When buying flame-resistant clothing, it’s important to know exactly how much protection each garment offers. FR clothing is categorized using an arc rating, or an Arc Thermal Protective Value (ATPV). This rating indicates how much heat will be transferred through the fabric in the event of an arc flash, and therefore, how much protection the clothing will offer the wearer.

Preventing heat transfer can significantly reduce the impact of a fire or arc flash and help to protect the wearer from the worst effects of the incident. The values used to determine arc ratings are expressed as calories per square centimeter. The higher the arc rating, the more protection the piece of clothing will provide. An arc rating of 4 is suitable for a task assessed as a Hazard/Risk Category 1 (HRC1), the lowest risk, while an arc rating of 40 or more will protect the wearer when carrying out tasks assessed as Hazard/Risk Category 4 (HRC4), the most severe risk.

Manufacturers are required to indicate the arc rating of their garments and most will list this crucial number on their labels. Wearing multiple layers of arc-rated clothing will increase protection against heat and flames. Three or more layers are often required to tackle the most hazardous tasks.

While all arc/APTV-rated clothing is flame resistant, it’s important to remember that not all flame-resistant clothing is arc rated. Some FR clothing is simply made with flame-resistant fibers and hasn’t been lab tested to ensure it meets set standards. Investing in products that have been thoroughly tested is the best way to ensure adequate protection against potential hazards.