completed.
When is an Arc Flash Study Required?
Regardless of the industry you are in or the country in which you work you can ask yourself these questions to figure out if you really do need an arc flash study:
- Is electrical work required to keep your operation running? Yes or No.
- Does the electrical equipment to be worked on have the capability of producing an arc flash (typically anything rated above 208 volts)? Yes or No.
If you answered Yes to both of these questions then you need an arc flash study.
Who is responsible for the arc flash study?
This is a very important question. I’ve heard several people claim things like “We contract all our work out” or “we don’t own the facility” as a way of refusing responsibility for purchasing an arc flash study. I can understand their perspectives, as few want to take responsibility for something that isn’t theirs. However, this still raises the question – who IS responsible?
Ultimately, it comes down to who owns the equipment! At the end of the day, the owner of the equipment is responsible for identifying the hazards at their site and making them known for on-site workers and contractors. A common myth is that contractors should come with the knowledge to work on any piece of equipment safely.
However, this is not the case, it is again the duty of the equipment owner to ensure the contractor he has hired knows how to work safely!
Who can perform an arc flash analysis?
Now that we know who is responsible to purchase the study, the next question to answer is who can perform the study. An arc flash study can only be performed by a qualified electrical engineer who is recognized by an engineering association.
This means that if you want to perform your arc flash study internally, you will likely need to hire a qualified electrical engineering team and purchase whatever software and equipment they require.
Common Reasons People Think They Don’t Need One
1. “We contract all of our electrical work out.”
I hear this one all the time, but it doesn’t mean you are off the hook.
Contractors, by law, are an extension of your workforce and when they are under your direction you are liable.
They are essentially treated as employees for the time that they are working on your site.
2. “Our electricians are all qualified and/or certified.”
This may be true and is a great asset to your organization, but it doesn’t mean they can run complex calculations with thousands (maybe millions) or variables in their head.
Without specialized software and knowledge, electricians can’t calculate the arc flash hazards.
3. “We’ve never had an arc flash before… we have a great safety record.”
*Long sigh accompanied by a facepalm*
What’s the old saying?
Past performance is not indicative of future results.
While past performance does matter (companies with better track records are less likely to experience incidents) it doesn’t hold up very well in the court of law.
Is the arc flash study date required to be on the labels?
If we were to look up this question in the standard, then the answer is yes. However, it is also true that nothing is required so long as you have a system in place to ensure the safety of the workers and prove your due diligence.
So, what is the value of having the date the study was performed on the label? If you want it just so you can wait until one of your workers notices the 5 years are up and that its time for new labels… then that’s okay. However, a better value would be to think about why you need to update your labels in the first place! Typically labels need to be updated every time a significant change is made.
A significant change would include things such as:
- a new installation or system modification,
- a change in utility or power source,
- a change in system impedance/configuration/loading, or
- a change in protective devices/settings.
From above, we can see that 3 of the 4 options are all internal changes. This means that only a significant change to the utility or power source should go by unnoticed. To remedy this, check in with your utility company annually (no more than 5 years) to see if they have had any significant changes. By choosing to update your labels every time a significant change has been made, you will not only be able to keep your workers safer, but also avoid the sometimes-unnecessary updates. In this way, you can focus on updating only the labels that were affected by the significant change and avoid updating every label.
Anyone who has attempted to remove an arc flash label, knows it is no easy task. It can be quite time consuming to remove and update every label, every 5 years. So, at the end of the day, as long as you have a system in place to recognize anytime you’ve had a significant change to your system, and update the labels accordingly, you can omit the date from the label.
CHAPTER 3: Benefits of an Arc Flash Study
Having access to hazard information is the obvious benefit of doing an arc flash study.
But don’t let that fool you into thinking it’s the only benefit.
In this chapter, I’ll go over all the benefits you’ll receive from doing an arc flash study and believe me, there is a lot!
So let’s dive in.
Arc Flash Labels Posted On Equipment
At the end of the day having the arc flash labels posted on your equipment is what you are after.
This provides the end-user with all of the necessary hazard information they need to perform their task safely.
There are three things with regards to arc flash that you want to make sure are listed:
- Arc flash incident energy level (measured in cal/cm2)
- Arc flash boundary
- Assumed working distance
Shock Hazard Information Listed
We haven’t talked about shock hazards much in this article but one of the added benefits to an arc flash study is also getting a better understanding of the shock hazards at each piece of electrical equipment.
Shock hazard is dictated by the voltage level of the equipment and this information (along with boundaries and PPE requirements) should be listed on the arc flash label.
Clear PPE Requirements
The first step is understanding the hazard levels.
The second step is deciding how to deal with them.. and more times than not arc flash PPE will be involved.
Completing the arc flash analysis gives your workers 100% confidence that they can choose the correct PPE for the job.
Safe Working Distances are Defined
There are three very important safe working distances one must understand and have information about with regards to electrical safety.
