How Do I Determine a Safe Layered Arc Rating?

If you’re a frequent wearer of AR / FR clothing, you are familiar with what a garment’s arc rating means. If you’ve wondered how you can simply and easily increase your protection, the answer is layering. Layering is a powerful tool to achieve the protection you need with the comfort you want.

There are three key elements to understand about layering AR garments:

1) Each layer MUST be arc rated to count toward the system arc rating.

It is important to note that a non-FR base layer does not count as a layering option, and could lead to additional risk because the material is flammable. The good news is that AR base layers which count toward layered arc ratings are now available. These garments are rapidly growing in popularity and are as light (or lighter) than your typical non-FR tee shirts. If you do not have any AR base layers in your wardrobe, we recommend adding a few.

2) You cannot simply add two FR garment ratings to get a layered rating.

Although it might seem logical, you cannot add garments’ arc ratings together to determine the combined protection. To get an accurate layered rating you MUST have the test data, and that data must be the same fabrics in the same layered configuration. It’s not only required by standards, it’s also to your advantage, because layered arc ratings are almost always higher, and often much higher than the sum of their parts. The test configuration must be the same as well; if fabric A is the inside layer and fabric B is the outside layer, the test data is valid ONLY for that configuration. Layering fabric B as the inside layer and fabric A as the outside layer can’t be assumed to have the same layered arc rating. The layers must be tested in the configuration they are to be worn.

3) Layered arc ratings are almost always greater than the sum of their parts.

This is due to air gaps between the layers of your AR garments. Air is an excellent insulator and can add calories to your arc rating. In fact, the actual combined rating is almost always considerably higher than adding the two would suggest.

For more assistance with these let Tyndale’s Vice President of Technical, Scott Margolin walk through these important guides for acquiring a safe layered arc rating.

Layering is not only a great way to protect, it’s also more versatile and more comfortable than separate, specialty garments for higher incident energies. Remember, to take advantage of the many benefits of layering, you need to have the test data. Luckily, Tyndale has one of the largest collections of layered arc flash testing data in the industry. Even better news – we’ve put it into the palm of your hand with our mobile app with layering tool!

The tool is simple to use and features the widest variety of garments and brands in the industry. With worker safety in mind we created this tool allowing you to quickly and accurately find the correct layered arc rating, ensuring you are protected and compliant even when you’re out in the field.

Tyndale’s mobile layering tool is available within our mobile app – Tyndale FRC – on your tablet or smart phone, or through your online Tyndale account. The app works in two easy ways:

  • Items you already own: the app looks at your purchases over the last five years to find combinations of clothing you already own that can be layered together to meet a desired level of protection. No purchase necessary!
  • New items: Shopping for new FR clothing? The app identifies items from your catalog that can be layered with items you already own to provide the level of arc flash protection you need.

Have a question? Need assistance? You can reach us at 800-356-3433, or contact us using the online web chat feature. We’re available from 8am to 7pm EST Monday through Friday.

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