Arc Flash Layering Explained - Comfort and Compliance


Finding the proper work wear and foul weather gear will depend on the environment, work conditions/practices, and potential hazards you face. Rain, low visibility, and cold temperatures are just a few of the factors that need to be considered when selecting the proper FR work wear and outerwear. Equally important to staying warm and dry is remaining compliant to industry standards for safety. Layering garments is a great way to stay warm and dry, but, if not done properly, it can interfere with the necessary requirements for compliance to the industry and employer standards.  



This Guide offers several examples of layering garment combinations we have to offer.

As always, a hazard risk assessment needs to be performed in order to fully understand your specific hazard and the protection it requires.


Layering is the method of combining two or more arc-rated garments into a layered system in order to achieve a higher level of arc protection. Layering can provide increased performance and comfort. Layering garments can also increase the total arc thermal protective value, ATPV, ratings to levels greater than the sum of individual arc ratings. Lightweight layers often achieve higher levels of protection than traditional solutions. Layering also allows for quick adjustments based on the level of protection needed for different tasks. In arc flash, 2 + 2 doesn’t always equal 4. This is due to the fact that when layering FR garments you create a layer of air between each item, which tends to boost the overall protection. Layers have to be tested as a system for the accurate arc rating to be determined. If audited by OSHA you will need to provide verification so it’s a good idea to always request test reports to have on file.

The arc rating of PPE should exceed that of the hazard. For example, if the job requires an arc rating of more than 20 cal/cm2 (hazard risk category 1), and you can’t satisfy that with a single layer, you should consider using multiple garments to achieve the required protection. Keep in mind that system arc ratings only apply to the area where the garments overlap. For example, if you are layering a coverall over a shirt, the layered arc rating only applies to the area where the coverall covers the shirt. Bottom protection will also need to be taken into account. To clarify, take the above example. Together, the coverall and the long sleeve shirt have a combined rating of 24 cal/cm². However, the rating only applies where the shirt and coverall are together, basically just the torso and arms. For lower body protection you can add the matching FR Control 2.0 Long John.


Additionally, while not required, it’s advised to wear FR base layers under FR arc rated clothing. The best way to achieve the required arc rating with the lowest clothing system weight is to use of all arc-rated clothing layers.


NFPA 70E, Annex M states:

  • Non arc-rated layers add no protection but may be allowed. – Cotton t-shirts cannot be counted as adding protection–Non arc-rated clothing may be worn IF it is non-melting (i.e. cotton, wool, silk, leather). In real-life, cotton undergarments may add some protection but may also ignite, causing serious burns.
  • Layers of arc-rated garments may provide additional protection, only arc –rated systems can count.–Putting an 8 cal coverall over a 4 cal shirt doesn’t automatically give you a 12 cal system.
  • Arc-rated outer layer (such as a high visibility vest) over a protective system (i.e. an 8 cal/cm² ARC 2 shirt) does not reduce the rating of the under layer.–Non arc rated melting vests may not be worn over arc rated layers.




1) Layering for Warmth

When it’s cold, the body’s main focus is to maintain the core body temperature, this is where the majority of its energy is spent. Much like heat stress – cold stress occurs when someone loses the ability to regulate their body temperature. As skin temperature drops eventually the core body temperature will begin to drop. For example, to increase warmth and protection, add an arc-rated sweatshirt and an unlined bib over your clothing to increase warmth and provide protection from the elements, while also increasing protection against an arc flash even. Adding a work shirt over a base layer is also an option to increase arc flash protection while adapting to temperature changes on warmer or cooler days.

2) Layering for Moisture

Layering for the weather seems obvious. What’s not as obvious is building a moisture management system. The secret to comfort no matter what the temperature, is keeping you and your garment dry. Not just for rainy days, a system that helps you regulate moisture from the inside out will also keep you safe, comfortable, and compliant:

  • Base layers and outer layers that pull moisture from the skin and dry quickly help to regulate skin temperature
  • Breathable; allow moisture to escape keeping you dry and comfortable throughout the workday
  • Utilizing an FR arc rated base layer in your moisture management systems provide increased arc ratings

“Stay dry in the cold because moisture or dampness, e.g. from sweating, can increase the rate of heat loss from the body” - OSHA, Cold Stress Guide

3) Layering for Compliance

When it comes to meeting compliance standards, one size does not fit all. Proper fit is an important consideration in meeting compliance standards. Poor fit can lead to increased risk of injury or accidents:

  • Ill-fitting hard hats can slide or fall off
  • Oversized safety glasses leave gaps • Poor fit leaving areas of exposure
  • Oversized garments lead to tripping or catching on equipment

Keep your arc flash layering system in mind; you’ll want a base layer to fit snug for example so an outer layer will fit comfortably on top. While the level of compliance and protection does not differ from person to person there are some considerations and proper sizing is paramount. An ill-fitting garment can become a hazard instead of serving its intended purpose of protecting the wearer. It is recommended to try on multiple garments to get the best fit. Altering garments should not be considered as an option as doing so can reduce the efficacy and/or intended protection value of the garment, comprising wearer safety.

Layering for arc flash is an effective tool you can use to make sure you are comfortable no matter what the day brings. Knowing that you are protected and compliant means that you can focus on the task at hand and not be distracted by extreme conditions or physical discomfort.


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