What Arc Flash PPE is Required if There's No Label

What arc flash PPE is required, if there’s no label? This is a great question!

But first let’s answer some of the questions you may have answered to get here.

 

THE ULTIMATE GUIDE TO IMPROVE ELECTRICAL SAFETY IN YOUR WORKPLACE [ACCESS NOW]

 

Do I Need Arc Flash PPE if I Turn off the Power?

Arc flash personal protective equipment (PPE) is critical to your safety when working on three phase industrial electrical equipment.

Remember, equipment is considered live until proven dead. So even if you’re turning off the power upstream to work on your equipment, lock it out and test before touch! This means wearing ‘good enough’ PPE for the task at hand, even if it’s just until you test zero volts.

For arc flash hazards that means covering any exposed skin with PPE rated to the arc thermal protective value equal to the worst case incident energy possible during a fault on your equipment.

Back to the main question: What arc flash PPE is required, if there’s no label?

Also read our previous blog How to label an electrical panel?

Who’s Responsible for Providing Arc Flash Hazard Information?

It is the reponsibilty of the employer to provide the hazard information to anyone required to work on the site’s equipment.

The main method of determining the hazard is through an arc flash hazard study.

This is when your site’s electrical system is modelled and the short circuit and arc flash hazard is calculated at every piece of equipment that may be worked on live.

Back to the main question: What arc flash PPE is required, if there’s no label?

Is There Any Other Way to Know My PPE Is ‘Good Enough’?

The standard for guidance on electrical safety in the workplace is CSA Z462 in Canada and NFPA 70E in the United States.

Both of these standards recommend an arc flash hazard study based on IEEE 1584-2018. This is a calculation method based on arcing tests measuring how much thermal energy is released in a short time during an arc flash.

Both standards also have an alternative method using tables, but still require knowing the short circuit current and the how quickly your breakers and fuses will trip.

Both fairly difficult to determine without practice.

Back to the main question: What arc flash PPE is required, if there’s no label?

Can You Figure Out the Hazard Using Information From Similar or Nearby Equipment That Have Labels?

The short answer is no.

The information in other labels on your site certainly have a method to them, but trying to interpret how or why one piece of equipment is high or low versus another is difficult.

You can’t necessarily check the upstream equipment and assume the hazard is equal or lower.

You can’t necessarily check an identical piece of equipment.

These arguments may have some truth to them but the actual hazard could easily be higher.

Back to the main question: What arc flash PPE is required, if there’s no arc flash labels?

Now with all that, let's answer the main question.

What Arc Flash PPE Is Required, if There’s No Label?

In 2021, CSA Z462 released a new edition and added a new Table V.1 to that’s very easy and safe to use for determining arc flash PPE.

It’s in Annex V, starting page 202, and is called Table V.1: Arc-flash PPE categories for alternating current (ac) systems.

It is based on the most up to date methodology for calculating arc flash, using IEEE 1584-2018 equations.

By assuming the worst case for the more difficult and less impactful parts of the calculations, it is able to reduce the complexity and time required if you need to know your hazard quickly.

How Do I Use Table v.1 to Determine Arc Flash PPE?

Here’s a clip of the 208 V section, with the inputs and outputs highlighted.

Columns 1-3 show the inputs, in which you select these properties:

• Equipment type and rated amperage;
• Voltage of the equipment;
• Upstream device type and size.

The first two are straightfoward, and just help you pick which part of the table to use.

The biggest step is detemining what the upstream device type and size is.

This is the most important selection because the size of the upstream device helps determine the upper limit of available energy over a range of trip times and fault current. This detemines the max thermal energy that could be released within the first two seconds of an arc flash.

The device can be either a transformer, fuse, or circuit breaker at the same voltage and in a separate upstream compartment from where you are working.

For example, if the equipment you’re about to work on is 208V, is rated for less than 800A, and has a disconnect upstream with a 200A fuse, the following selections may be used (check Table V.1 – Notes p.207)

Columns 4 & 5 show the outputs:

• arc flash PPE category = PPE Category 2 (4-8 cal/cm2)
• arc flash boundary = 2.0 m (6 ft 7 in)

The result is that if you use arc flash PPE at category 2 it will be good enough.

This is easy, fast and awesome.

How Does Table v.1 Compare to an Arc Flash Hazard Study?

To make the table easy and fast to use, it had to be very conservative and always chooses the worst possible case fuse, breaker, or transformer impedance given the specified sizing.

Say you have a 75KVA transformer feeding a 208V cabinet on your site floor.

Let’s select that in Table V.1 below:

You now have a situation where your arc flash PPE category 4 (25-40 cal/cm2). This means wearing a lot of PPE to work on that cabinet until you test for dead.

In reality, the cabinet could easily be PPE category 2 (4-8 cal/cm2), but only if you look in more detail at the fault current and specific protective device.

To show a quick comparison between the Table V.1 method and an arc flash study, look at this SLD and see the differences in hazard resolution.

My takeaway from comparing these the results is that the arc flash study results are much lower than Table V.1.

Let’s call this the hazard resolution.

Both answers may be safe enough, but it may cost more time and require more data to get better hazard resolution.

What Are the Trade-Offs of an Arc Flash Hazard Study Versus Table v.1?

The big difference is in hazard resolution.

Both methods are accurate, the reality of the worst case hazard is captured in both.

A good way to think of this is resolution, like a video or camera picture.

Both show the same reality but with more or less detail.

Here is a table that shows some other trade-offs:

The table allows you to quickly start to see the picture, and then the study allows you to work at the parts that need more detail.

Can I Use Both the Table v.1 Method and an Arc Flash Hazard Study?

Using the Table V.1 method for your entire site might work if you want answers fast, but will probably cause more problems overall.

The results will be very conservative, and with your most hazardous equipment, maybe even ‘off the charts’.

However, Table V.1 could be great for your floor equipment or anything that is newly added or changed in the day to day running of the site. The table allows you to quickly start to see the hazard picture, and then the study allows you to start seeing a clearer picture of the real hazards.

Every site will have equipment that ends up Category 2 or lower and depending on your electrical safety program, you might wear the same PPE for any task at that level.

Here is a graphic to help remember one of the most useful distinctions the table makes for Category 2 Arc Flash PPE (≤8 cal/cm).

Just remember that the THEN is Arc Flash PPE Category 2 that is ≤8 cal/cm2 at 18 inches working distance, and with an arc flash boundary of 2m (6’7”).

There are also more explanations and details in the standard itself on page 207.

Find your site a copy of CSA Z462-2021 at www.csagroup.org

So, whether you are looking to wear arc flash PPE that is ‘good enough’ for today, or you are tackling your entire site and want to get into the details:

Table V.1 is a great tool to add to your safety toolkit.

Conclusion

I hope this article has helped to better explain what arc flash PPE is required for your site.

The safest thing you can do is get an Arc Flash Study.

An up-to-date label from a completed study is the best way to protect your team, saving time and eliminating all guesswork.

Learn more about our Arc Flash Studies and how they fit into our comprehensive electrical safety services.

Do you know anyone else that would benefit from this blog? Use the share buttons below to share the content.

Feel free to reach out with any questions to me jon.dobbelsteyn@leafelectricalsafety.com.

• Category:
• Arc Flash Study
• PPE
• Arc Flash PPE