- The Arc Flash Boundary - this is the distance from an arc flash incident that a person could stand to remain relatively unharmed (they would still be exposed to about 1.2cal/cm2 which is the onset of a second-degree burn).
- The Limited Approach Boundary(shock) - this is the distance away from an electrical source that all unqualified persons must be kept away from the equipment (while electrical work is being performed).
- The Restricted Approach Boundary (shock) - this is the distance away from an electrical source at which an electrical worker must be wearing protective PPE for shock protection.
All of these distances should be posted on your labels.
Updated Single Line Diagrams
Having an up-to-date single line is a must.
Not only is it a legal requirement to post single line diagrams in your electrical rooms but it also is foundational for your electrical safety program.
Most electrical jobs will begin by de-energizing the system and proving zero energy.
Without up-to-date drawings, your workforce will have a hard time determining if they’ve got the right disconnect for the panel they are working on.
Proof of Your Due Diligence
In the event of a serious injury or fatality, the incident investigators will be looking for evidence that the employer had taken every reasonable precaution to reduce the risk of the incident.
Specifically, the investigators will look for these three things:
- Did the employer properly identify the hazards and notify the workforce of them (arc flash study and labels)?
- Did the employer ensure that the workers had the appropriate training?
- Did the employer have an effective policy in place and was it being followed?
CHAPTER 4: Getting an Arc Flash Study Done
If you are still reading this article then I’m assuming you are bought into the idea of getting an arc flash study done.
Now, you need to figure out how to get it done.
In this chapter, I’ll go over the steps you need to take in order to get the right person (with the proper qualifications) on the job.
Let’s dive in!
Who Can Perform an Arc Flash Study?
An arc flash study must be performed by a licensed professional engineer who has the appropriate amount of experience with power system studies and arc flash hazard analysis.
The individual who completes the study can be an in-house engineer, from an external general engineering firm, or ideally, from an arc flash study company.
Developing an Arc Flash Study Cost Estimate
The cost of an arc flash study is directly proportional to the time it takes the engineer to complete the work.
The trick is to figure out how much work is required to end up with quality labels that you can trust.
To get started, try going through the steps outlined in this arc flash study cost estimate post.
Fundamentally, you need to determine:
- The size of your facility (square footage helps figure out how long it will take to get around the place).
- How much electrical equipment do you have (usually a single line diagram has everything required for an arc flash analysis)?
- How much information do you already have (and if it’s any good)?
From that, anyone who has a good handle on how that translates to engineering hours can come up with an accurate estimate.
Creating Your Arc Flash Study Scope of Work
When it comes to putting together your arc flash study scope of work you don’t have to worry so much about the technical details of how to perform an arc flash study as you do the practical steps of performing a successful project.
IEEE 1584 Guide for Performing Arc-Flash Hazard Calculations takes care of the technical side for you (as long as you specify it as the standard to follow).
IEEE 1584.1 Guide for the Specification of Scope and Deliverable Requirements for an Arc-Flash Hazard Calculation Study in Accordance with IEEE Std 1584 is a great tool to help you define your scope of work.
Regardless of what you refer to, you will want to make sure that whoever does your study includes the steps that will increase the accuracy of the study (steps 1-3 below), and then increase the usefulness of the study (steps 3-6 below).
An Arc flash study scope of work must include the following items:
- Data collection - gather all system data from documentation, specifications, equipment nameplates, datasheets. inspection and maintenance reports, and field verifications.
- Single line diagram review - ensure the accuracy of the single line diagram and that all equipment is accounted for.
- Power system model - use professional arc flash software to build an engineering model of the electrical power system.
- Complete the arc flash calculations and analyze the results (using IEEE 1584-2018 as the basis of the calculations).
- Write a detailed report of the findings.
- Print the arc flash labels and post them on the equipment.
Specify Your Arc Flash Study Report
Engineers are great at packing reports full of information.
What you are concerned with though is the information that will help you protect your workers.
That’s why you need to be clear on what goes in your arc flash study report.
Make sure you ask for these 4 things (on top of all the “fluff” you’ll usually receive):
- A table that shows all of your equipment and the associated incident energy for each piece (this should be included already, but it’s very useful).
- Recommendations on what arc flash PPE you should have available for your workforce.
- A list of recommendations on how to improve (by lowering the incident energy) your arc flash numbers.
- A list of electrical engineering “red flags” that were noted during the study. These may or may not impact the arc flash study results but could be serious safety concerns.
CHAPTER 5: Keeping Things Up-to-Date
Once you’ve put all the effort into getting an arc flash study done, you’ll want to make sure you keep things up to date.
With a good strategy, you can maintain your study for years for a reasonable investment (both time and money).
In this chapter, we will go over a few of the misconceptions with regards to maintaining your model and give you some ideas on what you should do.
So let’s keep going.
Do You Need an Arc Flash Study Every 5 Years?
At a minimum, you need to review your arc flash study every 5 years. This means that you need to account for any changes to the electrical distribution system or for changes to the IEEE 1584 standard (the latest update was in November 2018).
