In this article, I’m going to teach you everything you need to know about how to read arc flash labels.
Knowing how to do this properly is so important!
In my opinion, too many people don’t understand all the information on the label.
So to help, I put together this guide.
After reading this you will understand:
- What is an arc flash label?
- What’s the required information on the label?
- What different examples look like (and offer).
- What locations in the field are the labels required to be placed?
- What each component of the arc flash labels means.
- Why the information is important; and
- How to apply that information to your safety procedures.
What Is An Arc Flash Label?
To get started we had better define exactly what it is that we are talking about.
Here’s my unofficial definition…
Also known as arc flash stickers (or electrical equipment hazard labels), arc flash labels are warning labels (not danger labels) that tell a worker information about the potential of electrical explosion or high voltages.
These labels give them an idea of the personal protective equipment required to stay safe while working on the particular equipment.
If you don’t know how to read them… then you won’t know how to stay safe!
Arc Flash Label Requirements
What is required on the label and what is useful on the label are two different things altogether!
The bare minimum is a warning label that states the hazards.
It’s says something like “WARNING: ARC FLASH and SHOCK HAZARD”.
But, that’s not all that useful.
At least not for an electrician.
Electrical workers need to know all the information in order to make the right decision on what personal protective equipment and tools to choose for the job!
Here’s is my list of the arc flash label requirements:
- Arc Flash and Shock Hazard
- Incident Energy (in cal/cm2)
- Working distance
- Arc Flash boundary
- Shock hazard level (volts)
- Limited approach boundary
- Restricted approach boundary
- Glove class
- Equipment and label information
With all of this information on your arc flash stickers then your workers will know what’s going on.
Another benefit to using this much data is that you will be able to keep track of things over the years!
Arc Flash Warning Label Examples
There are a few different styles you may see for the labels but here are the most common.
First, the basic warning label.
As I mentioned before, this one might satisfy the standards and regulations for safety signs and tags but it’s fairly useless in the real world.
Next is a middle-of-the-road label with a little bit more information but still not as much as I like to see.
Next is an example of a custom arc flash label that we generated during an arc flash study.
This has all the information I listed above.
You can see that there is a lot more information.
Exactly what an electrician needs to do the job correctly!
But now let’s ask the question…
On what equipment should you place your arc flash warning stickers?
To find out keep reading…
Where Are Arc Flash Labels Required?
At this point you may be thinking “okay, this is great… but where are these labels supposed to go?”.
Remember, the purpose of the warning label is to draw the attention of the worker and prepare them for the hazards they are about to face.
So you’ll want them on anything that an electrical worker might have to open up and be exposed to electrical hazards.
In a perfect world, there would be a sticker on every single piece of electrical equipment.
But, in reality, that just doesn’t happen…
So what’s the most important equipment?
Here is a quick list of where you should expect to see arc flash labels:
- Transformer enclosure doors (line and load side)
- Motor control centres
- Splitter panels
- Field disconnects (optional)
With that, I think we are ready to move onto figuring out what all of this information really means!
So, let’s go to the next section.
How To Read Arc Flash Labels
We are finally ready to go through each component on the arc flash warning label.
Reading them correctly and applying the proper safety protocols is the most important part of the electrical workers job at staying safe.
It might seem like a small thing, but one small mistake can lead to catastrophic results.
So what are you waiting for?
Let’s get into it.
At the top of the label is the warning label.
It’s a warning designed to grab your attention and make you aware of the hazards that exist.
Note that it explicitly describes two hazards (arc flash and shock).
This is very important as a shock hazard is statistically a greater danger than its counterpart.
Another thing to mention with the warning label is the color.
Orange is a safety signs color which typically means moderate risk.
Don’t let this fool you!
With electrical hazards I would agree that the risk is moderate, however, the hazard level is extremely high!
The reason for this is that when the electrical panel doors are closed the risk is moderately low that anything will happen… hence the orange arc flash warning labels.
#2: Working Distance
Not to be confused with the limited approach boundary (which it often is), the working distance is the assumed distance of an electrician’s torso from a perspective arc flash source.
Typically, standing in front of a 600 volt MCC bucket your body is going to be about 18 inches away.
The thing you need to remember is that the incident energy on the label is the energy expected at that specific working distance.
The working distance is used in the calculation and the incident energy numbers will change if you work from a different distance.
If you get closer the energy you are exposed to goes up, if you get further away it goes down.
Distance is your friend when it comes to arc flash.
#3 Incident Energy
This is the one you are probably most familiar with if you have been using arc flash labels at all.
The incident energy is the amount of thermal energy that you will be exposed to during an arc flash event.
It’s really really hot.
The key here is to make sure your PPE (Face shield, balaclava, shirt, pants, gloves, boots) can withstand more than the posted incident energy level.
Take a look at the tag on your PPE and make sure that the Arc Thermal Performance Value (ATPV) is greater than the incident energy level posted.
#4 Arc Flash Boundary
At this distance, someone standing at the boundary wearing normal everyday clothes would get a second-degree burn if an arc flash occurred.
Seems like a funny place to put a boundary.
The reason you need this number is for helping to decide where to put your barricades to keep unqualified people away from the work area.
You will also need to take into account the shock hazard limited approach boundary when choosing your barricade.
I always say to pick the greater of the two and add a couple of feet.
Now let’s take a look at the right-hand side, titled Shock Protection
#5 Shock Hazard when cover is removed
In order to test the system (either to verify it’s de-energized or to troubleshoot), you are going to need to select the appropriate test instrument.
The voltage level is the most important piece of information to help you select the right one.
This is how shock hazards are measured… by voltage!
If the label does not list the glove class (our example label does), then you need to use the voltage level to determine what rubber insulated gloves you need to wear.
#6 Limited approach boundary
Once you have crossed the limited approach boundary you are now in the territory of a potential shock hazard.
This number signifies how close you can come to the equipment if you are an untrained or unqualified person.
The limited approach boundary is a safe distance away from exposed live conductors.
Use this number along with the arc flash boundary as discussed above to help set up your barricades.
#7 Restricted approach boundary
At this distance from an exposed conductor, the risk of arc over is increased.
Have you ever watched those YouTube videos where something comes too close to a power line and the electricity looks like it jumps over to the object before it even gets there?
Well, this is the same thing that can happen inside an MCC bucket or switchgear assembly except the moving object is you.
Once you are inside the restricted approach boundary you need to protect yourself.
What’s important to remember here is your insulated rubber gloves.
You just don’t go past the restricted approach boundary without them on.
Video to show why there is a restricted approach boundary
#8 Glove Class
This number is directly correlated to the voltage level and helps you choose the proper rubber insulated gloves.
The numbers are coming from this glove chart.
Cross-reference the number on the label to the number on the glove tag and make sure you have a match!
Now you know exactly what gloves you need for the job.
Quick side note on gloves…
Rubber insulated gloves with leather protectors will also protect you from arc flash hazards!
It’s a great idea to make sure:
- the equipment information,
- date of the study,
- responsible engineer for the calculations,
- and any other pertinent information
is listed at the bottom of the label to help maintain the system model when changes are made or updates are required.
Hopefully, you now have a full understanding of the importance of each piece of information on an arc flash label and how it’s going to help you get the job done safely.
Now it’s your turn!
Please leave a comment. Let me know…
- what section has helped you the most;
- if you see any ways I could improve this article; or
- if you have any questions.