Arc-Rated vs. Flame-Resistant Clothing: What Is the Difference?

The terms flame resistant and arc rated are often used together, but they do not mean the same thing.

Flame-resistant clothing is designed to reduce burn injury by limiting flame spread and stopping continued burning after the ignition source is removed. It is not fireproof: sufficiently intense exposure can still ignite, damage, or break open the material.

Arc-rated clothing is flame-resistant clothing that has undergone additional testing to measure its performance against the thermal energy of an electrical arc flash.

The simplest way to remember the difference is:

All arc-rated clothing is flame resistant, but not all flame-resistant clothing is arc rated.

That distinction matters whenever employees work on or near energized electrical equipment. A shirt may provide suitable protection for an identified flame hazard yet still be unsuitable for arc-flash exposure if it has no tested arc rating.

What Flame-Resistant Clothing Is Designed to Do

The main purpose of flame-resistant clothing is to reduce the severity of burn injuries caused by clothing ignition and continued burning.

Unlike ordinary workwear, properly designed FR clothing limits flame spread and self-extinguishes after the ignition source is removed. It can still ignite, char, shrink, or suffer other damage during a severe exposure, so FR should never be understood to mean fireproof.

FR clothing is used in oil and gas operations, utilities, chemical processing, industrial maintenance, and some welding or hot-work applications. For welding and similar work, the garment must be selected for the actual exposure to sparks, hot slag, radiant heat, and molten metal; an FR label alone does not prove that it is suitable.

The presence of an FR label also does not show how the garment will perform during an electrical arc event. That requires an arc rating.

What Makes Clothing Arc Rated

Arc-rated clothing has been tested specifically for exposure to electrical arc energy. The result is expressed in calories per square centimeter, written as cal/cm².

For example, a shirt labeled with an arc rating of 8.2 cal/cm² has been evaluated through standardized arc testing and assigned that protective value. An FR shirt without a cal/cm² rating may still resist flame, but it has not demonstrated the same level of arc-flash performance.

This is why purchasing decisions should be based on the actual label and test information—not simply on product names such as “FR work shirt” or “electrical safety clothing.”

Arc-Rated vs. Flame-Resistant Clothing: Key Differences

The practical differences come down to the hazard and the testing behind the garment:

| Feature | Flame-Resistant Clothing | Arc-Rated Clothing | | ----- | ----- | ----- | | Resists ignition and continued burning | Yes | Yes | | Tested for electrical arc exposure | Not necessarily | Yes | | Carries an arc rating in cal/cm² | Not necessarily | Yes | | Suitable for arc-flash work | Only if also arc rated | When properly matched to the hazard | | Common applications | Flash-fire and other identified industrial flame or heat hazards; certain welding or hot-work tasks when the garment is designed for those exposures | Electrical work with an identified arc-flash exposure |

The difference is not simply fabric weight or thickness. An ordinary heavy shirt does not become arc rated because it feels substantial, and an FR garment does not become arc rated because it looks similar to electrical PPE.

How Arc-Flash Testing Is Different

General flame-resistance testing evaluates characteristics such as ignition, flame spread, afterflame, and material damage.

Arc testing exposes the material or clothing system to controlled electrical arc energy. The test examines how much thermal energy passes through the material and whether the fabric breaks open during exposure.

That testing produces the arc rating used on the garment label. It allows safety professionals to compare the clothing’s tested performance with the expected incident energy for a particular task.

What an Arc Rating in cal/cm² Means

An arc rating represents the material’s tested resistance to the thermal effects of an electrical arc. It is not a guarantee that burns cannot occur, nor is it a universal safety score for every electrical task.

The rating must be compared with the incident energy identified by the employer’s arc-flash risk assessment. If the expected exposure is higher than the garment’s arc rating, that garment alone does not provide an adequate protective system.

A higher number also does not automatically make a garment the best choice for every job. Protection must be sufficient for the hazard, but excessive clothing weight or unnecessary layers may restrict movement and add heat stress.

Understanding ATPV and EBT Values

An arc rating may be reported as ATPV or EBT.

ATPV, or Arc Thermal Performance Value, relates to the amount of incident energy at which there is a 50% probability of enough heat transfer to predict the onset of a second-degree burn.

EBT, or Energy Breakopen Threshold, relates to the energy at which there is a 50% probability that the material will break open.

One value is not automatically better than the other. They describe different responses observed during testing. For garment selection, the important figure is the final arc rating shown on the label.

How to Select Arc-Flash PPE Clothing for the Hazard

Choosing arc-rated clothing should begin with the work being performed, not with a preferred shirt or fabric.

Start with the Arc-Flash Risk Assessment

Before selecting clothing, confirm whether the task exposes the worker to an arc-flash hazard. The assessment should consider the equipment involved, the task being performed, equipment condition, available fault current, fault-clearing time, and working distance.

Its purpose is not simply to decide whether protective clothing is needed. It should also provide the information used to select an appropriate PPE system, such as the expected incident energy or the applicable PPE category. Without that information, an arc rating cannot be matched reliably to the task.