Oftentimes, companies are under the impression that they have to complete another arc flash study at the 5-year mark.
This is just plain wrong.
If you have maintained your system model or there have not been any significant changes, then everything would be the same.
A review is all that is required.
Accounting for the 2018 IEEE 1584 Update
Any arc flash study performed prior to November 2018 used empirically derived equations that were based on as little as 300 laboratory tests.
The latest version (IEEE 1584-2018) uses more than 2000 additional tests to come up with equations that are closer to real-world situations.
Some of the most significant changes are:
- Inclusion of both vertical and horizontal bus configurations
- Factoring in enclosure size
- Accounting for variations in arcing current
- Additional voltage ranges introduced
- New formulas added
It has been found that using the new equations some arc flash levels are significantly higher than what was earlier thought.
Any study performed prior to November 2018 should be updated.
For more details on the changes, I recommend reading Jim Phillips’ post on the topic.
How Often Should an Arc Flash Study Be Done?
An arc flash study only needs to be done once.
However, revisions, modifications and updates are required for items such as:
- Changed fuse sizes
- Changed relay settings
- Additions of new equipment
- Changed transformer sizes
- Updates to the standards
- Errors found in original data
- and more
Ideally, you are making these revisions any time you make a change to the system and then verifying that the arc flash labels (and incident energy values) are not impacted by the change.
At an absolute minimum, you should be accounting for these changes on a 5-year cycle (as mentioned above).
If you do find that the new numbers are significantly different (an example would be that the PPE your workers have is no longer rated for the incident energy) then you’ll have to print a new label.
CHAPTER 6: What Comes After an Arc Flash Study?
In my opinion, getting the arc flash study completed is only the beginning.
Remember, the reason we did it in the first place is to increase the safety of your workers.
Identifying the hazards is a crucial and necessary step but now we want to go deeper.
How can we improve on these numbers?
What training do our workers require?
Is there anything else to consider?
Let’s find out.
Arc Flash Mitigation
Arc flash mitigation techniques are primarily considered to be engineering activities that result in the overall reduction of arc flash levels (incident energy levels).
Once an arc flash study has been completed, the focus should be given to the equipment that has the highest incident energy levels (severity of consequence) and then the equipment that is most frequently accessed (increased likelihood of occurrence).
The following is a list of proven arc flash mitigation techniques you could explore further:
- Zone-selective interlocking
- Differential relays
- Maintenance switches
- Arc flash detection relays
- High-resistance grounding
- Current-limiting protective devices
Arc Flash Training
To keep things fairly straightforward you can divide your workforce into two buckets.
- People who do electrical work; and
- People who don’t
When it comes to arc flash training, the people who have nothing to do with arc flash should still have some basic level of the hazards just in case they find themselves working near these hazards.
The need to be able to recognize where those hazards might exist and be able to stay away from them.
I would call this arc flash hazard awareness training.
Now, for the electrical workers, they need to go a little bit more in-depth.
This article here gives a lot more information on what should be covered in an arc flash training course.
Fundamentally, you want your electrical workers to:
- Understand the severity of arc flash
- Understand how it happens (more from a practical side of things than a scientific)
- Know how to protect themselves if an arc flash happens
- Learn about the safety-related work practices that will reduce their risk
- Learn about the arc flash PPE, Tools and equipment
- Understand how to work safely if they can’t turn things off
Arc Flash Study Results
What results should you expect from an arc flash study? Many companies sought out arc flash studies in order to get those “shiny arc flash labels”, but are those really all an arc flash study has to offer? An arc flash study has the ability to not only identify and quantify electrical hazards, but also uncover potential problems that can increase the likelihood of those hazards being exposed to workers.
Arc flash studies can accomplish this in a number of ways. One way is through equipment interrupt ratings. As an arc flash study incorporates a short circuit study, an arc flash engineer can compare equipment/protective device interrupt ratings with the maximum available short circuit current. This can be a vital component of the study, as this will deem whether any equipment may fail in the event of a fault and not operate as expected, which can void the arc flash labels!
Another means of reducing risk is mitigation through the use of time current curves (TCCs). All software used by arc flash engineers has the potential to create TCCs which allow engineers to visualize how the protective device will respond to the fault current. By using this tool, engineers can recommend optimal protective devices or settings to mitigate hazards and prevent nuisance tripping.
Some companies (like ours) will even take things a step further! Every time we perform an arc flash study, we always include several bonuses like an updated single line diagram, a PPE plan, and training sessions! We have recognized that an arc flash study, although a very useful exercise, does not cover all the bases. It may give you the hazard information but doesn’t explain how to apply it. This is why we began offering package deals – because an arc flash study is only the beginning!
I hope this article has helped explain the different elements of an arc flash study.
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If you have any questions, you can always reach out to me at email@example.com.
Looking To Learn More About Arc Flash Studies?
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