When it comes to electrical safety, not all flame-resistant (FR) clothing is created equal. Workers exposed to arc flash hazards need garments that don’t just resist ignition but also provide tested, measurable protection. That’s where Arc Ratings and PPE Categories (CAT 1–4) come in.
At Novarlo, we help crews in utilities, construction, and heavy industry understand what these categories mean and how to choose the right gear for the job.
What Is an Arc Rating?
An arc rating is a measure of how much thermal protection a fabric provides against an arc flash. It’s expressed in calories per square centimeter (cal/cm²), which indicates how much incident energy the garment can withstand before the wearer risks second-degree burns.
The higher the number, the greater the protection. These ratings are determined through standardized testing defined by ASTM F1506 and NFPA 70E.
Understanding CAT Levels
NFPA 70E uses PPE Categories (CAT 1–4) to group FR clothing by arc rating ranges. Here’s the breakdown, with examples you can find at Novarlo:
· CAT 1: Minimum Protection (4–7 cal/cm²)
o Example: Lightweight Ariat FR Work Shirt & FR jeans
o Suitable for low-risk tasks like operating a breaker or working in a control room.
· CAT 2: Moderate Protection (8–24 cal/cm²)
o Example: DRIFIRE Shirt & DRIFIRE Pants
o Common for utility work, basic maintenance, and construction electrical tasks.
· CAT 3: High Protection (25–39 cal/cm²)
o Example: AirLite 25 Cal Arc Flash Shroud or Kit (CAT 3) - Enespro
o Needed in environments with higher arc flash potential, such as switchgear rooms.
· CAT 4: Maximum Protection (40+ cal/cm²)
o Example: Enespro AGP 40 Cal Arc Flash Kit With Lift Front Hoods
o Used for the most hazardous electrical work where incident energy levels are extreme.
Why OSHA’s guidance matters:
OSHA requires employers to perform a hazard or incident energy assessment to determine arc flash boundaries and appropriate PPE. This assessment is the foundation for selecting the correct CAT level. You can review OSHA’s resource here: Protecting Employees from Electric-Arc Flash Hazards (OSHA Publication 4472).
Choosing the Right Category
When selecting FR clothing:
- Start with your hazard assessment. OSHA requires employers to perform an arc flash risk analysis to determine expected incident energy.
- Match apparel to the hazard. For example, if your analysis shows 18 cal/cm², CAT 2 clothing is required at minimum.
- Don’t forget layering. Multiple garments can increase arc rating, but they must be tested and compliant as a system.
Why It Matters
Wearing the wrong gear can mean the difference between walking away from an arc flash or suffering catastrophic burns. CAT levels aren’t just numbers they’re lifesaving guidelines.
At Novarlo, we stock a full range of FR apparel from Ariat, Drifire, and other trusted brands, covering everything from CAT 1 work shirts to CAT 4 arc flash suits. With inventory on hand and same-day shipping, we make it easy to get compliant, protective gear in the hands of your crew fast.
Stay Protected
Choosing the right FR apparel is about more than compliance it’s about ensuring every worker goes home safe. By understanding CAT 1–4, you can confidently equip your team with protection matched to the hazards they face.