Do not select arc-flash clothing based only on system voltage. Equipment operating at the same voltage can produce very different incident-energy exposures because of differences in fault current, protective-device clearing time, configuration, and working distance.

Match the Arc Rating to the Expected Incident Energy

When the incident-energy method is used, the clothing system’s arc rating must be at least equal to the expected incident energy at the working distance.

Do not estimate this requirement from appearance, occupation, or a coworker’s clothing. Use the documented assessment and follow the employer’s PPE program.

Arc-flash PPE categories provide another selection method under applicable safety procedures, but category numbers and cal/cm² ratings should not be treated as interchangeable shortcuts. The next article in this series will examine CAT 1 and CAT 2 in more detail.

Consider the Entire Arc-Flash PPE System

An arc-rated shirt protects only the areas it properly covers. Depending on the hazard, the complete system may also include arc-rated pants or coveralls, a face shield or hood, head protection, hearing protection, gloves, and suitable footwear.

Every layer can affect performance. Sleeves should not be rolled up, shirts should be fastened and worn as intended, and outer garments should not introduce a melting or ignition hazard.

Where Arc-Flash Shirts Fit Into a PPE System

Daily-Wear Arc-Rated Shirts

For workers who regularly enter environments with identified electrical hazards, daily-wear arc-rated FR shirts can provide a practical foundation for the required clothing system.

For example, a CAT 2 work shirt carrying an 8.2 cal/cm² arc rating may be appropriate where that rating satisfies the employer’s hazard assessment. The number on the label—not the CAT 2 description by itself—should be checked against the required protection.

Comfort still matters because PPE must be worn correctly throughout the task. Fabric weight, airflow, fit, range of motion, and moisture management can influence whether a shirt remains comfortable during a long shift. These considerations are especially important when choosing lightweight FR shirts for warm conditions.

When Additional Arc-Flash Protection May Be Required

A daily-wear shirt and pants may not be enough for every exposure. Higher incident energy, closer working distance, or different equipment conditions may require additional layers or a complete arc-flash suit.

Layering must be evaluated as a system. Adding two garment ratings together does not necessarily produce the tested rating of the combination. Use a documented system rating whenever layered garments are intended to provide combined protection.

How to Verify Arc-Rated Clothing Before Buying

Check the Garment Label and Arc Rating

The label should clearly identify the arc rating in cal/cm². Depending on the garment and applicable requirements, it may also show the manufacturer, model, size, relevant standards, tracking information, and care instructions.

Be cautious with vague claims such as “FR treated,” “electrical workwear,” or “NFPA approved.” NFPA develops safety standards but does not approve individual garments.

Review the Applicable Testing Standards

ASTM F1959/F1959M is used to determine the arc rating of materials for clothing, while ASTM F1506 addresses performance requirements for flame-resistant and arc-rated textile materials worn by electrical workers.

A standard printed in a product description should match the garment label and supporting test information. If the arc rating cannot be confirmed, do not assume the garment is suitable for arc-flash work.

Confirm Layering, Fit, and Coverage Requirements

The garment must fit well enough to cover the body during normal movement without creating unnecessary restriction. Check sleeve length, shirt-tail coverage, closures, and compatibility with the rest of the PPE.

Care instructions matter as well. Contamination, improper laundering, unauthorized repairs, severe wear, or damaged closures may affect protection. Clothing should be inspected before use and removed from service when its condition no longer meets the employer’s requirements.

Conclusion

FR and AR describe related but different levels of protection.

FR clothing is designed to resist ignition and continued burning. Arc-rated clothing is FR clothing that has also been tested against electrical arc energy and assigned an arc rating in cal/cm².

For arc-flash work, an FR label by itself is not enough. Start with the hazard assessment, verify the garment’s arc rating, and make sure the entire PPE system matches the task.

FAQ

Can Flame-Resistant Clothing Be Worn for Arc-Flash Work?

Only when the garment is also arc rated and its rating is sufficient for the identified exposure. FR clothing without an arc rating has not been tested for electrical arc exposure.

Does a Higher cal/cm² Rating Always Mean Better Protection?

A higher rating indicates protection against a greater tested level of arc energy, but it is not automatically the best choice for every task. Clothing should meet the required rating while allowing appropriate movement, comfort, and correct use.

Can Arc-Rated Clothing Lose Its Protective Performance Over Time?

It can become unsuitable because of damage, contamination, improper care, excessive wear, or unauthorized alterations. Follow the manufacturer’s instructions and the employer’s inspection and replacement procedures.

Can Non-FR Garments Be Worn Underneath Arc-Rated PPE?

Meltable synthetic garments can create additional injury hazards during an arc event. Any underlayer should comply with the employer’s PPE requirements and applicable safety rules. Do not assume the outer AR layer makes every garment underneath it acceptable.

Is Arc-Rated Clothing Required for Every Electrical Task?

No. The requirement depends on the task and the identified electrical hazards. The employer’s risk assessment and electrical safety program should determine when arc-rated clothing and other PPE are necessary.