High demands are placed on arc flash clothing in terms of the materials used for heat insulation and its reaction to contact with flames.

And that’s a good thing too because the reaction to an electric arc is unpredictable. This type of clothing falls under Category III: risks with fatal or irreversible effects.

As you might expect, protective clothing must comply with the relevant standard.

So, what should you pay attention to?

We provide you with five tips so that you can confidently assemble an arc flash clothing package that is safe for your staff.

For clarity’s sake: the electric arc standard IEC 61482

Protective clothing safeguarded against the thermal risks of an electric arc must comply with EN IEC 61482.

The standard describes two methods used to measure the electric arc resistance of an article of clothing.

• Box Test
• Open Arc Test

Box Test

During the Box Test, a piece of clothing fabric is exposed to an electric arc with a force of 4kA or 7kA. The penetrating heat must not cause second-degree burns.

The test is then repeated on an article of clothing. The article of clothing must remain functional. The seams must not burst open, the zippers must still work, and so on.

If both test results are positive, the article of clothing will be rated as Class 1 (4kA) or Class 2 (7kA).

Open Arc Test

In the Open Arc Test, the article of clothing is exposed to a known amount of energy (heat) and the energy that passes through the material is tested.

The value found is known as the ATPV value, which is a measure of the calories per square centimetre. This is the energy value (heat) where the risk of second degree burns when exposed to an electric arc is 50%. The higher this value, the higher the incident energy and thus the higher the level of the protection.

So, now that we’ve covered this part of the standard, let’s get to the tips to help you choose the most suitable electric arc clothing.

Tip 1: Work in layers

When choosing protective arc flash clothing, it makes sense to assess all of its layers. On the one hand, it is critical that electric arc clothing contains no materials made of fibres that can melt under your electric arc be worn. On the other hand, each layer must contribute to your total protection.

Deciding to choose separate layers with known protection allows you to have a lighter outer layer that is more comfortable. So, choose base and intermediate layers that are also electric arc resistant. For example, shirts, polo shirts, and even underwear.

The extreme heat of an electric arc can even melt underlying work clothing (polyester, polypropylene, etc.). Clearly, it is critical that articles of clothing do not melt. Melting clothing will burn into the skin and the wearer can experience extremely serious burns.

Combining different protective layers provides you with optimal protection and maximum comfort.

The ATPV values of the different layers are cumulative. In practice, the protection value will be higher than the sum of the individual values.

This is due to the layers of air between the different articles of clothing. Air provides insulation, which provides additional thermal protection.

For example:

This Sioen polo shirt (7.4 cal/cm²) combined with an electric arc vest (15.2 cal/cm²) exceeds the cumulative ATPV of 22.6 cal/cm². A test of the complete combination attained an ATPV value of 44.8 cal/cm².

That’s almost double!

The manufacturer can have a layer combination tested by an independent testing agency.

You can also supplement your electric arc clothing with accessories, such as hoods, neck protectors, and even ear flaps.

Tip 2: Treated or inherently flame retardant?

Knowing that an electric arc can expose you to temperatures of up to 20,000°C makes it critical that you know what clothing you should buy.

There are two types of arc clothing: treated flame retardant and inherently flame retardant.

Treated materials are made from fibres that are not naturally flame retardant. These materials are treated with chemicals during the production process so that these acquire fire-resistant properties. The best-known brand names are Proban and Pyrovatex.

If properly maintained, this clothing will also last longer. Washing these incorrectly can breakdown the finish, which removes the protective properties.

Inherently flame-retardant fibres, such as Modacryl or Nomex (Dupont), are naturally flame retardant and do not have a special finish.

These retain their flame-retardant properties even after long and intensive use.

Wear and tear

With low wear and tear, it's okay to buy inherently fire-resistant clothing. They will last longer.

It may be more expensive to purchase at first, but it pays off in the long run. For instance, clothing with a low rate of wear and tear is perfect for workers.

But it’s different with clothing that has a high rate of wear and tear. Here, the pieces often wear out faster than the fire-resistant finish is washed out of the fabric.

Welders or grinders are good examples of professions where the clothing has a high rate of wear and tear.

Price

Each raw material has its pros and cons. Choosing between treated and inherent material makes a considerable difference in price as well.

Prices are always higher for inherent materials with a long service life. Lower-priced, treated raw materials do not last as long.

Tip 3: Flame retardant ≠ electric arc protection

You might imagine that electric arc protective clothing provides as much protection as any type of flame retardant clothing, right? No! It’s doesn’t.

The level of protection provided by electric arc clothing is higher. It is intended to protect against fire as well as a massive amount of thermal energy.

The term flame retardant refers specifically to the self-extinguishing nature of a material. Electric arc protection requires a high level of insulation against the extreme heat emitted by the electric arc.

Tip 4: Single or double layers

Some electric arc clothing has two layers at the front and one layer at the back.

Obviously, the higher mass of a double-layer fabric provides better protection than a single layer.

The back is often only a single layer because there is less of a risk of an electric arc burn at the back. Of course, the extra comfort is also a plus.

The manufacturer must indicate the test results (from the Box or Open Arc test) for both the single and double layers.

Tip 5: Mind the details

The requirements for each type of electric arc clothing are also clearly stated in the standard. The manufacturer will take the necessary steps to ensure the article of clothing is electric arc proof.

When buying accessories, keep the following points in mind:

Metal parts must not be visible on the outside. Do not add metal accessories to your outfit, such as a belt buckle.

Considering having your logo printed on your t-shirt, vest, or jacket? Then make sure you ask your printing service to provide flame-retardant logos.

All sewing threads must be inherently flame retardant and must not melt except for non-essential stitching. Keep this in mind if you are considering repairing your protective clothing yourself.