What is Arc Flash PPE?

Arc flash personal protective equipment (PPE) is a combination of clothing and safety equipment worn for protection from arc flash and shock hazard by a person performing electrical work. Primarily, arc flash PPE is divided into the following subgroups:

 

  • Head, face, neck and chin protection

  • Eye protection

  • Hearing protection

  • Body protection

  • Hand and arm protection

  • Foot and leg protection

All arc flash apparel and equipment must be given an specific arc rating to ensure that it meets or exceeds the hazard levels present where the work is to be performed.

Using PPE to Protect Yourself from an Arc Flash.

There are many ways to protect yourself from an arc flash, but quite often your only option will be to use electrical arc flash ppe.

Ensuring you are covered head to toe with equipment that is properly rated is paramount to your safety.

In order to understand the arc rating you first need to understand what it is correlated to…

The incident energy value. Incident energy is the amount of heat energy produced by the arc flash explosion. Typically, it’s measured in calories per square centimeter (cal/cm2). So let’s say you are standing in front of 30 amp disconnect (600 volts) and an arc flash occurs. You would be exposed to a certain amount of heat energy.

Let’s just say we worked it out and it was 3.7 cal/cm2.

As long as your arc flash gear had a arc rating higher than 3.7 cal/cm2 then you will be protected from the arc flash.

But how do you determine the arc rating?

Keep reading to find out.

How to Determine the Arc Flash Rating

In order to determine the arc rating of a given material you have to send it for laboratory testing. Basically, they blow up the clothing or equipment in a lab and see if it passes the test.

What’s the test?

This depends on the type of personal protective equipment you are trying to get rated. Each type of protection has it’s own standard (or standards) for testing that it must meet. Here are the main ones:

  • ASTM F1506 (arc rated apparel)

  • ASTM F2178/F2178M (arc rated face shields)

  • ASTM F2675/F2675M (arc rated gloves)

  • ASTM F1891 (arc rated rain gear)

During the testing there are two things that can happen that determine the results of the test and therefor determine the arc rating. At a certain incident energy you will either reach the material’s Arc Thermal Performance Value or it’s Breakopen Threshold Energy. Whichever one comes first dictates the number that goes on the equipment’s tag. Usually, it’s the arc thermal performance value or ATPV Rating.

What is ATPV Rating?

When you are performance testing arc flash apparel you expose the material to a certain amount of heat energy. We call that the arc flash incident energy. The arc thermal performance value (ATPV) is the material’s ability to withstand the incident energy.

How do you determine the ATPV rating?

 

The value is determined by the amount of incident energy required to transfer enough heat through the material to create a 50% probability that the person wearing the ppe will experience the onset of a second degree burn.

 

What?

Yup, sounds crazy but this is how it works.

So… let’s say you are in an arc flash that is has an incident energy of 8 cal/cm2 and you are wearing clothing that is rated 8 cal/cm2 (because the ATPV was 8).

 

Now what?

Well… now there is a 50% chance that you will experience the onset of a second-degree burn. This means the skin under your clothing is exposed to about 1.2 cal/cm2.

What is EBT Rating?

Another factor in performance testing your arc flash gear is determining when it will break open. Break open is defined as a hole that’s either has an area of 16 mm2 or an opening of 25 mm in length. The breakopen threshold energy (EBT) is similar to the the ATPV… It’s the amount of incident energy that would result in a 50% chance that breakopen occurs.

What’s the Difference Between AR & FR?

There are many ways to protect yourself from an arc flash, but quite often your only option will be to use electrical arc flash ppe. Ensuring you are covered head to toe with equipment that is properly rated is paramount to your safety. In order to understand the arc rating you first need to understand what it is correlated to…

 

The incident energy value.

Incident energy is the amount of heat energy produced by the arc flash explosion. Typically, it’s measured in calories per square centimeter (cal/cm2).

So let’s say you are standing in front of 30 amp disconnect (600 volts) and an arc flash occurs.

You would bee exposed to a certain amount of heat energy.


Let’s just say we worked it out and it was 3.7 cal/cm2.EEEE

As long as your arc flash gear had a arc rating higher than 3.7 cal/cm2 then you will be protected from the arc flash.

But how do you determine the arc rating?


Keep reading to find out

When is Arc Flash PPE Required?

Trying to figure out when arc flash ppe should be worn is not as straight forward as you might think. But I’ve got a nice way you can approach it. There a 4 steps to a basic risk assessment:

 

  1. Identify the hazards

  2. Estimate the severity

  3. Estimate the likelihood of occurrence

  4. Determine your mitigation technique

Step 3 is by far the most important step!

 

Here’s why.

Step 1 and 2 almost always have the same answers for any electrical work. The hazards are arc flash and shock and the severity is high (or high enough that we don’t want it to happen to us without PPE). So really it boils down to estimating the likelihood of occurrence. Luckily in both CSAZ462 and NFPA70E they have a table that estimates the likelihood of occurrence for you. Simply go to that table, find the job you are doing, and if the likelihood is a “yes” then you’ll need to wear arc flash PPE.

 

Voila!

How to Select Your Arc Flash PPE

Once you’ve completed your arc flash risk assessment and you know the likelihood of occurrence is high enough to warrant ppe you’ll need to select something suitable for the hazard.

There are two methods you can use to select the proper ppe for the job.

 

  1. The incident energy analysis method

  2. The arc flash ppe category method

The first method is always preferred as it takes the guesswork out of it for the electrical worker.

But, in reality there is much more equipment out there that is not labelled so that’s why you will also need to understand the second method.

I’ll go through each one in detail so you can understand more about them and what you have to consider before making your choice.

The Incident Energy Analysis Method

The incident energy analysis method requires an arc flash study to be done on the equipment in order to determine the hazard levels.

Once you have the arc flash study completed you will have labels on each piece of equipment. On those arc flash labels will be all kinds of information required to perform the task safely but most importantly will be the incident energy.

 

Getting to this point will require time and resources but it will be well worth it! At this point, determining the ppe required is easy. Simply look at the arc flash label, find the incident energy and then make sure all of your arc flash gear is rated higher than the incident energy shown on the label.

 

That’s it!

Easy.