Arc flash hazards are one of the most dangerous threats in electrical work environments. Wearing the right arc-rated apparel isn’t just a recommendation—it’s a regulatory requirement that could save your life. At Novarlo, we’re committed to helping you stay safe and compliant by making it easier to understand your options. A common question we get is:
“What cal rating do I need for arc flash apparel?”
Let’s break it down in detail,what arc flash protection is, how the cal rating works, and how to choose the right level of protection for your job.
What is arc flash?
An arc flash is a sudden, explosive release of electrical energy through the air due to a fault between energized conductors. It can generate:
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Temperatures exceeding 35,000°F (19,400°C)
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A shockwave strong enough to knock workers off their feet
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Shrapnel and molten metal injuries
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Fatal or life-altering burns
Because standard clothing can ignite or melt in these conditions, proper arc-rated clothing is essential.
Why arc flash apparel matters
Arc-rated clothing is designed to resist ignition, insulate against thermal energy, and minimize injuries during an arc flash event. It forms part of a broader Personal Protective Equipment (PPE) system that may include:
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Flame-resistant (FR) shirts, pants, and coveralls
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Arc-rated suits, balaclavas, and face shields
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Voltage-rated gloves and rubber insulating gear
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Safety-rated footwear and hearing protection
But knowing you need PPE isn’t enough—you need to understand how much protection is required, which is where the cal rating comes into play.
What is a cal rating?
The cal rating, or calories per square centimeter (cal/cm²), measures how much heat the protective clothing can withstand before the wearer would likely receive a second-degree burn.
In simple terms: Higher cal = more protection.
For example:
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A shirt rated at 8 cal/cm² can protect against a moderate arc flash.
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A full suit rated at 40 cal/cm² is designed for extreme arc flash exposures.
This rating is determined through standardized testing (ASTM F1959) and is required labeling for arc-rated apparel.
Arc flash PPE categories and NFPA 70E
The NFPA 70E standard categorizes arc flash risk levels into four PPE categories, each with a minimum cal rating:
|
PPE category |
Minimum rating |
Examples of tasks |
|
Category 1 |
4 cal/cm² |
Operating breakers ≤240V, maintenance of small panels |
|
Category 2 |
8 cal/cm² |
Work on energized components ≤600V |
|
Category 3 |
25 cal/cm² |
Work on switchgear, circuit breaker panels (600V) |
|
Category 4 |
40 cal/cm² |
High-capacity systems, arc energy above 25 cal/cm² |
How to determine what cal rating you need
Here’s how to determine the appropriate arc-rated clothing:
1. Start with a risk assessment
A qualified person should perform an incident energy analysis to determine the arc flash energy level at each point in your electrical system.
2. Check equipment labels
Most modern electrical panels will be labeled with incident energy levels or PPE categories. This tells you exactly what cal rating is required for that task.
3. Use NFPA 70E tables when applicable
If no arc flash study has been done, refer to the task-based tables in NFPA 70E to determine the PPE Category and minimum cal/cm² rating required.
4. Consider layering
You can achieve higher protection ratings by layering arc-rated garments (e.g., an 8 cal/cm² shirt over a 12 cal/cm² jacket doesn’t necessarily equal 20 cal/cm²—layer testing must confirm the final rating).
Common Cal ratings and typical use cases
|
Cal Rating |
Protection Level |
Use Case |
Products |
|
4 cal/cm² |
Low exposure |
Small panel work (240V), control circuits |
|
|
8 cal/cm² |
Moderate exposure |
Panels ≤600V, disconnect switches |
|
|
25 cal/cm² |
High exposure |
MCCs, switchgear, transformers |
|
|
40+ cal/cm² |
Very high exposure |
High-energy switchgear, arc flash suits |
Comfort vs. protection: can you have both?
Yes, and that’s where modern materials and design come in. Today’s arc flash apparel is significantly more comfortable, lighter, and breathable without sacrificing protection. Moisture-wicking FR fabrics, ergonomic designs, and better fit mean you don’t have to choose between safety and comfort.
At Novarlo, we stock a carefully selected range of arc-rated gear designed to meet the demands of real-world jobs while keeping you cool, mobile, and fully protected.
Make safety a standard, not a guess
Wearing the right arc flash apparel is not just about checking off a box—it’s about preventing catastrophic injury. The cal rating you need depends on your task, environment, and equipment condition.
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If your equipment has an arc flash label: Follow it.
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When uncertain: Choose higher cal-rated apparel for added peace of mind.
Whatever your needs, don’t guess, assess.
Explore our full line of Arc Flash Kits to find complete solutions from 8 to 100 cal/cm², including suits, face shields, balaclavas, gloves, and more—all compliant with the latest NFPA 70E and ASTM standards.